Hydrologic Assessment of the Great Dismal Swamp using NASA Earth Observations

EarthzineOriginal, Spring 2013 VPS

False color images of the Great Dismal Swamp. Credit: DEVELOP

False color images of the Great Dismal Swamp. Credit: DEVELOP

Image Credit: DEVELOP

Author: Taylor Beard

Mentors/Advisers (affiliation): Dr. Kenton Ross (Langley Research Center)

Team Location: NASA Langley Research Center, Hampton, Virginia

Abstract: The Great Dismal Swamp (GDS) has an annual hydrologic cycle that results in changing water levels throughout the year. The hydrological cycle in the GDS is an important factor affecting ecosystem health by controlling species composition, habitat dynamics, and threats from wildfires. The hydrology of the GDS has been modified through years of human activities. The construction of canals and ditches, with their accompanying spoil bank roads, have combined to form the most significant alteration to the swamp’s water regime. The refuge’s ditches form a network that channels much of the current surface flow into Lake Drummond, which in turn drains into the Feeder Ditch through a gated spillway and then into the Dismal Swamp Canal. Shifts in hydrology, soil, and vegetation have become more pronounced in the last 30 years due to the construction of ditches and canals. Peatlands in the GDS, formed from the accumulation of organic matter into the soils, are several feet thick and capable of burning when dry. Peat fires are dangerous and difficult to fight, as they travel underground through the peat soils and move behind firefighting lines. Hydrology management in the swamp has focused on raising the water table. Landsat 5 and 7 were used to create Normalized Difference Vegetation Indices that can be used as an indirect interpretation tool of changing hydrological conditions over the last decade. These products will help to aid in revealing areas that are especially vulnerable to drying or inundation.