Modeling hydrological response to potential climate change and urbanization in the Kishwaukee River Basin (Illinois, Wisconsin)

This is a comprehensive study of basin hydrology under potential climate change and urbanization in the Kishwaukee River Basin (KRB) in Illinois and Wisconsin, USA. The Hydrologic Simulation Program - FORTRAN (HSPF) was applied for the KRB after being calibration. The calibrated HSPF model was run first with urbanization scenarios generated by a dynamic urban growth model (LEAMluc) and hypothetical urbanization scenarios to investigate the basin response to future urbanization. The results show that the urbanization scenarios generated by LEAMluc result in little changes in total runoff, but some noticeable changes (+38.5%) in the surface flow under the Uber scenario, which is associated with very high population growth. They also show that runoff is predicted to increase linearly with increasing imperviousness level. The climate scenarios were generated based on climate simulations by a transient general circulation model (HadCM3) under A2 and B2 greenhouse gas emission scenarios. The potential climate changes simulated by HadCM3 are found to be much more influential to the streamflow in the KRB than the urbanization simulated by LEAMluc. The runoff of the KRB is predicted to decrease under both climate scenarios in this study, and Q95 flow is predicted to decrease more remarkably than mean runoff. However, the interactions of climate change and urbanization have not been confirmed. The impacts of both climate change and urbanization are almost identical to the linear sum of separate impacts of climate change and urbanization, based on the analysis of the changes in annual and seasonal runoff. This dissertation has demonstrated the importance of considering the factors in different scales simultaneously in assessing the human impacts on physical systems, and has identified some features of the dynamics of basin hydrology in response to continuing increase in imperviousness. It also identifies the need to consider the interactions of the atmospheric and land surface processes in scenario development.