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Chesapeake Bay Forecast System (CBFS)
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SWAT

To determine the effects of various climate and land use conditions on freshwater transport and nutrient dispersion in the bay area, CBFS uses a model called the Soil and Water Assessment Tool (SWAT). SWAT provides fine-scale mapping of the ways in which rainwater, groundwater, nutrients and sediments move through the earth and, ultimately, into the bay.

Researchers use satellite imagery, aerial photography and ground measurements to create detailed representations of topography, ground cover and physical characteristics of as many as 10 different layers of soil. The maps delineate watersheds that are further divided into sub-basins and individual streams, ponds and wetlands, and finally into minimal units - which can be smaller than a football field - that have unique soil and land-use properties.

The physical model is then updated continuously with weather and climate information, as well as input from numerous on-site sensors such as stream gauges and data about groundwater used for irrigation and thus "lost" to the system.

Rappahannock Watershed

CBFS is using the Rappahannock River complex, one of seven main freshwater inputs to the bay, to test and fine-tune the model. Eventually, SWAT analysis will be applied to all the bay tributaries.