Quantifying Sediment Provenance Using Multiple Composite Fingerprints in a Small Watershed in Oklahoma

Area of Science:

• Environmental Science
• Geochemistry
• Hydrology

Background:

• Accurate sediment provenance data are essential for refining soil erosion models.
• Directly measuring sediment source contributions at watershed scales presents significant challenges.

Purpose of the Study:

• To estimate sediment source contributions in a 15-km watershed using a three end-member mixing model with multiple composite fingerprints.
• To compare these estimates with those derived from a single radionuclide tracer, Cesium-137 (Cs).

Main Methods:

• Collected surface soil samples from croplands, rangelands, and gully banks.
• Analyzed 31 geochemical elements as tracers, screening them using statistical tests.
• Applied analytical solutions to a three end-member mixing model with composite fingerprints.

Main Results:

• Gully or subsoil erosion was identified as the primary source of fine sediment in most subwatersheds.
• Source contributions were significantly influenced by topography and land use patterns.
• Using multiple composite fingerprints enhanced accuracy and reduced uncertainty in source contribution estimates.

Conclusions:

• The multiple composite fingerprint method provides reliable sediment provenance data for small watersheds.
• Estimated source contributions using this method showed good agreement with Cs-137 data, particularly for gully contributions (r=0.69).
• This approach improves confidence in identifying sediment sources for improved soil erosion modeling.