The response of coastal systems to global change is currently not well understood.
To understand current patterns and predict future trends, we establish a geologic record of
coastal change along the Gulf of Mexico coast.
A study examining the natural versus anthropogenic mechanisms of erosion reveals
several sand sources and sinks along the upper Texas coast. It appears that hurricane
washover and offshore sand deposits are minimal sand sinks, while flood-tidal deltas are
areas of significant sand sequestration. Additionally, it appears that damming of rivers has
had only a minimal effect on sedimentation along the upper Texas coast. However, hard
engineering structures placed on the beach have exacerbated erosion due to trapping sand of
that would otherwise be in the longshore transport system.
Coastal sand budgets are derived to put geologic events (such as hurricanes and
erosion) into context. Sand budgets often use engineering assumptions to establish sand
transport within a coastal system. However, a disconnect typically exists between
engineering principles and geologic concepts when quantifying these budgets. Geologic
principles are relied upon to calculate a sand budget and evaluate published sediment
budgets. This reveals that assuming too shallow a depth of closure can result in ~17% error
in the total calculated sediment flux and an error of ~40% of the total longshore transport
flux for the upper Texas coast. This suggests that revised approaches are necessary to
accurately represent sand transport within the coastal zone.
The long-term probability of hurricane impacts in the western Gulf of Mexico is
constructed. For south Texas, an intense hurricane landfall probability of ~.46% is
established for the past ~5,000 years. Based on published studies, this is similar to the
intense hurricane impact probability of ~.39% for the eastern Gulf of Mexico.
Studying the evolution of San Luis Pass provides a unique opportunity to study the
response of accelerated sea-level rise and hurricane impacts on the evolution of a natural
tidal delta system and adjacent Galveston Island. This study reveals an increased sand flux
into San Luis pass tidal delta, and suggests that the erosion along Galveston Island has
more than doubled over historic time relative to geologic time.
| Identifer | oai:union.ndltd.org:RICE/oai:scholarship.rice.edu:1911/62044 |
| Date | January 2010 |
| Creators | Wallace, Davin Johannes |
| Contributors | Anderson, John B. |
| Source Sets | Rice University |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | application/pdf |
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