Assessing drought resilience of the South Loup River using age tracer, streamflow, and continuous water-quality data Active
Streams in the Loup River basin have a close hydrologic connection between groundwater and surface water. Groundwater springs are important hydrologic features that sustain the flow of the South Loup River. This study assesses the ability of these springs to maintain consistent flow of the South Loup River over periods of prolonged drought.
Project Overview
Streams in the Loup River basin are sensitive to groundwater withdrawals because of the close hydrologic connection between groundwater and surface water. In a previous study, the U.S. Geological Survey (USGS), in cooperation with the Upper Loup Natural Resources Districts (NRD) and Lower Loup NRD, and the Nebraska Environmental Trust, collected aerial thermal imagery along the South Loup River to map locations of focused groundwater discharge points (Hobza and Schepers, 2018). These mapped springs are important hydrologic features that sustain the flow of the South Loup River and its tributaries. Although their location has been mapped, the ability of these springs to maintain consistent flow over periods of prolonged drought has not yet been studied. To assess groundwater interaction and possible effects of a multiyear drought on the streamflow of the South Loup River, the USGS in cooperation with the Upper Loup NRD and Lower Loup NRD, and the Nebraska Environmental Trust, began a study examining the age and water-quality characteristics of groundwater from selected springs and monitoring wells located near the South Loup River.
Study approach
In August and September of 2019, 20 samples were collected to characterize the age and water-quality characteristics of groundwater discharging from Pliocene-age deposits (called Pliocene-age springs) and groundwater from wells completed in Quaternary-age deposits, Pliocene-age deposits, and the Ogallala Formation. Samples springs and wells were analyzed for major ions, trace elements, nutrients, stable isotopes, dissolved gases, and selected age tracers. Age tracer and supporting geochemical data were interpreted to determine the age distributions. Continuous water-quality, stage, and discharge data were collected from May to October 2019 at three locations provided additional support and context for age tracer interpretations.
Groundwater/Surface-Water Interactions in the Loup River Basin
Streams in the Loup River basin have a close hydrologic connection between groundwater and surface water. Groundwater springs are important hydrologic features that sustain the flow of the South Loup River. This study assesses the ability of these springs to maintain consistent flow of the South Loup River over periods of prolonged drought.
Project Overview
Streams in the Loup River basin are sensitive to groundwater withdrawals because of the close hydrologic connection between groundwater and surface water. In a previous study, the U.S. Geological Survey (USGS), in cooperation with the Upper Loup Natural Resources Districts (NRD) and Lower Loup NRD, and the Nebraska Environmental Trust, collected aerial thermal imagery along the South Loup River to map locations of focused groundwater discharge points (Hobza and Schepers, 2018). These mapped springs are important hydrologic features that sustain the flow of the South Loup River and its tributaries. Although their location has been mapped, the ability of these springs to maintain consistent flow over periods of prolonged drought has not yet been studied. To assess groundwater interaction and possible effects of a multiyear drought on the streamflow of the South Loup River, the USGS in cooperation with the Upper Loup NRD and Lower Loup NRD, and the Nebraska Environmental Trust, began a study examining the age and water-quality characteristics of groundwater from selected springs and monitoring wells located near the South Loup River.
Study approach
In August and September of 2019, 20 samples were collected to characterize the age and water-quality characteristics of groundwater discharging from Pliocene-age deposits (called Pliocene-age springs) and groundwater from wells completed in Quaternary-age deposits, Pliocene-age deposits, and the Ogallala Formation. Samples springs and wells were analyzed for major ions, trace elements, nutrients, stable isotopes, dissolved gases, and selected age tracers. Age tracer and supporting geochemical data were interpreted to determine the age distributions. Continuous water-quality, stage, and discharge data were collected from May to October 2019 at three locations provided additional support and context for age tracer interpretations.