Year Established: 2012 Start Date: 2012-03-01 End Date: 2014-02-28
Total Federal Funds: $24,000 Total Non-Federal Funds: $60,016
Principal Investigators: Randy Stotler, James Butler
Abstract: In areas of groundwater mining, year-over-year increases in water levels are not expected to occur because water extracted from the aquifer is not replaced by recharge (e.g., Butler et al. submitted). In one area of the Kansas High Plains Aquifer (HPA) with assumed groundwater mining conditions (water level declines exceed 20 m, saturated thicknesses reduced in excess of 35% of pre-development values), unexpected year-over-year increases in water-levels were recently recorded by enhanced monitoring as part of the Kansas Geological Survey (KGS) Index Well Program (Stotler et al. 2011). Hydrograph analysis indicates post-irrigation season recovery is not tied to precipitation, amount of water pumped, length of pumping, or pumping rate. Rather, recovery is constant from year to year indicating an unknown source of inflow (recharge) to the system (Butler et al. submitted). The goal of this research is to identify the source, and quantify the amount, of recharge contributions to the High Plains Aquifer in northwest Kansas. Two possible sources are: 1) The recharge is a pulse of water from the period of inefficient flood irrigation (1960s-1980s) finally reaching the water table (>60m below ground surface). In this case, the recharge would be of a finite duration. Thus, the first objective is to identify the depth of the recharge pulse from historic inefficient irrigation practices. 2) The recharge is from the slow draining of low permeability units that were left behind (perched) by the rapidly falling water table over the last 50 years of high intensity groundwater use. Recharge would again be finite in duration and would depend on the permeability and size of the unit. Thus, the second objective of the research is to quantify contributions from slow draining, low permeability units that were left perched by water table declines since development of the HPA for irrigation.