Changing Surface Water Availability in Texas

Texas is characterized by extreme hydrologic variability both spatially and temporally, rapid population growth, declining groundwater supplies, intensifying demands on surface water resources, and progressive water management policies. A statewide water availability modeling system is routinely applied by agencies and consulting firms to support planning, water rights administration, and other activities. The modeling system was applied in the university research study reported in this paper for comparative analyses of stream flows and river system water budgets for natural undeveloped versus current conditions of water development/use. Long-term changes in stream flow and storage characteristics and water supply capabilities are explored based on the simulation studies combined with analyses of actual observed precipitation, reservoir evaporation rates, and stream flows. Long-term changes in water availability are significant throughout the state and vary greatly across the state.