Geology topics

Kiki Patsch

Publications and source records attributed to Kiki Patsch.

2 recordsLinked to original sources

USGS2014

The potential for sea-level-rise-induced barrier island loss: Insights from the Chandeleur Islands, Louisiana, USA

As sea level rises and hurricanes become more intense, barrier islands around the world become increasingly vulnerable to conversion from self-sustaining migrating landforms to submerging or subaqueous sand bodies. To explore the mechanism by which such state changes occur and to assess the factors leading to island disintegration, we develop a suite of numerical simulations for the Chandeleur Islands in Louisiana, U.S.A., which appear to be on the verge of this transition. Our results suggest that the Chandeleurs are likely poised to change state, leading to their demise, within decades depending on future storm history. Contributing factors include high rates of relative sea level rise, limited sediment supply, muddy substrate, current island position relative to former Mississippi River distributary channels, and the effects of changes in island morphology on sediment transport pathways. Although deltaic barrier islands are most sensitive to disintegration because of their muddy substrate, the importance of relative sea level rise rate in determining the timing of threshold crossing suggests that the conceptual models for deltaic barrier island formation and disintegration may apply more broadly in the future.

Louisiana, Mississippi↗

USGS2012

Barriers on the brink? The complex intertwined roles of geologic framework, sediment availability and sea-level rise in island evolution

Sensitivity experiments in the North Carolina Outer Banks (OBX) have previously revealed that substrate sand proportion, followed by substrate slope, sea-level rise rate and sediment-loss rate are the most important factors in determining how barrier islands respond to sea-level rise. High sediment-loss rates and low substrate sand proportions cause barriers to be smaller and more deeply incised. Thus, as sea level rise rates increase, more deeply incised barriers do not need to migrate as far landward as larger, less-incised barriers to liberate sand from the shoreface. However, if the combination of sand losses and substrate sand proportions requires a barrier to migrate landward faster than the shoreface can erode to replenish losses, a barrier will change state and begin to disintegrate. Because the substrate of the OBXis sand-rich, these barriers are likely to persist in the near-term. In contrast, model simulations for the Chandeleur Islands, Louisiana suggest sediment loss rates are too high and/or substrate sand proportions are too low to be matched by liberation of shoreface sand. These simulations further suggest that a state change, from a landward-migrating barrier system to a subaqueous shoal complex, is either already underway or imminent.

Conference Paper↗