This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Project Completion Report, OWRT Project No. A-091-ARIZ / Agreement No. 14-34-0001-8003 / Project Dates: October 1978 - September 1979 / Acknowledgement: The work upon which this report is based was supported by funds provided by the United States Department of the Interior, Office of Water Research and Technology, as authorized under the Water Resources Research Act of 1978. / This report contains the results of a one year study to develop improved methods of evaporation control using wax impregnated foam. The foam used was expanded polystyrene and the wax used was paraffin with a 140° F melting point. The report tells of a pressure chamber that was used to wax impregnate sheets of expanded polystyrene. Based on tests made in the laboratory the pressure chamber was modified into a vacuum chamber. Problems were encountered getting the interior of the sheets impregnated using a vacuum. There was no way this problem could have been predicted based on the smaller laboratory models. The pressure method, however, was successfully used to impregnate up to 3 -inch thick sheets of expanded polystyrene. During the project it was found that the paraffin impregnated rafts worked very well until high temperatures, 100° F plus, are encountered Under dusty conditions. The heat causes the surface of the wax to get tacky, the dust darkens the otherwise white surface, which in turn captures more heat, and then more dust, etc. The high surface temperature caused an accelerated weathering of the material. Because of this, waxes with higher melting points were tried. Additional work is needed in this area as no satisfactory combinations were found. Two polyethylene copolymers with a melting point close to the 190° F destruction point of the expanded polystyrene were tested. This wax was too viscous for impregnation but provided a hard surface coating when the previously wax impregnated expanded polystyrene is dipped into the molten polyethylene wax. This dipping might be the best method for surface protection at low cost but additional testing is needed before trying the material out on a large scale. Progress was made in the development of wax impregnated lightweight concrete rafts. The wax impregnation of the lightweight raft solves the vapor penetration problem. This type of raft was found to resist removal by wind and weathered very well in the one year of testing. Connecting rafts with strips of sheet metal bonded to the expanded polystyrene was done on a small scale, and needs to be field tested. The PVC pipe C clamps work well on partially submerged rafts but need to be lengthened to interconnect wax impregnated rafts. Square wax impregnated rafts lx1 ft in size did not stay on a small test pond in high wind. Circles are presently being tried but additional testing is needed in this area before their reliability is known.

An Office of Arid Lands Studies Report to the City of Tucson, Real Estate Division, Contract No. 0255-83 / "This report represents one of two parts of the project "Evaluation, Monitoring and Operation of Existing City Water Harvesting System and Expansion Plan for Future Development of Rainfall Utilization," funded by the City of Tucson during the period November 1982 to June 1983." / Introduction: This report deals with the potential harvesting of rainfall and runoff in the Tucson urban area, as distinguished from the rural (farmland) setting that is discussed separately. The principal differences are that 1) rainfall catchment surfaces like rooftops and pavement already exist in the urban area, and 2) harvested rainwater in the urbanized area can be put to a variety of beneficial uses.

Water Brief, Fourth Draft / 6.16.76 / Introduction: The need for an efficient method of storage of water in arid zones has long been recognized. Efforts have been made everywhere to develop small storage tanks to provide water at critical periods. However, most of the existing tanks have such annual or seasonal evaporation losses that they are equal or even greater than the average depth of the tank. Thus many of these tanks are completely depleted before the end of the dry season, often with dramatic consequences for human beings, livestock or agricultural activities depending on the water supply. Reducing the heavy evaporation and seepage losses in these tanks is an important way to increase the supply of water. Several methods have been developed to reduce these losses but one of the most effective ways is to make the tanks with a smaller surface but deeper. The importance of making tanks deeper has been recognized for many years but there are several constraints for achieving depth in tanks: (a) the gradient of the water stream, (b) the unsuitability of dozers to work in deep pits, and (c) shallow soils. However, these constraints can be removed by using high rise banks and water pumps. Efficiency can also be improved by keeping the water concentrated. With this idea in mind, Mr. Cluff, FAO Consultant, has developed the concept of the compartmented tank, which is being tried out successfully in Mexico, and whose main features are summarized below.

Project Completion Report, OWRT Project No. A-082-ARIZ / Agreement No. 14-34-0001-8003, Project Dates: October 1977-September 1978 / Acknowledgement: The work upon which this report is based was supported by funds provided by the United States Department of the Interior, Office of Water Research and Technology, as authorized under the Water Resources Research Act of 1978. / This report contains the results of a one year study to apply the compartmented reservoir concept to water storage problems in Arizona. The range of selected projects was from a ten thousand cubic meter (8.1 af) reservoir for a water harvesting agrisystem at Black Mesa, to a 238 million cubic meter (200,000 af) flood control dam, Tat Momolikot Dam on the Papago Reservation, to supply water for irrigation. Other sites studied were the Santa Cruz River at Continental, to supply an industrial /domestic water, Leslie Creek site for recreation, and improvement of Mormon Lake for recreation. Evaporation from Tat Momolikot and Mormon Lake are presently consuming most of the available water. Through compartmentalization this evaporation can be significantly reduced. At the other potential dam sites on the Santa Cruz and Leslie Creek the use of a compartmented reservoir will make these otherwise marginal projects practical. The Black Mesa Agrisystem is presently demonstrating the utility of the compartmented reservoir system.