Abstract:
With rapid urbanization, uncontrolled storm water runoff is one of the major problems facing urban areas at the present. Therefore, it can be seen as inducing flash flood events and water quality degradation in urban areas. In the Sri Lankan context, this same problem can be seen in urban areas. One of the issues facing urban areas is inadequate storm water drainage systems and limited space. At present, most urban areas have broadly used Green Infrastructure (GI) to reduce this situation in developing countries as an innovative and sustainable SWM approach. This Research is basically focused to examine the capability of reducing the impact of surface runoff using GI considering before- after situations (2005, 2021) in Diyatha Uyana and its surrounding as a case study area. When examining the research question, is explained the result with runoff retention index, runoff volume per watershed (m3), and runoff retention volume per pixel (m3) of the study area. Under various rainfall depths can be seen as a high retention index rather than before-situation of Diyatha Uyan
