Subsidence and Sea Level Rise Study


Many severe hurricane-induced urban floods occurred in coastal communities in the recent decades (Harvey (2017), Isaac (2012), Ike (2008), Gustav (2008), Katrina (2005), Rita (2005), and Ivan (2004) etc.). The latest flood caused by Hurricane Harvey (2017) in the Houston-Galveston region (HGR) was regarded as one of the costliest disasters in the U.S. history, with damage exceeding $100 billion. Unfortunately, other than being vulnerable to natural hazards like hurricanes, many coastal cities also experience significant land subsidence (LS) and sea level rise (SLR) which exacerbate the urban floods. Traditional hydrologic and hydraulic modeling approaches often neglect the impacts of LS and SLR. Many previous studies have indicated the significance of the impacts imposed by LS and SLR to coastal communities, but incorporating both factors into flood inundation modeling and sustainable and resilient planning is still a challenge. Since the current SLR is primarily due to human activities and LS is owing to subsurface movement of earth materials, SLR and LS are two interrelated geo-environmental hazards which have rarely been considered in the existing urban flooding simulation in conjunction with extreme events. Thus, the PI and Co-PIs are motivated to establish the first and innovative methodology to understand and identify urban flood exacerbated by the contributing impacts from LS and SLR by achieving the following five objectives: I. To bridge fundamental gaps among the LS and SLR projection models, and the hydrologic and hydraulic simulation mechanisms (HHSMs) for urban flood modeling; II. To build corresponding HHSMs from 1992 to 2017 through modifications of topography along with the projected LS and SLR and calibrations for selected historical hurricane events (SHHEs); III. To identify the baseline flood conditions without considering any contribution from LS and SLR for each SHHE; IV. To quantify individual flood impact only due to LS and SLR, respectively, for each SHHE; V. To evaluate the combined flood impacts from LS and SLR for each SHHE. The Houston-Galveston region (HGR) with LS and SLR will be selected as the testbed for the proposed project. Given the facts that the HGR, a historical LS zone, has subsided up to 10 ft. since 1940s and that SLR is projected to rise another 1 to 4 ft. by 2100 by IPCC, it is very imperative for us to understand the contributing impacts from interconnected LS and SLR on urban floods.