GIS Visualization and Analysis of River Operations Impacts on Endangered Species Habitat

Many river systems include natural and manmade backwater areas providing habitat for a diverse community of aquatic and aviary species, including several listed as endangered by the U.S. Fish and Wildlife Service. Concern has been raised over ecological impacts of river operations on these species and their habitat in these backwater areas. A methodology is presented that utilizes a geographic information system (GIS) in association with a numerical hydraulic model to assess these impacts. The GIS provides geostatistical estimates of water surface elevations within the backwaters during passage of a hydrograph created by reservoir releases, and then quantifies and provides animated visualization of the changes in habitat for many species dwelling in these areas. This generalized tool is applied to a portion of the Lower Colorado River in Arizona/California, which includes several dams and diversion structures controlling flow for a variety of important purposes. It is demonstrated that this GIS-based tool provides effective support for river system operators in assessing the impacts of operations on endangered species habitat and evaluating remedial measures.