Streams in the Loup River basin are sensitive to groundwater withdrawals because of the close hydrologic connection between groundwater and surface water. Pumping from aquifers that are hydrologically connected to surface-water bodies can have a significant effect on the streams by reducing the groundwater discharge to surface water. An evaluation of any groundwater management strategy needs to involve consideration of the impact on surface-water resources. Four stream reaches, totaling approximately 320 river miles, have been identified by the Upper and Lower Loup Natural Resources Districts as priority streams where additional groundwater/surface-water interaction information is needed to properly manage their water resources. The USGS, in cooperation with the Upper and Lower Loup Natural Resources Districts, received a grant from the Nebraska Environmental Trust to study and address these water supply concerns.
This study is focused on investigating and describing the spatial and temporal characteristics of groundwater/surface-water interaction for selected stream reaches in the Loup River basin. Specific goals are:
Over these reaches, airborne thermal infrared imagery will be collected and used to map stream surface temperatures to identify thermal anomalies, which may be indicative of focused groundwater discharge. Airborne thermal data will be verified with continuous water-temperature data from stream-gaging stations and from self-logging thermistors. Mapped thermal anomalies will be investigated with a variety of techniques including water temperature, potentiomanometer, and seepage meter measurements.
Thermal image of focused groundwater discharge on the South Loup River.
Groundwater seep on the bank of the South Loup River.