Impact of political, scientific and non-technical issues on regional groundwater modeling: Case study from Texas, USA

Recent legislation required regional "grass-roots" water resources planning across the entire state of Texas. The Texas Water Development Board (TWDB), the state's primary water resource planning agency, divided the state into sixteen planning regions. Each planning group developed plans to manage both groundwater and surface water sources and to meet future demands of various combinations of domestic, agricultural, municipal, and industrial water consumers. This presentation describes the challenges in developing a groundwater model for the Llano Estacado Regional Water Planning Group (LERWPG), whose region includes 21 counties in the Southern High Plains of Texas. While surface water is supplied to several cities in this region, the vast majority on the regional water use comes from the High Plains Aquifer System, often locally referred to as the Ogallala aquifer. Over 95 percent of the groundwater demand is for irrigated agriculture. The LERWPG had to predict the impact of future TWDB-projected water demands, as provided by the TWDB, on the aquifer for the period 2000 to 2050. If detrimental impacts were noted, alternative management strategies must be proposed. While much effort was spent on evaluating the current status of the groudwater reserves, an appropriate numerical model of the aquifer system was necessary to demonstrate future impacts of the predicted withdrawals, as well as the effects of the alternative strategies. The modeling effort was completed in the summer of 2000. This presentation concentrates on the political, scientific, and non-technical issues in this planning process that complicated the modeling effort.