Remote sensing of water clarity and sediment dynamics in Chesapeake Bay

Time Series Maps of Total Suspended Sediment and Chlorophyll in Chesapeake Bay 1997 to Present

An issue of particular concern in Chesapeake Bay is optical water quality. Over the past three decades, submerged aquatic vegetation (SAV) in the Bay has declined dramatically, and poor water clarity (hence low light availability) has been targeted as a primary cause. Since the 1980's, a great deal of attention has been devoted to nutrient loading and its impact on water clarity. Only in more recent years have sediments been recognized as a significant additional consideration. At present, many fundamental questions about sedimentary processes in Chesapeake Bay and its tributaries remain unanswered.

In addition, the need for frequent, high-resolution monitoring data is becoming increasingly apparent in ongoing Chesapeake Bay Program (CBP) restoration efforts. Of particular interest would be information about the new chlorophyll-a, dissolved oxygen (DO) and water clarity criteria that have been established for the Bay. CBP currently maintains a network of more than 100 water-quality monitoring stations, but this field sampling program cannot adequately resolve the details of spatial and temporal variability within the Bay.

Satellite imagery can provide frequent, bay-wide views of optical parameters related to water clarity and suspended sediments, but coastal remote sensing presently offers methodological challenges as well as potential promise.

The overall goal of this task is to use multi-platform remote sensing coupled with optical modelling and ancillary meteorological, water quality, and hydrologic data to better understand the sources of Chesapeake Bay suspended sediments, and to examine the consequences of suspended sediments for water quality and benthic habitats in the Chesapeake Bay.

The objectives of this task are to:

• Describe the spatial and temporal variability of water quality parameters related to optical water quality in Chesapeake Bay.

• Investigate the causes of suspended sediment plumes that are observed within the Chesapeake Bay.

• Undertake research to improve capabilities to retrieve information about suspended sediments and other light-attenuating substances from optical satellite observations.

• Characterize variable water clarity in Chesapeake Bay and its effect on the benthic light environment.

For more information:

• Image of Chesapeake Bay after Hurricane Isabel, September 2003