SPATIO-TEMPORAL ASSESSMENT OF GROUNDWATER RESOURCES IN THE SOUTH PLATTE BASIN, COLORADO

In the South Platte Basin, Colorado, groundwater withdrawals account for approximately 11% of the total water supply. Due to occasional drought and increasing water use among users (e.g. agriculture, urban development, industry, recreational, unconventional energy development), increased reliance on local water supplies presents groundwater sustainability challenges and highlights the need to better understand system dynamics to help meet future water demands within the basin. However, understanding the groundwater dynamics is extremely complicated given the lack of adequate temporal and spatial groundwater data. This study analyzes and characterizes groundwater storage changes within the Denver Basin Aquifer System using groundwater water level data from state and federal databases. The groundwater data contains large gaps between measurements, with many water level measurements only collected once per year. A spatio-temporal kriging approach is used to create spatial groundwater maps utilizing data in adjacent time periods to improve confidence in generated maps. Spatial and temporal influences on groundwater levels are evaluated to understand areas experiencing high water stress. Preliminary results show improved confidence in using spatio-temporal techniques to generate groundwater maps, compared to purely spatial techniques. Depending on the aquifer and location of the observation well, either declining, rising, or relatively stable water level trends are observed. Since 2000, groundwater levels in the Arapahoe aquifer have significantly declined over 300 feet between Denver and Castle Rock, highlighting the groundwater reliance of several municipalities. The results provide an improved understanding of groundwater storage changes in the basin and identify areas experiencing higher water stress and increased groundwater depletion.