PhD Proposal Defense: Molly Bost

The PhD Proposal Defense of Molly Bost is presented by the Department of Marine Sciences and the Institute of Marine Sciences (IMS). The main location of this event will be in room 222 at IMS in Morehead City, NC. The defense will be streamed live to room 3204 on the 3rd floor of Murray Hall on UNC campus in Chapel Hill, NC. This event will be held on Monday, November 19th from 10:00 to 11:00 AM.

Title: The efficiency of tidal creeks as conduits for sediments between watersheds and estuaries

Abstract: Rivers that discharge into the heads of estuaries are thought to be the primary conduits of sediments and nutrients between uplands and coastal waters along embayed coastal-plain shorelines. Between the bayhead delta and tidal inlet, however, there are many smaller lower-coastal plain rivers (tidal creeks) that discharge into the estuary and their contribution to coastal sediment budgets is unknown. Tidal creeks have small watersheds (<50 km2) that developed on or seaward of the last interglacial shoreline. Tidal-creeks are tidal their entire length, comprised of distinct channel and embayed sections, and discharge into larger estuaries, lagoons, or back-barrier salt marshes. They support important intertidal and shallow subtidal habitats, which rely on sediment deposition to maintain their areal extent with accelerating sea-level rise. This research is aimed at identifying the principle drivers of changes in tidal-creek sediment deposition and accumulation, which is mainly driven by changes in storminess, sediment accommodation, and sediment supply. While coastal watersheds have little relief, area, and flow, they are disproportionately impacted by land-use change (% of watershed area) versus their larger river counterparts because coastal zones are experiencing higher rates of population growth than inland areas. This study will examine the effects of land-use changes in tidal-creek watersheds on sediment accretion rates over the last century. Extracting records of sediment accumulation rates from adjacent intertidal and subtidal environments at the head of tidal-creek embayments and analyzing the two time-series jointly, should differentiate sedimentation from storms and watershed pulses recognized in saltmarsh sediments, from more persistent sedimentation from sea-level rise and local geography recognized in the adjacent creek bottom. Gaining an understanding of how expansion of suburban development and agriculture in these coastal watersheds affected sedimentation in downstream salt-marshes and the adjacent tidal-creek embayment, will improve sedimentation- and erosion-management decisions and predictions of habitat quality and area under future anthropogenic and climate-change scenarios.