Catchment scale effects of low impact development implementation scenarios at different urbanization densities

Abstract

• The study quantified the increase of catchment runoff induced by urbanization and climate change using the SWMM model. • The study quantified the impact of different implementation strategies of low impact development (LID) on runoff mitigation. • The most sensitive parameter of SWMM catchment model were the baseflow of drainage pipes, the depression storage of pervious areas and the hydraulic conductivity. • Intense urbanization scenario (90%) resulted in increased peak drainage discharge of 100% and the total volume outflow by 20%. • Implementing LID measures at the downstream subcatchments achieved the highest peak and flooding reduction at the catchment’s outlet, while placing LID measures at the upper parts of the catchment reduces flooding at downstream manholes. Climate change and urbanization put stress on urban stormwater systems, triggering hydraulic overloading and urban flooding increase. Low Impact Development (LID) techniques have a high potential to mitigate their impacts. This study investigates the consequences of climate change and urbanization on the urban runoff in the Risvollan catchment in Trondheim, Norway, and the effects of LID implementation and the influence of LID spatial distributions on their performance. A SWMM model of Risvollan was implemented, along with different scenarios of urbanization and climate change. The performance of various spatial distributions of LID infrastructures in the catchment was investigated, using the outflow volume and the peak runoff at the outfall as indicators. The rainfall event-based simulation results confirmed the negative effects of urbanization and climate change on urban runoff. These effects were partially mitigated by a homogenous LID implementation. The different spatial distributions of LID had little impact on volume reduction but targeting the most downstream zones of the model was more efficient in reducing the peaks at the catchment’s outlet. These findings confirm that the spatial configuration of LID might be a determinant parameter towards an efficient design of LID infrastructure in urban settings, depending on the local stakes and criteria of urban water management.