Author ORCID Identifier

https://orcid.org/0000-0002-3773-1259

Semester

Spring

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Omar I. Abdul-Aziz

Committee Co-Chair

Omar I. Abdul-Aziz

Committee Member

P.V. Vijay

Committee Member

Radhey Sharma

Abstract

Stormwater runoff is widely considered a significant factor in coastal inundation and water quality degradation. The main objective of this thesis is to determine the potential impacts on stormwater runoff in lowly urbanized coastal/subcoastal environments under a changing climate and land use/cover. The East Fork San Jacinto River Basin (Area = 2577 of southern Texas, USA was considered a pilot area for this study. Given the sparse availability of high-resolution precipitation data in space and time, this research first evaluated four remotely sensed and/or reconstructed precipitation products (CMORPH-CDR, MERRA, PERSIANN-CDR, and PRISM) by comparing the data with the historical gauge observations during 2004-2013. A mechanistic hydrologic model was then developed with the appropriate input data to predict stormwater runoff in the lowly urbanized subcoastal basin. A full factorial design of 27 climate and land cover change scenarios was constructed by incorporating the projections from 18 General Circulation Models and ICLUS percent imperviousness to quantify the potential range of storm runoff changes by 2050s (2043-2052) and 2080s (2073-2082). The results suggested a complete lack of skill with the precipitation products to reproduce the historical hourly observations at the gauge locations. Only MERRA and CMORPH exhibited some (albeit low) skill in reproducing the daily precipitation with a coefficient of determination ( ) of 0.34 to 0.39 and a root-mean-squared error (RMSE) of 6 to 6.5 mm. Based on the findings, the stormwater model was run with the available observations of gauge precipitation during 2013-2022 (termed 2020s) and was calibrated/validated with the daily streamflow records for the same period. The outcomes emphasizes that precipitation serves as the primary driver, while land use remains a significant contributing factor in the generation of runoff within sparsely urbanized subcoastal environments, with actual evapotranspiration contributing the least. The climate and land cover change scenarios indicated a potential increase of 19 to 46% (on average 32.5%) in annual runoff in the lowly urbanized subcoastal basin by 2050s-80s, compared to that of 2020s. Notably, the monthly runoff increases were in a comparable range, suggesting that variations in future changes would be minimal across the year in these environments. Furthermore, scenarios closely aligned with the Representative Concentration Pathway (RCP) 4.5 (moderate emissions) suggested annual runoff increases of 27 to 40% by 2050s-80s. In contrast, scenarios comparable to RCP 8.5 (high emissions) suggested annual runoff increases of 25% by 2050s and 34% by 2080s. The research would aid water resources engineers, managers, and policymakers in effective stormwater management and ecosystem conservation in lowly urbanized subcoastal/coastal environment.

Embargo Reason

Publication Pending

Available for download on Thursday, April 24, 2025

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