Remote sensing of coastal wetlands and estuaries

Abstract

To protect and restore coastal ecosystems, scientists and managers need reliable, up-to-date information on how and why these systems are changing. Remote sensors on satellites and aircraft offer cost-effective means for determining the rates and causes of ecosystem changes. The U. D. Center for Remote Sensing has been developing remote sensing techniques for observing changes of landscape-level, coastal environmental indicators, including wetland size, biomass, fragmentation; invasive species; riparian buffers; estuarine suspended sediment and chlorophyll concentrations. One particularly useful result is a method for detecting changes of wetland and upland vegetation using biomass as an indicator. By employing a vegetation index (MSAVI) which is locally normalized, we minimize the effects of atmospheric, weather and seasonal differences between images in a time series. This model is applied to a time-series of medium resolution (30 m) Landsat/TM images in a GIS to identify and “flag” areas where significant change has occurred. Only the “flagged” areas are then examined in more detail with more expensive high-resolution (1-4 m) IKONOS satellite or aerial imagery.