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ASSESSING THE IMPACT OF LANDUSE/LANDCOVER ON STREAM CHEMISTRY IN MARYLAND
Citation:
Senay, G., S M. Cormier, B Subramanian, AND J SchubauerBerigan. ASSESSING THE IMPACT OF LANDUSE/LANDCOVER ON STREAM CHEMISTRY IN MARYLAND. Presented at National Conference on Environmental Problem Solving with Geographic Information Systems, Cincinnati, OH, September 22-24, 1999.
Description:
Spatial and statistical analyses were conducted to investigate the relationships between stream chemistry (nitrate, sulfate, dissolved organic carbon, etc.), habitat and satellite-derived landuse maps for the state of Maryland. Hydrologic Unit Code (HUC) watershed boundaries (8-digit) were used as the basis for grouping stream chemistry data. Percent land cover area (forestland, cropland, pastureland, etc.) within an HUC was computed in a Geographic Information Systems (GIS) environment in Arc/Info. It was shown that percent agricultural lands (crop, pasture, etc.) were positively correlated (significant) with nitrate and dissolved organic carbon (DOC), while percent forest cover was negatively correlated (significant) with nitrate and DOC. The results were in agreement with the reports of other researchers and with the fundamental understanding of the role of the land cover types in chemical loadings to the streams. Generally, percent forest and percent agriculture displayed opposite signs in the correlation matrix with stream chemistry data, including sulfate and pH variables. Although there was a negative correlation between percent forest and nitrate in the streams, this was likely due to a reduction in the area occupied by agricultural lands (source of nitrate), not the amount of forest area per se. This was supported by the presence of a negative correlation between percent forest area and percent agricultural area. These data indicated that agriculture was the main source of nitrate pollution in Maryland streams. Further study is needed to investigate the nitrogen retaining capacity of stream-buffer types and identify best management practices that reduce loss of valuable nutrients from farm soils and their deleterious export to streams and estuaries.