The influence of groundwater seepage on morphological changes in the intertidal zone in a macrotidal environment
Topics:
Keywords: Macrotidal beach, groundwater dynamics, coastal geomorphology
Abstract Type: Paper Abstract
Authors:
Jinsu Bae, University of Alabama
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Abstract
Beaches are one of the most dynamic landforms, allowing the observation of morphological change on a short temporal scale. Among various factors influencing sediment transport along beaches, groundwater dynamics have been relatively neglected. Therefore, investigating the influence of groundwater dynamics is essential for the further understanding of processes that induce the geomorphic change of beaches.
The study area is Hakampo beach, located on the west coast of South Korea where the average tidal range is about 4.6m. Groundwater level was measured using a water level meter at one point on beach, one on dune, and one on backswamp. Digital elevation model was reconstructed from a terrestrial LiDAR survey. Data were analyzed to produce groundwater seepage flow and volumetric change of beach profile. Ordinary least square (OLS) and Geographically weighted regression (GWR) were conducted to examine how much groundwater seepage induces volumetric changes.
The results suggest that volumetric changes are dependent on the amount of groundwater seepage. Significant erosion occurred during spring tide while insignificant change was observed during neap tide. Volumetric changes are also spatially correlated to the groundwater seepage flow, which is enhanced along tidal channels where most seepage flows are concentrated. Because most seepage occurs along lines where the slope abruptly changes, it serves a critical role in producing a concave profile with abrupt slope change observed in macrotidal environments. Since beach slope affects sediment distribution during swash and backwash, this study could be further applied to examine beach morphologic change under the effect of swash and backwash.
The influence of groundwater seepage on morphological changes in the intertidal zone in a macrotidal environment
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Paper Abstract