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Transcript of Water Resources Plan
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INTRODUCTION
Irrigation is an artificial application of water to the soil. It is usually used to assist in
growing crops in dry areas and during periods of inadequate rainfall. Additionally, it is
very vital in crop production especially in rain-fed farming.
The future of agriculture and food production lies much on irrigation. At the global
scale 2,788,000 square kilometers of agricultural land is equipped with irrigation
infrastructure. About 68% of the area equipped with irrigation is located in Asia, 17%
in America, 9% in Europe, 5% in Africa and 1% in Oceania. A number of dams and
irrigation infrastructure were built to increase the supply of water as well as to
maximize the use of its availability.
In the Philippines, agriculture is the lifeblood of the Filipino people. Various crops
such as rice, corn, vegetables and others are widely cultivated to meet the
increasing demand for food as the countrys population is in the boom. With this, to
elevate food self-sufficiency of the country, the government together with private
sectors joins hand in hand to provide adequate irrigation water for food production
through implementing water resources infrastructure project throughout the country.
While the Tucalan Communal Irrigation System has been in service for several
cropping seasons, its efficiency has gradually deteriorated over the years. The
increasing demand of water irrigation use has led into many constraints such as
capacity problems, insufficient water quality and the technical deficiencies of existing
irrigation infrastructures. It is in this view that the rehabilitation of the system had
been included as a priority project in order to ensure efficient delivery of irrigation
water to the farms of the existing irrigation system.
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PROBLEMS AND CONSTRAINTS
The identified problems in the project area were related to production, technical and
social problems.
Production Problems:
The unit yield of rice in the area prior to the project was considerably low at an
average of 50 cavans per hectare. With no irrigation system, rice was grown
under rain fed conditions. During some cropping seasons, the vegetative growth
of rice was severely damaged due to lack of soil moisture. Harvest, therefore,
during these periods were below the national average.
Technical Problems:
Agricultural activities were limited in the project area for lack of adequate
irrigation water. Cultivation of rice as a major crop depended on rainfall which
resulted to very low yields. The heavily silted reservoir has led to very low water
head which was not sufficient to supply the irrigation water requirement of the
farmlands. Additionally, deteriorating intake and canal structures resulted to
inefficient water delivery and distribution to the service areas. Most of the lined
canals were cracked and silted. On the other hand, the earth canals were eroded
and required reshaping.
Social and Institutional Problem:
Non-existence of the Irrigators Association led to the insufficient knowledge of
water users on proper water management which in turn resulted to the
proliferation of illegal users, damage to canal structures and wastage of irrigation
water. With no peoples organization supervising the operation of the system,
collection rate of irrigation service fee was low and no sufficient maintenance
resources were available during maintenance period. Damage structures and
facilities were not restored and their conditions were aggravated with passing of
each cropping season.
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OBJECTIVES OF THE PROJECTThe identification of long term and short term is hoped to guide public and private
sector development decisions and activities direction. The results are expected to
support the sustainability of the projected growth intensity for the 50-year period.
The short-term and long-term objectives of the rehabilitation of the project are
presented below:
Short-Term Objectives
1. To restore the intake structures and drainage facilities of the irrigation system
in order to re-establish its functionality and operation.
2. To strengthen the Irrigators Association capacity to undertake productive
activities by providing institutional and agricultural support such as extension
services, cooperative organization and social capability building.
3. To improve the productive potentials of the agricultural farmlands in the area
through increased cropping intensity and crop diversification.
Long-Term Objectives
1. To alleviate poverty and improve well-being of the farmer beneficiaries by
giving them opportunities to increase their income.
2. To transform the Irrigators Association into a self-sufficient organization
capable of efficiently and effectively managing the operations of the system.
At full development, production from the project area is expected to increase from
2.50 tons/hectare to 5.00 tons/hectare for the first crop and 5.00 tons/ha for the
second crop. However, production cost will increase considering the introduction of
modern methods of farming with more inputs to be supplied. The target cropping
intensity will be up to 148% in the whole service area. Palay production is also
expected to reach 1,150 tons annually in the whole area from the present 387.50tons.
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EXISTING CHARACTERISTICS AND CONDITIONS OF THE STUDY AREA
A Br ie f H is to ry o f Lasam
History is by and large, the story in retrospect of a land and its people. The land, its
name and occupancy, its location and wealth, the people , their idiosyncrasies and
attributes, their tradition and culture, their faith and beliefs, their occupation andpursuits, their tribulations and ordeals, nay, their settlements and systems of
government, are history's subject matter and reasons for being.
The Land
Barrio Macatabang was a place along the bank of the Cagayan River called so
inhabited by Ybanag, Ilocano immigrant Filipino Chinese, and Malaweg.
Macatabang was a part of Gattaran, but as the population increased, the people of
the western part of Gattaran made a resolution that it be made a separate town.
Congressman Paulino Alonso of the 2nd District of Cagayan introduced a bill in
congress creating the municipality of Santo Tomas. Representative Cabarroguis of
Nueva Vizcaya vigorously objected the suggested name on the first reading of the
bill. Finally, Lasam was agreed upon in honor of the late Governor Honorio Lasam,
the sixth governor of Cagayan (1915-1918)
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On June 13, 1950, the late President Elpidio C. Quirino signed R.A. 507 which made
possible the creation of the municipality of Lasam.
January 1951 was eventful for Lasam
because it was her official inauguration as a
town. However, another problem arose after
the celebration of its inauguration. Although,
it was stated in the bill that the site of Lasam
would be the barrio be made the town site. In
order to settle the dispute, an arrangement
between the two political factions (the Jurado
faction of Macatabang and the the Acre faction of Nabannagan) was made. They
agreed that whoever was elected Mayor would have the privilege to situate the seat
of government in his respective barrio. Fortunately, Jurado was elected Mayor by a
margin of only two votes over Acre, thus, Macatabang became the town proper.
The Immigrants
In the early part of the 40s, immigrants
from other provinces came to settle in
Lasam and its nearby environs. They
came from the central plains and the
Ilocano provinces. Majority of them were
Ilocanos who brought with them
industriousness, thriftiness and sturdiness.
Settling in the plains and meadows of the
municipality, the Ilocanos with diligence who howed their lands into productive forms
which boosted no less than the economic progress of Lasam.
Eager and desirous to improve their lot, many of the immigrants have managed to
send and continue to send their children to the schools, colleges, and universities
enhancing on the process the literacy pasture of the municipality. From their ranks
have emerged many of the municipality's teachers, artisans and professionals.
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It is important to note in this connection that a number of them have become Chief
Executives of Lasam.
Lasam is considered the largest municipality of the second district of the province of
Cagayan in terms of population. It is also known as the rice bowl of Western
Cagayan. It is the nucleus of the
Zinundungan Valley and was
endowed an abundant forest
resources particularly hard umber
and mangrove species. The
municipality boosts excellent
education system where one tertiary
level, two vocational/agricultural
secondary level, three academic
high school, one TESDA institution
and complete elementary and primary schools scattered all the barangays all over
the area. The town is the second youngest town in the province.
Location and Wealth
Lasam town proper barely 13 kilometers, 20 degree south west of Magapit
Suspension Bridge. It is 68 kilometers north of Tuguegarao, Cagayan by crossing
the Cagayan River from the municipality of Gattaran, but following the Lasam-Logac-
Magapit National Road, is 106 kilometers
from Tuguegarao, Cagayan. It is bounded on
the north east by the municipality of Lallo,
Cagayan, on the north west by the
municipality of Allacapan, Cagayan and
Flora,Apayao, on the east by the Cagayan
River, and Gattaran, Cagayan, on the south
by Santo Nio, Cagayan and on the south
west by the municipality of Rizal, Cagayan.
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It must have been for its location, its agricultural and commercial potentialities that
prompted early immigrants to transfer to Lasam. Future events
proved the wisdom of their choice for, with the Cagayan River and the Zinundungan
River as the chief means of transportation at that time and for the long period, Lasam
became the hub of trade and commerce for a wide area.
The rivers were teeming with freshwater
fish and shells and forests were
everywhere abounding with raw building
materials and wildlife. In fact, venison
and meat of wild pigs were commodities
which the traders from Aparri, with their
roof-flat-bottomed rafts and boats, bough
in quantity.
Greed and ignorance soon took its toll. Forests were denuded without the thought of
the future resulting in big floods and extensive soil erosion. Fingerlings, too, were
trapped or caught for food or sale.
The saving grace from all these senseless wastes came later when with advanced
technology, a breakthrough in rice production was achieved. Farmers who would
harvest only 15 to 25 cavans per hectare could now produce 70 to 100 cavans. Corn
also became a prime crop augmenting the income of the farmers to a marked
degree.
Area and Population
Lasam has a total land area of 234 square kilometers or 23,400 hectares.
The total area of the municipality is divided among 30 barangays namely:
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PINSAL FALLS
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BARANGAY POPULATION
Aggunetan 1,083
Alannay 2,022
Battalan 1,073
Cabatacan East (Duldugan) 1,799
Cabatacan West 1,606
Calapangan Norte 825
Calapangan Sur 749
Callao Norte 828
Callao Sur 840
Cataliganan 323
Centro I (Pob.) 2,259
Centro II (Pob.) 2,078
Centro III (Pob.) 1,817
Finugo Norte 520
Gabun 1,125
Ignacio Jurado (Finugu Sur) 1,573
Magsaysay 1,404
Malinta 1,070
Minanga Sur 713
Minanga Norte 397
Nicolas Agatep 884
Peru 1,807
San Pedro 1,644Sicalao 1,508
Tagao 376
Tucalan Passing 844
Viga 712
Nabannagan East 1,183
Nabannagan West 2,519
New Orlins 1,065
TOTAL 36,646
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COVERAGE OF THE PROJECT
The project will involve 141 farmers from Barangay Cabatacan East with a service
area of 155 hectares of agricultural lands suitable to rice.
VARIOUS TECHNICAL CONDITION OF THE STUDY AREA
A. Topography and Slope Classification
The service area is generally flat in terrain. According to the Bureau of Soils,
the study area is among the 14,000 hectares or 60% of the total area of Lasam
town that has a 0.30 slope which is level to nearly level. These land area are suitedfor agriculture.
B. Meteorology and Hydrologic Investigation:
The water source of the proposed service area is the Tucalan Creek and
some tributaries.
C. Climate:
Under the climatic classification, the climate at the project area fall generally
under Type III, i.e. rainfall is more or less evenly distributed throughout the year.
Seasonal very pronounced, relatively dry from November to April and wet during the
rest of the year.
D. Rainfall:
The project area is on the windward side during the northeast monsoon so
that rainfall is generally heavy during this part of the year. Although the northeast
monsoon season starts affecting the country by the later part of October and last in
the month of April, rainfall generally declines significantly in the project area by
February.
The period March to April which covers the later part of the northeast
monsoon season and the trade wind season has generally the lowest rain fall during
the year.
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The project area is on the leeward side during the southeast monsoon from
May to the later part of October, however, the area still receives substantial amount
of rainfall during the period especially during the period from August to October.
E. Flood Studies:
Flood study to evaluate the occurrence of flood at the proposed damsite were
not undertaken, however there were accurate information of flooding in the area.
F. Sedimentation:
There is no data on suspended bed load sediments for Tucalan Creek, hence,
the sedimentation rate of this creek was based on the studies for various watershed
in northern luzon. In the sedimentation studies at Magat River Reservoir, erosion
rates are from 0.75 mm/year to 1.55 mm/year. As far as the sedimentation study is
concerned wherein denudation or deforestation is extensive at the drainage area it
can be presumed that there are erosions considering the present situation of the
upper section of the damsite which is actually silted.
G. Water Quality:
The water flowing at the Tucalan Creek is 100% suitable for irrigation.
Tucalan CIS had been diverting water from Tucalan Creek for some years ago. It
was found out that there is no harmful effect that have been noted and recorded.
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GENERAL LAYOUT OF TUCALAN COMMUNAL IRRIGATION SYSTEM
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Pictorials of the Existing Condition of the Study Area
Canal Structures
Some canal structures are heavily
silted and clogged with debris. Steel
gate of gated structure as shown
above were already out of place and
others were damaged with passing ofeach cropping season.
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Canalization
The condition of main canals and laterals needs rehabilitation. Lined canals werecracked that results to seepage loses. Most of the stretch of canal are heavily siltedwhich lessen the capacity to carry the flow of water, thus, decrease in the efficiency.
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Service Road
This is the portion of service road that needs rehabilitation like surface stabilizationand gravelling. This will ensure convenience in the mobility of crop production andeasy access to different farm site.
Diversion Dam
Washout portion of the overflow damgreatly affects the efficiency andfunctionality of the irrigation systemespecially to quantity of water beingdiverted to canal networks.
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Institutional Development
The situation shows that there is no management plan for cropping schedule of
farming. This results to the inefficient use of irrigation water.
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AGRICULTURE CONDITION OFTHE STUDY AREA
Rice is the principal crop of the project area. Depth of water needed during
land preparation is 150 mm, maximum. Reduce water depth from 20-50 mm during
transplanting and 5 days after the end of transplanting, increase and maintain the
depth of water from 25-75 mm with maximum of 150 mm until 14 days before
harvesting.
Provision for water losses includes seepage, leakage and consumptive use of
vegetation on the slope and/or along the stretch of the canal, the operational losses
on account of some damaged structures, excess delivery and waste water incurred
during transplanting and poor maintenance of paddy field dikes.
A. Vegetative Cover
The Tucalan Creek water shed area as estimated from the 1:50,000 m scale
military map is 13.20 square kms. The drainage area is heavily forested despite the
presence of selective logging operation. The low lying hills portions show baldness
for no big forest trees is present. Tall grasses like bamboos, bohos, shrubs, cogons
and those belonging to gramineae family are found.
Some of the low land rice areas are found at the foot of the hills. On
established paddy fields, the dominant grasses are cogon, and talahib. Other
common grasses are echinochloa glabrescens, echinochloa coloma, cyperius iria,
fimbristylis littoralis, ipomoea aquatica and monochoria vaginalis.
B. Soil Type
The general soil type of the service area is clayey and loamy types. These
soil types crack easily upon drying; however it becomes soft within few hours after
saturation. Along hillside in cultivated areas the soil dries to a depth from 50-70 cm
or more.
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C. Land Use
The service area of 155 has is cultivated and planted to rice. Originally the
area is irrigated. However, since the dam was washout the area became rain fed
rice paddies.
D. Land Ownership
Approximately the distribution of land ownership is as follows:
OWNERSHIP/CULTIVATORSHIP DISTRIBUTION BY PERCENTAGE
AREA FARMERS
Full Owner 73.90 84
Share Tenants 11.00 22
Lease Holder 14.20 15
Amortizing Owner - -
Full Owner & Lease Holder 39.50 10
Full Owner & Share Tenants 11.80 7
Share Tenant & Lease Holder 4.60 3
Full Owner & Amortizing Owner - - _______
T O T A L 155 141
AGRO-ECONOMIC DATA
A. General:
To ascertain the economic viability of
the project an agro-economic survey
was conducted. The method and
approach was through interview of
randomly picked farmer beneficiaries.
Information was also obtained from
other government entities national
and local who are involved with the
different data. These pieces of
information and data were compiled,Water Resource Plan Tucalan Communal Irrigation System 17 of39
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transcribed and consolidated and became the basis of projection and estimate of the
project.
B. Present Production
The present average production per hectare for rainfed areas is 2.50 tons/ha. The
present family net income of owner-operator for one (1) hectare rainfed rice is
P17,104.00 annually. This meager farm net income cannot sustain the economic
needs of the farmer, thus an irrigation system is vital to increase the rice production.
Marketing of farm product in the area is not a problem. The farmers sell their
palay to traders at the poblacion, others sell their products at NFA warehouse at
Allacapan, Cagayan.
IDENTIFIED UNCERTAINTIES
1. Calamities and Weather Disturbances
This Water Resource Plan aims at establishing a sustainable and functional
irrigation system to improve the agricultural potentials of the study area. But
because of calamities and weather disturbances such as typhoons, excessive
flooding, El Nino, La Nina and others, risks that may lead to the destruction of
irrigation infrastructures, access roads and casualty on crops are at stake.
2. Production Cost
In recent years, high prices of agricultural supplies such as hybrid seeds,
fertilizers, insecticides and pesticides is one of the major burdens of farmers.
It is also aggravated by the low market price of crop yields because trading is
monopolized by private individuals. As an adverse effect, farmers might suffer
indebtedness that will affect their quality of living.
3. Fund Source
In Philippine setting, realization of various infrastructure projects like this
water resource plan depends on government funds. In most cases, there are
limited available budget for the restoration and rehabilitation of existing
irrigation infrastructures to sustain its functionality. This has been the scenarioWater Resource Plan Tucalan Communal Irrigation System 18 of39
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for Tucalan Communal Irrigation System. Funds may be available for certain
year but uncertain of its next funding period.
4. Political Will and Rapid Changing Priorities
Because most of infrastructure projects are government funded, it takes a
political will to ensure the potentials of the irrigation projects. These irrigation
projects like the Tucalan CIS might be affected by the changing priorities of
government officials as an effect of the transition of political administration.
5. Accessibility/ Isolation of Production Area.
The study area has 1.20 kilometers without proper access road which was
included in this project plan to be developed. Problems in the future may
include the maintenance for the serviceability of the access roads.
6. Irrigation Association Capability
The functionality and operation of the irrigation system depends on the
effectiveness of Irrigator Association in carrying out irrigation management
plan. Failure to establish its stability might hamper the optimum utilization of
the system.
ALTERNATIVES
In determining the project irrigation requirements, all the above mentioned technical
data and agricultural conditions were considered. For instance the cropping
calendar shows that land preparation is set during the first week of May and
September. Transplanting and vegetative or growth management follows until the
start of harvesting which falls on the first week of October and February to complete
a year-round cropping season. Another two and one half months (2) period is
provided for repair and maintenance of the system before the on-set of the first
cropping season of the following year.
Three alternatives were identified for the project to suit the existing conditions: (1)
Overflow-Type Weir, (2) Pump Irrigation Project (PIP) and (3) Shalow Tube Well.
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Alternative 1: Overflow-Type Weir
Scope
This alternative involves the modification of the intake and earthfill dam across the
Tucalan Creek to harness the potentials of the stream for irrigation. Major
components of the project include the rehabilitation of irrigation and drainage
network to ensure irrigation water will reach the whole service area. Other items of
work will also include the provision of service road along the existing canal network
and farm level facilities to guarantee efficient water delivery into the paddy level.
Environmental Impact
Results of field investigation conducted have revealed that there are no human
settlements that could be affected in the diversion works location and with the stretch
of the diversion canal to be undertaken.
As far as the project is not within the environmentally critical areas, considering the
works to be undertaken does not require massive excavation or quarrying, no big
trees will be cut down nor reforestation areas will be traversed by canal, hence it is
possible to ascertain within the project area, that there are no archeological sites,
historical or native landmarks that will prejudice development of the project.
Investment Cost
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OVERFLOW-WEIR TYPE OF DAM
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The total investment cost of the project amounted to P18,382,002.56. This includes
old loans amounted to P413,922.68. and this program for construction amounted to
P18,600,000.00. Total Project Cost is P19,013,927.00 and the development cost is
P122,670.47/ha.
The estimated cost breakdown is as follows:
Items of Work (Balance of Old Loan) This Investment Total Investment
Diversion Works P 260,869.02 P1,439,660.00 P 1,700,529.02
Canalization 153,053.66 10,356,850.00 10,509,903.66
Canal Structure 3,286,100.00 3,286,100.00
Terminal Facilities 303,505.00 303,505.00
Drainage Facilities 100,000.00 100,000.00
Project Facilities 75,000.00 75,000.00
Service O & M Road 800,000.00 800,000.00
Total Direct Cost P 413,922.68 P16,361,115.00 P16,775,037.68
GESA 818,056.00 818,056.00
Institutional 490,833.00 490,833.00
Management Fee 930,000.00 930,000.00
Total Indirect Cost 2,238,889.00 2,238,889.00
Total Estimated Cost P 413,922.68 P18,600,004.00 P19,013,926.68
To Estimate, Say P19,013,927.00
Economic Internal Rate of return
The final evaluation Economic Internal Rate of Return (EIRR) of the Overflow-Type
Weir yielded 29.35% considering normal plan. However with the foresighted 20%
increased in construction cost it yielded an IRR 23.85%. A 20% increase in
construction cost and two years delay in attaining full project benefits resulted to an
IRR of 22.34%.
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Net Present Values and Benefit-Cost Ratios (NPV/BCR)
At Normal Plan
FUTURE NOMINAL VALUE PRESENT WORTH @ 10%
INV. COST O & M BENEFIT 10% INV. COST O & M BENEFIT
( P'000) ( P'000) ( P'000) D.F. ( P'000) ( P'000) ( P'000)
1 446.96 0.90912 10,042.44 0.8264
3 10,042.44 0.7513
4 779.50 5,792.50 0.6830 532.40 3,956.27
5-50 779.50 5,792.50 6.7449 5,257.65 55,814.04
Total 20,531.84 5,790.05 59,770.31
Net Present Value ( NPV ) = 59,770.31 - ( 16,250.26 + 5,790.05 )
= 37,730.00
Benefit Cost Ratio ( BCR ) = 59,770.31
( 16,250.26 + 5,790.05 )
= 2.71 > 1.00
YEAR
406.338,299.06
7,544.87
16,250.2600
Advantage
1. It can supply water to large irrigation areas.
2. Reservoir form is a good storage of irrigation water that can be used
especially during dry season.
3. The service period efficiency is high compared to other irrigation option that is
why it is the most adopted irrigation component in the Philippines.
DisadvantageWater Resource Plan Tucalan Communal Irrigation System 22 of39
t Normal Plan
FUTURE NOMINAL VALUE ( P'000 ) AT PRESENT WORTH ( P'000 )
Year Benefit on Increment At
Investment Irrigation Benefit DF Value DF Value
446.96 -446.96 0.7692 0.80 -357.5
2 10,042.42 -10042.42 0.5917 0.64 -6427.1
3 10,042.42 -10042.42 0.4552 0.512 -5141.7
4 779.50 5,792.50 +5013.00 0.3501 0.4096 +2053.3
5-50 779.50 8,275.00 +7495.50 1.1671 1.6353 +12257.
T O T A L + 2384.2
5 ( 30-25) ( 2384.27
= 29.35
- 354.15
COST
O & M
At30% 25%
+25INTERNAL RATE OF RETURN ( IRR ) =
-343.80
-5942.10
-4571.30
+1755.05
+8748.00
384.27 - 354.1
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1. Construction cost is quit high.
Alternative 2: Pump Irrigation Project
Scope
The main component of this alternative will involve 2 units-250 watts diesel engines
with a capacity of 3,200 cubic foot per minute. The water delivery component will
include 36 diameter Reinforced Concrete pipe to augment the trapezoidal and
square lined canals. Like the first alternative, other items of work will also include the
rehabilitation of irrigation and drainage network to ensure irrigation water will reach
the irrigable area.
Economic Internal Rate of return
Economic evaluation of this alternative shows that the increased investment cost and
decreased irrigation benefits exert a considerable influence on the Economic Internal
Rate of Return. The variations, however, are relatively slight. An increase of 25% in
the investment cost corresponds to a reduction of 9.13% in the EIRR and a
decreased of 20% in the irrigation benefits reduces the EIRR by about 10.77%
points. The combined effect of the two cases on the EIRR is a reduction of
approximately 18.72% points.
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PUMP IRRIGATION PROJECT
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Based on the preceding assumptions and by discounting the cost and benefit
streams over a 12 year period, the EIRR is estimated at 22.46%.
Analysis of with and without project situations yielded to the annual financial gross
value of production is P179,153.44 per average farm lot and the same value for
future without project. For the future with project, annual financial gross value of
production increased to P240,189.94 without costing labor. With the use of farm
budgets, analysis of annual net farm incomes indicate that present net crop income
of P62,474.12 would increased to P91,171.22 per average farm lot with the project.
The difference in net crop incomes between the present and the future situations
with project are substantial in determining adequate incentives to farmer
beneficiaries.
Benefit-Cost Ratio
The project has a benefit-Cost Ratio of 1.51 considering incremental benefits for a
15 year period at 15% discount rate of P8,591,680.00 and total Cost of
P5,702,940.00.
Investment Cost
The total project cost was estimated at P9,842,025.30 with the following breakdown:
Item of Work Amount
I. Canalization
3,000 PSI Reinforced Concrete 79,718.10
Structure Excavation 59,361.10
Installation of 36 diameter RCP 582,782.00
Structure Backfill with Compaction 27,062.50
II. Laterals (Lined Canal) 8,251,101.60
III. Diesel Engines (2-250 watt) 842,000,00
Total Project Cost 9,842,025.30
Environmental Impact
There is no significant environmental impact expected from the pump irrigation
project. As with the first alternative, works to be undertaken does not requireWater Resource Plan Tucalan Communal Irrigation System 24 of39
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massive excavation or quarrying, no big trees will be cut down nor reforestation
areas will be traversed by canalization.
Advantage
1. Pump is essential if irrigation by gravity is not possible.
Disadvantage
1. When pumps and other equipments break down, the resulting lack of water
can be critical for plant growth.
2. The cost of pumping water increases with the size of the service area.
Therefore, its irrigated service area is limited.
3. Functionality of the irrigation system declines as the efficiency of pump
decreases.
4. Cost of maintenance is expensive considering the continuous increase in the
price of diesel and machine spare parts.
Alternative 3: Shallow Tube Well
Scope
The Shallow Tube Well alternative will comprise 16 units of 2.5 Hp pump engines
drilled on site and involves well boring and development. Suction pipes will be
encased and will deliver water into the main canals.
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SHALLOW TUBE WELL
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Investment Cost
Total cost for the Shallow Tube Well is P6,528,977.20 and will have the following
items of work:
1. Pipe Casing2. Well Development3. Pumping Test4. Suction Pipe5. Pump & Engine6. Excavation7. Pump Chamber8. Stilling Basin
Operation and Maintenance Cost
Considerations in computing the operation and maintenance cost per hectare of rice
is as follows:
AssumptionsCost of Palay Per Cavan PhP 450.00Fuel Consumption Factor Per Pump Tear 0.6
Crop Water Requirement for Rice Per Day 0.008Crop Maintenance 89
(Number of Days Per Cropping)Irrigation Water Requirement Per Hectare (cu m/ha) 7,120Pumping Hours Required (hrs) 152.14Assumed Cost of Diesel (PhP/Liter) PhP 25.00
Energy CostCost (Fuel Cost Per Hectare) PhP 2,282.05Consumption (Liters) 91.28
Repair and maintenanceOil and Parts PhP 200.00Operator Php 216.00Well PhP 800.00
Replacement Cost (Every 10 Years) PhP 680.00
Total Estimated Operation and Maintenance Cost PhP952,595.70
Advantage
1. Good for small-scale irrigation projects
Disadvantage
1. The amount of water that can be abstracted from shallow well is limited, and,
as a result, the areas which are irrigated from this water source will also be
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limited.
2. Excessive exploitation of the ground water by many users, however, will bring
about a decline in the water table.
3. Source of shallow tube well are likely to be very thin with a limited storage
capacity for ground water..
MULTI-CRITERIA ANALYSIS
The three alternatives were subjected to a multi-criteria analysis in order todetermine which option is most responsive in terms of achieving the short-term andlong-term objectives of the project. Three criteria were selected: Impact onProduction, Social Equity and Sustainability.
Criteria 1: Impact on ProductionThe provision of the irrigation system and the transfer of appropriate farmingtechnologies to the beneficiaries directly translate to the extension of areas forcultivation, crop intensification and adoption of modern crop varieties.Adequate irrigation water supply also results to higher agricultural outputswithin the projects influence area. Consequently, higher production yieldsignificantly contributes to the increase in the average household income ofthe farmers. The element to be rated in this criteria is the Yieldof Productionrepresented as the ratio of the average annual volume of production (in ton)and the area of production (in hectare).
Alternative 1
The Overflow-Type Weir is expected to irrigate the whole service area of 155
hectares during the first cropping and 75 hectares during the second
cropping. This will increase cropping intensity by 148% and will improve palay
production from 387.50 tons to 1,150 tons annually. Production yield of 6.2
tons per hectare will result to an increase in average annual on-farm income
from P17,104.00 to P53,379.87.
Alternative 2
The Pump Irrigation Project will increase cropping intensity by 130% and is
expected to irrigate 155 hectares during the first cropping and 47 hectares
during the succeeding cropping season. While the whole irrigable area will be
serviceable during the main cropping period, the projected low water level of
the stream during the dry season which coincides with the second cropping
will drastically affect the volume of source water. The annual volume of
production is projected at 700 tons and yield is computed at 4.5 tons per
hectare.
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Alternative 3
The Shallow Tube Well is expected to irrigate the whole service area of 155
hectares during the main cropping. However, based on available aquifer data
in the area available water source will serve only 39 hectares during the
second cropping which will achieve a cropping intensity of 125%. Over theyears this is projected to decrease as aquifer levels will be critically depleted
especially during pronounced dry seasons. Volume of production is estimated
at 670 tons and a yield of 4.3 tons per hectare.
The Overflow-Type Weir best satisfies the Criteria on Impact of Production as
presented above. It posted the highest relative weight of 36%.
Criteria 2: Social Equity
A demand-driven and equity-based approach is adopted in the
implementation of the project. Social equity refers to the involvement of the
project beneficiaries in whole process of project development from planning,
design, construction and operation. This will encourage them to actively
participate in the implementation of the project. The provision of equity or
counterpart from the beneficiaries is crucial and significant in ensuring the
achievement of the projects purpose. Social equity also requires the
establishment of a stable Peoples Organization to manage and supervise the
operation and maintenance of the project. The element to be rated in this
criteria is the relative participation and involvement of the beneficiaries in
terms of labor provided (jobs generated) and the amount of counterpart fund
contributed (pesos). The alternative with the most jobs generated in theconstruction of the project and with the highest counterpart fund provided will
best satisfy the social equity criteria.
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Alternative
1 6.29 tons/ha 35.86%
2 4.51 tons/ha 32.61%
3 4.36 tons/ha 31.53%
Production Yield Weight
Impact on Production Criteria
Alternative Weight
1 53.73%
2 27.81%
18.45
oc a qu ty r ter
984,202.53
652,897.72
128
66
44
Counterpart
Fund (PhP)
Jobs
Generated
1,901,392.70
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In terms of the Social Equity Criteria, Alternative 1 (Overflow-Type Weir)
posted the highest relative weight of 54%.
Criteria 3: Sustainability
The project must be sustainable so that local mechanisms will be in place to
ensure that the community shall continue to benefit long after the project is
completed. The sustainability criteria will look into the optimum usable lifespan
of the project including the level of investment required for the maintenance of
the structures and facilities. An outright observation of the three alternatives is
that the project cost is inversely proportional to the cost of maintenance. On
the other hand, the total project cost is in direct proportion to the projected
usable lifespan of the project.
The alternative with the highest incidence of sustainability is the Overflow-
Type Weir with a relative weight of 61%.
COMPARATIVE ANALYSIS
1. Summary of Alternatives
2. A comparative evaluation of the three alternatives shows that the Overflow-Type
Weir (Alternative 1) provides the best option in terms of higher Economic Internal
Rate of Return and Benefit-Cost Ratio.
Water Resource Plan Tucalan Communal Irrigation System 29 of39
Alternative Weight
1 60.98%
2 24.39%
3 14.63%952,595.70 8-12
175,537.50 25-50
1,054,000.00 15-20
Sustainability Criteri
Maintenance
Cost (PhP)Lifespan (Yrs)
1 Overflow-Type Weir 19,013,927.00 29.35 2.71 175,537.50
2 Pump Irrigation System 9,842,025.30 22.46 1.51 1,054,000.00
3 Shallow Tube Well 6,528,977.20 - - 952,595.70
Alternative EIRR (%) BCR O&M Cost (PhP)Total Project
Cost
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3. The EIRR of Alternative 1 is 7% percent higher than Alternative 2 and 120%
higher in terms of BCR. The Overflow-Type Weir is also most advantageous in terms
of O&M cost with a 1% O&M Cost Project Cost ratio.
4. Since the irrigable service area is large, over-flow weir is best suited for its
capacity to supply water to larger areas.
5. The source of irrigation water when the overflow-type weir is adopted (Tucalan
Creek) would be sufficient to meet the diversion requirements for the service area
based on the discharge capacity of Tucalan Creek and its nearby tributaries. The two
other alternatives pose uncertainties on underground water source.
Based on the comparative analysis of the three alternatives, the Overflow-Type weir
was selected for implementation in the project area. Though more expensive than
the other options, it is chosen for its high incidence of sustainability.
IMPLEMENTATION
Scheme of Development
The design approach for all items of work shall conform to NIA standards and
specifications for irrigation projects.
1. Diversion Works
This involves the repair of the earthfill type diversion dam across Tucalan
Creek at approximately 180500 N latitude and 1212815.90 E longitude. Thedam will serve to divert the flow of water thru a gated intake structure, which will
regulate the flow of irrigation water to the canal network. Although it is not of the
impounding type, the dam was originally constructed as earthfill because of the very
wide section of the diversion site. The height of the dam to command the highest
portion of the area entails high cost if concrete-overflow type is adopted.
2. Canalization:
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This involves the rehabilitation of dilapidated canal system from the existing
outlet of intake up to the tail end of both the main canal and lateral canals.
3. Canal Structures:
This involves the construction of additional canal structures along the stretch
of canal system, repair of damaged structures and replacement of all siphon
structures to flume.
4. Terminal Facilities:
This involves the construction of additional turn-out structures, construction of
main farm ditches and supplementary farm ditches to efficiently deliver water to the
farm level.
5. Service / Access Road:
It involves the repair of 1.20 kms existing dirt road from the barangay road to
Cabalacan West leading to the diversion dam and construction of service roads
along the canal system.
6. Drainage Facilities
It involves the construction of drainage culverts along waterways and
depression areas being traversed by the system.
7. Project Facilities:
This involves the construction of bunkhouse in the project area to be used
during construction period.
Construction Scheme and Schedule
The project will be under the supervision of the Provincial Irrigation Engineer
of Cagayan-Batanes. The proposed works will be undertaken into two categories
force account works and contract works, major item of work will be awarded to
contractors requiring the utilization of heavy equipments, while minor work and other
work requiring intensive labor will be done by force account works to promote
participation of farmer-beneficiaries during construction. In this process the projectWater Resource Plan Tucalan Communal Irrigation System 31 of39
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could generate 10% equity thru labor. Another way to generate equity, the farmer-
beneficiaries could give cash or construction materials. The project will be
scheduled for construction for 2 years.
OPERATION AND MAINTENANCE
Technical:
1. Dam & ReservoirFor dam and reservoir to function properly the following are somemaintenance works that should be undertaken:
a. Clearing of the reservoir area of any debris or floating materials
b. Regular de-silting of the reservoir
c. Restoration of upstream and downstream slope of the embankment
d. Repair of upstream slope riprap.
e. Repair of water gauge or staff gauge in the reservoir.
2. Spillway
The spillway should always be capable of releasing probable excessfloodwaters from the reservoir.
a. The approach channel of the spillway should always be free of any obstructionor temporary structures.
b. Repair of riprap in the approach, discharge and terminal sections should be donewhen necessary.
3. Irrigation Distribution System
a. Checking of any leakage or malfunctioning of the outlet structure.
b. Cleaning and cutting of grasses in irrigation canal & embankment
c. Removal of debris that can obstruct the flow of water along canals & canalembankment.
d. Removal of silt deposits on canal bottom w/c can lessen the capacity of irrigationcanals.
3. Paddy Fields (farmer beneficiaries party)
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a. Leveling of paddy fields for even distribution of applied water.
b. Height of paddy dikes must be maintained to not less than 20 cm to prevent overtopping or spillage of water.
c. Paddy dikes should be properly compacted & plastered to minimize seepage flow.
d. Farm ditches should be properly constructed & maintained such that each farmcan receive its equitable share of water.
e. Additional paddy spillways provided for upland irrigations should be properlyclosed during lowland irrigation.
Agro-Economic/ Financial
At full development, production from the project area is expected to increase from
2.50 tons/hectare to 5 tons/hectare for the first crop and 5 tons/hectare for the
second crop. The cropping intensity will increase up to 148 % in the whole service
area. The production is expected to reach 1,150 tons annually in the whole area from
the present 387.50 tons. Annual net income is expected to increase from P
17,104.00 to P53,379.87. These benefits are successfully attained with the
application of farming innovations and policies. Irrigation by itself cannot do much
way of development, but combined with other factors may create a potentially
favorable situation for agricultural development. Other program supports such as
credit sources, extension services and creation of money-lending cooperative in the
association which has been shown to be inadequate in the area will
have to be established and strengthened.
Social Requirements
The project after completion and successful test run of its facilities will be turned over
to the Irrigators Association (IA) for operation and maintenance. Training and
seminars will be conducted in order to assist the Irrigators Association as regard to
proper Irrigation System Operation, Maintenance and Management. In this aspect
the IA will be able to acquire knowledge to formulate their own plans and strategies
applicable to their needs.
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Impact of the Water Resource Plan
The water resource plan for Tucalan Communal Irrigation System is designed to
make a sustainable management of water and re-establishment of the operation and
functionality of its irrigation components. Its impact in the increase of crop production
contributes to social transformation and economic development of the area including
the municipality itself.
1. Urban Center and Commercial Development
Beneficiaries seek to attain higher educational learning to further
improve quality of living.
With the increase of income for every household, consumption of
various commodities and services would also increase. This will lead to
commercial development on the area as well as nearby business
centers.
2. Human Settlement areas
In the fulfillment of quality living, beneficiaries choose to have quality
construction materials for their houses. They also strive to achieve
electrical services for household purposes.
3. Additional Roads
The well-planned operation and maintenance of the irrigation system
will create a continuous improvement of farm-to-market roads. These
includes clearing, surface stabilization and gravelling of road networks.
Aside from the convenience it provides, the cost of transporting farm
production will be minimized.
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CLIMATE MAP
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THIS SITE
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LAND CLASSIFICATION MAP
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LAND USE MAP
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SOIL MAP
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ANNEXES