Water Resources Research Act Program

Details for Project ID 2011DE206B

Sediment Transport through Historic Mill Dams of the Christina River Basin

Institute: Delaware
Year Established: 2011 Start Date: 2011-03-01 End Date: 2012-02-28
Total Federal Funds: $3,500 Total Non-Federal Funds: $7,000

Principal Investigators: James Pizzuto, Kimberly Teoli

Project Summary: This research project aims to study the influence of historic mill dams on alluvial sedimentation in the Christiana River Basin. After European settlement of the watershed, many dams were constructed for hydropower. It has been argued that the dams controlled the subsequent evolution of the river and its floodplain by trapping sediment behind them. Now that many of these dams have failed or are being removed, the river valley will continue to erode these deposits away and carry them downstream to the Delaware Bay. Because these deposits are believed to be rich in nutrients, they may represent a serious water quality problem for the watershed and the Delaware Bay itself. The goal of this study is to test the hypothesis that deposits trapped behind mill dams reach a steady-state form after many decades of sedimentation, and to define (through mapping) the nature of these deposits. Several methods will be used to determine the types and patterns of sediment formed behind mill dams. This includes mapping patterns of sediment size and thickness in several typical impoundments in the Christiana River Basin. Sediment size will be measured using standard field protocols, and a steel rod (pounded to refusal) can be used to determine the thickness of sediment deposited above the gravel riverbed that existed before dams were constructed. A survey of the morphology and bathymetry will also be conducted at these sites. The surveying methods will include total station and high resolution GPS techniques.