A process-based impact of tropical cyclone and hurricane on surface water-groundwater interaction and contaminant mobilization of coastal aquifers

Abstract

Coastal aquifers are hydraulically connected to the sea and a storm (cyclone/hurricane) can disrupt the surface water-groundwater (SW-GW) interaction process which is largely unexplored. Thus, this study aims to explore the impact of storm surges (both positive and negative) on coastal aquifers, focusing on pollutant mobilization, groundwater level (GWL) fluctuations, and solute concentration (Salinity, Cl^-) and subsequent re-stabilization based on pre-existing studies from the coast of USA and India through a systematic review process. The outcome of this study revealed that there is a positive relationship between cyclonic speed, rainfall, storm surge height and GWL in lithologically conductive aquifers. Positive surge raises GWL, salinity and transportation of surface contaminants into groundwater while negative surge induces fall in salinity, and accelerates submarine groundwater discharge and exports contaminants/nutrients to sea. The restabilization of SW-GW interaction dynamics is case dependent, which takes a week to month to years, and is dependent on local hydrogeology and intensity of storm. So, the study recommends prioritizing to safeguard the coastal groundwater otherwise increasing storms will lead to questions on freshwater sustainability and coastal ecosystems in present climate change scenario.