Evaluation of water-level trends in the Mimbres Basin, southwest New Mexico (USA), using spatiotemporal kriging

Groundwater-level trends over the past 40 years in the Mimbres Basin of southwest New Mexico (USA) were characterized with sequential water-level maps and maps of water-level change generated via spatiotemporal kriging. In the region of the most abundant irrigated agriculture, water levels have declined up to 24 m and cones of depression have expanded greatly. Increases in area of irrigated land and groundwater withdrawals in the past 10 years are coeval with water-level declines near the USA-Mexico border. Known areas of groundwater recharge from streamflow infiltration, and springs discharging deep-sourced water, show evidence of net water-level rises in the past 40 years, but declines in the last 10 years, in concert with declining precipitation over the basin. Formerly irrigated lands exhibit water-level rises, suggestive of flattening of cones of depression after cessation of extensive groundwater pumping. Manual water-level measurements are vital for understanding and managing groundwater resources, yet they are expensive and laborious to collect, which has resulted in much fewer data in recent years. Spatiotemporal kriging is more complex in mathematical development and implementation than spatial kriging, but it yields improved precision and accuracy, predictions at times with no data as well as at locations with no data, and fewer artifacts due to changing well networks. Its ability to leverage historical data recommends its use in hydrologic studies dependent on water-level maps and changes in water levels over time.