ARS | Publication request: Using environmental radionuclides as fingerprints to study streambank erosion

Submitted to: American Water Resources Association Conference Proceedings
Publication Type: Proceedings/Symposium
Publication Acceptance Date: September 30, 2008
Publication Date: N/A

Technical Abstract: The identification of sediment source areas in the watershed is a key component for designing management strategies to reduce sediment and chemical loads from watersheds. Potential sediment sources in watersheds can be characterized (fingerprinted) using diagnostic environmental radionuclides, chemical, and/or physical properties. Comparison of these properties with equivalent properties for suspended (or deposited) sediment samples permits the relative importance of the potential sources to be evaluated. The objective of this study was to show the application of Cesium-137 (Cs-137) to determine the relative importance of streambank erosion from watersheds. Fallout Cs-137 can be used as a tracer or fingerprint to identify sediment sources within watersheds. In order to understand the relative contribution of streambank erosion, samples are collected from the various geomorphic surfaces (upland soils, colluvial slopes, floodplain deposits, streambanks, and suspended sediments) within a watershed and analyzed for fallout Cs-137 concentration. Then using simple or multivariate mixing models, the relative contribution of the different geomorphic surfaces to sediment loads can be determined. Application of the fingerprinting techniques in several watersheds will be used to illustrate the technique. These studies (along with many in the literature) show the potential for using Cs-137 to determine the relative importance of different sediment sources in a watershed. Environmental radionuclides (Cs-137) have been shown to be a key and useful tracer in environmental processes. Used in combination with other properties (fingerprints), the relative contributions of different sediment sources can be determined.