Improving Water Availability Assessments in the High Plains Aquifer In Kansas

Changes in water level – or the rate at which the water level is changing – are considered the most direct and unequivocal measure of the impact of aquifer management strategies. In the High Plains aquifer (HPA) in Kansas, water-level change is determined through a survey conducted each January. The manual measurements obtained in this survey are subject to errors from three major sources (in addition to the inherent accuracy and precision of the measurement): barometric pressure fluctuations, nearby pumping, and incomplete recovery from the previous irrigation season. As a result, these measurements are only useful for discerning impacts over large spatial and temporal scales. An ongoing project is focused on improving the reliability of estimates of year-to-year water-level changes for scales of more relevance for aquifer management.

Telemetered, transducer-equipped wells were installed at three HPA sites in 2007. These index wells are used to develop methods for improving water availability assessments and provide real-time information to the public.  Determination of the fully recovered water level is of vital importance for assessing management strategies, but full recovery is not observed at any of the wells. Thus, methods to project water levels to full recovery are under development. New wells are expensive to install to the depths of the western Kansas HPA, so an additional focus is on assessing the utility of wells of opportunity (e.g., retired irrigation wells). Transducers were installed in a number of such wells in the vicinity of two index wells, and water-level responses to barometric-pressure changes and nearby pumping are used to get insight into the often unknown well construction. Further refinement of water-level estimation procedures, combined with a calibrated budgetary approach incorporating water use and precipitation data, appears to have considerable potential for evaluating the effects of aquifer management in a timely fashion.