Date of Graduation
Statler College of Engineering and Mineral Resources
Civil and Environmental Engineering
Omar I. Abdul-Aziz
Seung Ho Hong
Climatic variability has caused significant shifts in the magnitude, frequency and spatiotemporal distribution of precipitation, generating excessive runoff that leads to frequent occurrences of extreme hydrologic events such as the pluvial (rainfall accumulation) and fluvial (riverine) floods. The conversion of natural areas into urban lands is further exacerbating the rainfall accumulation by increasing surface imperviousness that hinders infiltration of water into the soil. This dissertation predicts and characterizes potential shifts in the future annual stormwater runoff
volumes and runoff extremes under the standalone and coupled changes in climate and land use across inland and coastal urban-natural settings. The research was performed by considering Southwest Florida Basin (28,530 km2) and Kissimmee River Basin (10,686 km2) as the test beds of, respectively, coastal and inland urban-natural environments. Process-based hydrologic models
were developed for these two basins by using the Storm Water Management Model (SWMM) of U.S. Environmental Protection Agency (EPA). The models were calibrated and validated to successfully predict the daily mean streamflow observations (Nash Sutcliffe Efficiency, NSE =0.70 to 0.86) during 2004-2013 (2010s). The models were then employed to investigate runoff
sensitivities to synthetic changes in climatic and land use variables in the two basins. Further, changes in the annual runoff volume, as well as in the extreme runoffs of 1-7 day durations with 2, 5, 10, 25, 50, and 100 year return periods, were computed for the future time-frames of 2050s (2044-2053) and 2080s (2076-2085) based on the climatic projections from 20 Global Circulation Models and land use projections from EPA. Results suggested higher, but comparable changes in
annual stormwater runoff volume under standalone climatic and land use changes in the coastal urban-natural basin. In contrast, the inland urban-natural basin exhibited much higher changes in runoff due to climatic changes than that due to land use changes. Simultaneous changes in climatic and land use variables led to much higher, non-linear changes in annual runoff volume for both basins. The annual runoff volume in the coastal urban-natural basin was projected to increase
by 18 to 62% under climatic changes, 24 to 39% under land use changes, and by 60 to 114% under concurrent climatic and land use changes during 2050s to 2080s, compared to that of the 2010s. The inland urban-natural basin had a comparable projected increase (11 to 30%) in annual runoff volume under land use changes. However, much higher increases in annual runoff volume were
projected in the inland urban-natural basin during 2050s and 2080s under the climatic projections (112 to 189%), as well as under concurrent climatic and land use projections (151 to 211%). The increasing patterns in extreme runoff were qualitatively similar to that of annual runoff volume for the corresponding basins. However, the projected increases in extreme runoff were generally higher than that of the annual runoff. Based on the runoff extremes, the cities of Tampa, St. Petersburgh, Naples, Sarasota, and Orlando were identified as areas of potentially higher pluvial flooding risk and vulnerabilities. The findings and tools of this dissertation would provide scientific understanding, insights, and planning guidelines for stormwater management and flood mitigation in inland and coastal urban-natural basins in tropical and subtropical regions across the world.
Khan, Mahmood, "Stormwater Runoff Response Under Changing Climate and Land uses Across Gradients of Inland and Coastal Urban-Natural Basin" (2022). Graduate Theses, Dissertations, and Problem Reports. 11158.
Available for download on Wednesday, May 01, 2024