DROUGHT MANAGEMENT PLAN FOR LOWER COLORADO RIVER IN TEXAS

The drought management plan (DMP) for the lower Colorado River of Texas is described. The plan identifies how the Lower Colorado River Authority (LCRA) will allocate stored water in the Highland Lakes of central Texas to meet projected water demands for year 2000 for rice irrigation, municipal, and other uses during a repetition of the most severe drought ever recorded. The irrigation planning model (IPM) is formulated to determine the optimal areas to cultivate, to maximize the net income of the rice producers when water supplies are limited. The IPM is solved, using mixed-integer linear programming, for a range of values for water availability to create planting decision tables. These tables are incorporated into the daily stream and reservoir hydrologic simulation model RESPONSE, to evaluate the hydrologic impacts of alternative reservoir operating rules for allocating irrigation (interruptible) stored water supplies from the Highland Lakes. Through repeated simulations, a DMP reservoir operating rule is developed, which maximizes available interruptible water during the critical drought and meets all municipal and other higher-priority water demands.