Effects of Low Tide Rainfall on the Development and Stability of Intertidal Salt Marsh Landscapes

EPA Grant Number: MA916370
Title: Effects of Low Tide Rainfall on the Development and Stability of Intertidal Salt Marsh Landscapes
Investigators: Hunsinger, Glendon B.
Institution: University of South Carolina at Columbia
EPA Project Officer: Zambrana, Jose
Project Period: January 1, 2004 through December 31, 2007
Project Amount: $107,552
RFA: GRO Fellowships for Graduate Environmental Study (2004) RFA Text |  Recipients Lists
Research Category: Fellowship - Environmental Science , Academic Fellowships , Ecological Indicators/Assessment/Restoration


Rainfall-driven cycling of intertidal salt marsh and mud flat sediment represents a nonpoint source of material that typically is not accounted for in coastal biogeochemical models. This sediment store represents a substantial source of nutrients, organic carbon, and contaminants that may be reintroduced into the water column by low tide rainfall events. Rainfall-entrained sediment is particularly important given that tidal and shallow water wave currents do not produce the shear stress needed to initiate cohesive sediment transport. Given that climate changes expected in the southern and eastern United States point to more intense and frequent rainfall, rainfall-driven sediment cycling will have unknown, but potentially vital or deleterious, effects on coastal ocean ecosystems. Indeed, few studies have addressed the erosive capability of low tide rainfall events, despite the potentially large effect on the remobilization of stored sediment. Uncertainty in rainfall effects on sediment cycling also presents an important consideration for the successful representation and management of intertidal zone sediment dynamics, particularly considering ecosystem vulnerability from the cycling of adhered contaminants. The objective of this research is to augment the current understanding of these processes by further expanding and quantifying the cycling of sediment mobilized by low tide rainfall episodes.


The combination of complexities, interrelated process feedbacks, and potential climate variations supports the need for continued advancement in understanding sediment dynamics in the intertidal zone. Using an interdisciplinary approach the research aims to quantify the following questions:

  • What is the frequency and significance of low tide rainfall events?
  • What is the quantity of sediment (and adsorbed particulates) entrained, and what is the geochemistry of this entrained sediment, with a focus on trace metals, organic carbon, and radionuclides?
  • Does the transport, redistribution, and fate of this sediment pose an environmental or ecotoxicological issue?
  • How does this flux change over spatial and temporal scale variations?
  • Can the GeoWEPP numerical model effectively simulate and predict rainfall driven mobilization, redistribution, and fate of low tide rainfall eroded sediment for intertidal marshes, or if not, what code adjustments are necessary?
  • How do/will these issues affect decision making and management of coastal zones?

Because of the interrelated feedbacks that occur in the highly productive and sensitive intertidal zone, it is imperative to both terrestrial and marine processes that we assess rainfall induced sediment flux on a timely and systematic basis.

Supplemental Keywords:

fellowship, intertidal sediment cycling, low tide rainfall, rainfall induced erosion, rainfall kinetic energy, biogeochemical models, coastal environments, sediment dynamics, salt marsh,, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, climate change, Air Pollution Effects, Aquatic Ecosystem, Environmental Monitoring, Atmosphere, coastal ecosystem, precipitation, ecosystem monitoring, sediment organic matter, biogeochemcial cycling, coastal environments, aquatic ecosystems, marsh ecosystem, biological indicators, sediment dynamics, ecosystem response

Relevant Websites:

2004 STAR Graduate Fellowship Conference Poster (PDF, 1p., 97.7KB, about PDF)

Progress and Final Reports:

  • 2004
  • 2005
  • 2006
  • Final