Longitudinal Patterns in Sediment Type and Quality During Daily Flow
Regimes and Following Natural Hazards In an Urban Estuary
Abstract
Understanding the transport of sediments in urban estuaries and their
effects on water quality and microorganisms is a convergent challenge
that has yet to be addressed especially as a result of natural hazards
that affect the hydrodynamics of estuarine systems. This study provides
a holistic view of the longitudinal nature and character of sediment in
an urban estuary, the Galveston Bay Estuarine System (GBES), under daily
and extreme flow regimes and presents the results of water and sediment
sampling after Hurricane Harvey. The sediment sampling quantified total
suspended sediment (TSS) concentrations, metal concentrations and the
diversity of microbial communities. The results revealed the impact of
the substantial sediment loads that were transported into the GBES in
terms of the sediment grain type, the spatial distribution of trace
metals and the diversity of microbial communities. A measurable shift in
the percentage of silt relative to historical norms was noted in the
GBES after Hurricane Harvey. Not only did sediment metal data confirm
this shift and its ensuing impact on metal concentrations; microbial
data provided ample evidence of the effect of leaks and spills from
wastewater treatment plants, Superfund Sites and industrial runoff on
microbial diversity. The research demonstrates the importance of
understanding longitudinal sediment transport and deposition in
estuarine systems under daily flow regimes, but more critically,
following natural hazard events to ensure sustainability and resilience
of systems such as the GBES that encounter numerous acute and chronic
stresses.