COMPARING GROUNDWATER ELEVATION DATA AND GROUNDWATER MODEL RESULTS IN THE CONTEXT OF DESIRED FUTURE CONDITIONS

In 2002, the Texas Water Development Board delineated 16 “groundwater management areas” in Texas. As required by House Bill 1763, passed by the Texas Legislature in 2005, groundwater conservation districts in each groundwater management area were required to adopt “desired future conditions” for relevant aquifers within the groundwater management area by September 1, 2010, and update them every five years. A desired future condition is essentially a quantified management goal that defines the philosophy and policy of groundwater management in a defined area. The process is termed “joint planning” because the groundwater conservation districts within a groundwater management area must work together to establish these goals in such a manner that they are physically possible.

Once the desired future conditions are established, the Texas Water Development Board issues “modeled available groundwater” values, or the amount of pumping that will achieve the desired future condition. The modeled available groundwater values are often developed using groundwater model results, and the development of the desired future condition has generally relied on model simulations.

Now that these goals have been initially set, efforts to compare actual groundwater elevation data, model results and desired future conditions are underway in some areas. These comparisons involve extracting predicted groundwater levels from the model files at the same locations as the wells and at the same times where actual groundwater elevation data exist.

Results of the comparison are providing the districts the ability to evaluate various assumptions that are embedded in the desired future condition as a foundation for any needed updates. Among these assumptions are the location, timing, and amount of pumping increases and decreases, the adequacy of the selected groundwater availability model to predict drawdown, and the appropriateness of recharge assumptions made over the planning period.