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Analysis of Historical Distribution of SubmergedAquatic Vegetation (SAV) in the York and Rappahannock Rivers as Evidence of Historical Water Quality Conditions 2001

Published: December 01, 2001

Historical black and white format photographs at scales of approximately 1:20,000, dating from 1952 to 1956 were used to delineate the maximum coverage of SAV in the study region.  Coverage of photography from decades before and after this period were found to generally to be of poorer quality and show less SAV [resence.  Photo-interpretation of the aerial photographs was accomplished using a head-up, on-screen digitizing system at fixed image scale:12,000 and followed as closely as possible the methods currently used to delineate SAV beds throughout the Chesapeake Bay as well as the delineation of historical SAV coverage for other regions.  Losses of vegetation have been much more extensive in the Rappahannock than the York.  In 1999, in the lower York River (YRKPH) approximately 23% of the historical SAV coverage remained while on 1% remained in the lower Rappahannock (RPPMH).  Areas along the bay shoreline had the highest proportion of remaining beds with baysegments CB6PH and MOBPH exceeding 50% of historical  coverage.

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