Tidal effects on groundwater dynamics in shallow coastal aquifers—southeast coast of Tamilnadu, India

Tides play a significant role in the coastal environment; the mangroves, back waters, creeks, and the coastal groundwater interface. Tidal range has been calculated by using TIDECAL software. This study attempts to find the relation between water table condition and tides in the shallow coastal aquifers. The study was conducted by selecting 12 open wells along the coast of the southern part of Cuddalore to the northern part of Nagapattinam district of Tamilnadu. Observations were made in situ for water table fluctuation, dissolved oxygen (DO), and electrical conductivity (EC) for 24 h during full moon (FM) and new moon (NM) of every 2 h. The present study shows the relationship between tidal variations with respect to water table fluctuations and helps to understand the behavior of DO and EC. An interpolation technique, inverse distance weighted (IDW) method was used to obtain the spatial distribution map. The temporal and the spatial relationships between water table fluctuation, EC, and DO were also used in order to understand the coastal ecosystem in the natural environment