AuthorMatias Filho, Jose,1927-
Water resources development -- Gila River Valley (N.M. and Ariz.)
Water resources development -- New Mexico -- Gila River Valley.
Committee ChairMatlock, W. Gerald
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractThe Wellton-Mohawk Irrigation and Drainage District occupies a valley and adjoining mesa along the lower Gila River, in the southwestern part of the State of Arizona. The area has been irrigated for centuries, and now shows problems which reflect past and present water management. First, the water supplies came from the Gila River; later, the groundwater reservoir was used and within about 30 years, groundwater levels declined and salt accumulation, as a consequence of water recirculation, put a limit on attempts to maintain irrigated agriculture. Recently, Colorado River water was brought into the area as the solution to assure permanent large-scale irrigation development. The application of water for crops and leaching of salts caused serious drainage problems. Salinity also caused a problem out of the District as drainage water from the aquifer with high salt content reached the Colorado River and became a source of friction between the United States and Mexico. The water conveyance system in the District is unique in that irrigation water is pumped up the valley into the distribution system. During flood flows along the lower Gila River, this leads to the situation where water is going down the River with little chance to be used, and goes up the valley through a sophisticated conveyance system. Flood flows along the lower Gila River are dependent on infrequent releases from Painted Rock Reservoir, at the upstream boundary of the lower Gila River. The few times they have occurred (2 in 15 years), they created high groundwater levels which were damaging to crop production. The water problems in the District could have short-run solutions through technically possible and economically feasible management practices. The objectives of the study are focused on better use of the water resources, reduction of risks of flood damages, and decrease of salt content of water being diverted to Mexico. A mathematical model was developed to analyze the impact of selected alternatives which could meet these objectives upon the hydrologic system of the District. The application of Strategy I, which proposes the increase of the irrigated acreage by about 5,000 acres, proved to be impracticable under present management conditions since the amount of drainage water to be disposed would be greater than the capacity of the disposal system. Strategies II, III, and IV, which propose increasing levels of change from flood to sprinkler irrigation (25, 50 and 100 rcent) showed results that although not economically encouraging, provide, however, for solution of the internal water problem of the area, and substantial decrease of drainage flow of high salt content delivered to the Colorado River. Strategies V and VI, which proposed reduction by 50 percent or complete elimination of riparian vegetation also proved to be impracticable. Under present management conditions in the District, phreatophytes are an important auxiliary of the water discharge system of the area. Strategies VII and VIII showed that the combination of changes to sprinkler irrigation and reduction of riparian vegetation at levels proposed (50 and 100 percent) practically counteract each other in terms of drainage water to be pumped and does not achieve the proposed objectives. Change in the water management system of the Wellton-Mohawk District would solve its water problems and significantly reduce salinity of the Colorado River water at Morelos Dam, for which hundreds of millions of dollars will be expended in a desalting complex. Drainage from excessive irrigation on the mesa flowing into the valley aquifer is the main cause of high groundwater levels there. Riparian vegetation, although increasing flood damages, is indispensable under the present management system.
Degree NamePh. D.
Degree ProgramWatershed Management