PREDICTION OF WATER-LEVEL CHANGES IN THE HIGH PLAINS AQUIFER IN KANSAS FROM CLIMATIC INDICES

The major driver of groundwater-level changes in the High Plains aquifer (HPA), one of the largest aquifers of the world, is the amount of water pumped for irrigation, which is primarily a function of the meteorological conditions for a given year. Correlations among climatic indices and changes in water levels can serve as valuable tools for assessing the aquifer’s response to various climatic scenarios. The areas of the five groundwater management districts (GMD) in Kansas spatially coincide well with four of the state’s nine climatic divisions. Selected periods of monthly climatic indices [Palmer Drought Severity Index, Palmer Z index, and especially the Standardized Precipitation Index (SPI)] for these divisions correlate well with water-level changes in the HPA in the GMD areas. Coefficients of determination, R², between nine- to twelve-month periods of SPI values and water-level changes are 0.71 to 0.81 for the GMD areas. A repeat of the most severe drought conditions recorded over the HPA in Kansas during the last century (1952-1956) would have an extremely deleterious impact on the Kansas portion of the HPA. Predicted water-level declines of 2 m to over 5 m are predicted for a drought of the same length and intensity for the GMD areas. Given the potential for increased drought frequency in the coming decades over areas of already very low potential recharge, the prospects for sustaining the current rates of pumping in the western portion (Ogallala) of the HPA in Kansas are not bright.