GIS application for assessment of low-impact development effects on stormwater runoff

Abstract

The growing urbanization is typically associated with increasing stormwater runoff and non point source pollution. Low Impact Development (LID) is extended as a new approach for stormwater management. LID components are utilized as supplementary devices besides conventional drainage system in urban areas to decrease the runoff and remove the non point source (NPS) pollution from the stormwater. In the previous studies, various hydrologic models are driven to calculate the volume of stormwater and NPS pollution. In addition, some prior literatures discussed the LID effects on the quality and quantity of stormwater runoff but most of those researches are restricted to LID site design and LID landscape. In this project, a fuzzy GIS model based on the LID site design criteria and hydrology principles introduced to find the suitable areas for LID components in the study area. To evaluate the accuracy of GIS fuzzy technique, a dynamic rainfall-runoff simulation model (SWMM) is exploited to derive the peak flows of conventional drainage system. The comparison between the results of two models, illustrates the accuracy of fuzzy criteria and their weights. Also, analyses are performed to calculate the effects of LID on amount of runoff and NPS pollution. A simple GIS model is used to estimate the NPS pollution in the study Area. According to experimental projects, the LID component effects on pollution and amount of runoff are calculated by the removal fraction. The final results show LID is a very effective in removing NPS pollution and runoff stormwater although its capability to absorb runoff in flash flood isn’t very reliable.