USGS Watershed Sediment Workplan for the Chesapeake Bay

WRD PROJECT #: MD172
PROJECT CHIEF: Gellis, Allen
BEGIN DATE: 01-July-2001
END DATE: 30-September-2005

Customers currently supporting the project:

U.S. EPA Chesapeake Bay Program
U.S. Geological Survey

Problem

Excess sediment is having an adverse affect on the living resources and associated habitat of the Chesapeake Bay and its watershed. Submerged aquatic vegetation (SAV) has declined drastically over the past 30 years due to degraded water clarity associated with suspended sediment and eutrophication. Excessive sedimentation can bury or affect the vitality of filter feeders in the Bay. The chemical constituents and potential pathogens associated with sediment are believed to impact fisheries and other living resources in the Bay and its watershed. Excess sediment degrades the habitat needed to support benthic invertebrates in streams throughout the Bay watershed. In addition, sediment is threatening the economic and recreational vitality of the Chesapeake Bay region due to filling of commercial and recreational shipping and boating channels. Due to some of these concerns, the Chesapeake Bay was listed as an impaired water body under the Clean Water Act.

During 2000, the Chesapeake Bay Program (Chesapeake Bay Program) will be setting a water-clarity standard in shallow habitat (less than 2 meters) of the Bay to support the light conditions needed for SAV. The Chesapeake Bay Program is developing an approach to estimate the relative influence of sediment and nutrients on light in different tributaries of the Bay (Gallegos, in review). By the end of 2000, model runs will be conducted to estimate sediment and nutrient load reductions needed to meet the goal during 2001, and strategies will be developed in 2002 on how to meet the goal. The goal must be met by 2010 and there will be an assessment of progress and refinement of the sediment-reduction strategies during 2005-06.

While nutrient sources and transport to the Bay have been addressed over the past 15 years, little is known about the sediment sources, transport, residence time, sites of deposition, and relation to water clarity and living resources in shallow habitats of the Bay. There is a need to formulate a rational sediment-reduction strategy. This part of the USGS research addresses work performed in watersheds draining to Chesapeake Bay to identify sediment sources in the watershed (i.e. land erosion, stream corridor erosion) and transport processes to the Bay.

Objectives

The principal objective of the USGS study in the Chesapeake Bay watershed is to determine the sources, transport, and residence time of sediment delivered to portions of the Bay impacted by sediment. This study will coincide with other USGS efforts to understand sediment processes of shoreline erosion, sediment transport in the Bay and sediment resuspension in the Bay. Information from all these sediment processes will be used to understand the relation of sediment delivery to sediment deposition, effects on water clarity, and effects on submerged aquatic vegetation and other biota in the receiving tidal tributaries.

Approach

1. Use existing data to characterize sediment concentrations, loads, and yields in the major watersheds
2. Cosmogenic Isotopes
3. Outputs
4. Enhance collection of suspended sediment data to improve load estimates of sediment
5. Sediment fingerprinting study
6. Subbasins
7. Residence time of sediment
8. Sediment Budget