A GIS-Based Simulation Application to Model Surface Runoff Level in Urban Blocks

Abstract

Simulation of flood inundation in urban areas longer important, given the magnitude of potential loss and disruption associated with non-river based, urban flooding. The complexity of the urban environment and lack of high-resolution topographic and hydrologic data compromise the development and implementation of models. Low impact development (LID) is technical know-how on a collection of sustainable practices that mimic natural hydrological functions including infiltration, evapotranspiration or use of surface runoff. Several studies have been carried out to discuss the impact of urbanization scenarios in reducing the urban flood risk in watershed scale in Sri Lanka. Yet, there is a gap remains in simulating the effectiveness of LID-based planning practices to reduce flood risk with the complex built form scenarios. In such a situation, this study attempts to make a significant contribution to simulate the variations of flood regulation functions under different high-intensive urban development scenarios, particularly focusing on the urban metropolitan regions. The analyses were carried out utilizing SWMM (Storm Water Management Model) which is open-source flood inundation simulation approach with the help of GIS in a more qualitative manner. The simulation results indicate that expanding built form scenarios increase the flood venerability for city functions, increasing inundation duration and LID scenarios able to reduce the surface runoff to reduce flood vulnerability at a significant level. The simulation results had been verified with the real ground situation (mean percentage change < 15.5%) which able to capture the thresholds of built form variation, as well as dynamic land uses and infrastructure supply which can be used as a tool for future planning practices and decision-making.

Patch Isolation Analysis of Peri-Urban Natural Ecosystem; The Case of Bahirawakanda Terrain, Kandy, Sri Lanka

“…However, in some of the urban areas, these ecological clusters are becoming more and more isolated, less dense and declining in size due effects from transit network developments and legal and illegal encroachments due to property developments (Ranaweera et al, 2021). These threats are global and will lead to problems in urban terrain ecosystem Biodiversity, environmental condition and urban microclimate (Wijayawardana et al, 2020).Of these urban areas, peri-urban areas are the most vulnerable as they still retain significant ecosystems which face development pressure.…”