Impacts of Changing Climate and Environment on the Stormwater Runoff in the Kissimmee River Basin, Florida

Abstract:

Changes in climate and land use/cover can cause great impacts on the hydrologic processes, especially on stormwater runoff generation. Considering the Kissimmee River Basin of Florida as an example of complex inland urban-natural basins, we quantified reference sensitivities of stormwater runoff to plausible scenarios of climatic and land use/cover changes by developing a large-scale, dynamic rainfall runoff model with EPA Storm Water Management Model (SWMM 5.1). Reference changes in basin rainfall, evapotranspiration, imperviousness, roughness and land use types resulted in substantial changes of total stormwater budget. Potential storm runoff in the coupled urban-natural basin exhibited high and notably different seasonal sensitivities to rainfall. The total basin runoff was highly sensitive to the basin imperviousness and roughness, while showing moderate sensitivities to the water storage capacity of pervious areas and soil hydraulic conductivity. The changes in runoff under simultaneous hydro-climatic or climate-land use perturbations were notably different than the summations of their individual contributions. The developed model was used to estimate the potential stormwater budget of the Kissimmee River Basin in 2050s using downscaled GCM-RCM climate projections and anticipated land use/cover scenarios. A significant change in basin runoff was noted by 2050s due to changing rainfall regimes and continuing urbanization. Our findings can be useful in managing stormwater runoff in the Kissimmee and similar complex urban-natural basins around the world.