Development of Integrated Geomorphological and Hydrological GIS Platform for Prospective Dam Site Analysis

Abstract

Constructing new reservoirs to ensure a reliable water supply in downstream areas and to alleviate overflow flooding along rivers during floods is an urgent task for the authorities. In this study, we developed a GIS platform that integrates a series of watershed geomorphological and hydrological models to assess the suitability of prospective dam sites. The built-in modules include watershed geomorphological analysis, rainfall analysis, flow analysis, surplus water analysis, and reservoir analysis. Using the digital elevation model, users can obtain the reservoir H-A-V curve at a prospective dam site and the upstream watershed's geomorphological factors. A topography-based hydrological model was used to estimate available water at the dam site, and surplus water was obtained by subtracting existing water demands and/or environmental flow requirements from the available water series. Exceedance probability analysis was then conducted for the surplus water to evaluate the dam site's feasibility for new water resources development. The system also provides a reservoir's useful-life evaluation to determine the time required for sediment accumulation to render the reservoir unable to serve its intended purpose. Moreover, for flood control, the platform includes a built-in module for estimating design discharge for different return periods. The planned Pingxi Reservoir site in New Taipei County, Taiwan, is used as an example in this study. Detailed analytical procedures are presented to demonstrate the use of the proposed integrated GIS platform system to assess the adequacy of prospective dam sites for new water resources development.