Sediment Transport in Chesapeake Bay During Floods: Analysis Using Satellite and Surface Observations

Abstract

Satellite data, when calibrated and compared with surface observations, can provide detailed information on sediment transport during high discharge in estuaries, as shown using LANDSAT and AVHRR reflectance data in Chesapeake Bay. In early March 1979, both the Susquehanna and Potomac Rivers had high discharge. In the Bay's axis, suspended sediment concentrations of 5 - 10 times normal were observed from both satellite and ship. The satellite data further revealed the flux of surface sediment into the tributaries. After two weeks, the surface waters below Annapolis contained 10% of the load of the Susquehanna River, and 5% had entered the surface waters of the northern tributaries. In the Potomac River, satellite imagery shows a turbidity maximum developed in the lower estuary with concentrations estimated at 10 - 20 times normal. Significant quantities of sediment entered the Bay from the Potomac. The satellite data further indicate differences in grain size between the Potomac and the Upper Bay. For the November 1985 event, only AVHRR satellite and USGS gauging station data exist. The imagery shows the movement and high concentrations of suspended sediment in the upper estuary, with estimated concentrations of 3 times 1979 and 100 times normal. This event may have supplied up to 50% of the average annual deposition in the lower Potomac estuary.