A B S T R A C TClimate change has affected both water quantity and quality by increased rainfall, runoff, and associated pollutant loading in urban areas. Stormwater Best Management Practices (BMPs) are now being popularly considered for the reduction of increased runoff due to urbanization. Most research has been conducted on the analysis of BMP effectiveness under current conditions. However, there is no extensive literature on BMP effectiveness studies considering climate change. In this study, the effectiveness of BMP, porous pavement in particular, has been assessed under climate change scenarios. Climate change scenarios were generated by trend analysis of the historical rainfall data. The 2-year and 100-year design storms having 24-h durations were determined for three scenarios: current conditions, 2020, and 2050 using frequency analysis. Storm Water Management Model was then calibrated and used to evaluate the impact of climate change and the effect of incorporating porous pavement on runoff. Geographic information system analysis showed that 33.4% of the basin was suitable for the installation of porous pavement. Hydrologic modeling demonstrated that climate change can increase peak flows by as much as 26.9% relative to current condition. Further analysis showed that porous pavement can be effective in reducing the runoff volume and peak flow below current conditions for all scenarios, offsetting negative impact of climate change.

Green roof is a low impact development (LID) practice used to mitigate imperviousness in urban areas and to reduce flood risks. In order to have sufficient designs and accurate runoff predictions, computer models should be utilized with full understanding of green roofs' hydrologic processes. Evapotranspiration is usually considered important by researchers in the water balance modeling of a green roof. The Storm Water Management Model (SWMM) version 5.1 is widely utilized rainfall-runoff modeling software which has LID controls capable of modeling green roofs. A previous study has evaluated the performance of this model in green roof simulations for single events without considering evapotranspiration in its application, but attained negative outcomes. Thus, the objective of this study is to determine the significance of considering evapotranspiration in producing accurate runoff simulations specifically using SWMM 5.1. The results of this study have shown that when evapotranspiration was not considered, simulations failed to agree with observed values, whereas when evapotranspiration was considered, simulated runoff volumes attained a very good fit with the observed runoff volumes proving the significance of evapotranspiration as an important parameter in green roof modeling.

Construction of hydraulic structures often leads to alteration of river dynamics and water quality. Suspended solids entering the upstream of the weir cause adverse effects to the hydroecological system and, therefore, it is necessary to build a modelling system to predict the changes in the river characteristics for proper water quality management. In this study, the discharges and total suspended solids upstream and downstream of the Baekje Weir installed in Geum River, Korea, was modelled using the environmental fluid dynamics code (EFDC) model. The resulting trend of four rainfall events shows that as rainfall increases, the total suspended solids (TSS) concentration increases as well. For the two larger events, at the upstream of the weir, TSS was observed to decrease or remain constant after the rainfall event depending on the lowering of the open gate. At the downstream, TSS supply was controlled by the weir during and after the rainfall event resulting in decline in the TSS concentration. The modelling produced good results for discharge based on %Diff. (4.37-6.35), Nash-Sutcliffe efficiency (NSE) (0.94-0.99) and correlation coefficient (r) (0.97-0.99) values as well as for TSS with acceptable values for %Diff. (12.08-14.11), NSE (0.75-0.81) and r (0.88-0.91), suggesting good applicability of the model for the weir reach of the river in the study site.

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