Sources of fine sediment stored in agricultural lowland streams, Midwest, USA

Geomorphology
University of Wisconsin-Madison; Dane County; WI DNR; the Nature Conservancy
By: , and 

Links

Abstract

Agricultural activities can accelerate the offsite transport of productive soil from fields leading to stream water quality degradation. Identification of the nature and relative contribution of different sources to fine-grained sediment (e.g., silts, clays) in streams is important to effectively focus agricultural best management practices in watersheds. Sediment fingerprinting techniques through the use of geochemical tracers are commonly used to differentiate relative contribution from various sources. Research was conducted in lowland streams in the Pleasant Valley watershed in South Central Wisconsin (USA) to identify provenance of fine-grained sediment deposits and evaluate the impact of land use on relative contributions from the following potential sources: cropland, pasture, woodland, and eroding stream banks. Results show that both agriculture (croplands and pastures) and eroding stream banks are primary sources to fine sediment deposits on the stream bed with contributions ranging from 19 to 100% and 0 to 81%, respectively. The increase in area under agricultural land use within a subwatershed results in greater contribution from agriculture (R2 = 0.846, p = 0.0034). Relative contributions from eroding stream banks increased with increasing area under grasslands and woodlands within a subwatershed (R2 = 0.814, p = 0.0055). Subwatersheds with greater mass of fine sediment deposited on the stream bed per unit area should be prioritized for best management practices. The conservation practices should be targeted to stream banks or croplands depending on the dominant source of fine sediment within a subwatershed. Site specific changes in relative contributions from different sources to fine-grained sediment in this watershed highlights the complexities involved in sediment transport dynamics. The nested sampling sites helped determine that sediment dynamics at the subwatershed scale need to be considered for application of targeted conservation techniques.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Sources of fine sediment stored in agricultural lowland streams, Midwest, USA
Series title Geomorphology
DOI 10.1016/j.geomorph.2015.02.001
Volume 236
Year Published 2015
Language English
Publisher Elsevier
Contributing office(s) Wisconsin Water Science Center
Description 10 p.
First page 44
Last page 53
Country United States
State Wisconsin
Other Geospatial Pleasant Valley watershed