CHAPTER- I

ABOUT IIWM

Introduction

The ICAR Indian Institute of Water Management (formerly Directorate of Water Management) was established by the Indian Council of Agricultural Research on 12 May 1988. The Institute aims to develop improved water management technologies for sustainable agricultural production and disseminate it amongst researchers, government functionaries, NGOs and farmers. The Centre is located at Chandrasekharpur, Bhubaneswar on a 5.71 ha of land along with its main office cum laboratory building, guest house and residential complex. Research farm of the Institute (63.71 ha of farm land) is located at Deras, Mendhasal whichis at 30 km away from main campus.

VISION

Sustainable development of water management technologies for enhanced water and agricultural productivities and improved livelihoods

MISSION

Basic, applied and strategic research to address water management issues with institutional linkages, infrastructural support and capacity building for achieving sustainable growth.MANDATE

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To undertake basic and applied research for developing strategies for efficient management of on farm water resources to enhance agricultural productivity on sustainable basis.

To provide leadership role and coordinate network of research with the state agricultural universities in generating location specific technologies for efficient use of water resources.

To act as a center for training in research methodologies and technology update in the area of agricultural water management.

To collaborate with the national and international agencies in achieving the above objectives.

PROGRAMMESIndian Institute of Water Management conducts its research activities in the field of agricultural water management through five Research Programmes as follows:

Rainwater Management Programme Canal water Management Programme Groundwater Management Programme Waterlogged area Management Programme On farm research and Transfer of Technology Programme

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CHAPTER-II

DESIGN OF CREEK SECTION

Creek irrigation:

A tidal creek, tidal channel, or estuary is the portion of a stream that is affected by ebb and flow of ocean tides, in the case that the subject stream discharges to an ocean, sea or strait.

A tidal creek, tidal channel, or estuary is the portion of a stream that is affected by ebb and flow of ocean tides, in the case that the subject stream discharges to an ocean, sea or strait. Thus this portion of the stream has variable salinity and electrical conductivity over the tidal cycle. Due to the temporal variability of water quality parameters within the tidally influenced zone, there are unique biota associated with tidal creeks, which biota are often specialised to such zones.

Creeks may often dry to a muddy channel with little or no flow at low tide, but often with significant depth of water at high tide. A tidal creek, tidal channel, or estuary is the portion of a stream that is affected by ebb and flow of ocean tides, in the case that the subject stream discharges to an ocean, sea or strait. Thus this portion of the stream has variable salinity and electrical conductivity over the tidal cycle.

Salinity changes at the scale of tidal creeks occur in response to runoff events. Lerberg (1997) examined water quality in tidal creeks of the Charleston Harbor estuary and found that salinity varied within creeks, among creeks, and among watershed classes. He found that tidal creeks were much more dynamic than most large estuaries and experienced salinity fluctuations greater than 6 ppt over a tidal cycle. Lerberg (1997) also found that the variance in salinity, as represented by the salinity range, was greater in creeks surrounding suburban, urban and industrial land uses, than those that were forested upland creeks. These changes in salinity variance were related to increased amounts of impervious surface at the anthropogenically impacted sites. Increased amount of impervious surface alters hydrodynamic processes, especially the rate at which runoff from rainfall events reaches receiving waters. Extreme and highly variable fluctuations in the salinity pattern are an indicator of hydrodynamic changes to tidal creeks resulting from watershed development. Saltwater encroachment can occur in the coastal environment from salt water displacing or mixing with fresh water in an aquifer (Todd 1980). Encroachment of salt water can be caused during drought conditions or through over pumping of fresh water from an aquifer. When this happens, fresh water ceases to flow into the ocean and additional salt water begins to enter the aquifer. Several methods can be employed to control saltwater encroachment including modification of pumping patterns,

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artificial recharge, extraction barriers, subsurface barriers, and saline scavenger wells (Todd 1980). A number of areas have been forced to deal with salinization of their ground water because of saltwater encroachment. Miami, Long Island, and Los Angeles in the United States (Todd 1980) and Lincolnshire, Kent, and Sussex in Great Britain are just a few of the cities forced to deal with this problem. In addition to groundwater usage problems, saltwater encroachment can cause an increase in saltwater intrusion of surface waters by cutting off freshwater supplies, thereby affecting fish and other aquatic organisms. This type of saltwater intrusion of surface waters occurred in the Sacramento-San Joaquin Estuary in the late 1970s (Wilson 1982). Coastal water resources management integrates surface-groundwater-seawater interactions which is associated with hydro geological, ecological, and environmental problems. Most research on the interaction between groundwater and seawater has concentrated on saltwater intrusion (Calvache and Bosch 1994). Li and Jiao (2003a, b) noted that research on tide induced coastal groundwater-level fluctuation has played an active and crucial role in improving understanding of the interaction between groundwater and seawater.

Design of creek irrigation system

Introduction:-

Open Channel flows deal with flow of water in open channels

Pressure is atmospheric at the water surface and the pressure is equal to the depth of water at any section

Pressure head is the ratio of pressure and the specific weight of water

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Elevation head or the datum head is the height of the section under consideration above a datum

Velocity head (=v2/2g) is due to the average velocity of flow in that vertical section

Types of channels:-

Man made Channel designed and made by human Examples: earth or concrete lined drainage and irrigation Prismatic channel (no change in geometry with distance)

Natural Examples: River and streams Changes with spatial and temporal (non prismatic channel)

Other types of channel

• Lined channels – minimizing lining material costs•Unlined channels – maximum permissible velocity and threshold of movement (stable hydraulic section)

Lined canal Unlined canal

Geometric properties necessary for analysis:-Depth (y)– the vertical distance from the lowest point of the channel section to the free surface.Stage (z) – the vertical distance from the free surface to an arbitrary datumArea (A) – the cross-sectional area of flow, normal to the direction of flowTop width (T) - the width of channel section at the free surfaceWetted perimeter (P) – the length of the wetted surface measured normal to the direction of flow.

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Surface width (B) – width of the channel section at the free surfaceHydraulic radius (R) – the ratio of area to wetted perimeter (A/P)Hydraulic mean depth (Dm) – the ratio of area to surface width (A/B)

Freeboard: Vertical distance between the highest water level anticipated in the design and the top of the retaining banks. It is a safety factor to prevent the overtopping of structures.

Discharge (m3/s) < 0 . 75 0.75 to 1.5 1.5 to 85 > 85 Freeboard (m) 0.45 0.60 0.75 S 0.90

Base slope (So)–So = tan θ

Side Slope (Z): The ratio of the horizontal to vertical distance of the sides of the channel

Maximum Canal Side Slopes (Z)

Sand, Soft Clay 3: 1 (Horizontal: Vertical)

Sandy Clay, Silt Loam, Sandy Loam

2:1

Fine Clay, Clay Loam 1.5:1

Heavy Clay 1:1

Stiff Clay with Concrete Lining 0.5 to 1:1

Lined Canals 1.5:1

Permissible velocity:- Defined as the mean velocity at or below which the channel bottom and sides are not

eroded. The channel size is selected such that the mean flow velocity for the design discharge

under uniform flow conditions is less than the permissible flow velocity.

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This velocity depends primarily upon the type of soil and the size of particles even though it has been recognized that it should depend upon the flow depth as well as whether the channel is straight or not.

The maximum permissible velocities for different materials are presented Material V (m/s) Fine sand 0.6 Coarse sand 1.2 Earth Sandy silt 0.6 Silt clay 1.1 Clay 1.8 Grass-lined earth (slopes < 5 per cent) Bermuda grass Sandy silt 1.8 Silt clay 2.4 Kentucky Blue grass Sandy silt 1.5 Silt clay 2.1 Poor rock (usually sedimentary) Soft sandstone 2.4 Soft shale 1.1 Good rock (usually igneous or hard metamorphic) 6.1

The steps for the design of a channel using permissible velocity are as follows:1. For the specified material, select values of Manning n, side slope s, and the

permissible velocity, V.2. Determine the required hydraulic radius, R, from Manning formula, and the required

flow area, A, from the continuity equation, A = Q/V.3. Compute the wetted perimeter, P = A/R.4. Determine the channel bottom width, B, and the flow depth, y, for which the flow area

A is equal to that computed in step 2 and the wetted perimeter, P, is equal to that computed in step 3.

5. Add a suitable value for the freeboard.

Channel Design-Basicsa. Find expected Q at point of interestb. Select a cross section for the slope, and any erosion control needed

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c. Manning’s formula used for designd. Assume steady flow in a uniform channel

Formula used in open channel design:-

A. Continuity Equation

Discharge =Inflow = Outflow

Q= A1 V1 = A2 V2,

Discharge; Q,

Area; A1 and A2 and Velocity; V1 and V2

B. The Manning formula is

Q= (1/n)×A×R2/3×S1/2

Where,

Q= discharge (L3/T),

A= cross-sectional flow area,

R= (area divided by wetted perimeter P) the hydraulic radius,

S= slope of energy grade line,

n= Manning roughness factor,

Values of manning, n

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Types of cross section generally used for channel design

1. Rectangular cross section,

2. Trapezoidal cross section,

3. Parabolic channel

1 2 3

Design of Creek hydraulic section:-

Q(M3/S) 25

S0 1/1000side slope 1.5:1VMIN (m/s) 0.75roughness’ co-eff. 0.035free board, (m) 0.75

1. Rectangular channel.

A=Q/Vmin Bassumed,(m) Y=A/B Pw= B+2Y Rh=A/P v=(1/n)*Rh2/3s0

1/2 Q=A*v

33.333 20 1.667 23.333 1.429 1.146 38.20133.333 25 1.333 27.667 1.205 1.023 34.10033.333 30 1.111 32.222 1.034 0.924 30.80533.333 35 0.952 36.905 0.903 0.844 28.14133.333 36 0.926 37.852 0.881 0.830 27.67033.333 37 0.901 38.802 0.859 0.816 27.21633.333 38 0.877 39.754 0.838 0.803 26.78033.333 39 0.855 40.709 0.819 0.791 26.35933.333 40 0.833 41.667 0.800 0.779 25.95433.333 41 0.813 42.626 0.782 0.767 25.56333.333 42 0.794 43.587 0.765 0.756 25.18633.333 43 0.775 44.550 0.748 0.745 24.822

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**With freeboard

Y=A/B depth with free board, m1.667 2.4171.333 2.0831.111 1.8610.952 1.7020.926 1.6760.901 1.6510.877 1.6270.855 1.6050.833 1.5830.813 1.5630.794 1.5440.775 1.525

2. Trapezoidal channel

A=(BY+mY2)

A=Q/Vmin Yassumed B=(A-mY2)/Y T=B+2mY P=(B+2Y(m2+1)1/2) Rh=A/P v=(1/n)*Rh2/3*s0

1/2 Q=A*V

33.333 1.5 19.972 24.472 25.381 1.313 1.084 36.11833.333 1.2 25.978 29.578 30.304 1.100 0.963 32.09233.333 1 31.833 34.833 35.439 0.941 0.867 28.91233.333 0.95 33.663 36.513 37.088 0.899 0.841 28.04833.333 0.9 35.687 38.387 38.932 0.856 0.815 27.15633.333 0.85 37.941 40.491 41.005 0.813 0.787 26.23233.333 0.8 40.467 42.867 43.351 0.769 0.758 25.27733.333 0.75 43.319 45.569 46.024 0.724 0.729 24.289**With freeboard

Yassumed Depth with free board, m1.5 2.251.2 1.951 1.750.95 1.70.9 1.650.85 1.60.8 1.55

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0.75 1.5

3. Parabolic channel

A=(2/3)*YTA=Q/Vmin Yassumed T=3A/2Y P=T+8Y2/3T Rh=A/P v=(1/n)*Rh

2/3*s01/2 Q=A*V

33.333 2 25 25.427 1.311 1.082 36.07533.333 1.8 27.778 28.089 1.187 1.013 33.75833.333 1.6 31.250 31.468 1.059 0.939 31.29533.333 1.5 33.333 33.513 0.995 0.900 30.00933.333 1.4 35.714 35.861 0.930 0.861 28.68533.333 1.3 38.462 38.579 0.864 0.820 27.32133.333 1.2 41.667 41.759 0.798 0.777 25.91633.333 1.1 45.455 45.526 0.732 0.734 24.466

**With free board

Yassumed Depth with free board, m2 2.751.8 2.551.6 2.351.5 2.251.4 2.151.3 2.051.2 1.951.1 1.85

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CHAPTER-III

STUDY ABOUT HARD ROCK REGION OF INDIA

Hard-rock aquifers

Hard rock is a term which was coined by drillers to indicate poor drillability of this type of rocks.

They are characterized by insignificant primary porosity and primary permeability. Due to

weathering and fracturing, such rocks contain secondary porosity and permeability which isn’t

constant in every location. Igneous and metamorphic rocks fall into this group because

hydraulic properties of these rocks are mainly controlled by secondary porosity and

permeability. Unlike sedimentary rocks, the hard rocks generally represent an isotropic and

heterogeneous media.

The main source of generation of porosity in hard rocks are the rock discontinuities which are

caused due to many forces like tectonic stresses, residual stresses, contraction-cooling and

desiccation ,unloading and weathering. The main rock discontinuities are foliation, fractures

(joints), faults and lineaments. Although fractures and other discontinuities are the most

important factors which contribute to the hydro-geological properties of the hard rocks, some

discontinuities like faults and dykes may act as barriers to groundwater flow.

1. These rocks give rise to a complex and extensive

2. Low-storage aquifer system,

3. The water level tends to drop very rapidly once the water table falls by more than 2-6

meters.

4. These aquifers have poor permeability which limits their recharge through rainfall.

5. This implies that water in these aquifers is non-replenishable and will eventually dry out

due to continuous usage

Hard-rock aquifers of peninsular India:

India is a country with a total geographical area of about 3.28 × 106 km2. A vast terrain, nearly

65% of the total area of India is occupied by hard rocks, more predominantly in the area of

peninsular shield covering southern and central part of India (encompassing Maharashtra,

Andhra Pradesh and some parts of Karnataka and Rajasthan, due to less cumulative rainfall,

groundwater availability is a problem). The peninsular shield is mostly constituted of granites,

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gneisses, basaltic rocks of volcanic origin and metamorphic complexes. A major part of the hard

rock terrain in the peninsular states is drought prone and hence groundwater is in intensive

use.

Hard rock’s whose receptiveness of precipitation is restricted to the degree of weathering and

secondary porosity, so also its capacity to store and transmit the water. Main source of

groundwater is from the fractured, weathered and vesicular horizons. As a result, even in high

rainfall areas of the state, water scarcity is experienced in summer months (GSDA, 2004). Hard

rocks derive its status as an aquifer on the basis of secondary porosity that gets developed due

to decomposive and weathering processes over a period of time (Radhakrishna, 1971; Powar,

1981). Consequently, groundwater occurs largely in the secondary porosity of weathered

mantle limited to a shallow depth. Main source of groundwater is from the fractured,

weathered and vesicular horizons. Hard rock aquifers are by nature limited in their potentials

and heterogeneous in occurrence. It is confined mostly to the weathered residuum, fracture

and fissure section generally up to the depth of 60 m. The aquifers in hard- rock are unconfined

and their water table generally follows the surface topography.

The shallow aquifers are phreatic and found to be occurring up to the depth of 10 to 15 m

underlain by massive rocks which forms the bottom of phreatic aquifer. The groundwater in

shallow aquifers gets replenished annually as the monsoon rainfall occurs only within a four-

month period (June to September). This recharge in unconfined shallow aquifer is dynamic and

groundwater continues to flow according to the surface gradient towards lower reaches.

Eventually, it gets discharged to the streams and rivers as a base flow. This flow movement

causes de-saturation and water level fluctuation in the aquifers. The pre and post monsoon

water levels indicate the degree of saturation in the hard rock aquifers. The low permeability of

hard rock aquifer is a redeeming feature under such conditions because it makes small

quantities of water available, at least for drinking purpose, in the dug wells or bore wells in

central valley portion of a sub-basin. If the hard rocks had very high permeability, ground water

body would have quickly moved towards the main river basin, thereby leaving the sub-basins

high and dry. The low permeability in the range of 0.05 to 1.0 meters per day thus helps in

retarding the outflow and regulating the availability of water in individual wells.

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A dug well section showing shallow aquifer in hard rock.

The nature of occurrence of groundwater, its hydrodynamics and role of water levels in

groundwater regime of hard rocks.

The groundwater occurs in the secondary porosity developed by weathering and disintegration

of hard rocks. The extent of secondary porosity depends on the degree of weathering, jointing

and fracturing due to various natural processes acting on these hard rocks. These conditions are

reflected in the built up of topography. The highly dissected plateau (HDP)/mountainous areas

have less weathered zone which develops poor secondary porosity in the rock. The similar

situation is reflected in the moderately dissected plateau (MDP) areas with moderately

weathered mantle. This process is observed to its maximum in the undissected plateau

(UDP)/valley terrain or peneplains where the weathered mantle is considerably high. As a result

of this varying secondary porosity, the groundwater storage and occurrence also gets limited in

these three situations as poor, moderate and good respectively.

Rainfall is the main source of recharge and the aquifers get saturated by infiltration process.

The recharging conditions also vary according to the topography. The HDP areas are

predominantly runoff due to steep gradients, MDP as recharge areas and UDP areas are storage

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zones. According to the storage conditions, the groundwater recharge also takes place with

different time duration. Aquifer gets fully saturated in short duration, by the end of July in HDP

as well as high rainfall areas; whereas it takes longer in UDP/valley terrain from June to

October. Variation in rainfall is reflecting in the full saturation of the aquifer in high and assured

rainfall zone and partial saturation in the low rainfall zone/drought prone area.

Representative Hydrograph showings recharge and discharge condition in hard rock.

The extent of saturation in the aquifers is reflected in the status of static water levels. Unlike

groundwater in alluvial areas, which is static and remains confined to porous zone, the

groundwater in hard rock is dynamic and gets its movement towards the direction of slope

from high hydraulic head to low hydraulic head. This provides a linear movement to

groundwater parallel to the surface topography and the water level contours remain parallel to

the surface elevation contours. This dynamism of the groundwater in shallow unconfined

aquifers provide a continuous decrease in saturation level as its movement towards lower

reaches where it gets discharged in streams and rivers in the form of a base flow. This

dynamism is very significant in the development and utilization of groundwater in the hard

rock.

The saturation of the aquifer starts depleting after monsoon and reaches to its minimum during

summer months which could be termed as residual recharge in the aquifer zone. This residual

level observed in the summer months is the combine effect of total withdrawal/abstraction and

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discharge to the streams. Whether it is utilized or not, the groundwater does not remain static

and the storage get emptied in the streams/lower reaches due to the movement of

groundwater.

Reasons for declining groundwater levels

Most of the aquifers get replenished annually and get depleted largely to full saturation

thickness before the onset of monsoon leaving no groundwater available for extraction. This

phenomenon is more predominantly and effectively observed in “basaltic rocks‟. Further,

aquifer is mostly unconfined and limits to the depth up to 20 m restricted to moderate to high

weathered zone. The degree of weathering and topography are the influential factors in

governing yield of wells. These are the main natural hydrogeological parameters along with

groundwater dynamics for the crisis period in the state.

1. Rainfall variation.

2. Groundwater withdrawal during rainy season for irrigating khariff (rain-fed) crops.

3. Increase in the withdrawals due to development.

4. Extraction from the deeper confined aquifers through bore wells.

5. The groundwater in hard rock in shallow aquifers is dynamic and hence joins the surface

water as base flow.

Extraction from the deeper confined aquifers through bore wells

The exploitation of deeper aquifer from bore wells provides additional well capacity for

obtaining more recharge during monsoon season. In fact, this helps in optimizing the

groundwater storage. The aquifers in hard rock get fully saturated during 1st two months of

monsoon (July to August) and there is no scope for further infiltration or recharge and the

rejected recharge results in increase in run-off.

The nature has already controlled the extraction in hard rock as the pumping of water is limited

to overnight recuperation and no well owner can extract than the capacity of well.

The decrease in saturation over the period of time reduces the overnight recuperation capacity

of the dug well and renders the well non utilizable for pumping during the summer months

where the residual saturation is to its minimum and no one can extract water for summer

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crops. This limitation has reduced the groundwater utility as a source of protective irrigation

during the water stress period of „khariff‟ season and „rabbi‟ crops. The depletion of water

levels within the saturated horizon of the aquifer recharge is not an indication of

overexploitation.

The depletion of water levels in the underdeveloped watersheds shows the ground truth and

evidence that these falling water levels are not due to over extraction but they are the effect of

increase in development and the quantity of abstraction. The groundwater potential in the hard

rock in the shallow unconfined aquifer is a heterogeneous and complex phenomenon.

The aquifers in these rocks have a very limited transmissivity and storativity providing a natural

control over the extraction of groundwater.

The base flow in hard rock

Water stored in hard rock

The volume of water stored in fractured hard rocks near the surface is estimated to total less

than 2 percent of the rock volume. This percentage decreases with depth as fractures become

narrower and farther apart. The total amount of water in storage in the rocks surrounding a

hard rock well is small, so that groundwater levels and the well's yield can decline dramatically

during the summers of dry years.

The volume of water stored in many alluvial soils can amount to 10-15 percent of the volume of

the alluvium. In areas where alluvium overlying the hard rock is saturated with water, the

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alluvium provides additional water storage for nearby wells in the hard rock. This situation most

often occurs in valleys or meadows.

Yield of well in hard rock

Half of all hard rock wells yield 10 gallons per minute (<2lps) or less, which is only enough for

individual domestic supplies. When conditions are good, wells drilled in fractured rock may

yield several hundred gallons per minute when pumped.

Good conditions include:

1. Large amounts of fractures;

2. Good interconnection between fractures;

3. Wide, large, clean fractures;

4. A source of recharge;

5. A large quantity of water in storage; and

6. Proper installation of the well, including removal of granular debris that may clog the

fractures.

Independent or interrelated factors, such as

1. Geomorphology (topography)

2. Lithology, brittle (neo-) tectonics, and

3. surface-water hydrology,

Groundwater research in hard rock terrains in India poses several challenges:-

1. Monitoring well densities are sparse. As water levels have been continuously falling,

there are few wells with long-term monitoring records.

2. Static water levels tend to be highly variable.

3. Static water levels differing by tens of meters. (A bore well could record static water

levels that fluctuate by tens of meters in a few months.)

4. No accurate maps of fracture aquifers exist

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CHAPTER-IVDESIGN OF GROUNDWATER RECHARGING SHAFT

Artificial Groundwater RechargeGroundwater development and management is one of the major challenges for the scientists and engineers worldwide. Artificial groundwater recharge is a feasible option to tackle the problem of water table decline in many part of the world. Water withdrawal pattern along with recharge components should be studied together for efficient groundwater management in any region. Natural recharge of an aquifer is directly related to the safe yield of aquifer system. Hence additional amount of rainwater can be added to the aquifer through artificial recharge techniques. Precisely, artificial recharge is the process by which the groundwater reservoir is augmented at a rate exceeding that under natural conditions of replenishment. Any man-made scheme or facility with the objective to add water to an aquifer may be considered as an artificial recharge system.

Sustainability of drinking water sources has become one of the major issues of rural drinking water supply sector. In this endeavor, role of government sector is being shifted from actual implementing authority to that of a facilitator. Since artificial recharge can play a major role in providing sustainability to drinking water sources, such activities can be taken up on a large scale by local communities as various kinds of rainwater harvesting structures through ages have been proved to be quite useful to the society constructed in different parts of the country worldwide.

Advantages of Artificial Recharge

Following are the main advantages of artificially recharging the groundwater aquifers

No large storage structures needed to store water. Structures required are small and cost-effective

Enhance the dependable yield of wells and hand pumps Negligible losses as compared to losses in surface storages Improved water quality due to dilution of harmful chemicals/ salts No adverse effects like inundation of large surface areas and loss of crops No displacement of local population Reduction in cost of energy for lifting water especially where rise in ground water level

is substantial Utilizes the surplus surface runoff which otherwise drains off

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Methods of Artificial RechargeThere are many reasons why water is deliberately placed into storage in groundwater reservoirs. A large number of artificial recharge schemes are designed to conserve water for future use. Other such projects recharge water for such objectives as control of saltwater intrusion, filtration of water, control of subsidence, disposal of wastes and for secondary recovery of crude from oil fields.

Artificial recharge methods can be further classified into two broad groups: direct methods and indirect methods. Direct methods can be classified into surface spreading techniques and subsurface techniques. The most widely practiced methods of artificial recharge of groundwater employ different techniques of increasing the contact are and resident time of surface water with the soil so that maximum quantity of water can infiltrate and augment the groundwater storage. Under the surface spreading techniques various methods available are flooding, ditch and furrows, surface irrigation, stream modifications and finally the most accepted one and suitable for small community water supplies are runoff conservation structures. Under the subsurface techniques injection wells and gravity head recharge wells are common ones.

Indirect methods of artificial recharge adopts the technique of induced recharge by means of pumping wells, collector wells and infiltration galleries, aquifer modifications and groundwater conservation structures, which require highly skilled manpower and other resources.

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Also one of the technique are rainwater harvesting techniques which are beneficiary in ground water recharge and it’s play a major role in providing sustainability to drinking water sources.

Rooftop Rainwater HarvestingIn rooftop rainwater harvesting, the rainwater is collected from roof of the buildings and

stored in groundwater reservoir for beneficial use in future.

Advantages

Provides self-sufficiency to water supply Reduces the cost of pumping Reduces soil erosion in urban areas Less expensive and simple and can be adopted by individuals Utilizes the rainfall runoff Improves the quality of existing groundwater through dilution Removes bacteriological and other impurities from sewage and wastewater so that the

water is suitable for re-use Rainwater may be harnessed at place of need and may be utilized at time of need

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In coastal areas, it provides good quality water as well as helps in maintaining balance between the fresh saline water aquifers

In islands, it provides the most preferred source of water for domestic use In desert, it provide relief to people

Rainwater harvesting plays an important role in not only managing the temporary crises faced by the humankind but also it augments the groundwater aquifers, which would cater to the needs of the future generations. Practicing rainwater harvesting at the community level has now become very essential for sustainable development.

Recharge of Dug Wells through Roof Top Rain Water Harvesting

Planning of Artificial Recharge System

The following issues are considered during the planning of artificial recharge system.

The availability of water sources for the recharge. The recharge potential of the study area. The type and geometry of the aquifer. Groundwater quality Selection of appropriate technique for recharge

Design of Artificial Groundwater Recharge Objectives

1. Maintain the groundwater level2. Reduce the surface runoff and increase groundwater storage

Some Recharge techniques:- Abandoned Dug Well

A dry/unused dug well can be used as a recharge structure

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The recharge water is guided through a pipe to the bottom of well or below the water level to avoid scouring of bottom and entrapment of air bubbles in the aquifer

Before using the dug well as recharge structure, its bottom should be cleaned and all the fine deposits should be removed

Recharge water should be silt free It should be cleaned regularly It is suitable for large building having the roof area more than 1,000 sq. m Periodic chlorination should be done for controlling the bacteriological contaminations.

Recharge Pit Recharge pits are constructed for recharging the shallow aquifer The size varies as 1 to 2 m wide and 2 to 3 m deep After excavation, the pits are refilled with pebbles and boulders Water to be recharged should be silt free Cleaning of the pit should be done periodically It is suitable for small buildings having the rooftop area upto 100 sq.m Recharge pit may be of any shape i.e. circular, square or rectangular If the pit is of trapezoidal shape, the side slopes should be steep enough to avoid silt

depositionRecharge Trench

It is constructed when permeable strata of adequate thickness is available at shallow depth

It is a trench of shallow depth filled with pebbles and boulders These are constructed across the land slope The trench may be 0.5 to 1m wide, 1 to 1.5m deep and 10 to 20 m ling depending upon

the availability of land and rooftop area It is suitable for the buildings having the roof area of 200 to 300 sq.m Cleaning of trench should be done periodically

Gravity Head Recharge Well Borewells/tubewells can be sued as recharge structure The technique is suitable where land availability is limited and when aquifer is deep and

overlain by impermeable strata The rooftop rainwater is channeled to the well and recharges under gravity flow

condition Recharge water should be silt free The well can also be used for pumping

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Most suitable for the areas where groundwater levels are deep The number of recharging structures can be determined in limited area around the

buildings depending upon rooftop area and aquifer characteristicsRecharge Shaft

These are the most efficient and cost effective structures to recharge the aquifer directly. These can be constructed in areas where source of water is available either for some time or perennially. Following are the site characteristics and design guidelines,

(i) To be dug manually if the strata is of non-caving nature.(ii) If the strata are caving, proper permeable lining in the form of open work, boulder

lining should be provided. (iii) The diameter of shaft should normally be more than 2 m to accommodate more

water and to avoid eddies in the well. (iv) In the areas where source water is having silt, the shaft should be filled with

boulder, gravel and sand to form an inverted filter. The upper-most sandy layer has to be removed and cleaned periodically. A filter should also be provided before the source water enters the shaft.

(v) When water is put into the recharge shaft directly through pipes, air bubbles are also sucked into the shaft through the pipe, which can choke the aquifer. The injection pipe should therefore be lowered below the water level.

The main advantages of this technique are as follows: It does not require acquisition of large piece of land as in case of percolation tanks. There are practically no losses of water in the form of soil moisture and evaporation,

which normally occur when the source water has to traverse the vadose zone. Unused or even operational dugwells can be converted into recharge shafts, which does

not involve additional investment for recharge structure. Technology and design of the recharge shaft is simple and can be applied even where

base flow is available for a limited period. The recharge is fast and immediately delivers the benefit. In highly permeable

formations, the recharge shafts are comparable to percolation tanks. The recharge shafts can be constructed in two different ways viz. vertical and lateral. The details of each are given in the following paragraphs.

1. VERTICAL RECHARGE SHAFT The vertical recharge shaft can be provided with or without injection well at the bottom of the shaft.

A. Without Injection well

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Ideally suited for deep water levels (up to 15 m bgl). Presence of clay is encountered within 15 m. Effective in the areas of less vertical natural recharge. Effective with silt water also Depth and diameter depends upon the depth of aquifer and volume of water to be

recharged. The rate of recharge depends on the aquifer material and silt content in the water. The rate of recharge with inverted filter ranges from 7-14 lps for 2-3 m diameter.

Vertical Recharge Shaft Without Injection Well

B. With Injection WellIn this technique an injection well of 100-150 mm diameter is constructed at the bottom of the shaft piercing through the layers of impermeable horizon to the potential aquifers to be reached about 3 to 15 m below the water level.

Ideally suitable for very deep water level (more than 15 m) Aquifer is overlain by impervious thick clay beds Injection well can be with or without assembly The injection well with assembly should have screen in the potential aquifer at least 3-5

m below the water level The injection well without assembly is filled with gravel to provide hydraulic continuity

so that water is directly recharged into the aquifer The injection well without assembly is very cost effective Depending upon volume of water to be injected, number of injection wells, can be

increased to enhance the recharge rate The efficiency is very high and rate of recharge goes even up to 15 lps at certain places

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Vertical Recharge Shaft with Injection Well

2. LATERAL RECHARGE SHAFT Ideally suited for areas where permeable sandy horizon is within 3 m below ground level

and continues up to the water level – under unconfined conditions Amount of water available can be easily recharged due to large storage and recharge

potential Silt water can be easily recharge 2 to 3 m wide and 2 to 3 m deep trench is excavated, length of which depends on the

volume of water to be handled With and without injection well

Lateral Recharge Shaft

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Design of Settlement/sediment tank

In dug well recharge/ recharge shaft, settlement tank is designed to filter the suspended solids, organic or inorganic substances and also harmful bacteria’s. In settlement tank sand is used as a filter media, which removes the suspended particles and maintains the turbidity of water. Gravel and pebbles are used in settlement tank, for energy dissipation and control of water flow rate. Clogging is the main problem in filtration unit with respect to time, hence periodic cleaning of filter material is required.

Generally two methods are applied for removing of clogging particles

1. Mechanically washing of sand2. Backwashing by water and high pressure air

The runoff contains high quantity of 1. organic or inorganic materials2. suspended particles3. Physical impurities (like leaves, dead animals, seeds etc)4. Industrial, agricultural wastes and 5. Harmful chemicals, bacteria’sSo, pre-treatment of runoff is necessary, if we pass the runoff water through gravel or sand bed before entering in tank, it increase the filtration capacity or working duration of media.

Assumptions for sand bed design

Filter Media

Sand bed → 30-90 cm depth, (This range of media size has the ability to handle turbidities in the range of 5 to 10 NTU.)

Sand particle size → 0.35 to 1.2mm (A typical effective size 0.5 mm)

Filtration capacity 2000-6000 lit./hr./m2 (may not be feasible in case of runoff water, which contains high sedimentation)

Uniformity coefficient of sand particle →1.3-1.7

Base Material

Gravel bed depth→30- 90cm

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Pebbles bed depth→30 to 90cm

Design of sedimentation tank (A Case study)

For runoff volume= 36 lit./min= 2160 lit./hr.

Sand size=0.5mm, Rate of filtration =5000 lit./hr./m2

Area of filter bed= (2160lit./hr.)/ (5000lit/hr./m2)=0.432m2

Assume No. of filtration tank is 2.

Then,

Area (of sand bed) for one unit= 0.432/2 m2

=0.216 m2

A. For rectangular tank,

Sand bed dimensions,

Area of rectangular bed= L×B, Vol. of rectangular sand bed= L×B×H

Length to width ratio (L/B) =1.5

Then,

L=1.5B

Bx1.5B=0.216

1.5B²=0.216

B²=0.144 0.3m

B=0.38m, say=0.4 0.4 m

L=0.38m×1.5=0.57m, say=0.6m 0.6 m

Length=0.6m

Therefore,

Width, B=0.216/0.6 =0.36m, say=0.40m Gravel

Provide 2 units of 0.6mx0.40mx0.3m

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Gravel and Pebbles bed dimensions are d=0.2m

Length and width is same as the sand bed= 0.6mx0.40m

But, for both gravel and pebbles, d=0.2m

Depth=0.2m Pebbles

Depth for water submergence=0.3m

Total area of rectangular tank

Length×Width=0.6m×0.4m

Volume of tank 0.3m

L × B × W=0.6m × 0.4m × 1m

0.3m

0.2m

0.2m

0.4m

0.6m

B. For circular tankArea of circular sand bed= πr2 0.3mVolume = πr2hWhere, h (assumed)= 0.3mThen, 0.3m

πr2=0.216 m2

r2=0.069 m2

r=0.26mTherefore, 0.6m

πr2= π×0.262

=0.212m2

Say, radius ‘r’= 0.3mThen,

Dia. ‘d’=0.3m×2

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=0.6mDimensions of Gravel and Pebbles bed are 1m

Depth (assumed)= 0.2 m for eachDia.= 0.6 m

Depth of water submergence isDepth (assumed)= 0.3m

Total volume of tankπr2h= π×0.32m2×1m

Further steps to be considered while designing sedimentation bed

1. Runoff volume of an area can be calculated based on area and depth of rainfall

2. Runoff water may be allowed to pass through the gravel bed before entering to the

main filtration unit.

3. A trap may be provided in the top of the filtration unit for checking the organic

materials like

4. Provision should be made for energy dissipation in the filtration unit (gravel layer at

the top)

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CHAPTER- V

INSTRUMENTS OF

IRRIGATION & DRAINAGE ENGINEERING LABORATORY

1. WATER PURIFICATION SYSTEM:

EASYpure tm RO (Reverse Osmosis System)I. FUNCTIONS

To purify the water for irrigation purposesII. OPERATION

It was designed to operate automatically. The unit will automatically turn off when the tank is full & will restart when the tank empty slightly. The unit will restart automatically for 5min. every 3hrs 55min. of inactivity to flush the membrane during period of non-use. This flush water will automatically run to the drains

III. INSTALLATION It must be located within six feet of an electrical outlet, within five feet of feed

water supply and close to an atmospherically vented drain When EASYpure RO is to be used when an accessory 30 litre reservoirs, the

reservoirs must be mounted farther than 4 feet away from the EASYpure RO. EASYpure RO can be either Bench or Wall mounted with necessary installation

modifications.IV. VARIOUS INDICATORS

Pressure gauge- it briefly indicates the feed water pressure, on initial startup. During normal operation, this gauge should read 55-65 psi.

LED’s- these are indicators light on EASYpure RO front panel that alerts the operator during operating status of unit.

SPECIFICATIONS

Max. Temperature : 50°C Min. Pressure (standard) : 30 psi Max. Pressure (standard) : 100 psi Inlet flow requirements : 53.5 lph pH : 4-11

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2. DIGITAL PLANIMETER (KP-90N)

I. FUNCTIONS To measure the areas, usually the area of irregular regions on a map or photograph

II. SPECIFICATIONS DISPLAY: LCD, 8 digit numerical display when “HOLD”, “MEMO”, “AVER” or “RS”

Key is pressed,6 digit pulse count display in measurement MEASURING RANGE:

Vertical width: 325 mm, roller rotary direction: infinite. An area measurable at a time without overflowing 999999 pulse counts. Vertical width: 325 mm. roller rotary direction: 30mMaximum cumulative area (scale 1:1): 99,999.9 cm2 (10 m2 approx.)

RESOLUTION: 0.1 cm2 when reduced scale 1:1 ACCURACY: within ± 0.2 (within ±2/100 pulses) POWER SUPPLY: Built-in Ni-Cd storage battery (rechargeable with its adaptor) WEIGHT: 750g including the whole unit

III. PROCEDURE Level the drawing board horizontally and placed the drawing paper in it. Place the instrument above so that the lens tracer should be at middle of the

drawing paper and roller at the position which will make the roller at right 90° angle with the main body.

Before switching “ON” trace the drawing with the tracer lens roughly 2 to 3 times Power “ON” Select the UNIT system and UNIT in which UNIT 1 key is horizontal shift and UNIT

2 is vertical shift Set a scale value by pressing “SCALE” key For confirmation of scale setting press “R-S” key, the set value is displayed. Then press the “START” bottom and trace an area from left side in clock wise direction. After tracing press the “HOLD” button and note the data.

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Digital Planimeter3. PRESSURE PLATE MEMBRANE EXTRACTOR

COMPONENTS:

1. Compressor unit

2. Low pressure chamber.

3. High pressure regulator.

4. Pressure display

5. Extractor chamber exhaust valve.

6. Air outlet

7. Low pressure regulator

FUNCTIONS

1. Is used to analyze the water holding characteristics of soil sample at extremely in high pressure

2. Makes possible the study of physical properties of soils which may not be possible by other means

3. Ultra filtration may also be carried out by the use of extractor4. Important moisture retention curve can be developed5. Moisture flow rates at high soil suction values can be measured from the outflow

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Pressure membrane extractor and its unit4. ULTRA SONIC DOPPLER INSTRUMENT:

Components:

1. Mounting bracket

2. Drying tube

3. Waterproof plug.

4.10m Signal cable

Application:

1. The instrument is intended for economically recording flows in channels, culverts, and pipes.

2. It can be used also where existing techniques are unsuitable or too expensive.

3. It is particularly useful at sites where no stable state or velocity relationships exist.

4. It is also used for where flows are affected by variable tail water conditions, culvert entry blockages, pipe surcharging, other unstable flow conditions or even reverse flows.

5. It can also be useful for measurement of velocity, depth& temperature.

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5. AUTOMATIC WATER LEVEL STAGE RECORDER (HORIZONTAL):

Components:

1. Clockwork

2. Time screw gauge

3. Pen carriage & pen

4. Chart drum

5. Gauge scale gear

6. Float pulley

7. Counter weight

8. End hole

9. Float line

Application:

1. It is installed for obtaining an accurate continuous record of varying levels of water in canals, reservoirs, wells, streams, rivers for management, design & scientific purpose.

2. It gives,

-Total amount of discharge/ runoff.

-Times of onset, rise, and fall & cessation runoff/discharge.

-Duration & rate of runoff/discharge.

3. It can be used to determine discharge using cross section area per discharging

Table or graph for location

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6. SET OF SIEVES:

Sieve analysis of the sample obtained during drilling of test hole or production wells is done using the set of sieves.

.

The standard method for analyzing for sand/soil samples by the dry sieving is adopted in the usual practice is to use the set sieves conforming to Indian standard (IS: 460-1962) or the particulars standard adopted by particular country.

The sieves are available in the laboratory are of size as;

2.80mm, 2.00mm, 1.70mm, 1.40mm, 1.12mm, 850mic, 600mic, 425mic, 250mic, 75mic,

Collectors

7. WATER LEVEL/ METER (VERTICAL):

Application:

(I) in the water level recorder is a vertical cylindrical tube. It consist of graph provided inside the at the top corner & float at the end corner. The pointer is also provided which is connected to the float & it’s pinpoint on the graph.

(II) Using this water level recorder the yearly data of water level can be calculated in the paddy fields for the other development purposes & water level determination.

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8. RESISTIVITY METER

Applications:

1. Ground water prospecting.

2. Mineral prospecting.

3. Geosciences Education.

4. Sand & gravel prospecting.

5. Bedrock depth determination.

9. NEPTHELO- TURBIDITY METER:

Applications:

1. This is designed to measure the content of suspended material in solution.

2. It also finds the wide application in laboratory & industries for water treatment & its analysis.

10. PH METER:

1. Applications:

It is designed especially for accurate pH measurement chemical research in lab. and Industries.

2. SPECIFICATION Range: 0 to 500 NTU in four decade range of 1, 10, 100, and 500 NTU

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Accuracy: ± 1% full scale in 10 and 100 NTU ranges and ± 2%of full scale in 1 and 500 NTU

11. RECORDING TYPE RAIN GAUGE:

There are three types of recording mechanisms are used:

1. Float

2. Weighing

3. Tipping bucket

FUNCTIONS Designed to give a continuous record of the rainfall The total amount of rainfall which has fallen since the record was started The times of onset and cessation of rain and The duration of rainfall Also gives the rate of rainfall, from the amount of rain which has fallen in a short

period centered about a given time.PRINCIPLE

Rain water entering into the gauge from the top of the cover is carried through the funnel to the receiver consisting of a float chamber and a syphon chamber.

The pen is mounted on the stem of the float and as the water level rises in the receiver the float rises and the pen records, on a chart placed on a clock drum, the amount of water in the receiver at any instant.

The clock drum revolves once in 24 h, so that a continuous record of the movement of the pen is made on the chart and as the rain continues pen rises again from the zero line of chart.

If there is no rain the pen traces a horizontal line from where it leaves off rising.OPERATIONThe chart is changed at the same time each day usually between 08300 and 0900 I.S.T. the following daily routine may be followed.

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Remove cover; lift off pen by loosening set-screw. Take off the old chart after removing clip, put on new chart and replace clip. Wind clock if necessary See that there is sufficient ink in the pen, and that it marks. Set the pen to zero as follows: pour sufficient water into the receiver slowly till the

pen reaches the top and water syphon out. After the water has drained out the pen should be on the zero line.

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CHAPTER-VI

DETERMINATION OF EC AND PH OF SOIL SAMPLE

1. DETERMINATION OF PH OF SOIL SAMPLE WITH THE HELP OF PH METER

PROCEDURE

Collect the soil sample from the desired depth using soil sampling auger. Air-dry the sample, break the aggregates in a mortar and pestle as far as

possible and pass through a 2mm sieve. Take a weight of 10 g of soil in weighing balance and pour it in 100 ml beaker. Then put a 25 ml distilled water in the beaker so that it should be in ratio of 1:2.5

(1= soil, 2.5= distilled water) Shake it for 5 minutes by stirring rod and keep it for around 2-4 h. After that, take the reading by pH meter and note the data.

OBSERVATION TABLE

Sl. No. Name of the Sample pH1 0-5 A 5.42 5-15 A 5.63 15-30 A 6.34 0-5 B 5.45 5-15 B 5.46 15-30 B 5.87 30-45 B 6.1

SOIL pH AND INTERPRETATION

<5.0 5.5 6.0 6.5-7.5 7.5-8.5 >8.5Strongly acid Moderately

acidSlightly acid Neutral Moderately

alkalineStrongly alkaline

Best range for most crops

2. DETERMINATION OF EC OF SOIL SAMPLE WITH THE HELP OF EC METER

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The procedure of EC will be same like the procedure of pH and in this; the reading will be taken by EC meter.

Sl. No. Name of the Sample EC (µS)1 0-5 A 37.72 5-15 A 54.63 15-30 A 67.74 0-5 B 53.95 5-15 B 62.46 15-30 B 85.47 30-45 B 67.7

3. DETERMINATION OF pH AND EC OF DIFFERENT SOIL SAMPLE

Sl. No. Name of the Sample pH EC (µS)1 5-1 7.20 4062 5-2 6.79 2653 5-3 6.07 11184 5-4 6.11 16165 5-4 6.83 4066 5-6 5.66 6507 5-7 5.28 2538 5-8 7.01 599

CHAPTER- VII

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Determination of pH, EC, salinity and TDS of water from different places of Sunity project site (Kendrapara district of Odisha)

Sl. No Name of the sample pH EC (mS) TDS (ppt) Salinity (ppt)Year 2014

1 T-1 8.77 1.90 1.98 1.002 T-2 8.34 3.29 3.11 1.583 T-3 8.80 2.32 2.23 1.094 T-4 8.29 2.66 2.53 1.225 T-5 9.21 2.57 2.55 1.276 T-6 8.39 3.14 2.95 1.537 T-7 8.18 2.15 2.06 1.028 T-8 8.67 2.40 2.32 1.199 T-9 9.05 2.38 2.28 1.16

10 T-10 8.63 3.10 2.90 1.5411 T-11 8.66 2.52 2.52 1.2812 T-12 9.26 1.64 1.71 85813 T-13 9.99 0.98 985 ppm 474

Year 201514 1 8.18 1.78 1.83 94815 2 9.15 0.64 676 ppm 31516 3 7.99 1.06 1.10 52917 4 8.07 5.59 4.94 2.6818 5 8.65 6.01 5.17 2.8419 6 8.47 0.88 882 ppm 94320 7 7.12 2.76 2.60 1.37

Year 201621 8 7.89 Error Error 5.8722 9 7.16 1.71 1.69 88223 10 7.52 Error Error Error24 11 9.23 2.14 1.98 1.0625 12 7.66 3.54 3.30 1.6926 13 8.26 1.07 1.06 54427 14 8.22 2.13 1.80 1.0228 15 7.87 2.69 2.63 1.3129 16 8.24 1.40 1.45 68430 17 6.78 Error Error Error31 18 8.33 1.65 1.59 86232 19 8.42 3.26 1.54 1.7433 20 8.28 1.66 1.71 860

CHAPTER-VIII

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EXPERIMENT ON PRESSURE PLATE MEMBRANE

PROCEDURE Take a soil from different required field, dry it and sieve it through 2mm. Saturate the soil for 24 h in beaker After saturation fit the pressure membrane plate extractor Place the saturated soil sample in retaining ring that is kept above the pressure

plate. Closed the extractor and tight it properly Start the machine and maintain the required pressure. Keep it for 24 h and measure the data.

OBSERVATION TABLE

For 0.33 bar (Field capacity)

Sl. No. Weight of empty container (g)

Weight of container + wet soil (g)

Weight of container + dry soil (g)

Weight of water (g)

% moisture content

1 24.3 52.1 44.4 7.7 38.302 19.9 44.5 37.2 7.3 42.193 19.8 42.1 35.5 6.6 42.034 20.6 43.2 36.3 6.9 43.945 20.8 46.1 38.5 7.6 42.936 19 40.1 33.4 6.7 46.527 18.8 42.3 36.7 5.6 23.828 20.8 44.6 36.7 7.9 49.68

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