OPTIMIZATION OF WATER RESOURCES FOR IRRIGATION IN EAST JORDAN1

The paper describes an approach towards optimal allocation of surface and ground water resources to three agricultural areas in the Jordan Valley under conditions of scarce water supply. The optimizing model allocates water from three main rivers, each with reservoir storage, and from two ground water sources to three irrigation regions. Productivity of irrigation water, expressed as the net present value of the regional agricultural output, but allowing for crop water deficits, is first maximized using nonlinear programming. The allocation process then adopts techniques of linear programming to determine the least cost alternative based on the unit cost of water from each resource at each destination, as it varies with time.     

Estimating Crop Water Use via Remote Sensing Techniques vs. Conventional Methods in the South Platte River Basin,Colorado

We compared two methods of estimating crop water consumption to assess whether remote sensing techniques provide consumptive use (CU) estimates commensurate with conventional methods. Using available historical satellite and meteorological data, we applied Mapping EvapoTranspiration at high Resolution using Internalized Calibration (METRIC) to 317,455 ha in the South Platte basin, in northeastern Colorado, for the 2001 irrigation season. We then compared these derived CU estimates with values calculated by using the Colorado Water Conservation Board's South Platte Decision Support System StateCU model. Evaluating the data by irrigation ditch service area, we disaggregated the output to allow for comparison by service area size, crop type, irrigation method, water supply source, and water availability. We concluded that METRIC is a suitable alternative to StateCU in the South Platte basin and could help to identify areas with inhibited crop growth or deficit irrigation practices. In addition, METRIC could be used as a complement to StateCU to refine StateCU model parameters, allowing for more accurate estimates of crop water shortages and groundwater recharge associated with irrigation delivery and application.     

EVALUATING DIRECT BENEFIT ESTIMATION PROCEDURES FOR IRRIGATION PROJECTS: A SIMPLIFIED APPROACH1

ABSTRACT: An integral part of evaluating the net benefits generated by an existing or proposed irrigation project is the assessment of the associated impacts in commodity markets. Traditionally, these impacts have been measured by either assuming no change in commodity prices and calculating net returns to project farmers, or by allowing commodity prices to fall in accordance with a given elasticity of demand and subtracting commodity production costs from the associated area under the commodity demand curve. In either case, it is implicitly assumed that supply is perfectly inelastic. This article establishes that traditional approaches to measuring direct benefits are biased. Formulae are presented for calculating the maximum absolute and relative error which may result from using these techniques as a function of project size. Direct benefit estimates are then evaluated for three irrigation projects in Nebraska, illustrating how these results can be used to improve project evaluation procedures.     

MOTIVATING REDUCTIONS IN DRAIN WATER WITH BLOCK-RATE PRICES FOR IRRIGATION WATER1

ABSTRACT: Increasing block-rate prices for irrigation water were implemented during 1989 in a 10,000-acre irrigation district in California's San Joaquin Valley. The program motivated improvements in irrigation practices that reduced the volume of water delivered to farm fields and the volume of drain water collected in on-farm drainage systems. The ratio of net crop water requirements to field deliveries increased from 0.65 in 1988 to 0.73 in 1989. The volume of drain water collected at a subset of 20 drainage systems was reduced by 351.1 acre-feet (11.5 percent). Estimated loads of salt, boron, and selenium were reduced by 2,407 tons (11.0 percent), 3.33 tons (11.0 percent), and 0.07 tons (9.2 percent).     

Multi-Criteria Decision Analysis of Treated Wastewater Use for Agriculture in Water Deficit Regions1

Al-Juaidi, Ahmed E., Jagath J. Kaluarachchi, and Ungtae Kim, 2010. Multi-Criteria Decision Analysis of Treated Wastewater Use for Agriculture in Water Deficit Regions. Journal of the American Water Resources Association (JAWRA) 46(2):395-411. DOI: 10.1111/j.1752-1688.2009.00409.x Abstract: Coastal regions such as the Gaza Strip of Palestine with limited freshwater supply suffer significantly due to the rapid depletion of water levels, seawater intrusion, and increased water demands. In such regions, use of treated wastewater (TWW) is a viable option if public health issues are addressed. The goal of this paper is to address the use of TWW in agriculture while considering net benefit, economic efficiency of water use (EEWU), environmental goals, and public health risks. The proposed methodology considers public health risk assessment and multi-criteria decision analysis to assess the beneficial use of TWW in agriculture. The methodology was demonstrated for the Gaza Strip. The health risk assessment suggests that increasing the elapsed time between irrigation and consumption and switching from surface to sprinkler and drip irrigation are practical measures to reduce public health risks. The optimization and decision analyses show that proper allocation of freshwater and TWW and distribution of land area by crop type can significantly increase the net benefit and EEWU. In most cases, net benefit increased by 44%, groundwater use reduced 29% while increasing the EEWU by threefold compared with the existing conditions. The multi-criteria decision analysis with weighted goal programming can develop flexible management options that considers a given decision-maker preference. When groundwater abstraction for agriculture reduced from 57 to 36 Mm³ as per decision analysis, the corresponding area below mean sea level decreased by 58% indicating significant aquifer recovery.     

COMPARATIVE STUDY OF OPTIMIZATION TECHNIQUES FOR IRRIGATION PROJECT PLANNING1

ABSTRACT: This study presents three optimization techniques for on‐farm irrigation scheduling in irrigation project planning: namely the genetic algorithm, simulated annealing and iterative improvement methods. The three techniques are applied to planning a 394.6 ha irrigation project in the town of Delta, Utah, for optimizing economic profits, simulating water demand, and estimating the crop area percentages with specific water supply and planted area constraints. The comparative optimization results for the 394.6 ha irrigated project from the genetic algorithm, simulated annealing, and iterative improvement methods are as follows: (1) the seasonal maximum net benefits are $113,826, $111,494, and $105,444 per season, respectively; and (2) the seasonal water demands are 3.03*10³ m³, 3.0*10³ m³, and 2.92*10³ m³ per season, respectively. This study also determined the most suitable four parameters of the genetic algorithm method for the Delta irrigated project to be: (1) the number of generations equals 800, (2) population size equals 50, (3) probability of crossover equals 0.6, and (4) probability of mutation equals 0.02. Meanwhile, the most suitable three parameters of simulated annealing method for the Delta irrigated project are: (1) initial temperature equals 1,000, (2) number of moves equal 90, and (3) cooling rate equals 0.95.     

SUBSURFACE RETURN FLOW AND GROUND WATER RECHARGE OF TERRACE FIELDS IN NORTHERN TAIWAN1

ABSTRACT: This study estimates subsurface return flow and effective ground water recharge in terraced fields in northern Taiwan. Specifically, a three dimensional model, FEMWATER, was applied to simulate percolation and lateral seepage in the terraced fields under various conditions. In the terraced paddy fields, percolation mainly moves vertically downward in the central area, while lateral seepage is mainly focused around the bund. Although the simulated lateral seepage rate through the bund exceeded the percolation rate in the central area of the paddy field, annual subsurface return flow at Pei‐Chi and Shin‐Men was 0.17 × 10⁶ m³ and 0.37 × 10⁶ m³, representing only 0.17 percent and 0.21 percent of the total irrigation water required for rice growth at Pei‐Chi and Shin‐Men, respectively. For upland fields, the effective ground water recharge rate during the second crop period (July to November) exceeded that during the first crop period (January to May) because of the wet season in the second crop period. Terraced paddy fields have the most efficient ground water recharge, with 21.2 to 23.4 percent of irrigation water recharging to ground water, whereas upland fields with a plow layer have the least efficient ground water recharge, with only 4.8 to 6.6 percent of irrigation water recharging to ground water. The simulation results clearly revealed that a substantial amount of irrigation water recharges to ground water in the terraced paddy, while only a small amount of subsurface return flow seeps from the upstream to the downstream terraced paddy. The amounts of subsurface flow and ground water recharge determined in the study are useful for the irrigation water planning and management and provide a scientific basis to reevaluate water resources management in the terrace region under irrigated rice.     

APPLICATION OF CROP YIELD FUNCTIONS IN RESERVOIR OPERATION1

ABSTRACT: A model is developed for real-time operation of an irrigation reservoir with the objective of maximizing the value of multiple crop yields during a growing season. The model employs monthly additive and product forms of crop yield functions for dry matter and grain crops, respectively. The resulting nonlinear optimization model uses a log transform to reduce nonlinearities in the model. An application of the proposed model is compared to a common operating rule used in simulation models. The proposed model results were better in terms of net benefits from crop yields. The model uses GAMS (General Algebraic Modeling System) language. It requires an IBM-compatible microcomputer and is suitable for use by a reservoir manager.     

THE ECONOMIC FEASIBILITY OF DUAL PURPOSE NUCLEAR DESALINATION OF GROUND WATER1

ABSTRACT: The economic feasibility of a large scale dual purpose (desalting water and power production) facility were evaluated. Although a site in the Tularosa basin of southern New Mexico was chosen as a case study for this analysis, it is believed that the approach and consequential results would be applicable to alternative sites in the Southwest. The basic project evaluated included: a) a ground water well field; b) a dual purpose, nuclear, desalination plant; c) a mineral recovery plant; and d) a reservoir for recreation and irrigation storage. Principle project outputs included electrical power, minerals, recreation, and water for either irrigated agricultural production or export to an adjoining river basin. Two alternative project designs were developed for detailed analysis. The first alternative encompassed all major project components. The results, in discounted net values used to assess the feasibility of the project, were essentially negative; that is, values were less than zero for full scale development. The net benefits ranged from $-986.57 million at a 5 percent discount rate, to $-1,137.528 million at a discount rate of 10 percent. In the second alternative, exportation of the desalted water from the Tularosa basin to two adjacent rivers was analyzed with somewhat better net benefits, ranging from $-382,527 million to $-478,612 million at the 5 and 10 percent discount rates.     

Assessment of Water Availability and Scarcity Based on Hydrologic Components in an Irrigated Agricultural Watershed Using SWAT

This study assesses the water availability and the water scarcity based on the hydrologic behavior under different weather conditions and crop coverages in an irrigated agricultural area of Rincon Valley in New Mexico using the SWAT (Soil and Water Assessment Tool) model. Two spatial crop coverages included normal (2008) and dry (2011) years with 14 different crop sets for each year. The SWAT was applied to generate the five essential indicators (surface flow, evapotranspiration, soil water, groundwater recharge, and irrigation water) to evaluate the integrated water availability based on hydrologic response units (HRUs) along with the Arrey Canal to supply irrigation water in the crop areas. The water availability index scores (0–1 range with 1 being the most available and 0 the least available) of alfalfa, corn, cotton, and pecans were 0.21, 0.56, 0.91, and 0.20, respectively, in the normal year and 0.16, 0.78, 0.88, and 0.24, respectively, in the dry year. In the dry year, water scarcity values were high in mostly alfalfa areas, whereas cotton areas have mostly no stress with good water availability. The major water users of crops, ranked in order, were alfalfa, pecans, cotton, and corn. During the dry year, water availability showed to be balanced in terms of water supply and demand by controlling crop patterns from reducing alfalfa acreage by 12% and increasing cotton acreage by 13%.     

Simulating the Impacts of Irrigation Levels on Soybean Production in Texas High Plains to Manage Diminishing Groundwater Levels

There is an increasing need to strategize and plan irrigation systems under varied climatic conditions to support efficient irrigation practices while maintaining and improving the sustainability of groundwater systems. This study was undertaken to simulate the growth and production of soybean [Glycine max (L.)] under different irrigation scenarios. The objectives of this study were to calibrate and validate the CROPGRO‐Soybean model under Texas High Plains’ (THP) climatic conditions and to apply the calibrated model to simulate the impacts of different irrigation levels and triggers on soybean production. The methodology involved combining short‐term experimental data with long‐term historical weather data (1951–2012), and use of mechanistic crop growth simulation algorithms to determine optimum irrigation management strategies. Irrigation was scheduled based on five different plant extractable water levels (irrigation threshold [ITHR]) set at 20%, 35%, 50%, 65%, and 80%. The calibrated model was able to satisfactorily reproduce measured leaf area index, biomass, and evapotranspiration for soybean, indicating it can be used for investigating different strategies for irrigating soybean in the THP. Calculations of crop water productivity for biomass and yield along with irrigation water use efficiency indicated soybean can be irrigated at ITHR set at 50% or 65% with minimal yield loss as compared to 80% ITHR, thus conserving water and contributing toward lower groundwater withdrawals. Editor's note: This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

DESALTING SALINE WATER FOR IRRIGATION A CASE STUDY,COACHELLA AREA,CALIFORNIA1

ABSTRACT .A case study was performed to evaluate potential applications of desalted saline water for agriculture using 2 distillation type processes and 2 membrane type processes. The investigation determined the costs and benefits associated with desalting saline water at concentrations of 1,500, 900, 400, 200, and 50 ppm. Benefits from desalting are generated by shifts to more profitable crops, reduced costs for drainage, and reduction in fertilizer and labor requirements with better quality water. Costs are based on the project features such as desalting plants, raw water diversion facilities, storage reservoirs, conveyance and distribution systems, brine disposal, blending facilities, and gypsum addition systems. Hydrologic studies determined the crop irrigation requirements, water demand schedules, desalted water storage requirements, brine disposal requirements, and size of facilities required. Reconnaissance design layouts were made for producing desalted water using a combination of 14 schemes. The study also included a review of irrigation practices. The benefit-cost ratios range from 0.4 to 1.0 for 1,500 ppm irrigation water to 0.8 to 1.0 for 50 and 200 ppm water. Investment costs per acre are high, ranging from $12,900 to $20,900. Irrigation benefits are based on the increase in production from a desert condition with no water supply to the irrigation conditions studied.     

EVALUATION OF ALTERNATIVES TO THE GARRISON DIVERSION UNIT1

ABSTRACT: The Garrison Diversion Unit is a multipurpose water resources project which is currently under development for the purpose of diverting water from the Missouri River basin to irrigate farmland in North Dakota. Due to the objections raised by various interest groups, the project has recently been reviewed by the International Joint Commission. This article surveys the background to the project and the various alternatives that have been proposed. By utilizing recently developed fuzzy set techniques, the proposed alternatives are evaluated and a plausible solution is proposed. The results of the study indicate that it may be advisable to remove the Souris Loop irrigation area from the Garrison project but the environmental impacts of the study may preclude the implementation of any alternative that can affect Canada. These findings are in partial agreement with the recommendations of the International Joint Commission.     

ANALYSIS OF NITROGEN MANAGEMENT STRATEGIES USING EPIC1

ABSTRACT: This paper illustrates a method of using a hydrologic/water quality model to analyze alternative management practices and recommend best management practices (BMPs) to reduce nitrate-nitrogen (NO₃^--N) leaching losses. The study area for this research is Tipton, an agriculturally intensive area in southwest Oklahoma. We used Erosion Productivity Impact Calculator (EPIC), a field-scale hydrologic/water quality model, to analyze alternative agricultural management practices. The model was first validated using observed data from a cotton demonstration experiment conducted in the Tipton area. Following that, EPIC was used to simulate fertilizer response curves for cotton and wheat crops under irrigated and dryland conditions. From the fertilizer response functions (N-uptake and N-leaching), we established an optimum fertilizer application rate for each crop. Individual crop performances were then simulated at optimum fertilizer application rates and crop rotations for the Tipton area, which were selected based on three criteria: (a) minimum amount of NO₃^--N leached, (b) minimum concentration of NO₃^--N leached, and (c) maximum utilization of NO₃^--M. Further we illustrate that by considering residual N from alfalfa as a credit to the following crop and crediting NO₃^--N present in the irrigation water, it is possible to reduce further NO₃^--N loss without affecting crop yield.     

Benefit‐Cost Analysis of Integrated Water Resource Management: Accounting for Interdependence in the Yakima Basin Integrated Plan

Integrated water resource management (IWRM) requires accounting for many interrelated facets of water systems, water uses and stakeholders, and water management activities. The consequence is that project analysis must account for the nonseparability among the component parts of IWRM plans. This article presents a benefit‐cost (B‐C) analysis of a set of projects included in the Yakima Basin Integrated Plan proposed for the Yakima Basin in south‐central Washington State. The analysis accounts for interdependence among proposed water storage projects and between water storage and water market development in the context of historical and more adverse projected future climate scenarios. Focusing on irrigation benefits from storage, we show that the value of a given proposed storage project is lower when other proposed storage projects in the basin are implemented, and when water markets are functioning effectively. We find that none of the water storage projects satisfy a B‐C criterion, and that assuring proposed instream flow augmentation is less expensive by purchasing senior diversion rights than relying on new storage to provide it.     

SPATIAL AND TEMPORAL ANALYSIS OF AGRICULTURAL WATER REQUIREMENTS IN THE GULF COAST OF THE UNITED STATES1

ABSTRACT: Competition for water resources is becoming an increasingly important issue in the southeastern U.S. The potential impacts of future precipitation and runoff estimated by a transient global climate model (HADCM2) on competing water resources in the Southeast has been conducted. Issues of agricultural management, irrigation water withdrawals, and water quality were studied over three time periods: 1974–1993, 2020–2039, and 2080–2099 in five water basins identified previously as exhibiting water-related problems. These basins, which encompass the boundary between Alabama and Mississippi, cover four important agricultural counties in Mississippi. Irrigation water requirements generated by crop growth models for corn, soybeans, and winter wheat were coupled with monthly runoff for the impacted basins estimated by the SWAT water balance model. The results of the study reveal that in the next 20–40 years water availability in the southern portions of the study area will decline as much as 10 percent during times when water requirements for agricultural production are crucial. Maintaining or expanding existing crop yields under future climate regimes may require additional irrigation water and increase competition among other uses such as domestic, industrial, recreational, and ecosystem quality.     

NEW METHODS OF MODELING WATER AVAILABILITY FOR AGRICULTURE UNDER CLIMATE CHANGE: THE U.S. CORNBELT1

ABSTRACT: This paper reports on new methods of linking climate change scenarios with hydrologic, agricultural an water planning models to study future water availability for agriculture, an essential element of sustainability. The study is based on the integration of models of water supply and demand, and of crop growth and irrigation management. Consistent modeling assumptions, available databases, and scenario simulations are used to capture a range of possible future conditions. The linked models include WATBAL for water supply; CERES, SOYGRO, and CROPWAT for crop and irrigation modeling; and WEAP for water demand forecasting, planning and evaluation. These models are applied to the U.S. Cornbelt using forecasts of climate change, agricultural production, population and GDP growth. Results suggest that, at least in the near term, the relative abundance of water for agriculture can be maintained under climate change conditions. However, increased water demands from urban growth, increases in reservoir evaporation and increases in crop consumptive use must be accommodated by timely improvements in crop, irrigation and drainage technology, water management, and institutions. These improvements are likely to require substantial resources and expertise. In the highly irrigated basins of the region, irrigation demand greatly exceeds industrial and municipal demands. When improvements in irrigation efficiency are tested, these basins respond by reducing demand and lessening environmental stress with an improvement in system reliability, effects particularly evident under a high technology scenario. Rain-fed lands in the Cornbelt are not forced to invest in irrigation, but there is some concern about increased water-logging during the spring and consequent required increased investment in agricultural drainage. One major water region in the Cornbelt also provides a useful caveat: change will not necessarily be continuous and monotonic. Under one GCM scenario for the 2010s, the region shows a significant decrease in system reliability, while the scenario for the 2020s shows an increase.     

THE IMPORTANCE OF SOIL IN EVALUATING POTENTIAL WASTE WATER DISPOSAL SITES IN THE MISSOURI OZARKS1

ABSTRACT: A number of criteria can be used in the selection of an area for the irrigation disposal of secondary treated waste water. The inherent capacity of the surface soil to retain, or at least detain, the various nutrient ions passing through the profile in the percolating waters becomes the prime consideration in regions with shallow water tables or in Karst areas such as the Missouri Ozarks where the risk of ground water supply contamination is high. A comprehensive study of the nutrient renovation potential of several soils was undertaken at a proposed effluent irrigation site along the Ozark National Scenic Riverways in south central Missouri. The surface soil hydrology was evaluated employing selected soil water parameters. Exchange equilibria studies determined the retention capacity for Ca and Mg while the concentrations of other selected ions were analyzed in the soil water to measure their retention time and net removal. The movement of a bromine tracer was monitored as an index of the renovation capacity of these soils for the more mobile anions such as nitrate. Neutron activation analysis proved to be a useful tool in the water quality analyses. All surface soil profiles demonstrated some degree of nutrient renovation for the various nutrients studied.     

A REMOTE SENSING APPROACH FOR MODELING WATER RESOURCE USE1

Remote sensing data combined with other spatially referenced data were used to predict water resource use in an irrigated area of Central Oregon. Crop type and irrigation method were determined using color infrared aerial photography and thermal infrared imagery, respectively. These data were combined with crop consumptive use and irrigation method application efficiency values to determine total water applied to a transect sample through the heart of the study area. This information, when integrated with data on canal leakage and storage reservoir seepage, allowed the researcher to predict total water use for the entire management unit. The model developed allowed the researcher to attain results accurate to within 92.0 percent of actual values, suggesting that predictive water use models which use such techniques have tremendous potential for providing water resource managers with near real-time statistics required for making wise management decisions.     

Application of game theory for a groundwater conflict in Mexico

Exploitation of scarce water resources, particularly in areas of high demand, inevitably produces conflict among disparate stakeholders, each of whom may have their own set of priorities. In order to arrive at a socially acceptable compromise, the decision-makers should seek an optimal trade-off between conflicting objectives that reflect the priorities of the various stakeholders. In this study, game theory was applied to a multiobjective conflict problem for the Alto Rio Lerma Irrigation District, located in the state of Guanajuato in Mexico, where economic benefits from agricultural production should be balanced with associated negative environmental impacts. The short period of rainfall in this area, combined with high groundwater withdrawals from irrigation wells, has produced severe aquifer overdraft. In addition, current agricultural practices of applying high loads of fertilizers and pesticides have contaminated regions of the aquifer. The net economic benefit to this agricultural region in the short-term lies with increasing crop yields, which requires large pumping extractions for irrigation as well as high chemical loading. In the longer term, this can produce economic loss due to higher pumping costs (i.e., higher lift requirements), or even loss of the aquifer as a viable source of water. Negative environmental impacts include continued diminishment of groundwater quality, and declining groundwater levels in the basin, which can damage surface water systems that support environmental habitats. The two primary stakeholders or players, the farmers in the irrigation district and the community at large, must find an optimal balance between positive economic benefits and negative environmental impacts. In this paper, game theory was applied to find the optimal solution between the two conflicting objectives among 12 alternative groundwater extraction scenarios. Different attributes were used to quantify the benefits and costs of the two objectives, and, following generation of the Pareto frontier or trade-off curve, four conflict resolution methods were then applied.