Water Resources Research Act Program

Details for Project ID 2019NE164B

Connecting groundwater quality to surface water quality in intensively managed landscapes

Institute: Nebraska
Year Established: 2019 Start Date: 2019-06-01 End Date: 2020-05-31
Total Federal Funds: $20,000 Total Non-Federal Funds: $40,000

Principal Investigators: Andrew Miller

Abstract: In the proposed study, we plan to characterize and quantify water quality and quantity from several different water sources within the Glacier Creek watershed to investigate how intensive row crop agriculture alters hydrologic and geochemical fluxes compared to restored prairie systems. Ongoing water quality work at the site includes the collection of surface water samples from various points within the stream, and porewater samples using porous cup lysimeters located in the top 1m of the soil under both agriculture and restored prairie land uses. More recently two shallow (<2 m) groundwater wells were installed, one closer to agricultural influences and one closer to prairie influences. Furthermore, the site has been outfitted with high frequency (~every 15 minutes) data loggers, including: an in-stream sonde capable of measuring basic water quality parameters (e.g., pH, DO, etc.), an in-stream flow meter, and downwell water level monitors in the groundwater wells. From the data collected to date, there are clear differences in water quality associated with the surficial land use (prairie vs. agriculture). The differences in water quality imply different mineral weathering patterns in the sub-surface. There are also diurnal changes in both water quality and quantity variables. These changes are likely due to the interaction between biological, chemical and hydrological processes. Despite the progress that has been made, we lack the ability to measure water quality in the deeper groundwater. This missing data is critical to connect the changes in water quality associated with soil processes as precipitation moves downward through the soil and eventually to the stream. For example, the nitrate concentrations in the porewater under agriculture are quite high, but that nitrate does not appear to be making it to the stream. Hence, we propose to install 4 groundwater sampling wells (up to 10 - 20 m) moving upslope away from the stream. Two will be placed in sections of restored prairie, and two will be placed under agriculture. Each well will be sampled regularly for water quality analysis, and will be instrumented with well loggers to track high frequency changes in groundwater levels. Surface and soil porewaters will continue to be collected every 2 – 4 weeks. The collected data will compare the water quality (including nutrient concentrations) from different positions in the watershed to determine processes controlling ion concentrations. Furthermore, from the well loggers and flow meter, we plan to develop a more nuanced hydrological conceptual model that may address water quantities associated with each land use. We plan to use the collected data as preliminary data in an NSF grant to either the Geobiology and Low-temperature Geochemistry or Geomorphology and Land-use Dynamics programs. Within these two programs, we plan to identify the proposal as a Critical Zone advancement that will leverage existing datasets from previously funded Critical Zone Observatories (CZO). Without the deep wells and the associated data, the NSF proposal would be missing a critical piece of information.