Introduction

Successful land management requires detailed knowledge of the terrain and the interrelationships between landscape and habitat characteristics. For terrestrial areas, much information can be gathered about a region through analysis of topographic maps and aerial photographs as well as through direct inspection and study. When lands to be managed are underwater, other techniques need to be employed to understand the landscape. While optical techniques can be used where the water is shallow or clear, other techniques are needed where the water is deeper or where optical transmission is limited by water clarity. Marine geophysical techniques provide quantitative measures of the nature of the estuary floor that can provide constraints on the distribution and movement of contaminated sediments as well as the nature of benthic habitats.

The Benthic Mapping Program, supported by the Hudson River Estuary Program of the New York State Department of Environmental Conservation (NYSDEC) and the Hudson River Estuary Action Plan, is being conducted in the Hudson River to characterize the river bed from the Battery to the Federal Dam at Troy. The study is using a range of acoustic and sampling techniques to gain new information of the river bed. This report summarizes the first phase of the Benthic Mapping Program which occurred from 1998 to 2000 and focused on four areas (covering about 40 river miles (65 km), Fig. 5.1) of the river, including details of the data acquisition and reduction and a discussion of results from one of the study areas. The products from the study have been incorporated into a GIS data management system for NYSDEC. This effort, supplemented by studies of benthic fauna and bathy-metric change is being continued under NYSDEC support for the remainder of the Hudson River from the Battery to the Federal Dam at Troy. About 35 river miles (57 km) were studied in 2001 and 2002 and the mapping phase was completed after studying about 66 river miles (121 km) in early 2003.

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