A non-linear programming model for evaluating water supply policies in the Texas coastal zone




Rios, Rafael A., James S. Sherman, Joseph F. Malina, Jr.

Journal Title

Journal ISSN

Volume Title


University of Texas at Austin


The water supply situation in the area of the City of Corpus Christi has the potential of becoming a constraint to development. Available municipal and industrial supplies could be exhausted in the foreseeable future based on reasonable economic growth. A nonlinear programming model was developed and used to determine the amount of fresh water required to satisfy future demands and to evaluate the effects of alternate methods for reducing demand on the primary source. In 1974, the use of the available water resource was less than optimal and a 10% reduction in demand was readily available through transfers of water among users. These transfers can represent a 12% reduction in demand by 1990, as a result of the higher quality effluents, required by PL 92-500, the Federal Water Pollution Control Act Amendments of 1972. The effects of three policies designed to reduce water demand were evaluated. These policies increased the cost of fresh water and the cost of effluent disposal for various combinations of users under the specified conditions. A uniform increase in the cost of fresh water for all users resulted in maximum recycle and reuse of effluents, effecting Zero Discharge of Wastewater. This uniform increase also caused the highest increase in total system cost of all the policies considered. Increasing cost of fresh water for only the industrial sector caused Zero Discharge of industrial wastewater, but the system did not achieve Zero Discharge, since this policy does not provide any economic incentive for the reuse of municipal wastewater. The application of an effluent tax to increase the cost of disposal also resulted in Zero Dishcarge of industrial return flows, but the reduction in municipal demand was less than with the other two policies. The total demand was reduced about one-third. The application of these policies would increase the cost of fresh water supply and wastewater treatment considerably, but the total costs still would be about 1 to 2 percent of the gross output of the industrial sector in the area. High concentrations of Total Dissolved Solids (TDS) in water supply, and thus in the municipal effluents in the area, is the most important constraint to water reuse. Removal of Total Dissolved Solids is required before this water can be recycled, and adds to the cost of the water. Socio-economic constraints also must be taken into consideration in any decision water reuse. The methodology developed in this report provides engineering and scientific insights into the effects of different policies of water management.


107 pgs.


coastal zone, coastal zone management, water supply, models, water use