Evaporation suppression in the reduction of evaporation by controlling the rate at which water vapor escapes from water surfaces. The need for water saving is greatest in areas of little rainfall and low runoff. Water losses by evaporation from storage reservoirs must be minimized for greatest utility of limited supplies. A review of the literature shows that evaporation can be retarded by either pysical or chemical means. It can be controlled by enclosure in a building, application of plastic covers, oil films, and monomolecular films. Monomolecular films hold the greatest promise for use on large areas of water such as reservoirs. From the litarature available it is apparent that these films introduce many chemical and physical problems. The suppressantsmust be nontoxic and odorless, especially if used on water-supply reservoirs. They should the free exchange of oxygen so that aquatic life is not endangered. The effects of water-borne bacteria on these films and the effects of the films on water of different qualities are not fully known. The physical problem of detecting the present of the film has not yet been solvet. Of the monomolecular films that have been investigated, the waxy alcohols such as hexadecanol and actadecanol show the greates promise.

Reservoir storage is essential for developing dependable water supplies and is a major component of the river system water budget. The storage contents of reservoirs fluctuate greatly with variations in water use and climatic conditions that range from severe multiple-year droughts to floods. Water surface evaporation typically represents a major component of the reservoir water budget. This thesis investigates the effects of evaporation and potential reductions in this evaporation on the water supply capabilities of reservoirs in Texas. As part of this research, a literature review based assessment of capabilities for reducing reservoir evaporation using monolayer films and other methods was performed. The literature review assessment provides an overview of past evaporation suppression studies performed using monolayer films and other evaporation suppression technologies including water shades and covers. The overview provides a summary on monolayer film application techniques, environmental impacts, operational and material costs, evaluation methods, and achievable evaporation reduction rates. This research project quantifies the impact of reservoir evaporation on water supply availability/reliability by using the Texas Water Availability Modeling (WAM) System which consists of the Water Rights Analysis Package (WRAP) and 21 sets of WRAP input files covering the 23 river basins of the state, a geographic information system (GIS), and contains over 8,000 water rights permits, which include 3,435 reservoirs. The impact of evaporation on water supply availability/reliability was evaluated by performing several analyses in which evaporation rates are reduced by specified percentages starting when storage levels drop below certain trigger percentages of reservoir storage capacity. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149357