Seasonal groundwater salinity dynamics in the mangrove supratidal zones based on shallow groundwater salinity and electrical resistivity imaging data

Abstract Soil salinity plays an essential role in the growth of mangroves. Mangroves usually grow intertidal zones. However, Karimunjawa National Park (KNP), Indonesia, mangroves are also found supratidal Thus, this study aims to determine why can zone, even during dry season. We analyze seasonal changes groundwater flow and dynamics using hydraulic head, shallow salinity, electrical resistivity imaging (ERI) data. The result shows that variation is caused by seawater intrusion, which generated a gradient due sea level being higher than water table KNP. Rainfall evapotranspiration, change seasonally, likely affect fluctuation salt concentration. ERI images indicate intrusion top sediment up bedrock boundary. difference wet seasons remarkable occurs at deeper layer (50–60 m below ground (BGL)), freshwater recharge from rainwater on land side. Groundwater KNP saline; thus, e.g., Ceriops tagal Lumnitzera racemosa , because their roots reach groundwater. These mangrove species still zone though very saline (46–50 ppt). condition might cause these stunted. availability crucial for dilute high salinity.