Identify less affected urban wetland areas by stormwater flooding, at parliament lake upper catchment; special reference to the proposed site for bird park wetland-Madiwela

Abstract

Stormwater flooding is a catastrophic disaster in urban contexts and high densification by urban population is a catalyst for these occasions. When considering the Sri Lankan context, urban agglomeration due to infrastructure development and other living standards in the urban contexts attracts people towards the cities. The wetland selected in this study which is located within the Parliament Lake catchment – Sri Lanka, has a high flood retention sensitivity; thus, less contribution to the urban flooding. This study focusses on the wise use of the selected wetland by providing recreational facilities to the urban community. Aim of this study is to develop a feasible masterplan for the selected urban wetland without affecting on the current retention capacities. this is achieved by identification of the controlling factors for hazardous events and topographical data of the site. Further, by identification of the fluctuations of flood levels occurred by elevation changes, using the simulations done by the hydraulic model, utilizing and already developed HEC-RAS model to develop a flood inundation map for the area. The study identified that the wise use of the wetlands can be utilized while considering the wellbeing of the urban community in environmental, socio-economic areas by maintaining the existing situation of the wetland. And this sustainable use of wetland will decrease the vulnerability to hazardous events and the complexities made around un-planned development. Further, this study implies the strong need to follow-up the regulations related to land development in urban wetlands with considering the social, environmental and hydrologically feasible scenarios.