Analyzing the influence of compound events on flooding in the downstream reach of the Houston Ship Channel

Abstract

Flooding is one of the most frequent and terrible natural disasters. For the coastal areas connecting inland with the open sea, the occurrence of flooding could be caused by high flows from inland rivers or high-water levels at open sea (e.g., from tsunamis or storm surge). There is also one extreme case that high sea level and high inland flow happen simultaneously, which is also known as the compound flood event. If a compound flood event happens, it has the potential to cause huge losses.

The Houston Ship Channel (HSC) is an important passage connecting “Greater Houston” area to the Gulf of Mexico which plays a critical role in the economic development of Texas and even the whole country. However, because of its special location, the HSC area is prone to flooding caused by both storm surge and heavy rainfall, which has been demonstrated by many historical flood events e.g. Tropical Storm Allison (2001), Hurricane Ike (2008) and Hurricane Harvey (2017). In the wake of Hurricane Ike, the Severe Storm Prediction, Education, and Evacuation from Disasters (SSPEED) Center at Rice University proposed to build a storm surge barrier near the downstream of Fred Hartman Bridge for the protection of the industrial facilities along the HSC from storm surges. One of the major questions related to the design of the storm surge barrier is ‘what are the probable boundary conditions associated with compound flood events (i.e., the combination of storm surge and upstream rainfall-runoff) in the Houston Ship Channel?’. Because once the barrier is closed, the upstream flow cannot flow out to the Galveston Bay, there is the potential to cause the flooding behind the barrier when the closure time is long and upstream discharge is large enough. Therefore, in this thesis, it is focused on the exploration of potential combinations of compound floods in the downstream reach of the HSC.