Document Type


Journal/Book Title/Conference

UNESCO Conference on Sustainable Water Resources

Publication Date



Making best use of water resources requires coordinating use of groundwater and surface waters--conjunctive use. Conjunctive water management is important on the regional (watershed or aquifer), water district and field scales. Goals might differ for the different administrative levels. A regionally optimal water management strategy is not necessarily optimal for water district managers and individual farmers. Interactions between levels are affected by laws, regulations, traditions and public pressure. To help each organizational level develop water management strategies that best achieve its goals, computer simulation/optimization (S/O) models are useful. Such S/O models couple water flow and transport simulation techniques with formal mathematical optimization algorithms. When properly calibrated, S/O models can be immensely valuable. S/O models have long been used for managing reservoir releases and surface water resources. S/O model use for large-scale groundwater management and contaminant plume management is becoming more common. Advances in computer power and mathematical optimization procedures make it possible to address large problems previously impractical. Likewise, increasing availability and power of PC computers and operating systems make it now practical for water district personnel and field engineers to develop optimal water management strategies. By exercising care appropriate for data and model accuracy, field-level S/O model users can develop better solutions for their management problems. The use of S/O models at all water management levels makes it easier to negotiate compromise solutions when goals differ. S/O models are easily used to develop trade-off curves showing how much of one goal achievement must be forfeited to achieve more of another goal. Communication is enhanced when both negotiating parties have reliable trade-off information. Furthermore, S/O model and trade-off curve use highlights differences in data or understanding of data available to the parties--making it easier to resolve those differences. This paper discusses robust S/O software available and useful for the spectrum of groundwater and surface water managers. This software promotes improved water management and goal achievement. Case studies illustrate benefits of S/O model use.