Sources of Suspended‐Sediment Flux in Streams of the Chesapeake Bay Watershed: A Regional Application of the SPARROW Model¹

Abstract

We describe the sources and transport of fluvial suspended sediment in nontidal streams of the Chesapeake Bay watershed and vicinity. We applied SPAtially Referenced Regressions on Watershed attributes, which spatially correlates estimated mean annual flux of suspended sediment in nontidal streams with sources of suspended sediment and transport factors. According to our model, urban development generates on average the greatest amount of suspended sediment per unit area (3,928 Mg ⁄ km 2 ⁄ year), although agriculture is much more widespread and is the greatest overall source of suspended sediment (57 Mg ⁄ km 2 ⁄ year). Factors affecting sediment transport from uplands to streams include mean basin slope, reservoirs, physiography, and soil permeability. On average, 59% of upland suspended sediment generated is temporarily stored along large rivers draining the Coastal Plain or in reservoirs throughout the watershed. Applying erosion and sediment controls from agriculture and urban development in areas of the northern Piedmont close to the upper Bay, where the combined effects of watershed characteristics on sediment transport have the greatest influence may be most helpful in mitigating sedimentation in the bay and its tributaries. Stream restoration efforts addressing floodplain and bank stabilization and incision may be more effective in smaller, headwater streams outside of the Coastal Plain.

Regional regression models of watershed suspended-sediment discharge for the eastern United States

“…model accuracy that may be realized through such a regional-scale analysis. In fact, a recent SPARROW model of suspended-sediment flux in the Chesapeake Bay watershed, which encompasses much of region 2, reported a RMSE of 0.96 (Brakebill et al, 2010). This is comparable to the average model prediction error reported for the region 2 regional regression model seen in Table 2.…”

Sediment Fingerprinting to Delineate Sources of Sediment in the Agricultural and Forested Smith Creek Watershed, Virginia, USA

“…However, many of the models used by management agencies in the Chesapeake Bay watershed rely on land use/land cover for sediment sources and do not include streambanks as a source of sediment, e.g., the USEPA Chesapeake Bay Watershed, Hydrologic Simulation Program—Fortran model (Shenk and Linker ), and the USGS SPAtially Referenced Regressions On Watershed attributes model (Brakebill et al. ).…”

Loss of genetic diversity in the North American mayfly Ephemerella invaria associated with deforestation of headwater streams

“…Recent reviews have highlighted the effects of land use in headwater stream catchments on water quality and ecosystem function in downstream rivers, estuaries and seas (Alexander et al, 2007;Craig et al, 2008;Brakebill, Ator & Schwarz, 2010). The contributions of headwater streams to biodiversity in river networks, reviewed by Meyer et al (2007), also are affected by local land use.…”