Changes in land use influence surface-water quality and thus present a potential threat to coastal ecosystem health. Land use–land cover changes (LULCC) in the lower Eastern Shore watersheds of Maryland have been rapid in the last decade, with increase in real estate development an obvious indicator. The objective of this study was to evaluate the extent of historical LULCC in the lower Eastern Shore watershed and coastal bays of Maryland from 1986 to 2006. Land use–land cover data were derived by supervised classification of Landsat TM 5 satellite imagery acquired in 1986, 1996, and 2006 using the Anderson level-1 classification system in Environment for Visualizing Images (ENVI 4.5), while LULCCs were detected in an Arc-GIS 9.2 environment.
The results showed that while urban and forest lands increased by 121.8% and 8.5%, respectively, in the lower Eastern Shore from 1986 to 2006, croplands and wetlands decreased by 19.6% and 21.3%, respectively. Area covered by surface water increased by 10%, submerging mostly wetlands of 150 km2 in 17 of the 23 subwatersheds studied. The loss of these coastal wetlands is attributable in part to the changing climate and the resultant sea-level rise and in part to the activities of the invasive rodent Nutria (Myocastor coypus), reported to be a major menace in Maryland's Eastern Shore. The declining wetlands have serious ecological health implications for the Chesapeake Bay and its watersheds for several species and thus require urgent attention. More intensive and frequent monitoring of this delicate estuarine ecosystem is suggested.
