Ph.D. PROPOSAL
MODELLING AND MEASURING WATER USE EFFICIENCY AT LARGE
SCALE RICE IRRIGATED SYSTEM
BY
ENGR. MUHAMMAD MOHSIN HAFEEZ
CENTER FOR RESEARCH DEVELOPMENT (ZEF)
UNIVERSITY OF BONN, GERMANY
JANUARY- 2000
Acronyms
DSR
Dry Seeded Rice
FAO
Food and Agriculture Organization
GIS
Geographic Information System
IRAS
Interactive River Aquifer Simulation
IRRI
International Rice Research Institute
IWBF
IIMI Water Balance Framework
IWMI
International Water Management Institute
NIA
National Irrigation Administration
P
Percolation
S
Seepage
S&P
Seepage and Percolation
SWIM
System Wide Initiative on Water Management
UPRIIS
Upper Pumpanga River Integrated Irrigation System
USBR
United State Department of the Interior Bureau of Reclamation
WSR
Wet Seeded Rice
WRI
World Resource Institute
ZEF
Center for Development Research
INTRODUCTION
The world’s thirst for water is likely to become one of the most pressing resource
issues of the 21st century. Since 1970, global demand of water for domestic, industrial
and agriculture have risen at roughly 2.4 % per annum. Gleick, 1993 showed that per
capita availability of water resources declined by 40-60% in many Asian countries
between 1955 and 1990, and is expected to decline further by 15-54% over the next 35
years. At a world level, withdrawals are expected to increase by 35 % by the year 2020,
with growth in demand rising fastest in developing countries (Rosegrant et al. 1997). To
keep up with the population growth and income-induced demand for food in most lowincome Asian countries (Hossain, 1997), it is estimated that rice production has to
increase by 56% over next 30 years (IRRI, 1997). Waste and nonproductive uses must be
carefully scrutinized to identify potential saving.
Rice irrigation has been practiced in Asia, Latin America and Africa for centuries.
Rice is major staple food in Asia where about 92% of the world rice is produced and
consumed (IRRI, 1997). More than 80% of the developed freshwater resources in Asia
are used for irrigation purposes and more than 90% of the total irrigation water is used for
rice production (Bhuiyan, 1992). The available amount of water for irrigation, however,
is increasingly getting scarce worldwide (Guerra et al., 1998). Irrigated rice is a heavy
consumer of water: it takes some 5,000 liters of water to produce 1 kilogram of rice
(IRRI, 1998).
Traditionally, farmers in Southeast Asia have established their rice fields by
transplanting seedlings but during the past 10-15 years, many have changed this practice
to sow seeds directly onto the field. The amount of water used by farmers for land
preparation in Philippines was 27% less with wet seeding than with transplanting (IRRI,
1998). IRRI study showed that maintaining a saturated soil throughout the growing
season could save up to 40% of water in clay loam soil, without yield reduction. Water
use efficiency of rice fields can be analyzed by studying the components of water
balance.
PROBLEM STATEMENT
The lack of water availability at critical time affects 40% of rain fed lowland and
all upland areas in Asia (IRRI, 1998). The future of rice production will depend heavily
on developing and adopting strategies and practices that will use water efficiently in
irrigation system. Rice grown under traditional practices in medium to heavy textured
soils in the Asian tropics and subtropics requires between 700 and 1500 mm of water
(Bhuiyan, 1992). The leading system of rice production in Asia is transplanting or direct
seeding in a field that is kept flooded throughout the growing season. Therefore, most
management interventions are focused on reduction of seepage and percolation losses,
such as water-saving irrigation techniques (Tabbal et al., 1999). Such techniques have
been shown to be efficient in reducing water input at field level, however, generally at the
cost of yield reduction (Bouman et al., 1999). On-farm water components such as
seepage and percolation (S & P) are losses, because they flow out of the farm without
being consumed by the intended crop.
During the crop growth period, the amount of water usually applied to the field is
much more than the actual field requirement (Guerra et al., 1998). When water supply
within the irrigation system is unreliable, farmers try to store much more water in the
field than needed as insurance against a possible shortage in the future. The actual
amount of water used by farmers for land preparation is often several times higher than
the typical requirement of 150-250 mm (Guerra et al., 1998). Ghani et al (1989) reported
water use for land preparation as high as 1500 mm in the Ganges Kobadak irrigation
project in Bangladesh.
More than half the water consumed in rice production is often used to prepare the
land and most of this is lost in the process through percolation and seepage (IRRI, 1998).
According to Sharma (1989), S & P accounts for 50-80% of the total water input to the
field. In large irrigation system, seepage occurs only in peripheries, but percolation
occurs over the whole area. S & P rates vary widely depending on soil texture and other
factors but usually increase as soil texture becomes lighter.
Estimating future water supply depends on several factors, including anticipated
rainfall distribution during the wet and dry season, type of water diversion and storage
system used, and reliability of hydrologic data and climatic data. Water demand is
primarily determined by estimating expected cropping pattern and irrigation efficiencies
at the on-farm and main system level. To accurately calculate water requirement for the
system, information is needed not only on cropping pattern, but also on the actual water
requirements of different crops under different soil conditions (Miranda, 1989).
The agriculture sector plays a dominant role in the economy of the Philippines,
accounting for about 26 percent of the gross domestic product (GDP) and 50 percent of
employment. In the Philippine, rice is the major staple food with two cropping seasons
i.e., wet & dry. Wet season runs from July-October with abundant rainfall. While the Dry
season runs from January-April with less rainfall. The Upper Pumpanga River Integrated
Irrigation System (UPRIIS), a major source of rice production for Philippines, warrants
an efficient use of an expensive and scarce resource, water. In Nueva Ecija, soils are
typically silty clay loam, clay loam, and clay, with SP rates varying between 0.2 and 20
mm d-1 (Tabbal et al., 1992).
Studies to evaluate overall irrigation efficiency and productivity of irrigation
system using a system level water balance accounting approach are lacking. Reducing the
period of land preparation would lead to a substantial saving in water, including water
lost because of evaporation, seepage and percolation, and surface runoff (Guerra et al.,
1998). Cabangon and Tuong (1998) found that in farmers’ fields in Bulcan and Nueva
Ecija, Philippines, shallow tillage reduced the total water input for land preparation by
31-34 %, which corresponds to 108-117 mm of water. A study in the Muda irrigation
scheme showed that dry-seeded rice (DSR) requires less water for land soaking than wet
seeded rice (WSR), and WSR requires less than transplanted rice (Guerra et al 1998).
Dayanand and Singh (1980) reported that puddling during land preparation could
reduce input water by 40-60% during crop growth because of the reduced percolation
rate. Reducing lateral infiltration into the bunds can be minimized under bund percolation
(Tuong et al 1994). Numerous studies conducted on the manipulation of depth and
interval of irrigation to save on water use without any yield loss have demonstrated that
continuous submergence is not essential for obtaining high rice yield (Guerra et al 1998).
According to Keller et al (1996), reducing S & P of upstream farms may not improve
overall efficiency if S&P water is used downstream. Overall water efficiency of irrigation
systems depend upon the control, reduction, and management of runoff and seepage and
percolation in both the water delivery system and on farm independently and
interactively.
In the Philippines, which has only two cropping season, the service area is often
reduced to about one-third the area served during the wet season. The area is rotated
every year, with the area served in one-year receiving water again in fourth year
(Miranda, 1989). IRRI studies showed that mal-distribution of water in the secondary
and primary parts of a system resulted in major differences in water availability from one
tertiary canal to another. In general, it was found that the tail-end portions had serious
water deficiencies while the head or upper portion had excess water.
Water lost from an individual field is not necessarily lost for the whole irrigation
system or for the water basin at large. Water that flows out of a field will enter drains,
creeks or groundwater, and flow downstream. Often, this water is again available for reuse, e.g., by blocking creeks and diverting the water in it into new irrigation canals, by
directly pumping from creeks and drains, or by pumping from the (shallow) ground
water. In fact, this is what happens in practice both within irrigation systems as well as
within the whole water basins.
There is an urgent need to develop management policies for efficient operation of
irrigation systems; technologies that reduce water consumption; changes in the rice plant
itself and ways in which it is grown, so as to use water more efficiently, increase water
productivity (i.e., grain yield over water input, in g grain kg-1 water), and also to provide
economic incentives to farmers to reduce water losses (IRRI, 1998).
REVIEW OF LITERATURE
The amount of the water (65 & 70%) used around the world was lost to
evaporation, leaks and other inefficiencies but it was possible to reduce these losses to 15
% (WRI, 1990). Lee Seung Chan (1992) reported that in many irrigation systems in
Korea, less than 50 % of the irrigation water reaches the command area. Percolation in
earth canals accounts for about 35% in the Korea (Lee Seung Chan 1994) and Iran
(Nickrawan and Nozari 1992), and about 25% in Bangladesh (Khan TA 1992) and the
Indus basin system in Pakistan (Ahmad 1994). Conveyance, field channel, and field
application efficiency are normally evaluated within an irrigation system. The proportion
of the seepage and percolation from the water distribution system that is recycled within
the whole irrigation system or basin is not quantified (Guerra et al 1998).
Reducing S & P losses would lead to an improvement in water efficiency onfarm. But if this water can be recovered for crop consumption at some point downstream,
these are not losses of the irrigation system. In the same way losses of an irrigation
system may not contribute to losses in the water basin. The potentials for water re-use
depend on a number of factors, such as topography (e.g., can creeks be dammed), subsurface hydrology (e.g., does percolated water re-charge a shallow ground water reservoir
that can subsequently be pumped), quality issues (water may be too polluted with
agrochemicals or salts) and costs of pumping. The possibility for re-use of irrigation
water has led some people to advocate that water saving at field scale are only paper
savings that do not really contribute to increased water-use efficiency: because of water
reuse, water use efficiency at system-level is higher than at individual field level.
Therefore the crucial issue is in finding “real” water saving, which is the reduction of
water flows to sinks from which it cannot be recovered any more i.e., the sea.
Bagley (1965) noted that failure to recognize the boundary characteristics when
describing irrigation efficiencies can lead to erroneous conclusions, and noted that water
lost due to low efficiencies is not lost to a larger system. Bos (1979) identified several
flow paths of water entering and leaving an irrigation project, clearly identifying water
that returns to a water basin and is available for down stream use. Bos and Wolters
(1989) pointed out that the portion of water diverted to an irrigation project that is not
consumed, is not necessarily lost from a river basin, because much of it is being reused
downstream.
Van Vuren (1993) listed several constraints on the use of irrigation efficiency and
pointed out situations when lower efficiencies are tolerable. According to Palacios Velez
(1994) “water that is lost, is not always necessarily wasted.” Molden (1997) pointed out
several weekness in using efficiency terms and scale effects in moving analysis from
farm to irrigated area and to river basin, and presented a common framework to describe
water use with in basin. Water balance considers inflows and outflows from basin, sub
basins, and service and use level such as irrigation system or fields (Molden, 1997).
According to Molden (1997), water accounting consists of four components i.e. inflow,
storage change, depletion, and outflow at all levels (field, irrigation & basin).
STUDY AREA
In the Philippines, about 61% of the 3.4 million ha rice land is under irrigation
(IRRI, 1997), with the majority of the production located in central Luzon. The
government of Philippines, through its National Irrigation Administration (NIA), is
dedicated to maintaining irrigation water availability by rehabilitation and expansion of
irrigation systems and by propagation of efficient water use techniques that optimize
water productivity.
The study area is District I of the Upper Pumpanga River Integrated Irrigation
System (UPRIIS) in the province of Nueva Ecija, Luzon, the Philippines. UPRIIS gets its
water from the Panatabangan Reservoir, and is owned and operated by NIA. UPRIIS with
the total area of 100,000 ha divided into 4 so-called districts is one of the most important
rice producing areas in the Philippines. The size of District 1 is about 25,000 ha and is
divided into a northern and a southern part. The northern portion of district 1 is Talvera
River Irrigation System (TRIS) with main city of San Jose. While the southern portion of
district 1 consists of cities like Santo Domingo, Quezon and Licab. TRIS main canal
originates from Talavera Diversion Dam, supply’s the water to the whole TRIS Area
including San Jose city. The boundary of District 1 is covered by Talavera River on one
side and ILOG Baliwag River on the other side.
UPRIIS is a major source of rice production for Philippines, an efficient use of an
expensive and scarce resource, water. On the average in district 1, canals or laterals
within each distribution system have a irrigation density of 75 hectares per kilometer of
canal; canal structures-27.30 hectare per unit; turnouts-40.63 hectares per unit; main farm
ditches- 15.12 meters per hectare; supplementary farm ditches-37.86 meters per hectare;
drainage ditches 12.28 meter per hectare and improvement of existing drainage channels9.94 meters per hectare (NIA, 1977). Turnouts are either double-gated (orifice type) or
combined single-gated turnout and parshall flume (NIA, 1977).
The texture of the soils in the District 1 ranges from moderately coarse to very
fine (loamy sand to massive clay). The structure of the surface soils in the project area
ranges; from granular to week fine and medium sub angular blocky to massive. The soils
are grouped into five based on terrace position like; most recent alluvial terrace, recent
alluvial terrace, natural levees, old alluvial terrace and residual terrace. There are six soil
series identified, namely; Maligaya, Qunigua, Prensa, Bantog, Zaragosa and Unclassified
(NIA, 1971). Several studies were undertaken during 1970s to investigate the soil
structure, texture and drainage characteristics of the project area.
IRRI and NIA have a long-standing history in cooperation in UPRIIS in issues
related to the optimization of water use. Many experiments have been conducted on so
called water saving irrigation techniques at the field level as well as experiments focusing
on system design and water delivery options.
OBJECTIVES
The proposed research will be under taken in the District 1, Upper Pampanga
River Integrated Irrigation System (UPRIIS). The specific objectives of the study are:
Develop methods to evaluate water use efficiency at large scale.
Design and construct simulation model for surface water flow into the system.
Use simulation model to explore effects of interventions in irrigation system (e.g.,
water saving irrigation at field scale, canal lining) on water productivity and water
use efficiency.
RESEARCH QUESTIONS
To measure water use efficiency at system level, there are still a number of
critical issues that need to be addressed in irrigation system:
 How much current water is flowing into the system?
 How much water is outgoing from the system?
 How much currently water is lost through seepage & percolation?
 What are the current levels of water re-use?
 What are the current water-use efficiencies at various scale levels with in
the irrigation system?
 What are potentials for water re-use at different scale levels in system?
 What are the potentials for true water savings?
 What is the true water saving irrigation techniques?
 How much seepage losses are controlled, if an intervention of the canal
lining is occurred?
 What happened if cropping practices of rice has been shifted i.e., from wet
to dry seeding?
 What is the associated cost for different water re-use interventions (like
creeks, drains, groundwater)?
METHODOLGY
To study the field level interventions such as water saving techniques & cropping
practices, the simulation model for water flow needs to start from water demand at the
field level. The water balance for an irrigation project is a complex set of inflows,
outflows, consumptive use, and recycling of water. The IIMI water balance framework
(IWBF), which is constructed as a workbook (consisting of five worksheets) in Microsoft
Excel version 5, is an easy to use computer model for analyzing the utilization of water
from surface irrigation and rainfall within an irrigation project (Perry, 1996). The IWBF
model accounts for two inflows of water (surface-delivered supplies and rainfall), four
outflows (crop evapotranspiration, nonbeneficial evaporation/ evapotranspiration,
drainage runoff, and net flows to groundwater). These elements are interlinked through
seepage from channels and irrigated fields, the disposition of rainfall between runoff,
infiltration, and evapotranspiration, and two modes of transfer i.e., pumping from
groundwater and pumping from drains (Perry, 1996).
The agro metrological data like temperature, humidity, radiation, wind speed,
rainfall, sunshine hours, will be available (if not then collected) by meteorological station
of the study area on daily/monthly basis for wet and dry season. For measuring the
evaporation, Class-A pan will be used. To measure reference crop evapotranspiration,
Penman-Monteith (combination) method will be utilized.
Originally, flow measurement devices like weirs & flumes were installed at all
lateral off takes and at various turnouts in the district 1, and the National Irrigation
Administration (NIA) maintained these records, but due to lack of funds few years age,
these measurement activities were stopped. The flow measurement activities will be done
at crucial points along the selected secondary canals, turnouts to tertiary channels from
secondary canal, and at some drains. Flow measurement by Ultra Sonic Velocity Flow
Meter (Model not decided yet) will be done at crucial points along the watercourse &
drains. This Ultra Sonic flow meter has the advantage like accurate average velocity, less
time consuming, handy and easy to install any where in the channel over other ordinary
flow measuring instruments (current meter).
IRRI is currently measuring monitoring all surfaces in and outflows into the
northern and southern parts of District 1 on daily basis. This will give an insight in the
water balance of the area, for calculating water productivity on the basis of actual amount
of water consumed. IRRI is also started an inventory of the number of pumps operating
with in the area (tapping shallow ground water and pumping from creeks and drains), and
try to estimate the total quantity of water being pumped. This is to get an idea of the total
amount of water being re-used with in the system by pumping (Bouman, 1999). That data
will also utilized for Ph.D. study. IRRI scientists identified 100 observation points like
culverts, creeks, drains, and canals for measuring water flows.
Percolation is the vertical movement of water beyond the root zone to the water
table, while seepage is the lateral movement of subsurface water. Seepage and
percolation rates are affected by a range of soil physical and hydraulics properties, like
structure, texture, conductivity, and by the hydrological environment e.g. sub soil
moisture content, ground water table depth, fields location, and condition of bunds
(Wickham and Singh, 1978). The amount of seepage is determined by piezometer head
differences between fields. The difference in piezometer head is large near drains, ditches
or creeks and in terraced rice-fields with considerable difference in elevation. Seepage
will be measured directly by using seepage meters constructed from plastic drums (detail
about the seepage meter will be provided later), similar developed by researchers Lee
(1977). Percolation rate is measured using double ring infiltrometer (FAO, 1984).
IRAS, an Interactive River Aquifer simulation program developed at Cornell
University of New York, USA primarily to assist those interested in evaluating the
performance or impacts of alternative designs and operating policies of regional water
resource systems. In IRAS, simulations are based on mass balances of quantity and
quality constituents, taking into account flow routing, seepage, evaporation, consumption,
and constituent growth, decay, and transformation, as applicable. A variable
computational time setup is used. Such systems can include multiple interconnected
rivers interacting with multiple aquifers serving large regions, or they could include only
a portion of a river or stream in a small watershed.
RESEARCH ACTIVITIES
To answer such questions requires new models and tools that explicitly address
water use at system level, that are able to quantify effects of interventions at different
spatial scale levels on water flows and water availabilities throughout the irrigation
system. Such models and tools are much needed to make water use in irrigated rice
production systems more efficient and to support strategic and tactical decisions makings
by institutes that manage irrigation water.
Furthermore, southern and northern part will be divided into 4 parts with the help
of digitized maps along the boundaries of the area. IIRI people will involve in digitizing
maps of canals, drains, creek, and road infrastructure, main structure, water control points
and integrate into GIS. I will give help in establishing GIS database and gain experience
with GIS tools. A geographic information system (GIS) using software ARC INFO/
VIEW will be developed to improve evaluation of system performance. IIRI has Landsat
satellite maps of 1992 of the whole project area. To get command and familiar with ARC
VIEW software, I will attend the four weeks-training course at Asian Institute of
Technology, Bangkok. IIRI has also collected GPS data on strategic coordinates and
points of flow measurements along the boundaries of the two parts of district 1 (Bouman,
1999).
The data related to hydraulic characteristics of the soils, and major soils type has
been collected in the past and available for the study (Bouman, 1999). To measure water
inflows accurately, the study area of district 1 will be divided into northern and southern
part. I will hire 2 field assistants, for flow measurement activity with in the canals and
drains along the northern and southern part of district1. I will visit the field project area
with Dr. Bouman to gain insight about the actual conditions of the area during May 2000
for two weeks. Most of the activities will be decided after general field visit of the area
and consultation with Dr. Bouman at IRRI.
First, I will utilize IWBF model to know water balance of different parts of the
district 1. The IWBF model allows simultaneous analysis of three agricultural seasons,
with different data for each season and division into sub areas. This model will also
consider the affect of different interventions like- lining canals, expanding conjunctive
use, changing canal schedules, or introducing drainage systems or new cropping patterns.
Then I will use IRAS model to evaluate overall water use efficiency of the Upper
Pumpanga River Integrated Irrigation System (UPRIIS). The developed model can serve
as a model for other irrigation systems.
WORK PLAN
A tentative timetable for the period of 3 years (October 1999 to September 2002)
showing the different activities has been presented in the table. The initial six months is
utilized as a development phase of proposal, and course work requirement of ZEF. The
research work will be conducted at the UPRIIS, Philippine with the coordination of
International Rice Research Institute (IRRI).
BIBLIOGRAPHY
Bouman, B.A.M., Wopereis, M.C.S., Kropff, M.J., Berge, H.F.M., and Tuong, T.C.,
1994. Water use efficiency of flooded rice fields II. Percolation and seepage
losses. Agricultural Water Management 26, 291-304.
Doorenbos. J., and Pruitt, W.O., 1977. Crop Water Requirements. FAO Irrigation and
Drainage paper 24. Rome, Italy.
Guerra, L. C., Bhuiyan, S. I., Tuong, T. P. and Barker, R., 1998. Producing more rice
with less water from irrigated system. SWIM paper 5. IWMI/IRRI, Colombo, Sri
Lanka.
Ismail E.S., and Moghazi H.E.M., 1997. A study of losses from field channels under arid
region conditions. Journal of Irrigation science 17: 105-110.
Isiorho S.A., Whitman R.L., Stewart P.M., and Beeching F.M., 1996. Seepage
measurements from long lake, Indian Dunes National Lakeshore. Journal of
Environment Geology 28.
IIRI and NIA, 1999. System-wide water use efficiency in the Upper Pumpanga River
Integrated Irrigation Scheme. Concept project workplan.
Miranda, S.M., 1989. Irrigation system principles and practices for reliable and efficient
water supply to rice farms. Agricultural Water Management.
Mckinney, D. C., Ximing C., Rosegrant, M. W., Ringler, C., and Scott, C. A., 1999.
Modeling water resources management at the basin level: review and future
directions. SWIM paper 6. IWMI, Colombo, Sri Lanka.
Molden, D., 1997. Accounting for water use and productivity. SWIM paper 1,
International Water Management Institute (IWMI), Sri Lanka, Colombo.
NIA, 1977. Upper Pampanga River Project. Completion report. Philippine.
NIA and USBR. 1971. Land classification and supporting studies. Upper Pampanga
River Project. Central Luzon, Philippine.
Ongkingco, P.C., Galvez, J.A., and Rosegrant M.W., 1982. Irrigation and rice production
in the Philippines: status and projections. IFPRI/IIRI, Philippine.
Perry C.J., 1996. The IIMI water balance framework: A model for project level analysis.
International Irrigation Management Institute. Research Report 5. Srilanka.
Spurgeon, D., 1998. Water: A looming crisis. International Rice Research Institute
(IRRI), Philippine.
Taylor C. D., and Wickham T.H., 1976. Irrigation policy and the management of
irrigation systems in Southeast Asia. The Agricultural Development Council, Inc.
Bangkok.
Wopereis, M.C.S., Bouman, B.A.M., Kropff, M.J., Berge, H.F.M., and Maligaya, A.R.,
1994. Water use efficiency of flooded rice fields I. Validation of the soil-water
balance model SAWAH. Agricultural Water Management 26; 291-304.