A WATER-BUDGET FOR THE STATE OF TEXAS WITH CLIMATOLOGICAL FORCING

The dependence of the Texas water budget upon climatological parameter s was examined by a simple annual accounting in which runoff, lake eva poration, municipal-and-industrial water use, power generation and for ced evaporation were expressed as specific functions of temperature an d precipitation, and the remaining water budget components related pro portionately. The state water budget was closed for present conditions , defined to be 1980 water uses in combination with 1951-80 climatolog ical norms, then the water budget was scaled to two different climatol ogical scenarios: the 1950-56 drought conditions and a ''greenhouse-wa rming'' condition. The water budget varies markedly across the state w ith regional hydrometeorology. Dependency on temperature and precipita tion is nonlinear, reinforcing, and cumulative, with even modest depar tures from normal implying large responses of runoff and diversion. Un der drought conditions, flow to the coast is reduced to one-third of n ormal. Under normal conditions with greenhouse-warming alterations, fl ow to the coast decreases by 35%. Under combined drought and greenhous e-warming, the coastal flows are reduced to less than one-fifth of nor mal.