Estuarine and Tidal Freshwater Habitat Cover Types Along the Lower Columbia River Estuary Determined from Landsat 7 Enhanced Thematic Mapper (ETM+) Imagery, Technical Report 2003.

Garono, Ralph ; Robinson, Rob

United States. Bonneville Power Administration.

关键词: Modifications;    Wetlands;    Columbia River;    Classification;    Habitat;   

DOI  :  10.2172/962829
RP-ID  :  DOe/BP-00008768-3
RP-ID  :  8768
RP-ID  :  962829

美国|英语

来源: UNT Digital Library

【 摘 要 】

Developing an understanding of the distribution and changes in estuarine and tidal floodplain ecosystems is critical to the management of biological resources in the lower Columbia River. Columbia River plants, fish, and wildlife require specific physicochemical and ecological conditions to sustain their populations. As habitats are degraded or lost, this capability is altered, often irretrievably; those species that cannot adapt are lost from the ecosystem. The Lower Columbia River Estuary Partnership (Estuary Partnership) completed a comprehensive ecosystem protection and enhancement plan for the lower Columbia River and estuary in 1999 (Jerrick, 1999). The plan identified habitat loss and modification as a critical threat to the integrity of the lower Columbia River ecosystem and called for a habitat inventory as a key first step in its long term restoration efforts. In 2000, the Estuary Partnership initiated a multiphase project to produce a spatial data set describing the current location and distribution of estuarine and tidal freshwater habitat cover types along the lower Columbia River from the river mouth to the Bonneville Dam using a consistent methodology and data sources (Fig. 1). The first phase of the project was the development of a broadbrush description of the estuarine and tidal freshwater habitat cover classes for the entire study area ({approx}146 river miles) using Landsat 7 ETM+ satellite imagery. Phase II of the project entailed analysis of the classified satellite imagery from Phase I. Analysis of change in landcover and a summary of the spatial relationships between cover types are part of Phase II. Phase III of the project included the classification of the high resolution hyperspectral imagery collected in 2000 and 2001 for key focal areas within the larger study area. Finally, Phase IV consists of this final report that presents results from refining the Landsat ETM+ classification and provides recommendations for future actions. Previous studies (Thomas, 1980; Thomas, 1983; Graves et al., 1995; NOAA, 1997; Allen, 1999) produced similar landcover data sets; however, most of these studies used multiple and varied data sources and differed from one another in methodologies. Currently, no single data set has been produced using a consistent methodology and uniform scale data, which describes current estuarine and tidal freshwater floodplain cover types from the Columbia's mouth to the Bonneville Dam (Fig. 1). Results from this study will be used by the Estuary Partnership and its cooperators to: (1) develop indicators of 'habitat health' for target species and populations, and biological integrity at the community and ecosystem scales; (2) develop definitions of 'important salmonid habitat'; (3) identify and evaluate potential wetland conservation and restoration sites; (4) track non-indigenous and invasive species; and (5) develop an understanding of how estuarine and floodplain habitats have changed over the past 200 years. This study focused on estuarine and tidal freshwater floodplain habitat cover types, which are important to native species, particularly juvenile salmonids. Results from this study are meant to provide support for the multiple efforts currently underway to recover 12 species of Columbia River salmonids identified as endangered or threatened under the Endangered Species Act. Spatial scale was an important consideration in this study. Our goal was to create a geographic information system (GIS) coverage depicting habitat cover types for the entire 146 river miles of the study area and the associated floodplain, at a spatial resolution sufficient to resolve important estuarine and floodplain features, wherever possible. Thus, in addition to the small scale (30 m pixel size) satellite imagery covering the study area described in this report, we also acquired high spatial resolution imagery ({approx}1.5 m pixel size) for key portions of the study area using a Compact Airborne Spectrographic Imager (CASI). Compared to the rather coarse, low spectral resolution of the satellite imagery, the CASI imagery provides the spectral resolution (19 CASI bands vs. 7 ETM+ Bands) necessary to discriminate between spectrally similar vegetation types and thus provided a greater ability to resolve habitat features important to species such as salmonids. Unfortunately, image acquisition costs and logistics (time and poor weather) prevented complete coverage of the study area at a 1.5 m spatial scale. However, in 2000/01 CASI imagery was collected for several key focal areas including the Chinook watershed, the area around the Astoria Airport mitigation site, Russian Island, Tenasillahe Island, Sauvie Island, Scappose Bay lowlands, Lord and Walker Islands and much of the shoreline. This report presents the classification methodology and initial results from the satellite image classification.