Impacts of Urbanization, Antecedent Rainfall Events, and Cyclone Trajectory on Extreme Floods at Houston Reservoirs during Hurricane Harvey
Abstract
Flood brought by extreme precipitation is one of the important causes for damages during hurricanes such as Harvey. However, most studies about hurricane floods focused on the precipitation, rather than streamflows. Meanwhile, the influences of both urbanization and antecedent moisture conditions on streamflows during hurricanes require further exploration as research shows that they play important roles in other types of flooding. In addition, hurricane events with the same total precipitation amount but different tracks can lead to different magnitudes of floods for specific watersheds. It is important for policy makers to prepare for future hurricane floods at the watershed scale, where water management is usually carried out. Therefore, the objective of this study is to investigate the effects from urbanization, antecedent rainfall events and the varying cyclone tracks on floods. Specifically, we focused on how these factors influenced the peak elevations and outflows of the two most important detention reservoirs in the Houston region — Addicks and Barker — during hurricane Harvey. The Distributed Hydrology Soil Vegetation Model (DHSVM) was used to simulate the inflow, reservoir elevation and outflow of the two reservoirs under multiple scenarios. MetStorm analyses, along with a suite of synthetic rainfall values from a variety of trajectories, were adopted to represent the truth and maximum possible rainfall during the Hurricane Harvey period, while Stage IV Radar precipitation data was used for the remainder of the simulation period. Results showed that: 1) Urbanization did not lead to a significant difference in the inflows into Addicks and Barker reservoirs during Harvey, given the amount of rainfall; 2) the antecedent rainfall event which occurred about two weeks before Harvey enhanced the flood peak and total flow volume during the hurricane; 3) the accumulative inflows into the two reservoirs could have been significantly larger than they were — thus increasing the peak reservoir elevations — if the cyclone had followed a track consistent with earlier forecasts, all else being equal.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC11B..07L
- Keywords:
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- 1622 Earth system modeling;
- GLOBAL CHANGE;
- 1655 Water cycles;
- GLOBAL CHANGE;
- 1812 Drought;
- HYDROLOGY;
- 1821 Floods;
- HYDROLOGY