[A-HW26] Hydrological processes of surface-groundwater interactions

[AHW26-02] Effects of creek topology on salinization of coastal marsh due to storm surges

Shuangshuang Yu¹, Xiaorong Li², Jiaqi Liu³, Philip Brunner⁴, Rongjiang Yao¹, Bing Yuan⁵, Xun Cai⁶, *Xuan Yu¹ (1.State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 2.School of Ocean Sciences, Bangor University, United Kingdom, 3.Department of Environment Systems, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan, 4. Centre for Hydrogeology and Geothermics, University of Neuchâtel, Neuchâtel, Switzerland, 5.Institute of Coastal Systems-Analysis and Modeling, Helmholtz-Zentrum Hereon, Geesthacht, Germany, 6.School of the Environment, Yale University, New Haven, CT, USA)

Keywords:marsh, storm surge, vertical saltwater intrusion, geomorphology, seawater intrusion, coastal resilience

Creek topology, which varies broadly across coastal marshes, affects both surface and subsurface flow and transport. In this study, we employed modeling tools to understand the role of creek networks in salt transport due to storm surges. We developed a stochastical morphodynamic model to represent three typical creek network groups: sparse, intermediate, and dense groups. We then utilized a variable-density, coupled surface-subsurface, flow and salt transport model to simulate a theoretical storm surge overwash event. Our model evaluated salinization of creek, marsh and aquifers. We examined how the presence of creek affect the extent and location of salinization by evaluating differences in salinity of surface waters and the subsurface. The salinization assessment showed that dense creek networks attenuated storm surge inundation and limited the salinization extent. The highest occurrence of opposite creek and groundwater flow directions was found in the sparse group, which delayed the salt flushing. The recovery from salinization varies nonlinearly in creek water, marsh sediments, and aquifers. Our study suggests that creek topology significantly affects the resilience of coastal marshes to saltwater intrusion, with important implications for coastal land management and ecosystem restoration.