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United States Department of Agriculture

Agricultural Research Service

Title: C-Band Radar Monitoring of Hydrology in Mid-Atlantic Coastal Plain Forests: Implication for Improved Water Quality Management in the Chesapeake Bay Watershed

Authors
item Lang, Megan
item Walthall, Charles

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: April 26, 2006
Publication Date: April 26, 2006
Citation: Lang, M.W., Walthall, C.L. 2006. C-Band radar monitoring of hydrology in Mid-Atlantic Coastal Plain Forests: Implication for improved water quality management in the Chesapeake Bay Watershed [abstract]. Abs. 19, BARC Poster Day.

Technical Abstract: The Chesapeake Bay Watershed has lost over half of its historic wetlands, and most of those that remain are forested, Coastal Plain wetlands. Unfortunately, remaining wetlands are at high risk for future loss, due to inadequate legal protection and rapid population growth. Hydrology (flooding and soil moisture) controls wetland function, and must be better understood to improve wetland mapping and watershed management. Broad-scale forested wetland hydrology is difficult to monitor using ground-based and traditional remote sensing methods (i.e., aerial photography). C-band synthetic aperture radar (SAR) data could improve the capability to monitor forested wetland hydrology, but the abilities and limitations of these data need further investigation. This study examined: 1) the ability of ENVISAT SAR (C-HH and C-VV) data to monitor inundation and soil moisture in forested wetlands; 2) limitations inherent to C-band data when monitoring forested wetland hydrology; and 3) the accuracy of forested wetland maps produced using SAR data. The study was primarily conducted at the Patuxent Wildlife Research Center in Laurel, Maryland but the influence of incidence angle was considered along the Roanoke River in North Carolina. This study showed: 1) significant differences in radar backscatter existed between forested areas of varying hydrology (uplands and wetlands) throughout the year; 3) C-HH backscatter was better correlated to hydrology than C-VV backscatter; 4) correlations were stronger during the leaf-off season; 5) the difference in backscatter between flooded and non-flooded areas did not sharply decline with incidence angle, as predicted; and 6) maps produced using SAR data had relatively high accuracy levels. Based on these results, forest hydrology is currently being mapped over a broader area, within the Choptank Watershed, Maryland. Preliminary results are encouraging and opportunities are being explored to include this forest hydrology metric, as well as other biophysical parameters, in a spatially explicit water quality model.

Last Modified: 10/21/2014