DECISION SUPPORT THEORY AND SUSTAINABLE MANAGEMENT OF THE KARSTIC EDWARDS AQUIFER

The Barton Springs segment of the Edwards aquifer, located in Austin Texas, is an area of rapid urbanization with increasingly observable effects on the water quality and quantity of the springs. To help mitigate the impacts of the urban growth, future management scenarios have been proposed that involve changing development rates and patterns for areas overlying and adjacent to the aquifer. The future of Barton Springs has become the subject of heated political debate involving the interests of developers, environmentalists, and property rights activists. Complicating matters is the fact that the aquifer and Barton Springs are home to two endangered salamander species. To help alleviate current and future conflict, we present a prototype decision support system (DSS) that addresses the issue of aquifer sustainability by merging existing spatially-variant, hydrogeological, urbanization, and GIS models into a systems dynamics framework. The DSS is developed and tested within the context of stakeholder deliberations with input from developmental, environmental, property rights, and government interests. Structured within a user-friendly interface, the DSS allows scenario and hypothesis testing, bracketing and optimization of possible outcomes, and real-time interactive feedback concerning current and future states of the system. A key innovation is the integration of spatially variable data (impervious cover, urban-enhanced recharge, and stream setbacks in the proto-type model) into the systems dynamics framework to examine heterogeneous urban growth patterns, spatially changing aquifer recharge characteristics due to urban development, together with economic and ecologic decision analysis. The proto-type addresses spring discharge and concerns of decreased well yields while future work will also incorporate stream discharge and ground and surface-water quality.