Water Resources Research Act Program

Details for Project ID 2018LA119B

Fine-Grained Floodplain Forest Flow Paths and Source Water Mixing in Shrink-Swell Clays of a Bottomland Hardwood Forest Using Stable Isotope Tracers

Institute: Louisiana
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $14,000 Total Non-Federal Funds: $28,640

Principal Investigators: Richard Keim

Abstract: As approximately 80% of the bottomland hardwood forest (BLH) in the Mississippi Alluvial Valley has been deforested, effectiveness of reforestation efforts is essential. Wetland restoration managers typically rely heavily on hydrologic modifications. The heterogeneity in shrink swell soils typically found in BLH make predicting impacts of hydrologic modifications on a site difficult to predict. Water stable isotopes of D and 18O can be used to gain a better understanding of groundwater sources and flow pathways in a BLH while bypassing the associated errors of using lab measurements of hydraulic conductivity. Over the course of a year water samples will be taken of local precipitation, 2 bayou surface water sites, groundwater, and ponded site surface water. These samples will be analyzed for δD and δ18O values. The relationship of these values will be plotted against each other to create a conceptual isoscape of the site as well as a three component isotopic mixing model. Together the resulting conceptual isoscape and mixing model will allow us to determine the sources of groundwater and site ponded surface water as well infer the hydrologic flow paths across the site. This information will extend the current knowledge of groundwater hydrology in shrink swell clays as a broad site-wide concept. Understanding groundwater movement in BLH can help restoration managers in planning and design as well as guiding adaptive management processes and decisions. This study is a collaborative effort with Natural Resource Professionals.