GIS-based watershed and water quality model (runoff model)

     Typical techniques for determining the extent and magnitude of point and non-point source pollution problems include long-term surface water monitoring and computer-based simulation. Due to the time and expense associated with surface water monitoring, however, computer simulations have been relied upon more frequently to provide needed information for the development and implementation of point and non-point source control programs. A numerical model is conceived as a system for supporting the development of Total Maximum Daily Loads (TMDLs). Developing TMDLs requires a watershed-based approach that integrates both point and non-point sources. An assessment of point and non-point sources is a multipurpose environmental analysis system for use by national, provincial, regional and local authorities/agencies in performing watershed and water quality studies.

     Watershed and water quality models are commonly considered an essential tool for evaluating the sources and controls of sediment, nutrient and pathogen loading to surface waters. Such models provide a framework for integrating the data that describe the processes and land-surface characteristics that determine pollutant loads transported to nearby water bodies. The utilization of watershed models, however, is a difficult, tedious task because of the broad spatial and temporal scales that must be considered, as well as the large amount of data that must be compiled, integrated, analyzed and interpreted. GIS (Geographic Information System) technology provides the means for processing, and presenting spatially-referenced model input and output data. Through the use of GIS, the numerical model has the flexibility to display and integrate a wide range of information (e.g., land use, point source discharges, water supply and withdrawals) at a scale chosen by the user. The model will be working under the GIS umbrella, allows users to quickly evaluate selected areas, organize information, and display results.

     The numerical model will take advantage of recent developments in open source software, data management technologies, and computer capabilities to provide the user with a fully comprehensive watershed management tool. The model is designed to facilitate scenarios of Climate Change. The core of the model is based on Generalized Watershed Loading Functions (GWLF) and designed to complement and interoperate with enterprise and full-featured open source MapWindow GIS (www.mapwindow.org). The goal of this development is to provide a GIS-based watershed and water quality tool, which is suitable for Asian conditions (weather, landuses, soils, etc.).

An application for Tri An region in Vietnam