AuthorMaletic, John T.
AffiliationWater Quality Office, Engineering and Research Center, Bureau of Reclamation, Denver, Colorado
KeywordsHydrology -- Arizona.
Water resources development -- Arizona.
Hydrology -- Southwestern states.
Water resources development -- Southwestern states.
Water management (applied)
Colorado River water quality improvement program
Colorado River international salinity control project
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RightsCopyright ©, where appropriate, is held by the author.
Collection InformationThis article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact email@example.com.
PublisherArizona-Nevada Academy of Science
AbstractIn the lower reaches of the Colorado River, damages from the increase in salinity to U.S. water users are now estimated to be about 53 million dollars per year and will increase to about 124 million dollars per year by the year 2000 if no salinity control measures are taken. Physical, legal, economic, and institutional aspects of the salinity problem and proposed actions to mesh salinity control with a total water management plan for the basin are discussed. A scheme is presented for planning under the Colorado River water quality improvement program. Recent legislative action is also discussed which provides control plans to improve the water quality delivered to Mexico as well as upper basin water users. These efforts now under study will assure the continued, full utility of Colorado River water to U.S. users and Mexico. However, more extensive development of the basin's natural resources puts new emphasis on total resources management through improved water and land use planning to conserve a most precious western resource - water.
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Alfalfa water-production functions under conditions of deficit irrigation with saline waterPennington, Karrie Sellers,1949- (The University of Arizona., 1986)This experiment was designed to determine the shape of the yield response function relating crop yield to total amount of saline irrigation water applied. Such a function contains a built-in leaching fraction that is the inevitable consequence of the inability of the plant to extract 100 % of the water from a saline soil. In order to define the production function and to determine the leaching fractions, alfalfa (Medicago sativa L. cv. 'Mesa Sirsa') was planted in soil columns in a greenhouse. Two experiments were run sequentially. These were irrigated with water of differing salinities. The first with an EC of 4 dS/m (1.4 bars) and the second with an EC of 8 dS/m (2.9 bars). Both solutions were prepared by adding equivalent amounts of sodium chloride and calcium chloride to distilled water. The treatment variables were amounts of irrigation water applied. The amounts in both experiments were 110%, 100%, 75%, 50% and 25% of the measured evapotranspiration (ET). Four crop harvests were made in each experiment. At the end of experiment 1, (approximately 120 days), one column from each treatment was destructively sampled for soil salinity and water content measurements. The remaining columns were similarly sampled at the end of experiment 2 (approximately 120 days). The crop-saline water production functions for both experiments were linear. Leaching fractions in experiment 1 were 9, 9, 6, 5 and 5% for treatments 1-5 respectively. Experiment 2 leaching fractions for treatments 1-5 respectively were 23, 25, 18, 15 and 17%. The lowest rootzone soil water osmotic potentials achieved by the end of experiment 1 for treatments 1-5 were -19, -20, -18, -26 and -24 bars. Corresponding treatment values achieved by the end of experiment 2 were -18, -22, -28, -31 and -45 bars.
Irrigation of High Maintenance Turf Using the Arizona Department of Water Resources Water Duty: Evaluation of Turf Performance and the Potential for Soil Salinization.Whitlark, Brian Stephen. (The University of Arizona., 1999)Water is an essential resource that requires careful management at all golf courses located in southern Arizona. The Arizona Department of Water Resources, through its enforcement of irrigation water duties, is forcing the golf industry to reduce water usage. The objective of this study was to evaluate turfgrass performance and the potential for soil salinization, when high maintenance desert turf systems are irrigated in accordance with the present Tucson area water duty of 1.4 ha-m/ha/yr (4.6 ac-ft/ac/yr). Two large weighing lysimeters supporting year-round turf systems consisting of bermudagrass (Cynodon dactylon x transvalensis (L.) pers.) overseeded with intermediate ryegrass (Lolium multiflorum x perenne) were irrigated at rates not to exceed the ADWR water duty using either low salinity (EC = 0.25 dS/m) groundwater or higher salinity effluent water (EC = 1.0 dS/m). Irrigation treatments were initiated in August 1997 and continued through September 1998 and consisted of applying water daily at rates set by applying appropriate crop coefficients to values of reference evapotranspiration generated by an on-site weather station. Soil moisture and salinity regimes were monitored weekly using the lysimeter subsurface sampling system and time domain reflectometry (TDR). Water percolating below the root zone was quantified and sub-sampled to facilitate assessment of leaching fractions and total lysimeter salt balance. For the year ending 30 Sept. 1998, each lysimeter received —1729 mm (68 in.) of water comprised of 1296 mm (51 in.) of irrigation water and 433 mm (17 in.) of precipitation. Turfgrass evapotranspiration (ET) totaled 1419 mm (56 in.) for the lysimeter irrigated with groundwater (east lysimeter) and 1466 mm (58 in.) for the lysimeter irrigated with effluent (west lysimeter). Approximately 421 and 311 mm of drainage water was removed from the east and west lysimeters, respectively, establishing leaching fractions of 0.24 in the east lysimeter and 0.18 in the west lysimeter. Salts accumulated in both lysimeters over the course of the study; however, the substantial amount of drainage did not allow for salts to accumulate to harmful levels. Turfgrass performance, as quantified by turf quality and growth was acceptable or better during most months of the study. Crop coefficients (Kcs) were slightly higher than previous years, however, Kcs compared favorably to previous research at the study site. Summer Kcs averaged 0.79 and were significantly higher than winter Kcs that averaged 0.73. Turf irrigated with effluent produced better quality turf and used slightly more water than turf irrigated with groundwater. These data indicate that the present ADWR water duty of 1.4 ha-m/ha/yr (4.6 acre-ft/acre/yr) is adequate to replace turfgrass evapotranspiration and provide for leaching of salts when rainfall exceeds normal amounts, assuming no water loss due to irrigation and plumbing inefficiencies.