Department of Local Infrastructure Development and Agricultural Roads(DoLIDAR)

Recharge Ponds

Handbook

For WASH Programme

Ministry of Federal Affairs and Local Development

i

Department of Local Infrastructure Development and Agricultural Roads(DoLIDAR)

Kathmandu, 2013

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HandbookHandbookHandbookHandbookHandbookFor WASH ProgrammeFor WASH ProgrammeFor WASH ProgrammeFor WASH ProgrammeFor WASH Programme

Ministry of Federal Affairs and Local Development

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Copyright © Department of Local Infrastructure Development and AgriculturalRoads DoLIDAR, 2013

About DoLIDAR, RWSSP-WN and NWCF

DoLIDAR: The Department of Local Infrastructure Development and AgriculturalRoads (DoLIDAR) under the Ministry of Federal Affairs and Local Development(MoFALD) undertakes infrastructure development programmes in accordance withdecentralization policies for attaining the goals set forth by the Government ofNepal’s National Strategy for Rural Infrastructure Development. MoFALD/DoLIDAR isresponsible for water supply schemes serving less than 1,000 beneficiariesthrough its decentralized structure. The schemes are implemented and managed bycommunities. MoFALD through the District Development Committees (DDCs) andVillage Development Committees (VDCs) is responsible for district and VDC levelWASH coordination.

RWSSP-WN: Rural Water Supply and Sanitation Project in Western Nepal (RWSSP-WN) is a sector support programme under Ministry of Federal Affairs and LocalDevelopment (MoFALD) for rural water, sanitation and hygiene (WASH) in Nepal. Theproject period is 5 years from August 2008 to July 2013 (including one year no-costextension). The second phase of RWSSP-WN is planned to start immediately afterthe first phase. RWSSP-WN is funded by the Governments of Nepal and Finland. Inaddition, the District Development Committees, Village Development Committeesand the users contribute to their respective WASH programme. RWSSP-WNoperates in nine districts: Myagdi, Parbat, Baglung, Syangja, Tanahun, Nawalparasi,Kapilbastu, Rupandehi and Pyuthan.

NWCF: Established in 1989 and re-organized in 1997, Nepal water ConservationFoundation (NWCF) is a non-governmental, non-political and not for profitorganization conducting interdisciplinary research on interrelated issues that affectthe use of management of water with specific focus on the Himalayan-Gangaregion. The foundation was reincorporated (registered) with the districtAdministration office Kathmandu in 2000 meeting the governmental requirements.

Since its establishment, the foundation has dedicated its focus to generate anddisseminate knowledge on water management through research, publications,training and engagement in public dialogues. It has also sought to addressemerging challenges and ever changing educational needs of water management.NWCF works with local community as well as with organizations at local, national,regional and international levels. At the local level, NWCF helps strengtheninstitutional capacity of community and civil society groups for informed participationin decision making process.

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The Government of NepalMinistry of Federal Affairs and Local Development

Department of Local Infrastructure Development and AgriculturalRoads (DoLIDAR)

PrefaceIt is my great pleasure to introduce the “Recharge Ponds Handbook for WASHProgramme,” that aims to implement groundwater recharge ponds and to managedepleting water resources in the districts covered by the Rural Water Supply andSanitation Project in Western Nepal (RWSSP-WN). This handbook will be used as aguiding document in all the 75 districts of Nepal, instead of being confined in the areascovered by RWSSP-WN program at present. Essentially, I believe the dedicatedprofessionals, who are working hard in securing and supplying fresh water for people,such as the respective district engineers, sub-engineers, technicians, social mobilizersand facilitators representing at the district, VDC and community levels, will find thishandbook substantially helpful. I am thankful to the resources and contributors whofacilitated and delivered this valuable guide for the welfare of the people particularly livingin the rural areas of the country.

By 2017, through three focused priority areas, the Government of Nepal remainscommitted to the sustainable use of water resources and to improve supply of drinkingwater. These include (1) “reaching to the unreached,” (2) “improving functionality andsustainability,” and (3) “improving the water quality.” However, challenges such asdepleting water resources impede our progress; and the fear that adverse impacts ofclimate change will make the situation worse. In this context, the “Recharge PondsHandbook for WASH Programme” sheds the hope and light we desperately needed.I trust this handbook provides impeccable features on planning, constructing andmanaging dug out ponds that facilitate groundwater recharge. In addition, the handbookis a practical guideline for recharge pond implementation, and supports the WASHstakeholders in managing depleting water sources in the Middle Hills, Mahabharat,Siwaliks, Bhabar and Terai region.

Moreover, the “Recharge Ponds Handbook for WASH Programme” includes the ‘generalcontext’ and ‘introduction’ on ‘recharge pond concept,’ which cover topics such as thephysiographic regions, hydrological context, different pond types and their specificadvantages, tips on practical implementation, and steps for planning and construction.Finally, this handbook is in line with Government of Nepal’s existing policies, guidelines, anddevelopment priorities; and, it can be used as a supporting document to the water resourcemanagement and sustaining water supply in the context of climate change in Nepal.

Bhupendra Bahadur Basnet Director General

Department of Local Infrastructure Development and Agricultural Roads (DoLIDAR)

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Acknowledgements

This document was prepared by an expert team composed of SushmaAcharya, Binod Sharma, Nirendra Basnet, Dipak Gyawali, and AnilPokhrel. We would like to thank them all. We acknowledge theconceptual guidance provided by Madhukar Upadhya. Thanks are alsodue to Mayanath Bhattarai and Govinda Sharma for providing logisticalsupport to the expert team as the tasks of preparing the documentprogressed. We duly acknowledge the support provided by SurendraPradhan in making the sketches. Overall guidance for the work wasprovided by Jari Laukka of RWSSP-WN. His support is highlyappreciated. Pilot works of making ponds in Myagdi, Nawalparasi andKapilvastu would not have been possible without the support of BishnuPrasad Sharma (LDO Myagdi), Guneshwar Mahato and others includingChandra Bista, Gambhirman Gurung, Suman Shrestha, Shashi BhusanThakur, Ramji Adhikari and other members of DDCs of the pilot districtsand RWSSP-WN. All of them deserve thanks.

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About this Handbook

This is a practical guideline for planning, construction and management ofdug out ponds, with focus on recharging groundwater aquifer in water scarceareas. The purpose of this Handbook is to help the WASH (Water, Sanitationand Hygiene) stakeholders in understanding concepts to manage depletingwater sources in the mountains, mid-hills and Terai regions in the context ofClimate Change. This Handbook draws heavily on Madhukar Upadhya’sbook- Pokhari ra Pahiro, Madhya pahadi Chhetrako Paani- Sanskriti, KhadyaPranaali ra Bhu- Kshayako Artha Raajniti. Though this Handbook, an outcomeof many years of experience in constructing ponds in Nepal, is aimed athelping WASH planners, it is a useful reference to everyone interested incatching rain where it falls (rather than just where it later concentrates), toenhance local water availability and to bring a positive change in the qualityof life for people dependent on stored groundwater, which, in the mountainsserves to feed Springs, providing water for everyday needs. It has becomeurgent in view of the fact that climate change induced impacts are alreadybeginning to be felt with incidents of increased frequency and intensity offloods and droughts, new approaches (such as that of water harvestingponds technology) have to be explored and adopted to enhance theresilience capacity of rural Nepal.

This Handbook has following chapters:The Introduction section provides the general context and elaborates onthe polices and strategies of the government with respect to promotingponds for increasing water yields in the watersheds by augmentinggroundwater. It also sets out the objectives for readers to get a clear idea ofthe purpose of this Handbook.

The Setting - The most important aspect of pond construction is to store asmuch rainwater as possible where it falls during the monsoon and save it for

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non-rainy season either in the pond itself or through recharge in thegroundwater below it. The best way to do this is to store water in the aquiferby activating the natural hydrological cycle in such a way that less water islost in immediate runoff and evaporation. The amount and the distribution ofrain and the nature of aquifer differ from one physiographic region toanother. This section provides brief account of the physiographic featuresand the significance of recharge ponds in each of the key physiographiczones. The section also provides information on the climate and hydrologicalcontext and explains the importance of spring hydrology in the mountains,which will be impacted directly by the emerging climate change with directconsequences on water and sanitation application in the rural areas.

The Recharge Ponds section helps define recharge ponds and therationale for constructing them in the context of depleting water sources andproviding water for income generating activities and WASH purposes. It alsogives practical information on the types of ponds, their advantages anddisadvantages as well as guidelines to the users in determining where,when, and how to build ponds.

The Practical Guidelines section has been developed to orient the usersabout important things to be considered before actual construction of thepond. It provides practical guidelines for selecting the site, shape, size, andnumber of the pond/s, obtaining official permits if necessary, and someaspects of design details. The section also talks about the time ofconstruction, construction tools and material required, and makes the usersaware of the need to protect the pond and its surroundings, mainly by theuse of bioengineering.

The Pond Construction section starts with the description of design layoutand guides the users through the steps to be followed for actual constructionof the ponds. Examples of the quantity and cost estimates as parts ofinvestment planning have also been included in this section.

The guidelines are presented using a matrix that summarizes informationgiven in detailed sheets for each type of pond layout for specific area andare supported by sketches for clarity. Steps for each action have beenprovided in bullet points to minimize confusion, therefore it is hoped thatmany water users of water supply projects will find it user-friendly.

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Abbreviations

DDC: District Development CommitteeDFO: District Forest OfficeDoLIDAR: Department of Local Infrastructure Development and

Agricultural RoadsDSCWM: Department of Soil Conservation and Watershed ManagementGON: Government of NepalHDPE: High-density polyethyleneLID: Local Infrastructure DevelopmentMBT: Main Boundary ThrustMCT: Main Central ThrustMFT: Main Frontal ThrustMoFALD: Ministry of Federal Affairs and Local DevelopmentNGO: Non-governmental OrganizationNWCF: Nepal Water Conservation FoundationRWSSP-WN: Rural Water Supply and Sanitation Project in Western NepalVDC: Village Development CommitteeWASH: Water, Sanitation and Hygiene

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List of figuresFigure 1: Physiographic RegionsFigure 2: Temperature Distribution in NepalFigure 3: Average Annual Rainfall Distribution (mm/Year)Figure 4: Typical “Water Tower” in the MountainsFigure 5 A: Excavated Pond (Unlined)Figure 5 B: Excavated Pond (Lined)Figure 6: Embankment PondFigure 7: Contour TrenchesFigure 8: Eyelash TrenchesFigure 9: Process Flow Chart of Pond ConstructionFigure 10: Runoff CollectionFigure 11: Diverting Natural Drainage to Recharge PondsFigure 12: Generic Type 1. Unlined PondFigure 13: Generic Type 2. Stone Lined Pond

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List of tables

Table 1: Advantages/Disadvantages of PondsTable 2: Advantages and Disadvantages of Excavated PondsTable 3: Advantages and Disadvantages of Embankment Ponds.Table 4: Advantages and Disadvantages of Contour TrenchesTable 5: Advantages and Disadvantages of Contour TrenchesTable 6: Format for Quantity and Cost Estimation for Pond ConstructionTable 7: Guidelines for Selecting Appropriate Recharge Pond Types

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Contents1. Managing Water Depletion Using Recharge Pond 1

1.1 The Context 11.2 Pond Policy and Strategy 21.3 Objectives 3

2. The Setting 52.1 Physiographic Regions 52.2 Climate 92.3 Hydrological Context 112.4 Water Sources in Terai 122.5 Spring Hydrology 132.6 Climate Change 14

3. The Recharge Ponds 153.1 Why recharge ponds? 153.2 Types of Ponds 163.3 Shape, Size and Depth of Ponds 213.4 Getting Started 22

4. Practical Guidelines 274.1 Site Selection 274.2 Location of Ponds 2�4.3 Important Design Principles 294.4 Design Details 294.5 Number of Ponds 304.6 Official Permits 304.7 Time for Construction 304.8 Construction Materials 304.9 Tools Required 314.10 Choosing a Lining 314.11 Plant Material for Slope Stabilization 314.12 Maintenance 324.13 Conservation Works in the Upper Catchment 32

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5. Pond Construction 335.1 Design Layout 335.2 Steps for Pond Construction 345.3 Investment Planning Estimate 355.4 Guidelines for Selecting Ponds Types 365.5 Design Descriptions of the Recharge Pond Types 37

Annexes 45

Glossary 51

Bibliography 54

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1

Managing Water DepletionUsing Recharge Pond1

1.1 The Context

An inherent problem of water is that it isdifficult to get good quality water in arequired quantity at the required placewhen one needs it. Therefore, makingwater available from its source to wherepeople are through use of technologyrequires substantial cost. But first andforemost, water must be available at thesource. The problem is that even thoughthe principal source of water isprecipitation that occurs for a limitedperiod, only a small part of it is storedas groundwater, which in the mountainwatersheds is released graduallythrough springs and seepages to formstreams and rivers. Geology, vegetation,and climate influence the hydrologicconnections within watersheds. Nepal,as with much of South Asia, lies in whatis called a semi-arid zone, arid for abouteight of the non-monsoon months. Inthis monsoon climate surface runoffoccurs during the monsoon in responseto rainfall events, while groundwatercontributes to springs and stream flow

during the non-rainy season. Up in thehigher elevations, snowmelt water feedsrivers that originate in the high elevationduring summer months, but before andafter summer months these rivers arealso augmented by tributaries thatoriginate in the mountains below snowline that are fed by groundwater. In theMid-hills and Terai zones where the bulkof Nepal’s population lives, there is nosnowfall of any kind. Some mountaintops have snowfall in rare, freak eventsof a few days, too little to make anyserious impact on all stream flowsexcept for major rivers.

Availability of water in the springs andstreams thus depends entirely on theamount of water stored in thegroundwater, which is augmented duringthe monsoon by continuous rain of fourmonths and supplemented to someextent by the less intense winter rains.At times when the groundwater withinthese hills is not fully replenished, forvarious reasons explained later in this

Managing Water DepletionUsing Recharge Pond

2

handbook, water availability becomesscarce. To counter such a risk,rainwater harvesting forms the majorcomponent of water management, whichhelps augment groundwater storage.

1.2 Pond Policy and

Strategy

Planning, monitoring, and evaluation ofwater supply and sanitationprogrammes; along with otherdevelopment programmes like ruralroads, irrigation systems, river control,rural energy and others; is a majorobjectives of the Department of LocalDevelopment and Agricultural Roads(DoLIDAR) as stated in its policystatement. One of the major issues inthe water supply function is severeshortages of water in the dry period inmany districts of Nepal. This problem islikely to be accentuated by the effectsof the ensuing climate change. Whileseeking to address this issue, the pondtechnology has emerged as a highlypractical means of increasing wateravailability in the rural sector throughrecharge of the ground water.Recognizing this potential of the pondtechnology, the Ministry of FederalAffairs and Local Development(MoFALD) and DoLIDAR have alreadyadopted a policy to make at least onepond in every village of Nepal.

Ponds are centuries old tradition inmanaging water and watersheds. TheDepartment of Soil Conservation andWatershed Management (DSCWM)

recognizes the construction andmaintenance of multipurpose ponds asa means for increasing water holdingcapacity of the watersheds and forincreasing water yields through waterharvesting. It is also one of the ninetechniques described in the DSCWMpublication “Soil Conservation andWatershed Management Activities” asappropriate and recommendedtechnique for Nepal.

The GON’s Three Year Interim Plan inirrigation sector has adopted a strategyfor irrigation development whichemphasizes implementation of non-conventional irrigation technologies suchas drip, sprinkler, and runoff harvestingponds to cater to the needs of small andmarginal farmers in areas wheredevelopment of conventional surface andgroundwater irrigation are not feasible. A“Non-conventional Irrigation TechnologyProject” has been conceived as aspecific programme under this strategy.It is also implicit in the current IrrigationPolicy 2060 of the Government of Nepal,which sates “For expanding year roundirrigation, water reservoirs, rainwaterharvests and ground water resourcesshall be developed, conserved,promoted and utilized as supplementarysources to the seasonal rainfall”.

Similarly, in the Agriculture sector theInterim Plan adopts a strategy to helpfarmers reduce their costs of productionthrough the Government’s investment inmicro irrigation and rain water harvestingtechnology in the hills for ensuringregular water supply. The ongoing workon Agriculture Development Strategy

3

also promotes rain water harvesting.The pond technology is also highlycompatible with the objectives of theNational Adaptation Programme ofAction to Climate Change (NAPA) whichstresses the need to combat theadverse effects of climate changethrough appropriate technology. NAPA(2010) specifically emphasizesempowering vulnerable communitiesthrough sustainable management ofwater resources, promotion of rainwaterharvesting structures and technologiesas well as by conserving water supplysources and strengthening of existingschemes.

This shows that the Governmentagencies are well aware of the “pond”technology and are willing to support itas it is very much within their agendadirectly (as mentioned specifically in theDSCWM and Irrigation Sectorstrategies) or indirectly as a means ofrain water harvesting. This, incombination with enthusiastic support

and involvement of local andInternational NGO community, thistechnology stands a fair chance of beingwidely adopted as a viable means ofrecharging groundwater sources as wellas possibly the only identified option foradapting to the anticipated adverseeffects of climate change in watersource protection.

1.3 Objectives

The main objective of this handbook isto help facilitate planning, construction,management and use of ponds forrecharging groundwater in differentgeographical regions of Nepal. Thehandbook specifically aims to helpwater managers in Middle Hills,Mahabharat, Siwaliks, Bhabar and Terairegions to build recharge ponds foraugmenting aquifers and realize theadditional benefits from water stored inponds.

4

5

2.1 Physiographic

Regions

Water regime across Nepal varies inamount and distribution from place toplace due to topographical and climaticvariations. Understanding naturalphenomenon of water regime acrossdifferent physiographic zones requires ageneral understanding about theorographic variations.

Nepal is often classified into threebroadly understood geographical regionsof Mountains, Hills and Terai. Actualphysiography, however, is a little morecomplex than this. The commonlyunderstood Mountain region consists ofthe high mountains and Himalayas withpermanent snow and ice; the Hillsinclude Mid-hills, Mahabharat andSiwalik regions; and the Terai refers tothe plains in the South. Thus, in thecontext of promoting recharge ponds,the following physiographic divisions ofthe country are appropriate: 1) The

Himalayas, 2) The High Mountain, 3)The Mid-hills and Mahabharat Region, 4)The Siwaliks, 5) The Bhabar Zone, and6) The Terai. A brief description of eachof the broad physiographic regions isgiven below (Also refer to Figure 1 forthe Physiographic Regions as describedhere).

2.1.1 The Himalayan RegionThe Himalayan Region includes thethree distinct high mountain regions of1) The Trans-Himalayan Hills andPlateaus; 2) The Inner HimalayanMountains; and 3) The Main HimalayanRange. The Himalayan Region occupiesabout 15 percent of the total land area ofthe country. Lying mostly above 4000Meters in elevation on an average, thisregion is sparsely populated. Aboutseven percent of the total population ofthe country inhabits this region.

The area lying to the north of the mainHimalayan range is in rain shadow and

2 The SettingThe Setting

6

receives less than 200 mm of rainfall.The westerly winds produceconsiderable amount of snowfall duringthe winter in high altitude valleys likeHumla, Mugu, Thak Khola (Mustang),and Manang. Snow stays on the groundfor quite a long time. Wind blows withhigh speed in the mountains and valleysof this region and streams freeze duringwinter. The main Himalayan range isbroken in several places and the majorrivers like Arun, Bhote Koshi,Marsyangdi, and Kali Gandaki flowsouthwards through deep gorges alongthese breaks. This region contains highpeaks covered with snow and ice,glaciers, and glacial lakes which serveas a source of water for the great rivers.Even though water demand is low due tolow population density managing wateris a big problem in the region.

2.1.2 The High Mountain RegionHigh relief and steep slopescharacterize the High Mountain region.It is not uncommon to find a relief of2000 meters in a single valley which canresult in tropical type of climate in thevalley bottom to cool temperate on themountain tops. The High Mountainregion comprises about 19% of the totalland area of the country. Due to anextremely rough terrain the region hashistorically remained remote andinaccessible. Only recently were a fewdistricts like Jumla and Mustangconnected with the rest of the countryby means of motor vehicles. Agriculturallands exist in pockets and are farmed atsubsistence levels. Forests are incomparatively better conditions than inother regions, mainly because the

demand for forest products is limiteddue to low population density. Theproblem of water availability andmanagement are similar to the ones inthe Mid-hills region as described below.

2.1.3 The Mid-hills and Mahabharat

RangeThe Mid�hills and Mahabharat rangeoccupies the largest geographical areawith about 40 % of the population livinghere. Diverse in culture, ethnicity, andlanguage; the area is also diverse inclimate and vegetation, precipitation,and everything that depend on them.One of the striking characteristics ofthis region is that the people havedepended on income from sourcesoutside the region because the incomefrom the farm production has not beensufficient to meet their needs. Theinterdependence between farms,forests, and livestock is quite evident inmiddle hills than in other areas of Nepal.These linkages are maintained byavailability of water, which provides abasis and the incentive for people tomanage these resources. However, inplaces where water availability hasreduced the incentive to manage theseresources also have weakened.

The southern slopes of the mountains inthe area are highly eroded but areheavily settled. The elevation rangesfrom below 1000 m to more than 3500 mwith varying degrees of mountain slopesfrom below 10 degrees to more than 60degrees. The average slopes can betaken as about 20-30 degrees. On thesevarying slopes one can find villages and

7

farms from the valley to the ridge areas,which make it completely unique interms of defining water problems. Forthose living at higher altitudes the onlysources of water are the springs andstreams located below the villages,because there is no place to capturewater during the monsoon and to store itfor later use. The villages in the valleysand at the foothills have sufficient watersources from springs and streamscoming from watersheds above. Inaddition they also have access to thewater from the rivers flowing in thevalleys. For the villages in the middleparts that are generally settled oncolluvial deposits there are springsabove and below the settlements.People dependent on the springs abovecan come down to the springs below thevillages when the springs above dry out.The water supply system uses thegravity flow and therefore is connectedto the springs above the villages.

The Mahabharat Range, which occupiesthe southern part of the Mid-hills region,is characterized by steeply sloping andrugged mountain slopes and deepvalleys. Soils are shallow and infertile.There is very little land available forsustainable agriculture. As a result, thepopulation density is low. The mountainslopes generally have dense forest coverwith patches of shrubs. The area oftenreceives high intensity rain and ischaracterized by high soil erosion withperiodic catastrophic erosion caused bycloud bursts that initiate hundreds ofshallow landslides in the denselyvegetated slopes.

2.1.4 The SiwaliksExtending from west to east, the SiwalikHills, locally known as the Chure, in thesouthernmost frontier is the youngest andthe last mountain range in the Himalayanrange. The Siwaliks has a width of about 8-10 kilometers. It rises abruptly from theBhabar and has a slope of more than 50degrees with deep gullies and verticallandslide scarps. The southern slopes aresteeper than the northern slopes. TheSiwaliks have thousands of smallcatchments from which numerous smallstreams originate. Though it is a separatechain of mountain, the Siwaliks isseparated from the Mahabharat by the innerTerai or Doon in some places. In otherplaces, it merges with the Mahabharat andit is difficult to distinguish the two.

The Siwaliks is characterized by higherosion, low water availability, and sparsesettlements. Spring sources are availablein isolated pockets whereas erosionduring the monsoon is widespread withgeneration of massive amount ofsediment that gets deposited in theBhabar – the piedmont of Siwaliks. Slopestability is a big problem in Siwaliks.

2.1.5 Bhabar ZoneThe corridor lying at the base of south ofthe Siwaliks is the Bhabar zone which isthe northern most flank of the Gangaplain and extends from the piedmont ofSiwaliks southward to a maximum widthof 8-10 kilometers. The region isextremely poor in water availability.Rainwater is retained for a short periodand is available only when it rains.Rainwater either seeps underground

8

immediately or runs as overland flowresulting in a flash flood. The rivers fromthe Siwaliks meander and sometimesflow in braided forms.

The Bhabar zone is mainly composed ofboulders, pebbles, cobbles and coarsesand derived from the rocks of Siwalikand Mahabharat Mountains. Theseboulders, pebbles, and cobbles aremostly made up of sandstones and therocks from the immediate northernvicinity.

Bhabhar zone is a major recharge zonefor the Terai. The rivers including Koshi,Gandaki, Karnali and all other minorrivers flowing from the Himalayas dumpa huge amount of water into thegroundwater aquifer continually whilepassing through the Bhabar. Evenephemeral rivers originating fromMahabharat and Siwaliks add water tothe groundwater of the Gangetic plainwhile crossing the Bhabar, but their

contribution compared with the snow fedrivers is only nominal. Water tables inBhabar are deep and fluctuate sharplybetween the wet and dry seasons.Therefore, agriculture and othereconomic activities that requirecontinued supply of water is difficult inBhabar.

Watershed boundaries within Bhabarare dynamic and change frequently.Stream density is low with undefinedboundaries between two streams. Smallirrigation channels built by villagers turninto large streams in no time causingmassive damages to settlements andfarms. Unlike in the middle hills, villagesin Bhabar cannot get water supply fromthe high grounds in the Siwaliksbecause Siwaliks does not have springslike in the middle hills or Mahabharat.Drawing water from groundwater is alsonot easy because of deep groundwaterlevel.

FIGURE 1: Physiographic Regions

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2.1.6 TeraiSouth of the Bhabar zone lies the Teraiwhich extends southwards up to theIndian border. The soils of this zone arequite deep and have high water holdingcapacity. Terai is frequently floodedduring the monsoon season. Watertable fluctuates considerably betweenthe wet and dry seasons. Amount andintensity of rainfall varies from east towest in Terai. While the soils remainsaturated almost always during themonsoon, the Western Terai begins toexperience water deficiency as early asNovember in contrast to the EasternTerai where the soils begin to dry outonly in January.

It should also be remembered thatNepal Himalaya range is crossed bythree major geological faults, the MainCentral Thrust (MCT) just along the footof Higher Himalayas, the Main BoundaryThrust (MBT) just south of theMahabharat Range, and the Main

Frontal Thrust (MFT) that straddles thebase of Siwaliks. The country is alsodivided geo-tectonically in “blocks” byseveral north-south transverse faults,making the entire region geologicallyvery dynamic.

2.2 Climate

Climate in Nepal varies from subtropicalin the Terai to arctic in the HighHimalayas within a short span of about125 kilometers across the breadth of thecountry. The wet season lasts from Junetill September and is caused due to thesouth-west monsoon. October throughMay is mostly dry, occasionallyinterrupted by a few showers in thewinter and spring season. Thus themain rainy season is confined to themonsoon season followed by a cool tocold, dry, post-monsoon season and ahot, dry pre-monsoon season.Depending upon the location of springs

FIGURE 2: Average annual temperature distribution in Nepal (OC)

Note: The axes in the figure indicate Latitude and Longitude

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10

in the mountains some springs begin todry out as early as October and otherscontinue to flow for longer period.

2.2.1 TemperatureMinimum temperatures occur inDecember and the maximum in May inall parts of the country. While this is ageneral phenomenon, the temperatureitself is strongly affected by thetopography. Especially in the Mid-Killsand Mountains, temperature is directlycorrelated with altitude. A lapse rate ofabout 0.6 degrees Celsius fall intemperature with every 100 m rise inelevation is a generally accepted norm.

Figure 2 shows the distribution of annualaverage temperatures for Nepal whichclearly reveals the inverse relationshipbetween elevation and temperature.

2.2.2 RainfallThe rainfall and its distribution in Nepalis characterized by the followingfeatures:

1. Main rainy season occurs duringthe four months of monsoon fromJune to September. About 80percent of the annual rainfall occursduring this season and the rainfallregime covers, the whole countryexcept the northern Himalayanregion.

2. Westerly weather systems bringoccasional rains during the winterand early spring. But occurringoccasionally, they affect isolatedhilly areas, often the western part ofthe country.

3. During the pre-monsoon seasonfrom March to May, local orographicor convective rains may occur

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11

mostly over the hills and inner Teraiareas. But they affect isolatedareas, mostly in the form of briefthundershowers.

The rainfalls of latter two types arerather unreliable and account for onlyabout 20 percent of the annual totalprecipitation. They are occasional andaffect isolated areas only. However, forlocal water management in the dryseason and maintaining soil moisture(i.e. Green Water), they are veryimportant. They occur after months ofpractically no precipitation from Octoberonwards, and the winter rains duringDecember and January come in lesserintensity at a colder period resulting inmore recharge to runoff and lessevapotranspiration. Ponds help incapturing more of this rain just beforethe onset of the driest hot period of Apriland May.

Annual rainfall varies from about 250mm in the rain-shadow areas of north-west Dolpa and Mustang to about 5000mm in the windward slopes of Kaskidistrict (Figure 3). Western parts receiveless rainfall in the monsoon comparedto central and eastern parts. During thewinter, however, rainfall is more reliablein the west than in the east. Morerainfall occurs on the south-easternslopes which act as windward side tomonsoon winds during the summer. Thehilly areas of western and north-westernslopes as well as those behind the highmountains receive little rainfall. Isohyetsof 1500 to 2500 mm cover most of theeastern and central hilly regions whilethose in the western region are between

1000 to 1500 mm. This difference inannual rainfall distribution may be due totopography, continentally and partly dueto late onset and early retreat ofsummer monsoon in the west.

The above analysis of rainfallcharacteristics indicates that across allthe physiographic regions there is toomuch rain during the Monsoon periodfollowed by severe shortage of waterduring the dry season for not onlyagricultural activities and animalhusbandry but also for daily necessitiesof the households. Capturing excesswater that falls during the Monsoon andin the winter is thus a practical meansof storing water underground for useduring the dry season.

2.3 Hydrological Context

Though Nepal receives an average of1500 mm of annual precipitation, itsdistribution is skewed. About 80 percentof the annual precipitation is dumpedwithin 3 – 4 months between June andSeptember. This rain recharges thewater sources including the groundwaterreserve, which supports ecological,environmental and economic demandsfor water. Between September and May,Nepal receives the remaining 20 percentof the annual precipitation. As a result,this period is mostly dry.

Water in the hills and mountains is oftenconcentrated in the streams in deepgullies too far below hill settlements tobe of much use due to the prohibitivelyhigh energy cost of pumping. As a

12

consequence, Nepal’s Mid-hill hamletshave traditionally relied on springsources for drinking water, for domesticanimals and for small-scale farming.Nearly half of the country’s 26.6 millionwho live in hills and mountains dependon spring sources for their water needs.The springs are fed mainly by themonsoon rains, and the winter rains toocontribute to prolonging their life wellinto the pre-monsoon dry season. It isultimately the rainwater that is stored inthe groundwater within the mountainsthat leaks out in the form of spring andsustains hill life and livelihood.

The Mid-hills of Nepal support highpopulation density and suffer from the“altitude challenge”. It consists of a dailybattle against gravity, which is mostpronounced in the availability of water fordomestic use as well as for animalhusbandry and farming.

It needs to be stressed that all streamsthat are used for collecting water alsoultimately depend on springs (and thehill ‘water towers’ that store themonsoon waters) for their flow. Watermanagement here unlike in the high-Himalayan watershed must be thoughtin terms of monsoon and winter rainsand harvesting and storing thisprecipitation to provide water securityduring the dry season.

2.4 Water Sources in Terai

Water sources in Terai include surfaceas well as groundwater sources. Allrivers flowing from the mountains and

the intermittent streams from theSiwaliks flow as surface water sources.In addition, there are ponds, lakes andwetlands. A huge amount of water in allrivers leaks to the groundwater reserveas soon as they cross the porous areasof Bhabar region. Water sources in Teraiare part of the far larger interlinkedGanga basin system. The groundwateris, in fact, an extension of thegroundwater of the Gangetic plain.

The interaction between groundwaterand surface water is strong in Terai. Asa result, in some places, the smallstreams disappear in the Bhabar andreappear as it reaches Terai plain. Thisindicates that much of the stream flowin the lower section near the Nepal-Indiaborder is probably contributed bygroundwater. Identification of a distinctbasin is difficult.

During the monsoon season, most ofthe Terai is inundated for weeks withseveral feet of standing water. Low lyingareas remain wet for a considerably longperiod after the monsoon season whilein the higher land water table starts togo down soon after the monsoon ends.This fluctuation of the water table in thewet and dry seasons determines theavailability of water in this region.

Groundwater is used for drinking in mostparts of Terai. Water is drawn either bydigging wells or by using hand pumps.In towns and cities, groundwater ispumped up to overhead tanks usingelectric pumps.

The basic purpose of ponds in the Terai

13

is to make water available to householduses as well as for animals. But it isoften used for income generatingactivities like fishery and for irrigatingkitchen gardens. Even if it is not assignificant as it is in the mountainswhere no specific area exists forgroundwater recharge, the rechargeponds in Terai do help replenishgroundwater. If strategically located,ponds may also serve as a mechanismfor controlling flood, which occursfrequently in the region

2.5 Spring Hydrology

The interdependence of rainfall andtopography in the hills results in thesprouting up of springs at variouselevations as the monsoon progresses.The eco-hydrology of these Mid-hillsprings is poorly understood. Springs(Mool in Nepali) have not been properlymapped in Nepal, nor have theirtypology, hydrology and socio-economicdependence been systematically

studied, even though the majority ofMid-hill Nepalis depend upon them fordomestic water supply as well aslivestock rearing and some homesteadfarming.

In terms of typology, based on theirlocation in the ‘water tower’, springs canbe classified as August springs (SauneMool), which are located at the higherelevation on the mountains. They areshort lived and dry out as soon asmonsoon ends. Located below Augustsprings are the July springs (AsareMool) which begin to flow in the middleof the monsoon season and continue toflow until middle of the dry season. Atthe bottom of the mountains are thepermanent springs (Sthai Mool) whichflow year round with varied level ofdischarge between the dry and wetseasons. These types of springs havenot been properly mapped, their varyingdischarge levels have not beenscientifically ascertained for villages thatare dependent upon them, nor have thecurrent uses as well as future needs

FIGURE 4: Typical “Water Tower” in the Mountains

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been charted. Without these physicaland social sciences in place, asustainable exploitation of thesevaluable resources, their properconservation and possibleenhancement through anthropogenic-induced recharge is not possible.

The soil moisture in the farms and theamount of water available around thevillages depend on two things: thelocation of the village and how muchwater has been saved in the soil andthe groundwater aquifer during themonsoon. Figure 4 depicts a typicalhill ‘water tower’. The monsoon rainspercolate into the soil contributing togroundwater replenishment and thebursting forth (‘Mool Phutne’ in Nepali)of springs at different stages of themonsoon. The August springs indicatecomplete recharge of groundwaterreserves. These springs and thegroundwater table begin to decline untilreplenished by winter rains or, if thesefail, only in the next monsoon. Thedrinking water supply systems in theMid-hills tap different sources, store itin a reservoir tank and distribute viacommunity tap stands. Gravity flowsystems have been built to supplydrinking water.

Water stress in the mountains isactually measured by farmers in termsof when or how early particular springsdry out. Immediately after the monsoonseason ends in September, the hillsbegin to face water shortage. Soilmoisture in all farms and grasslandbegins to deplete. Springs located inthe upper areas start to gradually dry

out. Springs, at the lower areas, keepflowing, but not for long. As the winterprogresses, the discharge reduces inthe springs even at lower foothill areas.Many of them dry out during April/May.Water taps connected to the springs atthe upper slopes also dry out.

2.6 Climate ChangeRising global temperature is projected tolead to a change in the existing climaticpattern with multiple impacts on naturalresources including water. The delicatebalance between various processes ofhydrological cycle will be threateneddue to the change in rainfall pattern, itsintensity, evapotranspiration, and so on.When that happens, there may be acritical decrease in stored water whetherin terms of soil moisture, groundwatertable or in ice and snow in the highermountain regions. This will result in ageneral decline in water availability in hillcatchments leading to increased waterstress both in the hills and plains. Thedifferences between wet and dryseasons are also likely to increase: thedry seasons are expected to be muchdrier for prolonged periods and wetseason much wetter with intense rainfallevents. Changes in frequency andmagnitude of high intensity rainfallevents are likely to increase flash floodsand water induced disasters as well asaccentuate the differences between highand low water flow regimes. Pondstechnology is one of the more feasibletechnical options for rural communitiesto cope with and adapt to climaterelated changes.

15

3 The Recharge PondsThe Recharge Ponds

3.1 Why recharge

ponds?

Rainfall distribution in Nepal is highlyskewed with too much of it coming withinfour months of the monsoon and very lowrainfall during the rest of the year. This"Too Much and Too Little" of rainfallcauses problems in terms of availabilityof water during the dry period. Winterrainfall is helpful in augmenting groundwater, if there is adequate amount of rain.In recent years, winter rain has beeninadequate in many parts of Nepalcausing extended drought. Thus, as allaspects of our livelihood for the eightmonths of the non-monsoon monthsdepend on the water stored in thegroundwater aquifer during the monsoon,there is need for a system to capture asmuch water as possible during themonsoon for later utilization.

Gravity water supply systems in thehills and mountains use springs andstreams as source of water. The springsand streams are fed by aquifer, which

are replenished naturally through rainsoaking through soil and rock to theaquifer below. Some of the streams alsofeed water to the springs throughinfiltration. The groundwater reservesbegin to deplete as soon as themonsoon rain stops, the springs beginto dry out gradually beginning from theupper elevation areas to the lower ones.Water supply systems connected to thespring sources suffer as soon as theflow rate in the springs decline or dryout completely. Water supply systemsgenerally fail to operate at the optimaldesign level when the sources deplete.Many water supply systems have turnedinto relics after they have ceased toprovide water. There are many reasonsfor the source to decline includingchange in the landuse, weathervariability, change in the rainfalldistribution and intensity, climatechange, population growth, andincreasing urbanization and so on. The

16

bottom line is that the water supplysystems fail affecting the livelihood andhealth and sanitation of the people whodepended on the system.

Enhancing natural rates of groundwaterrecharge by using ponds is an easy andlow cost method of augmentinggroundwater sources. Ponds are anappropriate and practical means ofestablishing such a system forcollection and storing water or in otherwords for replenishing the "water tower"in the Hills and Mountains. Rechargeponds can be used to store rainwater,runoff, and waste water or even waterfrom spring sources before they flowdown the slope. Recharge ponds involvediverting surface water into ponds thatallow water to soak through theunsaturated zone to the underlyingunconfined aquifer. Once captured in theponds, water continues to seep downand recharge the ground water long afterthe rainfall ceases. Pond water can alsobe used for watering animals, washingclothes, doing dishes, and kitchengardens irrigation. Ponds are also usefulfor a number of other purposes likemaintaining soil moisture for the growthof shallow rooted vegetation as well asto put out fire. In higher elevations wherethere are very few or no springs, storingwater in the ponds is the only option formaking water available in the dry period.

The "water tower" concept explains thefluctuation of groundwater table in thehills but the situation in Terai is different.While springs constitute the source ofwater supply in the hills, in Terai it is thegroundwater that provides water which

needs to be pumped up either manuallyor using machines. The water tablefluctuates considerably and manyplaces experience drought during thedry season. Thus, the strategy ofstoring as much water as possibleduring the monsoon for later utilizationis a valid strategy for the Terai region aswell.

As mentioned earlier, climate change isgoing to cause increased droughts andfloods. Drought will be more intensewhere rainfall decreases, and floodswould increase where amount andintensity of rainfall increases. Balancingthis skewed distribution of rainfall isessential to adapt to both floods anddroughts.

Experience of using ponds has shownthat it helps to reduce landslides anderosion in the hills and flooding, to acertain extent, in the Terai by regulatingrunoff. Therefore, ponds will be helpful inadapting to the changes in water regimetriggered by climate change.

Major advantages and disadvantages ofponds for a community and possiblemitigation measures to reduce thedisadvantages are shown in Table 1,below.

3.2 Types of Ponds

There are several types of ponds thatcan be built depending upon the areawhere they are built and purpose forwhich they are built. If the purpose is tostore water for a long time, for instancefor irrigation or for fishery, the sides and

17

bottoms of the ponds must be partiallyimpervious. At one end of the spectrumare the ponds built with heavy masonryand concrete linings and at the otherend are those simple dugout typeswithout any lining. There can be manyintermediate types between these twoextremes. For recharge purpose, pondsmust be able to hold water for sometime as well as to percolate it down intothe ground water system. Depending onlocation and geological condition, atleast some sides of the ponds mayneed to be lined, but the bottoms mustremain unlined. The basic types ofponds identified for the purpose ofrecharge are described in brief in thefollowing sections:

Potential Advantages

z Recharge ground water.z Enhance water availability.z Controls instant over flow of

runoff and reduces floodsand erosion.

z Watering animals (pondshave been useful inwatering animals andbuffalo wallowing.)

z Watering kitchen garden.z Fish production (in Bhabar

and Terai).z Fire protection (access to

water to put out fire).z Helps in maintaining soil

moisture.z Supports in maintaining

ecosystems.z Can be used for recreational

activities.

Disadvantages

z May cause risk tosmall children if thepond is deep.

z Mosquito breeding islikely in warm andpolluted areas.

z Big ponds in thesteep areas havepotential to breakcausing erosion inthe downstream area.

z Landuse restricted topond only.

Mitigation Measures

Risk for children: To avoidthis risk fences can bebuilt around the pond.Mosquitoes: Regularcleaning if scum devel-ops.Erosion in hills can becontrolled by making thepond small.

TABLE 1: Advantages/Disadvantages of Ponds

3.2.1 Excavated PondsAn excavated pond is often built on levelterrain by digging soil and sometimesrocks if it is near the surface (Figure 5).An excavated pond is generally built onresidual soil or ridge of the hill or agrazing land where flat area is available.An excavated pond requires lowmaintenance and can be built to holdmore water by increasing depth or itssize, if enough area is available.

The excavated ponds built in pervioussoils such as that of Siwaliks must havevertical sides of stone masonry incement mortar to prevent seepagethrough the sides and allow infiltrationthrough the bottoms of the ponds. The

18

ponds in the Bhabar region, on the otherhand, must have unlined sloping sidesso that infiltration can take place fromthe sides and bottoms of the ponds.In Bhabar region, ponds can be locatedclose to streams originating from theSiwaliks, so that the stream flow can bediverted to ponds fed by flow from theserivers. Caution should be exercised insome areas of Bhabar where divertingwater from streams can result in floodsin new areas.

3.2.2 Embankment PondsEmbankment pond is built by erecting astone masonry or earthen dam toimpound flowing water in a stream or ongently sloping gully (Figure 6).Embankment pond is suitable in smallstreams at the foothill areas, because ofgentle slope of the stream beds. Exceptfor building foundation of the stonemasonry dam there is no excavationinvolved. Earthen dam can be built bypulling soil from the lower areas andsides where impounding is done.

FIGURE 5 B: Excavated Pond (Lined)FIGURE 5 A: Excavated Pond (Unlined)

Advantages

z Facilitate re-charge intosurroundingground which inturn improves soilmoisture,improves agricul-tural productivityand mitigatesagainst drought.

z Can assistaugmentingspring dischargethrough rechargeof shallow aquifer.

z Can reducesalinity of soil inhigh evaporationarea.

Disadvantages

z They can silt upeasily.

z Maintainingdams requireseffort.

z High evapora-tion rates.

TABLE 2: Advantages and Disadvantagesof Excavated Ponds

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In embankment ponds there will beplenty of water coming in the pond.However, impounding flowing water canbe problematic for fish and other aquaticanimals which travel up and downstream. Floods can also be problem forthe dam. Therefore, expensive cementmortar should be avoided becauseearthen or dry masonry dams can be re-built if it is damaged by floods in themonsoon. Generally, this type of pondshould be considered for specificpurpose of slowing down the stream flowand recharging the groundwater.

3.2.3 Contour TrenchesContour trenches are ditches dug alonga hillside to check the runoff on the

FIGURE 6: Embankment Pond

slope (Figure 7). Trenches are dug insuch a way that they follow a contourand run perpendicular to the flow ofwater. The spoil material taken out ofthe ditch is used to form a bund on thedownhill edge of the ditch. The bundneeds to be planted with native grassesto stabilize the soil and for the roots andfoliage in order to trap any sediment thatwould overflow from the trench in heavyrainfall events.

Contour trenches are used to catchrunoff water, which then infiltrates intothe soil. Small scale contour trenchescan also be used within farms. Thewater that infiltrates can be used as soilmoisture for crop. This technique willhelp farmers to grow crops such asvegetables and at the same time helprecharge the aquifer.

Advantages

z Reduces flow inthe gully andhelps rechargegroundwaterfaster for longerperiod.

z Plenty of wateravailable in theimpoundment forirrigation.

z Easy to build as itdoes requireconstruction orexcavation on oneside only.

Disadvantages

z They can siltup easily.

z High flood inthe gully cancreatedamagingfloods in thedown stream.

z Maintainingdams requireseffort.

z High evapora-tion rates.

TABLE 3: Advantages and Disadvantagesof Embankment Ponds

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Long trenches can be risky for heavyrain and therefore the trenches can bemade short in length and not connectedif the area has a history of receivingcloudburst rainfall events.

3.2.4 Eyelash TrenchesEyelash trenches are small trenchesthat are built as eyelashes across theslope (Figure 8). It is suitable for slopeswhere coutour trenches are not feasibledue to steepness slopes. Slopesgreater than 30 degrees are not suitablefor counter trenches and hence shouldbe land out as eyelash trenches. Thedepth of the eyelash trenches need tobe about 30 to 60 cm, while the widthcan be maintained at 50 cm. Biggerthan 50 cm may cause erosion as theyhold more water and can fail duringheavy rainfall events.

FIGURE 7: Contour Trenches

Advantages

� Improves soilmoisture andhelps aquiferrecharge.

� Improves grazingpotential andhelps mitigateagainst drought.

� Reduces soilerosion Canassist rechargeof shallowaquifer Canimprove soilfertility by addingorganic matter.

Disadvantages

� Trenches silt upfaster and willneed periodicmaintenance.

� Difficult tomaintain bundsalong the trenchwhich whenbreaks due toanimals or byhigh runoff, cancause erosionalong the slope.

� Reduction ingrazing areawhen trenchesare full of water.

TABLE 4: Advantages and Disadvantagesof Contour Trenches

FIGURE 8: Eyelash Trenches

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Advantages

� Silt up in eyelashtrench is slower thancontour trench.

� Helps break erosiveforce of runoff alongthe slope.

� Holds water in smallpockets to improvesoil moisture andhelps aquiferrecharge

� Improves grazingpotential and helpsimprove residenceagainst extendeddrought.

� Reduces soilerosion

� Can assist rechargeof shallow aquifer.

Disadvantages

� Cumbersometo make themin severalnumbersalong properalignment.

� Reduction ingrazing areawhen trenchesare full ofwater.

TABLE 5: Advantages and Disadvantagesof Contour Trenches

3.3 Shape, Size and

Depth of Ponds

ShapeExcavated recharge ponds can be builtto almost any shape desired suiting localsite conditions. It can be rectangular orcircular or elliptical in shape. If the plan isto line the pond with stonewall, it isbetter to build a circular pond because ofits cost effectiveness. A circular pondhas higher volume for the same perimeteras that of rectangular or square ponds(also see the box 1).

SizeThe size of recharge pond depends onthe area available to build it on and thelocation of the pond. In the hills, forinstance, a recharge pond can be assmall as a small pit of say one cubicmeter (1m x 1m x 1m) to as large as 2to 3 thousand cubic meters (say 50m x30m x 2m). In the valleys and plainsponds can be built to hold hundreds ofthousands of cubic meters of water. Thesize is also determined by the amountof inflow that can be expected in a givenperiod, and the fund available.

In Mid-hills and Siwaliks, large numberof small recharge ponds is preferredcompared to few and big ones, whereaslarge ponds are suitable in valleys andin plains of Bhabar and Terai.

Assume a square shape with side 4m. Itsperimeter will be 16m. Now, if we want tocreate a circle whose perimeter or the circum-ference is of the same length, it’s radius will be2.55m, and with 2m depth, the volume will be40.76m3, about 27% more volume than for thesquare shape whose volume is 32m3 (Seecalculation below).

Square Length X 4.00Perimeter P=4*X 16.00Area A1=X^2 16.00Depth D 2.00Volume V1= A1*D 32.00

Circle Circumference P=2*pi*R 16.00Radius R=P/(2*Pi) 2.55Area A2=Pi*R^2 20.38Depth D 2.00Volume V2=A2*D 40.76Difference in volume V=V2-V1 8.76% Difference V*100/V1 27.39

Box 1. Volume comparison betweencircular and square shaped ponds

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DepthThe most important dimension in a pondis its depth. For practical purposes, thedesign depth of water in the rechargepond should be up to 1.5 to 2 m. In Mid-hills and Siwaliks, the design depth ofwater recharge pond should be 1.5 mand it can be increased to up to 2 m inBhabar and Terai region.

The following "rule of thumb" may beapplied while fixing the size of pond.

z Small pond: small pond can be builtin privately owned land, dug by onefamily. It is mostly used for collectingrunoff from homestead area and forreducing runoff damage further down.Water thus collected will helprecharge the soil moisture. [Seeponds type 1 and 4], they are about1x1 to at the most 2x3 meters andabout 1 to 1.5 meter deep.

z Medium sized pond: it is preferableto build medium sized ponds near atap stand or at the saddle over passin the mountains. It is a commontype that fits into the requirement ofmany and fits well with available areain the mountains. The size under thiscategory could be 10 to 25 meterwide and 25 to 30 meter long. [Seepond types 2, 3, and 5]

z Large pond: suitable for foot hills andgrazing areas in the hills. Largeponds in the ridge are suitable as faras they do not reduce grazing area.Average size under this categorycould be could be 25x25 meters ormore. [See pond type 2, and 3],

however, it is always desirable tobuild small but several ponds on theridge rather than one or two big ones.

z Terai ponds: ponds in Terai can bequite large and are usually built forfish farming. Big ponds allowmultipurpose uses like Fish Farmingin combination with water used forirrigating a fairly large area andrecharging the groundwater as well[See pond type 6].

Technically recharge ponds can bemade deeper (more than 3 meter deepfrom the surface). In fact deep pondshelp hold more water in a small areaallowing continued infiltration toaugment groundwater storage. But dueto safety reason, especially where smallchildren are likely to play around, it isappropriate to make pond not deeperthan 2 meter with water level not morethan 1.5 meters when it is full. Shallowponds require large area to hold requiredamount of water, but they have largerarea as well for infiltration allowing morewater to seep in a short period. Shallowponds also allow grass to appear onlarger area around the pond, whichhelps reduce surface erosion.

3.4 Getting Started

Organized planning and construction ofponds requires a team work andcoordination among variousstakeholders. The team could includecommunities, field coordinators,engineers, technicians, constructionmasons, contractors, social

23

development officers. Water Users andSanitation Committee is an ideal localinstitution that can take the lead inconstructing recharge ponds.

3.4.1 Preparatory WorkIdentifying water scarce areasAreas that are water scarce or areasthat have shown indication of decreasingspring discharge or falling water tablesmust be identified. A good way toidentify such areas is to compare thewater discharge in water supplysystems, with design discharge rate.Generally, in water scarce areas watertaps have reduced flow, and the usersneed to wait for longer time to fill thepots.

Mapping of existing pondsNumber of the preexisting as well asnewly constructed and proposed ponds,history behind their existence, or lossand local concerns for the particularpond should be recorded systematically.Such information would help in flaggingthe number of the existing ponds andcalculate the location and number ofthem to construct further in need basedcriteria.

Prioritization of VDCs for pondconstructionListing VDC’s with specific criteria forpond construction according to recordsmade in mapping and other relevantsocial and environmental aspects, willhelp in selecting the location and thesites based on VDC’s with need basedpriorities in particular. Prioritization canbe based on few or all of the followingideas:

z Examination of local needs.z Information about landscape and

water issues at the location.z Household benefited/affected by the

water issues.z Core interest of the community and

the local authorities regarding theconstruction work on selected sites.

z Selection of communities.

Identifying linkagesFind out how proposed recharge projectcan be linked with developmentactivities of other government and non-government agencies so thatappropriate support can be sought andrequired coordination can be establishedfor potential cooperation, funding,technical support, construction, andmanagement. If there are variousagencies supporting the construction ofponds, it should be made clear fornecessary coordination. Permissionfrom forest office is usually needed toconstruct ponds in the forest area,which is usually the case in high ridgeswhere ponds are essentially importantfor recharging the groundwater.

Purpose of pondsType and size of ponds to be built aredetermined by the requirement of theiruses. If the pond is constructed only foraugmenting the groundwater, the pondsneed to be located at higher elevationsand away from the villages, but if thepond is also to be used for otherpurposes such as irrigating kitchengarden, or watering animals, then itmust be close to the villages. Similarly,if it is being built in ridge area, it isnecessary to build several ponds, ratherthan one or two big ones.

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If the pond is used for wallowingbuffaloes, it should be made in such away that animals can enter and exit thepond without damaging it. Stones mustbe paved on the slope used as entrancefor animals. Pond in such a case mustbe wide enough and not so deep.

3.4.2 The Users and their

InvolvementIt has been widely accepted that usersmust be involved in pond construction tomake them sustainable. For this, theusers must be encouraged to participatein every stage of project development.Information about local needs; varyinginterests of people; availability ofresources; and the level of localknowledge, skills, and technology willhelp make ponds more durable. It willhelp in making decision, and garnerphysical and sometimes materialsupport for pond construction. Therefore,the people must be consulted and theirpriorities and needs assessed at theplanning stage. Every member of thecommunity must be involved in thedecision making process as well as inactual construction of the ponds. Allcommunity people have an equal right toinfluence and participate in the process.

3.4.3 Equity ConcernsA recharge pond is intended to improvethe water availability and help waterusers in drier areas. But other benefitsof the ponds such as washing, irrigationare equally valuable and thus it isimportant to consider the possibledisputes it may create over thedistribution of benefits. In other words,the question of equity on the basis of

gender and other social context must beconsidered. Perhaps some group maytry to take undue favor in use of pondsuch as irrigation or fishery, and maynot involve itself in construction andmaintenance in a fairer manner. Theseshould be kept in mind during thedesign stage. Particular attention shouldbe paid to the rights and equalparticipation of people who arevulnerable and socially excluded.

3.4.4 Land TenureLand tenure issues can have a variety ofinfluences on pond construction projects.On one hand the people may bereluctant to invest in pond constructionon land which they do not own. Whereland ownership and rights of use arecomplex it may be difficult to persuadethe water users to construct ponds thatmay be used later by others who theland belongs to. On the other hand thereare examples where the opposite is thecase - farmers like to construct trenchesbecause they own the land and can usethe benefits rightfully.

The most difficult situation is that ofcommon land, particularly where nowell-defined management traditionexists. Villagers are understandablyreluctant to treat areas which arecommunally grazed.

3.4.5 Village Land-use ManagementThe question of land management byvillage communities is extremelyimportant. Degraded land in and aroundvillages can only be improved if land usemanagement issues are addressed bycommunities themselves. One of the

25

techniques which can assist inrehabilitation of degraded land iscatching rainwater - but it is only onetool among several others and cannotbe effective in isolation. Unless, forexample, grazing controls areimplemented, there is little pointspending money on pond structures.This is particularly important if pondsare constructed in grazing land, which isused by large number of people.

3.4.6 Building ConsensusIt is essential that consensus will bebuilt on all issues regarding pondconstruction. Therefore, it is importantto hold a meeting in the beginning withcommunity members. Meeting of thelocal users should be called beforemaking important decisions. If needed,

follow up meetings will be necessary toshare concerns of all in making the finaldecision about the types of ponds, sizeof ponds, and location of ponds. Suchmeetings will help understand localconcerns for more inclusive andinformed decision, while it will also helppromote the local resources andknowledge and make users moreresponsible for upkeep of the pond.

The meeting should focus on:

z Information sharingz Understanding with local concernsz Planning and construction detailsz Task assignment with designated

team leaderz Monitoring and maintenancez Dispute resolution method

26

FIGURE 9: Process Flow Chart of Pond Construction

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27

4 Practical GuidelinesPractical Guidelines

4.1 Site Selection

Selecting the site for building pond(s) isan important decision. The site shouldbe selected with clear understanding ofwhy the ponds are being built, what typeof ponds will be built, how many pondswill be built. Therefore, the time spenton selecting the site will pay dividendsin the easier management andconstruction of ponds(s). Whileselecting site for a recharge pond, localpeople should be consulted so that theirconcerns are addressed andcooperation obtained.

4.2 Location of Ponds

Ponds should be located by consideringthree factors: runoff collection, drainagechannels and safe disposal of excesswater.

4.2.1 Runoff CollectionRecharge ponds should be placed instrategic areas such as a pass or baseof slopes where run-off from around

concentrates. They are most commonlybuilt in areas comparatively flat but well-drained. The low point of a naturaldepression is often a good location. Apond can be located in a drainage wayor to one side of a drainage way if therunoff can be diverted into the pond. Thepond must be sited on suitable place sothat it can hold adequate amount ofrainwater or runoff water and remainstable when heavy rain causes overflow.

FIGURE 10: Runoff Collection(The roof of the house is guttered tocatch rain water and stored in the ponds)

28

The pond can also be located near ahouse or a school building to collectwater from the roof and open areaaround the building each time it rains.While making ponds near houses, thedepth should not be more than 1 meterfor safety reason and should be at least20-30 meters away from the building.

Pond can be built near a tap standwhere the waste water from the tap canbe collected in the pond before it flowsdown. These ponds could be of smallsize. Also the excess water from intakeor RVT can be diverted to the pond.

4.2.2 Drainage ChannelsIt is always necessary to ensure thatrunoff from around the pond is directedto the pond by shallow drainagechannel. Usually there are trails in thecatchment which divert runoff from oneplace to another. Such trails can beconnected to the pond to ensure

continued flow of runoff to pond. Figure11 is a sketch of a drainage network todivert water to ponds.

4.2.3 Disposal of Excess WaterAfter the pond is filled, excess runoffescapes through regular drainage ways.Also, consider availability of safedrainage site in the vicinity so thatoverflow from the pond can bedischarged safely and economically.

4.2.4 Locations to be Avoidedz A pond should not be located near

compost pit, cowshed, septic tanks,or along the main trail.

z It should not be built in an area thatalways stays wet.

z Don’t locate a pond close to big treesthat may collapse into the pond.

z Don’t locate it on a disputed land.z Avoid building pond in a rocky land

because it is difficult to dig.

FIGURE 11: Diverting Natural Drainage to Recharge Ponds

29

4.3 Important Design

Principles

Ponds have multiple uses and theirdesign and construction depends on thepurpose for which they are built. Thepurpose of making recharge ponds is tocatch rainwater or runoff to augmentgroundwater, and hence a person whodesigns a pond needs to adhere tosome principles as laid out below.

z A pond must be designed to promoteaugmentation of groundwater.

z To ensure recharge over a wide areait is advisable to build many smallponds rather than a few larger ones.It is about how wide area is coveredby a pond than how much water isheld within the pond.

z A pond needs to suit local needs andrequirements and be built accordingto the decision of local water users.

z A pond should not be deeper than 2meters with water depth of about 1.5meters to reduce risks to smallchildren.

z A pond should be built with localmaterials as far as practicable.

4.4 Design Details

4.4.1 Free BoardA free board of 0.5 m must be providedabove designed water level of pond tosafely accommodate sudden excessinflow to the pond.

4.4.2 Side SlopeSide slope of earthen pond should bekept as 1:2 (Vertical: Horizontal). In caseof lined pond side slope can be reducedto 1:1.5, which can be lined by stonepitching (thickness of 10cm - 15cm).Thesides can also be made vertical, inwhich case, the side should be linedwith stone wall whose thickness shouldbe at least 60cm.

4.4.3 Bottom of PondBottom of pond should be left unlined toallow infiltration for recharging of aquifer.However, it can be partially lined withdry stone pitching to reduce the rate ofinfiltration so that comparatively morewater is available for other purposes.

4.4.4 InletGenerally, runoff enters the pond fromseveral points around the pond, but ifthe runoff from a particular point such asa house or front yard of a house is to becollected in the pond, consider usingstone lined inlet or simple HDPE pipefor collecting run-off in the pond.

4.4.5 OverflowStone lined spillway can be provided foroverflow. If needed consider usingsimple HDPE pipe for draining out theexcess water above designed waterlevel (Pond level).

4.4.6 Spoil BankThe excavated earth shall be depositedaround the pond to form spoil bank. Theinside toe of spoil bank should be kept 1m away from the edge of the pond so asto create a berm. Top width of spoil

30

bank should be kept 2 m and inside andoutside slopes as 1:1.5.

4.4.7 FenceNormally, fencing is not necessary for arecharge pond, but if it is located withinor close to a village, where smallchildren are likely to get close, the pondshould be fenced with hedge plants. Theshoulder and edges of the pond must beput under suitable shrubs and grasscover. In any case, avoid a wall orbarbed wire fence.

4.4.8 RampIf the pond is to be used for wallowing ofbuffaloes, a ramp needs to be built for theanimals to enter and exit the pond. Thestones used for ramp must not have lengthsmaller than 15 cm or larger than 30 cm.The ramp must be built in such a way thatit extends to the pond floor so that therepeated tamping by the hooves of theanimals does not reduce the infiltrationcapacity of the bottom of the pond.

4.5 Number of Ponds

Recharge function by one or two pondsis ineffective in augmenting groundwater.The key is to make tens of ponds instrategic locations in a wider area. If theland is flat and has no limitation, theponds can be large. But, in Mid-hills andSiwaliks where the area available isconstrained by topography and slope,large number of small recharge ponds ispreferred instead of a few big ones.

4.6 Official Permits

Usually ponds are built on public landswhich are either under the authority of

the VDCs or the District Forest Office.Many of such public land are also likelyto be part of community forests orleasehold forests. In such casespermission from the concerned groupsand authorities must be obtained beforebuilding ponds.

4.7 Time for Construction

There is no specific time for makingponds. They can be built at any time ofthe year, but it is appropriate to makethem before the onset of monsoon sothat they can store rainwater during thewhole monsoon. The advantage ofmaking the before the rainy season isthat it allows adequate amount of time forgrass to grow on the freshly depositedsoil on the spoil deposit, which will helpstabilize the outer area of the pond. Apond constructed before the monsoonwill have entire monsoon period toexperience the rain and runoff impact.One can monitor if there are any weakpoints from where the pond can break, orwater leak, in which case repair andmaintenance can be done in time.

4.8 Construction Materials

If the pond is going to be lined, stones forlining the pond would be collected. Thestones would be normal size that can beused in making the lining. If there are oddsize stones, they need to be chiseled togive desired shape. If erosion controlmeasures are also planned, it isnecessary to identify source of plantmaterials. Tree seedlings are availablefrom the nursery of forest offices. Thegrass seedlings can be collected from

31

either a nursery of from farmers’ field. Listof suitable grass species is given in theannex 1.

4.9 Tools RequiredDigging tools such as spades and picksare enough for making pond. The spoilneeds to be safely deposited on theshoulder, for which simple burlap sackscan be used.

4.10 Choosing a Lining

A recharge pond needs to allow storedwater to seep into the soil. Therefore thepond bed is generally left unlined to allowregulated infiltration for a long period.However, in the initial years the bed of thepond is generally quite porous and waterseeps in very fast. The pond dries fast.When it dries fast, the recharge functionalso stops.

As the pond gets old, the silt getsdeposit at the bottom, which thenreduces the infiltration rate. Water in thepond will be available for a longer periodproviding recharge functions for a longerperiod. The bed can be lined with stonesleaving sizable gaps in between thestones. Stone lining on the bottom alsofacilitates cleaning pond regularly withoutfurther deepening it.

Lining on wallsIf a pond needs lining to save its sideslopes from collapsing stone masonry isuseful. If seepage from the side slopeshas to be reduced, then cement lining isrequired on those slopes. It can be usedin combination with stone lining withouter part lined with cement

Lining on the floorIf in case the infiltration at the bed isunlikely to decline even after few years,which generally happens in places wheresoil is made up of coarse material, thepond bed requires partial lining.

4.11 Plant Material for

Slope Stabilization

Spoil material deposited on the outerslopes of the pond is generally looseand needs to be protected againsterosion. The most appropriate method ofstabilizing such slopes is to usebioengineering methods such as brushlayering, fascines and live staking. Ofcourse, there are other techniques thatcan be used, but for a quick andeffective result, it is recommended touse brush layering and fascines (Seeannexes 2 and 3).

It is always good to have shade over thepond especially for small ponds whereevaporation loss can be very high. Theshade can be provided by plantingshrubs around the pond. Pond will allowgrass to appear on the shoulder of thepond. The grass must be maintainedbecause it helps reduce erosion andenhance aesthetic view of the pond.Grass can also be planted on the outerslopes to protect the pond from erosion.If planting is planned, it needs to be donein the beginning of the monsoon seasonpreferably in early July, when the soil iswet and allows plants to get establishedbefore the monsoon ends. The suitableplants species are given in the annex 1.

32

4.12 Maintenance

The pond should be inspected periodi-cally. It should be examined after heavyrains to determine whether it is function-ing properly or needs minor repairs. Anydamages should be repaired immedi-ately to avoid the need for more costlyrepairs later. The damage may be small,but if neglected it may increase untilrepair becomes impractical and theentire structure must be replaced.

A pond, no matter how well planned andbuilt, must be adequately maintained ifits intended purposes are to be realizedthroughout its expected life. Propermaintenance extends ponds’ useful life.Maintenance of pond involves two majoractivities: (1) maintaining the lining andside slopes, and (2) cleaning the floor ofdeposited sediment.

Maintaining the Lining and Side SlopesStone lining provided around the pond islikely to be damaged by human activity orby animals walking over it. Sometimes thewalls also collapse due to activities ofrodents and crabs in the dry season. Ifthey are damaged, they should be main-tained immediately. If unlined lopes havecollapsed due to erosion from inside, theyshould be fixed by redoing the slopes.,

Cleaning the Floor of Deposited SedimentDeposition of sediment in the pondreduces pond’s capacity to hold waterand hence is a major problem in maintain-ing the pond. Ponds keep accumulatingsediment during the monsoon. Runoffitself brings sediment from surface erosionin the catchment or from the scouring ofthe channel during heavy rainfall events.The sediment thus transported by runoff

eventually is deposited in the pond. Heavysediment fills the pond in a short period.Generally the ponds need to be cleanedand sediment removed every two to threeyears. Sediment should be removed fromthe pond when the depth of deposition ismore than 30 cm.

The flowing can be done to minimizesedimentation:

Sediments can be reduced by carefuldesign of runoff channel or trails that divertwater to the pond. Diversion and intakestructures should be made so as tominimize input of silt to the ponds. Keep agood cover of grasses in the run-off area.

In larger ponds such as Terai ponds,constructing ridges on the floor of thepond and controlling water level canallow fine silt to deposit in troughs,allowing most infiltration to take placeon the sides of the ridges. If removingthe sediment is difficult in large areas,mechanical ploughing of the floor of thepond can also increase permeability.

4.13 Conservation

Works in the Upper

Catchment

If the ponds are made away from thevillages, it is recommended to protect thecatchment area of recharge pond againsterosion by applying soil conservationtechniques, such as landslide stabiliza-tion, gully stabilization, plantation etc. Inaddition to this, networking with theForestry Groups and other actors in thecatchment area for better ConservationWorks should be done.

33

5 Pond ConstructionPond Construction

5.1 Design Layout

From purely engineering consideration,the recharge ponds are of two differenttypes; the first is an unlined dug outpond with sloping sides and the other iswith vertical sides lined with stonemasonry. The plans and cross sectionsof these two generic types of ponds aregiven below (Figures, 12 and 13). Thesecan be taken as reference designlayouts in guiding the design in the fieldwhich can assume different shapes andsizes depending upon the location andpurpose.

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34

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FIGURE 13: Generic Type 2. Stone LinedPond

5.2 Steps for Pond

Construction

Once the size, shape and type of pondis finalized, and site for construction islocated pond construction can begin.The following are the key steps for pondconstruction.

5.2.1For Unlined Pond (no stone

walls from inside)1 Make sure that work is divided

among the workers, who will do thedigging and who will take the spoilout of the pit.

2 Outline the shape on the surfacewhere you want to make ponds usinga rope and pegs.

3 Dig out the pit using local tools suchas spade and picks.

4 Make sure that the side slopes frominside are maintained while makingthe pit.

5 Deposit the spoil on the shoulderaround the pond and beginning withthe lower side.

6 If the slope is steep, start depositingspoil from the lower end and packevery layer properly as you proceed.

7 If internal shelve is also plannedmake sure to create internal shelvesfor planting.

8 Use a plank to pack the spoilproperly.

9 Plant grass and shrubs as a surfacecover on the fresh spoil deposit.

5.2.2 For Stone Lined Ponds1 Required quantity of stones of proper

size and shape are collected forlining and stored nearby pond site.

2 Work is divided among the workersfor digging and taking the spoil out ofthe pit.

3 Outline the shape on the surfacewhere you want to make ponds usinga rope and pegs.

4 Dig out the pit using local tools suchas spade and picks.

5 For a lined pond the side slopes frominside are generally vertical.

6 Make sure that the side slopes aremade vertical while making the pit.

7 Deposit the spoil on the shoulderaround the pond and beginning withthe lower side.

8 If the slope is steep, start depositing

35

spoil from the lower end and packevery layer properly as you proceed.

9 Once the pit is dug to the requireddepth, dig foundation for the stoneline from inside about 20 cm deepfrom the bed level around the pit.

10 Build the stone wall as per thedesign as lining around the pondgiving it the required slope around thepond.

11 Plant grass and shrubs as a surfacecover on the fresh spoil depositoutside the pond.

5.3 Investment Planning

Estimate

Table 6, below is a recommended formatfor calculating the work volume and costestimates for constructing simple dugout pond and stone masonry work inmud mortar.

TABLE 6: Format for Quantity and Cost Estimation for Pond Construction

………………….. VDC/Municipality, Nepal

Detail Estimating and Costing Sheet

Project Name:Fiscal Year :Site:Date:

Note: In the column of Amount, the figure is computed by multiplying rate and quantity. The rate should be as per VDC/DDC/Municipality norms or as per authentic norms.

S.N. Description of work No. Length

(m) Breadth

(m) Height

(m) Quan-

tity Unit Rate (Rs/m3)

Amount (Rs.) Remarks

1 Earth work in excavation

1 10.00 5.00 2.30 115.00 m3 X

2 Stone masonry work in mud mortar

Long walls- 1st step

2 11.20 0.60 1.30 8.74 m3 L= 10+0.6+0.6=11.2

2nd step 2 10.80 0.60 1.30 8.42 m3 L=10+0.4+0.4=10.8

Short walls- 1st step

2 5.00 0.40 1.00 2.00 m3

2nd step 2 5.00 0.40 1.00 2.00 m3

21.16 Y

Total amount X+Y

�

36

5.4 Guidelines for

Selecting Ponds Types

As explained earlier, the types, shapesand sizes of recharge ponds varydepending upon the location. The matrixbelow (Table 7) provides a simpleguideline for selecting appropriate typeof pond for a particular situation. Thefirst column refers to the rainfallcharacteristics of the area categorizedinto either high or low rainfall areas. Thesecond column refers to the slope of the

site where the pond is to be located.Three landform types depending on theslope are envisaged: 1) the top of a hillor a ridge 2) the middle slope where theslope is moderately steep to steep; and3) the relatively flat valley floor or lowerslope in case of the hills and the plainsin the Terai. The third column queriesabout the size and number of ponds tobe built, and the fourth column refers tothe pond design type described in detailin individual sheets in the next section(Pages 37 to 44).The fifth columnprovides additional remarks.

TABLE 7: Guidelines for Selecting Appropriate Recharge Pond Types

Rainfall Slope Size and number of pond

Design type

Page numbers

Remarks

Ridge Top Small but many 1, 7 37, 43

Middle Few 3, 4, 5, 7 39, 40, 41, 43

Ensure safe disposal through spillway

High rainfall

Valley/Plains Large and few 2, 4, 6 38, 40, 42

Ensure safe disposal through spillway

Ridge Top Shallow, small, many

1, 8 37, 44

Middle Shallow, many 3, 4, 5 39, 40, 41

Collect water from surrounding area through drainage

Low rainfall

Valley/Plains Large and few 2, 6 38, 42 Collect water from surrounding area through drainage

37

Type No. 1 Area: Ridge area pond Size : 10 m x 10 m Suitable for Mid-hill, Mahabharat and Siwalik regions.

Layout Staggering with spacing at more than 20 m between each other

Location On the slopes or in the small valleys of the ridge area

Runoff collection

From around the pond

Spoil deposit Usually on side valley or around the pond

Maintenance Every 3-4 years Lining on the sides

Not required

Lining on the floor

Not required

Materials: Not required Tools: Agriculture tools for

digging

Construction Steps: x Select the site in the ridge area, which are usually open and gently sloping. x Clear the pond area of all undesired vegetation. x Mark the location of ponds which are placed in a staggered manner. x The ponds are usually round or oval in shape. The size can be about 10m diameter, but

depends upon area available. x Mark the outside limits of the proposed excavation with stakes. On the stakes indicate the

depth of cut.x Dig the pond to a depth of about 1.5 meters. x Deposit the spoil around the pond or on the lower side. x Compact the soil in layers while making spoil bank. x Make small drainage channels from around the pond to direct runoff to the pond. x Leave space in spoil bank as spillway for overflow during heavy rain. x While making spillway, ensure that the runoff does not cause erosion on the lower slopes.

5.5 Design Descriptions of

the Recharge Pond Types

38

Type No. 2 Area: Foot hill (water impounding)

Size : Variable

Suitable for streams at the Foot Hills.Layout Not required because of

limited number of ponds made by erecting small dams

Location No specific location. Any place suitable on a stream to catch water, but away from main trail

Runoff collection

Divert from gullies to pond if stream is small

Spoil deposit Around the pond with good bioengineering

Maintenance Every yearLining on the sides

Not required if the dam is wide enough with gentle slopes on both sides. Lining from inside may be required if the slope is less than 1:1.5

Lining on the floor

Not required

Materials: Stones, clayey soil Tools: Agriculture tools for digging

Construction Steps: x Select the site in the stream valley where water impounding is feasible and can be used for

irrigation. It is usually suitable for low gradient streams in the hills or in Bhabar region. x Mark the line where the dam will be created. x The dam needs to be long enough to block stream water for impounding. x Dig the foundation of the pond. x Build the dam, which could be earthen dam with stone lining from inside. x Construct masonry structure from inside of the dam. x Provide overflow pipe to safe drainage point or irrigation channel.x Plant grass and trees toward the end of the dam on both sides on the dam if required.

39

Type No. 3 Area: Community pond in the village

Size : 20 m x 25 m

Suitable for villages in Mid-hills and Siwaliks.Layout Only one Location Away from houses and

without any risk to them, but must be accessible for all

Runoffcollection

Divert from homesteads

Spoil deposit Around the pond Maintenance Every yearLining on the sides

Partial lining is necessary if water is to be retained for other purposes, such as buffalo wallowing.

Lining on the floor

Not required

Materials: Stones, clayey soil Tools: Agriculture tools for

digging

Construction Steps: x Select a site close to the village and in a place accessible to all community members. x Mark the outside limits of the proposed excavation with stakes. On the stakes indicate the

depth of cut. x Mark the size as planned but should not be bigger than 20-25 m in diameter or on the sides. x Mark the inside limits of the proposed spoil bank for disposal of excavated material to form

Bank around the pond. x Excavate the pond area (about 1.5 meters deep).x Construct masonry structure in case side slopes of pond are lined. x Leave space in spoil bank for constructing inlet and overflow structures. x Deposit the spoil around the pond or on the lower side. Compact the soil in layers while

making spoil bank.x Make small drainage channels from around the houses and direct the runoff to the pond. x Collect the runoff from the front yard of the houses also to the pond. x Ensure that the overflow is directed to a safe drainage point.x Plant grass and trees on the spoil bank by using appropriate method as given in annex 2-4.

40

Type No. 4 Area: Private pond Size : 2 m x 3 m (max)

Suitable in all physiographic regions.Layout Only one per

householdLocation On terraces in front

of the house but at least 20 m away from the house

Runoff collection Divert from roof top and homestead

Spoil deposit On the terrace Maintenance Every yearLining on the sides Preferable, but not

compulsoryLining on the floor Not required Materials Stones, clayey soil Tools Agriculture tools

for digging Construction Steps: x Select the site on the second terrace in front of the house for pond construction. x Mark the line that will be the boundary of the pond. x Excavate the pond area to a depth of about 1.5 meters.x Deposit the spoil around the pond or on the lower side. Compact the soil in layers while

making spoil bank.x Construct masonry structure in case side slopes of pond are lined. x Make small drainage channels from around the house and direct the runoff to the pond. x Collect the runoff from the front yard also to the pond. x Plant perennial vegetables (Tamatar, Ishkus) or spices (DalleKhursani, Cardamom) on the

banks.

41

Type No.5 Area: Pond for tap water collection

Size : 1.5 m x 10 m (max)

Suitable for all physiographic regions.Location In front of the tap

stand and bit below it

Runoffcollection

Waste water from the tap and runoff from around the slope

Spoil deposit On the lower side slope

Maintenance Every yearLining on the sides

Required

Lining on the floor

Not required

Materials: Stones for lining Tools: Agriculture tools

for digging, mason tools

Construction Steps: x Select the site in front of the tap stand about 3 meters away from it so that the pond does not

disturb the tap users. x Mark the line that will be the boundary of the pond. The length can be as much as the space

allows, but the width is generally 1.5 to 2.5 meters. x Excavate the pond area to a depth of about 1 meter.x Deposit the spoil on the lower side of the pond. Compact the soil in layers while making spoil

bank.x Construct masonry structure to line the pond with stones. x Make small drainage channels from around the tap stand and direct the runoff to the pond. x Plant woody plants on the lower slope, if the slope length is longer than 2 meters.

42

Type No.6 Area: Terai ponds Size : 50 m x 100 m (often variable)

Suitable for Mountain Valleys, Bhabar and Terai regions.Location Accessible

to users and close enough to regular supervision

Runoff collection

Runoff fromaround

Spoildeposit

On the sides

Maintenance Every 2 years

Lining on the sides

Notrequired

Lining on the floor

Notrequired

Materials: Clayey soil for bunds

Tools: Agriculture tools

Construction Steps: x Select the site in the village where public land large enough is available where water

harvesting is possible. It could be a grass land or forest area. x Mark the line that will be the boundary of the pond. The length can be as much as the space

allows. x Large ponds are generally square of rectangular in shape. x Excavate the pond area to a depth of about 3-4 meter depending upon the purpose for which it

is being built. For fish farming the depth of the ponds need to be fixed after consultation with agriculture technicians of the area.

x Deposit the spoil on the side of the pond. Compact the soil in layers while making spoil bank.x Allow spillways in suitable points for overflow.

43

Type No. 7 Area: Contour Trenches Size : 1.5 m x 10 m (max)

Suitable for Mid-hill, Mahabharat, and Siwalik regions.Layout On a contour at a

spacing of about 2 meter

Location Away from home on grassland and forest areas

Runoffcollection

Runoff from the slope

Spoil deposit On the lower side slope

Maintenance Every yearLining on the sides

Not required

Lining on the floor

Not required

Materials: Stones, clayey soil Tools: Agriculture tools

for digging

Construction Steps: x Mark the alignment of trench using a stick of about 2 m length along the contour. x Clear the trench area of all undesired vegetation. x Restrict the length to about 5 meter maximum. x If longer trench are to be built, break them into 5 meter each with a clear boundary of about 2

meters undisturbed slope in between the trench to avoid large amount of water on shallow trenches.

x Excavate the trench to about 75 cm depth and 1 m width and make spoil bank as per drawing. x Deposit the spoil on the lower side slope. x Compact the soil while making spoil bank. x Ensure safe points for overland flow.

44

Type No. 8 Area: Eyelash Trenches Size : 2 m x 2 m (max)

Suitable for Mid-hill, Mahabharat, and Siwalik regions.Layout Placed on a staggered

manner on a contour at a spacing of about 2 meter from each other

Location On gently sloping grassland and forest areas

Runoff collection

Runoff from the slope above

Spoildeposit

On the lower side slope as back of the trench

Maintenance Every yearLining on the sides

Not required

Lining on the floor

Not required

Materials: NoneTools: Hand tools for digging.

Construction Steps: xxxx Mark the positions of each trench at a spacing of about 2 meter from each other and on

contour. xxxx Clear the trench area of all undesired vegetation. xxxx The length should not be more than 2 meters. xxxx Mark the trench on the ground in such a way that they form an arc with convex part facing

the lower side of the slope. xxxx Dig the trenches to about 50 cm depth and 1 m width. xxxx Deposit the spoil on the lower side slope. xxxx Smoothen the spoil for grass cover.

45

1 AnnexAnnex

Suitable and Commonly Available

Plants for Slope Stabilization in

Nepal

Shrubs and grasses must be plantedaround the edges of the ponds, espe-cially on the sides that are filled withspoils from excavation to help stabilizethe soils and protect the sides of theponds. Some medium sized trees may

sometimes be planted a little furtheraway from the pond so that theyenhance the aesthetics of the generalarea and cast shadows over the pondsand reduce evapotranspiration, butgenerally trees are not recommended forpond protection.

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S.N. Elevations (m) Trees Nepali Name Botanical name

1 T- 1900 Chuletro (seto) Braesaiopsisnainla 2 800- 2000 KalkiPhul Callistemorcirinus 3 950- 1900 Sissoo Dalbergiasissoo 4 T- 1400 Phaledo Erythina spp. 5 T- 1700 Lankuri Fraxinus floribunda 6 1200- 2700 Dabdabe Garugapinnata 7 T- 1300 Kangiyo Grevillearobusta 8 T- 1800 AsharePhul Lagerstroemia parviflora 9 T- 1800 Sitalchini, Sohijan Noringaoleifera 10 T- 1000 Kimbu Morus alba 11 T- 2400 Amala Phyllanthusemblica 12 1000- 1700 Painyu Prunuscerasoides 13 100- 2500 Bainsh Salix spp. S.N. Elevation (m) Bushes/Shrubs 1 T- 1500 Assuro Adhatodavasica 2 1500-3000 Ban Chutro Berberisaristata 3 900- 2500 Chutro BerberisAsiatica 4 T- 1600 Bagamkali Bougainvillea Spaetabilis 5 T- 1600 Nilkanda Durantarepens 6 900- 1800 Siuli. Siudi Euphorbia royleana 7 T- 1000 Bihaya. Besharm Ipomeafistulosa 8 T- 1600 Sajiwan Jatrophacurcas 9 T- 2100 Bilouni Maesachisia

S.N. Elevation (m) Legumes/ Herbs

1 T- 1500 Stylo Stylosanthesguianensis 2 Palpa Ban Silam Eisholtziablanda 3 Palpa Arile Kanda Caesaliniadecapetata 4 800- 1500 Khasre - S.N. Elevation (m) Suitable Grasses 1 T- 1800 Dubo Cynodondactylon 2 500- 2000 Salimokhar Chrysopogongryllus 3 T-1800 Babiyokhar Eulailopsisbinnata 4 500- 2000 Kikuyu Pennisetumclandestinum 5 T- 2000 Amlisso, Amrisso, Kucho Thysanolaena maxima 6 500- 1800 Bansoghans Eragrostistenella 7 T- 2000 Narkat Phrageites maxima �

47

2Stabilization of Loose and Deep Slope

Brush layering:Stabilizing shallow loose soil slopes onthe valley side slope of a pond. Benchesare excavated in the loose slope,branches of vegetatively propagatedplants such as willow are laid, on aslight angle, on the benches; branchesare covered with soil, with just the tipssticking out.

Construction Steps:z After the spoil is deposited and

compacted it should be treated withbioengineering method forstabilization especially on the lowerside slope of the pond where spoildepth is more than 30 cm.

z To begin the vegetative treatment ofbrush layering, start the processfrom bottom of the slope.

z Collect enough branches ofvegetatively propagated plantmaterial.

z Prepare the branch of about 100 cmlength each from freshly cut pieces.

z Once the branches are ready, makea bench of about 70 cm width on aslight slanted way across the slope

on a contour.z Place the branches on the bench

with tips facing outside the slope atan angle as shown in the figure andcriss-cross with each other.

z Make sure that 20 % of the top of thebranch is sticking out of the slope.

z Mark another bench about a meterabove the first one on the slope andmake the bench. Spoil removed fromthe second bench should be used tocover the branches of the first bench.

z Repeat the process of making benchand putting branches up to the top ofthe slope.

z Water the slope until the rainfalloccurs.

AnnexAnnex

48

3

Stabilization of Shallow Slope

Fascine:Stabilizing shallow loose soil slopes onthe valley side slope of a pond. Benchesare excavated in the loose slope,branches of vegetatively propagatedplants such as willow are laid, on aslight angle, on the benches; branchesare covered with soil, with just the tipssticking out.

Construction Steps:z Collect vegetative propagated

branches of over a meter length froma freshly cut branches in enoughquantity.

z Tie about 20-30 branches togetherwith rope as shown in the drawing toform bundle of about 15 cm diameter.

z Mark a channel across the slopestarting from the bottom in thefreshly deposited spoil.

z Dig the channel to about the samedepth as the diameter of the bundle.

z Place the bundle in the channel in

such a way that the bundle is barelyvisible on the surface.

z Drive wooden pegs at every 2 meterto fix the bundle.

z Repeat the process in the nextchannel about 1 meter above fromthe first one.

z Water the slope to keep moist untilthe rainfall occurs.

AnnexAnnex

49

4Greening Bare Slopes

Live Stakes:Greening and stabilizing shallow loosesoil slopes on the valley side of a pondwhere runoff is less likely to erode theslope. This technique is simple andrequires no further earthwork as in brushlayering or fascine.

Construction Steps:z Begin the treatment just before the

monsoon.z Take live branches of about 1 meter

length of one year old vegetativelypropagated plant.

z They should be prepared from afreshly cut branch.

z The branches should be driven intothe slope on a contour. The cuttingsshould be driven at every 60 cm fromeach other.

z The space between the lines can bemaintained at about 1.5 – 2 meters.

z If the treatment is done in March,which is favorable for most vegeta-tively propagated plants, the cuttingsneed to be watered regularly untilrainfall occurs.

AnnexAnnex

50

51

August Spring: Late breaking spring in the upper parts of a watershed. It be(SauneMool) comes active only towards the later part of the monsoon

season.Bhabar Region: An 8 to 10 Kilometer wide strip at the foothills of the Chure

rangeand adjacent to the Terai plains. It mainly consists of thecoarse sandy soils and boulders and gravels at depth.

Braided: One of a number of channel types and has a channel thatconsists of a network of small channels separated by small andoften temporary islands called braid bars.

Brush Layering: A bioengineering method used to stabilize shallow loose soilslopes on the valley side slope of a pond. Benches are exca-vated in the loose slope, branches of vegetatively propagatedplants such as willow are laid on a slight angle, on thebenches; branches are covered with soil, with just the tipssticking out.

Bursting of Springs The time when a spring becomes active and starts to discharge(MoolPhutne): water.Chure Region: Please see "Siwalik Region"Contour Trench: A trench made along a contour (a line with equal elevations)

across a slope to collect runoff from above.Dallekhursani: Nepali name for small round chilli.Doon: Flat valleys within the Siwalik physiographic region, also called

‘inner Terai’Drainage Channel: Natural or artificial removal of surface and sub-surface water

from an areaDrip Irrigation: An irrigation method that saves water and fertilizer by allowing

water to drip slowly to the roots of plants, either onto the soilsurface or directly onto the root zone, through a network ofvalves, pipes, tubing, and emitters

Dug out pond: Please see "excavated pond"

GlossaryGlossary

52

Earthen Dam: A massive artificial water barrier built to impound water.Embankment Pond: A pond made by impounding water by building a small dam

across a flowing stream.Equity: The value of an ownership interest in property, including share-

holders' equity in a business.Evapotranspiration: Sum of evaporation and plant transpiration from the Earth's land

surface to atmosphere.Excavated Pond: A ponds built by excavating earth from the ground and with or

without linings on the sides and the bottom.Eyelash Trench: Small trenches built in the shape of eyelashes across a slope

to collect runoff from above.Fascine: Rough bundle of brushwood or other material used for strength-

ening an earthen structure.Gorge: A deep ravine between cliff s often carved from the landscape

by a river.Gullies: Landform created by running water, eroding sharply into soil,

typically on a hillside. Gullies resemble large ditches or smallvalleys, but are meters to tens of meters in depth and width.

Iskhus: Nepali name for chayote.July Spring(AsareMool): Early breaking spring, usually on the lower parts of a water-

shed. It becomes active soon after the monsoon starts.Land tenure: The legal regime in which land is owned by an individual, who is

said to "hold" the land.Mahabharat Region: A mountain range consisting of narrow valleys, steep slopes

and sharp peaks that lies just north of the Chure or Siwalik hillsand to the South of the mid-hills.

Masonry: A stone or brick work to build structures from individual unitslaid in and bound together by mortar.

Meander: Formed when the moving water in a stream erodes the outerbanks and widens its valley and the inner part of the river hasless energy and deposits what it is carrying.

Mid-hill Region: The hilly region of Nepal that lies between the high mountainregion in the North and the Mahabharat range in the South.

Mool: A Nepali term for spring.Permanent Springs(SthaiMool): A spring that remains active throughout the year.Piedmont plains: Piedmont Plains are those plains which are found on the foot of

mountains or hills. Piedmont Plains are formed by the deposi-tion of materials.

Pond: A body of standing water, either natural or man-made, that isusually smaller than a lake.

53

Post-monsoon A brief period of scattered rains during mid-August to September,season: just after the main monsoon season.Pre-monsoon A short season (April-May) characterized by scattered rains andSeason: thundershowers that occurs just before the main monsoon

season.Rain Water Accumulation and deposition of rainwater for reuse before itHarvesting: reaches the aquifer.Recharge Pond: A pond built for the purpose of recharging the groundwater by

collecting rain water.Runoff Harvesting A pond used for collecting water from different sources likePond: springs, streams, tap water, and rain for future use.Scouring: Washing away of materials from the bed and sides of a stream

or river by the rapidly flowing water.Shallow Ponds: Ponds that are usually less than one meter deep used primarily

for watering livestock and wallowing for buffaloes and can beused as recharge ponds.

Siwalik Region: A system of fragile hills just North of the Terai plains andmerges with the Mahabharat range in the North. It also containsthe inner Terai valleys (locally called Doons) like the Chitwanand Dang valleys.

Slope Failure: Geographical phenomenon which includes a wide range ofground movement, such as rock falls, deep failure of slopes andshallow debris flows.

Spillway: A structure used to provide the controlled release of flows froma dam or levee into a downstream area.

Spoil Bank: Pile of refuse, created by excavation of earth materials from asite.

Springs: A natural source of water.Sprinkler Irrigation: A system of irrigation that uses water under pressure to operate

sprinklers to water plants; mainly used for vegetables, highvalue crops, and gardens.

Surface Erosion: Degradation and removal of the soil by water, wind or gravity.Tamatar: Nepali name for tomato.Terai Region: The flat plains bordering India in the South and the Chure hills in

the North. The region contains deep and fertile soils and isoften referred to as the bread basket of Nepal.

Trans-Himalayan The hills and plateaus to the North of the main Himalayan range.Hills and Plateaus:Water Tower: The height or rise of groundwater table when it gets fully

recharged.Watershed: The region draining into a river, river system, or other body of

water.

54

A model Guideline for District Water Supply for Sanitation and Hygiene (WASH), Rural WaterSupply and Sanitation Project- Western Nepal (RWSSP-WN), Pokhara, 2009.

Handbook for Bio-Engineering Methods in Gully and Landslide Stabilization works,Lamosangu- Jiri Road, Charnawati Rehabilitation Programme, Phase III; HMG/N/SDC, 1990.

Land Systems Report, Land Resource Mapping Project (LRMP); Kenting Earth Science Ltd.,1986.

Log-frame of the Department of Soil Conservation and Watershed Management Programme;Department of Soil Conservation and Watershed Management, Kathmandu, 2007.

Pahadi Chhetrama Paani Intajaam, A. Dixit, Upadhya M., Tamrakar A., Nepal Paani SadupayogFoundation, Kathmandu, 2062 BS.

Pokhari ra Pahiro, Madhya Pahadi Chhetrako Paani- Sanskriti, Khadya Pranaali ra Bhu-Kshayako Artha-Raajniti, M.Upadhya, Nepal Water Conservation Foundation,Kathmandu, 2009.

Ponds and Landslides: Water culture, food systems and the political economy of soil conser-vation in mid-hill Nepal; M. Upadhya, Nepal Water Conservation Foundation,Kathmandu, 2009.

Soil Conservation and Watershed Management Activities (definition, objective, scope andworking strategy); Department of Soil Conservation and Watershed Management,Kathmandu, 2001.

Soil Conservation and Watershed Management Measures and Low cost Techniques, SoilConservation and Watershed Management Component (NARMSAP); Department ofSoil Conservation and Watershed Management, Kathmandu, 2004.

Three Year Interim Plan (2007/08 - 2009/10); National Planning Commission, Government ofNepal, Kathmandu, 2007.

Hyperlinkshttp://www.moir.gov.np/pdf_files/irrigation_policy_2060.pdfhttp://www.dolidar.gov.np/about-dolidar/function/http://www.rwsspwn.org.np/materials/guidelines-manuals-and-normshttp://www.dolidar.gov.np/programme-projects/western-nepal-rural-water-supply-and-sanitation-project.

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