Modeling urban stormwater management in the town of Dodola based on landuse and climate change using SWMM 5.1

Abstract

This study was conducted in Dodola town, Ethiopia. This study aims to examine the impacts of landuse and climate changes on peak runoff and flooding volumes, and also evaluates the effectiveness of low-impact development using SWMM 5.1. Three decades of landuse landcover were analyzed to assess the performance of the existing drainage system. Furthermore, the effect of climate change on drainage system performance was assessed using the estimated design storms from two global climate models (CanESM2 and HadGEM2-ES). The trend of landuse landcover analysis shows that the town has experienced a significant increase in the impervious surface area ranging from 59.73 % to 86.01 %. In response to urbanization, the trend of peak stormwater showed a continuously increasing trend. The field observations confirm that the landuse change has had a significant impact on the performance of stormwater drainage systems. The study also found that the peak runoff and flooding volume of the study area was increased under separate and combined effects of rainfall intensity variation due to climate change and increased impervious surface area. This finding indicates that existing drainage systems flooded due to discharge exceeding the design capacity and that profit is required when considering the effects of both land-use and climate change scenarios. Three environmentally friendly low-impact development approaches: bio-retention, permeable pavement, and a combination of the two are applied to reduce increased peak stormwater and mitigate flooding problems.