Development Of A GIS-Based Watershed Modeling Tool

Abstract

A GIS-based numerical tool makes watershed and water quality studies easier by bringing key data and analytical components under one GIS roof. Using the familiar Windows environment, analysts can efficiently access international and national environmental information, apply assessment and planning tools, and run a variety of proven, robust point and non-point loading and water quality models. With many of necessary components together in one system, the analysis time is significantly reduced, a greater variety of questions can be answered, and data and management needs can be more efficiently identified. Minimal data requirements and an ease of application are a motivation to develop a new simpler GIS-based watershed modeling tool, particularly for developing countries where there are a lack of temporal and spatial series of data. An objective of this study is to develop such GIS-based numerical tool for assessment of water balance and runoff pollutions caused by point and non-point sources in watershed systems. The core of the model is based on Generalized Watershed Loading Functions with a number of additions and enhancements of runoff, sediment and daily time step calculations. The model is programming in VB.NET, and designed to complement and interoperate with enterprise and full-featured MapWindow open source GIS. It has two components: a runoff component included water balance and nutrient load modules, and a routing component engaged with HEC-RAS model. All components are merging under GIS MapWindow functions as plug-ins. The model has been verified and validated for the Spring Creek watershed (Pennsylvania) and the Tri-An watershed (Vietnam). A comparison between the results obtained from the model and observations, as well as with results from a well-known AVGWLF shows very good agreements. This watershed modeling tool can be served as a multipurpose environmental analysis system in performing watershed- and water-quality-based studies