Year Established: 2016 Start Date: 2016-03-01 End Date: 2017-02-28
Total Federal Funds: $15,000 Total Non-Federal Funds: $46,253
Principal Investigators: Troy Gilmore, Daniel Snow
Abstract: Water resources for crop production in parts of western Nebraska are a complex mix of North Platte River water (delivered to producers via canals), precipitation, and groundwater storage. In some cases, canal leakage is a major source of recharge to the alluvial aquifer, and also dilutes contaminants (e.g., nitrate) in the groundwater system. An integrated study of groundwater age, recharge rate, source, and quality has not been conducted since the late 1990s. Groundwater age in the alluvial aquifer near Morrill, NE was mostly <30 years, with a mean groundwater age of 8.8 years. The relatively short groundwater transit times suggest that the aquifer may respond relatively quickly to changes in water resources management, irrigation practice, and/or precipitation. Since the study in the 1990s, there have been significant changes in irrigation management, including moratoriums on new wells and new surface water appropriations, as well as allocations. Further, the type of irrigation in the study areas has shifted from gravity (flood) irrigation to center pivot technology, which could lead to decreased recharge under irrigated land. Precipitation over the last 15 years has also differed slightly compared to the 15 years prior to 1999 (lower, but within inter-annual variability). The proposed research is designed to determine whether groundwater age-dating tracers, isotopes, and dissolved nitrogen measurements can be used to quantify the impact of recent changes in irrigation management on groundwater recharge rates, source, and quality.