GROUNDWATER MANAGEMENT ON THE TEXAS HIGH PLAINS1

ABSTRACT The effects of major water management practices on the pumping requirement from the Ogallala aquifer are discussed. Demand on the aquifer may be reduced as much as 15 percent by recycling irrigation runoff, 25 percent by recycling irrigation runoff and irrigating with water from playas, and 29 percent by recycling irrigation water in combination with irrigation from playas and artificial recharge of playa water to the aquifer. Other practices that can result in more efficient use of precipitation and groundwater are limited irrigation, land forming, soil profile modification, and improved irrigation systems, thereby reducing the pumping demand on the Ogallala. Additional water supplies can possibly be obtained by water harvesting, weather modification, and water importation. Conclusions reached were that the overdraft on the aquifer can be reduced by the application of sound water management practices on an area-wide basis.     

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).     

POTENTIAL WATER USE AND AGRICULTURAL PRODUCTION PATTERNS UNDER ALTERNATIVE WATER PRICES1

Out study deals with the demand for water and alternative agricultural production and land use patterns under varying prices for both surface and ground water. We derive irrigation water demands for both the United States and regions of it. Not only is a different amount of water used at each set of water prices but also a different mix of crops, livestock, and production technology develops among the different regions. Under the highest set of prices used, more than fourteen million acres are converted into dryland farming. Total irrigated water use decreases by more than 25 million acre-feet. Irrigated crop yields are reduced and cropping patterns shift away from irrigation. Commodity shadow prices increase as much as 15 percent under high prices for both surface and ground water. A redistribution of farm income occurs between irrigated and dryland regions.     

DESERT HOUSE: A DEMONSTRATION/EXPERIMENT IN EFFICIENT DOMESTIC WATER AND ENERGY USE1

ABSTRACT: In May 1993, a single-family home and adjoining information center opened to the public at the Desert Botanical Garden in Phoenix, Arizona. Desert House is designed as an example of what can be achieved today using available technology to improve residential water and energy efficiency. The home is expected to reduce water and energy use by 40 percent compared with that for the typical three-bedroom, single-family residence in the Phoenix area. Water-conserving features include: landscape design employing low-water use plants, minimum turf area, mulch around plants to reduce evaporation, and drip irrigation system; spa cover for evaporation reduction; rainwater harvesting; low-flow shower heads, faucets, and toilets; and graywater reuse system. The home will be occupied by a family and monitored for water and energy use by computer. Visitors are able to access real time water and energy use data about the home, as well as tour the information center, technical exhibits, surrounding landscape, and the home when it is open (one afternoon a week).     

Predicting Satisfaction with Smart Irrigation Controllers and Their Long‐Term Use among Homeowners in Central Florida

Studies throughout Florida have shown smart controllers can substantially reduce irrigation under residential high‐water use conditions. However, successful promotion requires understanding the link between controller performance and the mechanisms by which they are adopted. This article compares irrigation water‐use and survey data collected from households installed with soil moisture sensor and evapotranspiration controllers. The study investigated whether the relative change in irrigation use between two years preceding and two years following installation was a reliable predictor of a homeowner's satisfaction with the device and likelihood of continuing to use it. Results indicated relative changes in irrigation use were only significantly associated with the quality of controller programming. Satisfaction with the controller was largely attributable to satisfaction with the appearance of the landscape and the perceived water‐saving effectiveness of the controller whereas the likelihood of its continued use was only significantly predicted by the level of technical knowledge regarding its functioning and whether or not challenges were experienced with it. Targeting homeowners with supplemental user‐friendly information may best support their long‐term adoption of smart controllers while providing irrigation contractors with training in implementation techniques would represent an integrated strategy for added reductions in residential outdoor water use.     

CASA DEL AGUA: WATER CONSERVATION DEMONSTRATION HOUSE 1986 THROUGH 19981

ABSTRACT: Casa del Agua (Casa) in suburban Tucson, Arizona, was designed as a residential water conservation facility for applied research, demonstration of operational results, and transfer of technology to the general public. Starting in 1983, an existing residence was located, modified and retrofitted to acquire operational data on residential water use. Modifications included retrofitting existing landscapes and enlarging the rooftop to collect and harvest rainwater; separating blackwater and graywater lines; installing meters, low‐water‐use appliances and fixtures, and underground storage tanks for rainwater and graywater; and creating a public information center. Over the 13‐plus years of actual operation, both the interior and exterior water use research results indicate large reductions in water use can be effected using water‐saving devices andlor harvesting and reusing rainwater and graywater. Casa achieved over a 24 percent reduction in total water use and a 47 percent reduction in municipal water used compared to the typical Tucson residence. Overall water used was comprised of harvested rainwater (10 percent), recycled graywater (20 percent), and municipal water (70 percent). Casa's Information Center was visited by approximately 13,000 people from September 1985 through April 1999 and the research has been featured in local, national, and international media.     

WATER USE REDUCTIONS FROM RETROFIHNG INDOOR WATER FIXTURES1

ABSTRACT: A water use model was developed to estimate water savings from installation of low-flow showerheads and toilet displacement devices in residential housing. The model measures household water use in per capita terms with adjustments for age of occupants, household income, if occupants responsible for direct payment of water bill, and type of water fixtures. Detailed data on 308 single family residences involved with a pilot retrofit program in the Seattle, Washington, area were analyzed. We estimated per capita indoor water use to decline by 6.4 and 2.1 percent from complete installation of low-flow showerheads and toilet displacement devices, respectively.     

WATER MANAGEMENT AND N,P LOSSES FROM PADDY FIELDS IN SOUTHERN KOREA1

ABSTRACT: Assessment and control of nutrient losses from paddy fields is important to protect water quality of lakes and streams in Korea. A four‐year field study was carried out to investigate water management practices and losses of nitrogen (N) and phosphorus (P) in rice paddy irrigation fields in southern Korea. The amount and water quality of rainfall, irrigation, surface drainage, and infiltration were measured and analyzed to estimate inputs and losses of N and P. The observed irrigation amount surpassed consumptive use, and approximately 52 to 69 percent of inflow (precipitation plus irrigation) was lost to surface drainage. Field data showed that significant amounts of irrigation water and rainfall were not effectively used for rice paddy culture. Water quality data indicated that drainage from paddy fields could degrade the recipient water environment. The nutrient balance indicated that significant amounts of nutrients (29.5 percent of total N and 8.6 percent of total P compared to input) were lost through surface drainage. Furthermore, up to half the nutrient losses occurred during nonstorm periods. The study results indicate that inadequate water management influences N and P losses during both storm and nonstorm periods. Proper water management is required to reduce nutrient losses through surface drainage from paddy fields; this includes such measures as minimum irrigation, effective use of rainfall, adoption of proper drainage outlet structures, and minimized forced surface drainage.     

ENERGY AND WATER CONSERVATION STRATEGIES IN IRRIGATED AGRICULTURE1

ABSTRACT: Growers in California used several energy and water conservation strategies in response to the drought conditions of 1976 and 1977. The strategies included an increased use of ground water, in creased irrigation efficiencies, and shifts in cropping patterns. Drought-related losses to irrigated agriculture were minimized as a result of these modifications. Some future problems may have been created, however, by obtaining the needed water supplies for 1976–77. These problems include the effects of extensive water pumping on ground water reservoirs and ground subsidence. In addition, reduced water application by less frequent irrigation and changes in irrigation methods may affect the total salt balance for future years. Several conservation strategies that have some potential application in California were identified as: maintaining and augmenting surface water supply, increasing power use efficiencies, and improving irrigation efficiencies. Electricity savings associated with water conservation have been estimated as high as 25 percent. Specific near term actions suggested for facilitating conservation included: an expanded irrigation management system, efficient water deliveries, and a continued effort on the part of the individual growers to use resources during periods of normal rainfall as they were used under drought conditions.     

PROJECTED EFFECTS OF ENERGY POLICIES ON AGRICULTURAL WATER USE AND IRRIGATION1

ABSTRACT: A national and interregional programming model was used in projecting the impacts of alternative energy policies and prices on agricultural production, land use, and irrigation. The alternatives analyzed include (a) natural gas deregulation, (b) natural gas curtailment, (c) doubled energy prices, and (d) tripled energy prices. These alternatives are compared with a base alternative where prices and conditions are at normal levels. Restraints in the model control availability of water, land, nitrogen fertilizers, and energy. Water production functions were used to adjust water use to conform with projected energy prices and policies. Natural gas curtailment would have the largest effect on nitrogen use on irrigated land. Values or shadow prices for lands that remains in irrigation would increase under all of the alternatives because of reduced supply. Increased energy prices generally would increase use of surface water for irrigation and reduce use of ground water due to higher pumping costs. Reductions of 50 percent or more in ground water use would occur in the South Central and Western regions of the United States. Water supply prices increase under all of the alternatives; with the amount varying by regions and the policy or price situation.     

A LOW COST DRIP IRRIGATION SYSTEM FOR SMALL FARMERS IN DEVELOPING COUNTRIES1

ABSTRACT: In areas where water is scarce, drip irrigation provides the most efficient way to conserve irrigation water, but its cost of £1000 an acre is prohibitive for most small farmers in developing countries. The cost was reduced by 90 percent by (1) making dripper lines moveable, so that each line reaches ten rows instead of one; (2) replacing 25-cent emitters with simple 0.70 mm holes punched by a heated needle; and (3) using £3.00 off-the-shelf 20 liter containers with cloth filters in place of expensive filter systems. This reduced the cost of a half-acre system to £50. The low cost system was field tested in the hill areas of Nepal, and in mulberry cultivation in Andhra Pradesh, India. Uniformity of flow from emitters was 73–84 percent. Small farmers reported that the low cost trickle irrigation system cut labor requirements in half, and doubled the area irrigated by the same amount of water. The low cost drip system is likely to be widely adopted by small farmers in semi-arid and hilly regions.     

PRICE BEHAVIOR IN THE WATER MARKET OF NORTHEASTERN COLORADO1

ABSTRACT Past prices of Colorado-Big Thompson water shares were analyzed using an asset pricing model which incorporated the growth rate in real returns to irrigation water and the value of potential urban water uses. A real growth rate in the returns to irrigation water was estimated at 5.3 percent. Nevertheless, market values for water shares have exceeded capitalized agricultural values since 1969. Historically, urban use potential was heavily discounted, but the implicit discount rate fell rapidly in the last decade. The expectation that water shares will eventually be sold to municipal or industrial consumers now appears to be reflected fully in water prices.     

WATER CONSERVATION KITS: A TIME SERIES ANALYSIS OF A CONSERVATION POLICY1

ABSTRACT: The effect on water usage of installing water conservation kits in the city of Oxnard, California, is statistically evaluated. Using binary multiple regression analysis on a large sample of residential units, water consumption was compared before and after receipt of the kit. For this sample, installers reduced water consumption by 4.2 percent each billing period. Income (wealth) and household size elasticities are reported along with the Characteristics of the installing households.     

RESIDENTIAL WATER CONSERVATION: CASA DEL AGUA1

ABSTRACT: A single-family residence in Tucson, Arizona, was retrofitted with water-conserving fixtures, rainwater harvesting, and graywater reuse systems. During a four-year study, efficient use of water was shown to significantly decrease demand for domestic water at the house without reducing the residents' quality of life. The use of municipal water was reduced by 66 percent to 148 gallons per day (gpd) and total household use was reduced by 27 percent to 245 gpd. Graywater reuse averaged approximately 77 gpd or 32 percent of the total household water use. Evaporative cooling required about 15 gpd. Water use for toilet flushing was only 9 gallons per capita per day (gpcd) or 14 percent of interior water use.     

ESTIMATING IRRIGATION WATER USE THROUGH SELECTIVE MONITORING: A NORTH FLORIDA CASE STUDY1

ABSTRACT: Selective placement - under a rigorous statistical sampling design - of newly available monitoring equipment on irrigation systems may provide effective and economical estimates of total irrigation water use in areas where complete water use inventories are impractical. In 1979, a joint effort by the U.S. Geological Survey and Florida's Suwannee River Water Management District was launched to estimate the District's 1979 irrigation water use using a selective monitoring approach. Analysis of previous inventories of irrigation equipment and amounts of water applied in the District indicated that total 1979 water use estimates with six to nine percent sampling error could be obtained using selective monitoring, given the time and equipment limitations for the monitoring program. Restricting monitoring to a sample of farms can introduce systematic error to water use estimates if farmers' participation is related to their water use methods. Preliminary results of the 1979 study indicate tht declining participation rates, if unchecked, could lead to serious systematic eror in future North Florida selective monitoring studies.     

A STOCHASTIC MODEL TO EVALUATE RIPARIAN IRRIGATION EXPANSION IN THE EASTERN UNITED STATES1

ABSTRACT: Irrigation has expanded in parts of the eastern United States. In some areas, the adjoining surface (riparian) water is the most economical source of irrigation water. Expanded demand for riparian water may lead to conflict among irrigators and other streamflow users. Accurate information on the potential for and impacts of riparian irrigation expansion is needed to decide if control of such expansion is necessary. In this study, a stochastic economic model to evaluate the impacts of potential irrigation expansion is presented. The model considers the soil, location, and land use characteristics of individual sites, as well as weather and streamflow patterns. The application of the model to an eastern Virginia watershed indicates that, with maximum potential expansion, water availability becomes limited and yields will be reduced in some years. As a result, the expected net returns from irrigation and the probability of breaking even on the investment are reduced substantially. The results suggest the need to consider regulation of surface water allocation for irrigation development in riparian watersheds.     

TRENDS IN WESTERN UNITED STATES AGRICULTURE: IRRIGATION ORGANIZATIONS1

ABSTRACT: From 1940 to 1978, irrigated acreage in the Western United States increased by over 150 percent, irrigated acres per farm increased by 204 percent, and the number of irrigation organizations grew by 31 percent. Understanding the factors affecting these trends (in the structure of irrigated agriculture) is the key to formulating policies for efficient allocation and transfer of water in the west. Four variables that impact the composition of irrigation organizations are farm size changes, organizational efficiency, intersectoral competition for water, and governmental policies. The conclusions show that from 1940 to 1978, the total number of irrigated farms and organizations declined, and the average farm size increased, and larger management oriented organizations such as districts and U.S. Bureau of Reclamation have become more prevalent. With respect to total quantities of water delivered, districts have increased over 50 percent since the 1959 Census and over 100 percent since the 1950 Census, while unincorporated mutuals have declined by approximately 20 percent. Future organizational structure tends to be moving in the direction of more management control as opposed to user control. Changes in water use, delivery, investment, transfers, and laws will continue to change the structure of irrigation organizations and institutions in the west.     

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.     

WATER USE RELATIONSHIPS AND PROJECTION CORRESPONDING WITH REGIONAL GROWTH,SEATTLE REGION1

ABSTRACT: The paper outlines both the methods used and the results obtained in a study of the demand for municipal and industrial water for the Seattle region. The study was made as part of a regional water management study program, one objective of which is to “… identify, quantify, and set priorities for all current and future water uses …”. A basic concept in the study of municipal and industrial water use is that the demand for water is derived from the demand for output and the direct services that water provides. Principal characteristics of the study are: (1) Water use is studied by type - residential, commercial, industrial and public -with identification of factors affecting each; (2) Water demands are studied by season as well as on an annual basis; (3) Projections of future water use are tied directly to projections of economic change in the service area; and (4) The effects of alternative policies on water use are estimated. Water use levels are projected under alternative regional growth assumptions provided by the Puget Sound Governmental Conference, a regional planning agency. Thus, the water use planning is consistent with other regional planning programs in this respect. The results can be varied according to changes in specific factors affecting water use. The factors considered in the present study include: single-family residential lot size, distribution of population between single- and multi-family units, per capita water use by multi-family unit residents, and industrial and commercial water use per employee. An income elasticity of demand was estimated for single-family residential water use.     

IMPROVING IRRIGATION RETURN FLOW QUALITY WITH A WATER RENTAL MARKET1

ABSTRACT: Current policies for correcting the problem of irrigation return flow pollution tend to attack the symptoms of the problem, rather than its cause. The present institutional arrangement for allocating irrigation water is seen as the source of the problem. This paper examines the water quality benefits of altering the institutional arrangement to allow for irrigation water transfers through a rental market. It is conceptualized that by creating a water rental market an opportunity cost would be associated with the use of irrigation water such that profit maximizing farmers would be induced to use his water supply more efficiently and rent the surplus to other irrigators, thus reducing return flow pollution. It is shown that a water rental market could increase water quality in the Yakima River in southcentral Washington by 31 percent as well as increase farm incomes and crop production.