Development and testing of an integrated water pollution assessment tool for analyzing impacts of urban sprawl.

摘要

Land use change is a major concern in developed and developing countries; nearly half of the world's land surface has been modified by human activity. Most land use change occurs without careful planning and scientific study to assess environmental impacts. Unplanned land use changes lead to local, regional, and global impacts that could be minimized if impact assessments were performed before changes occurred. The Long-Term Hydrological Impact Assessment (L-THIA) model is a tool to aid in planning decision-making and in developing regulations to minimize negative hydrologic impacts associated with land use change. The L-THIA model predicts surface runoff and nonpoint source pollutant loads from different land uses. However contributions from point sources also play a significant role in impairing water bodies. In this research point source water pollution assessment and baseflow prediction capabilities were added to L-THIA to address integrated point and nonpoint source pollution concerns for total stream flow. L-THIA results from subwatersheds in northeastern Ohio demonstrated the benefits of protecting riparian areas as a way to reduce the hydrologic impacts of development. Watershed managers used these results to evaluate existing land use policy and educate decision-makers, and pointed out the need for L-THIA results to match observed streamflow. A simple calibration model for L-THIA was developed and tested successfully. A web based, GIS enabled automatic hydrograph separation model, iSep, was developed to perform automatic calibration of L-THIA as well as for use in point source water quality modeling. iSep connects to the USGS long-term, daily stream flow database through the Internet. A GIS based prototype point source water pollution assessment model was developed and integrated with L-THIA. The integrated L-THIA/NPS-PS model can be used to assess stream flow quality and quantity for past, current, and future alternate land use conditions in a watershed. The enhanced L-THIA model provides important new insight into the relative magnitudes of point and nonpoint sources of pollution at different watershed scales. The integrated watershed assessment approach developed here will be helpful in targeting sensitive areas for effective management efforts, and for site suitability analysis in locating new point source discharge facilities.