Signature of Sinking Streams on Calcarenite Rock Study Using Geophysical and Geochemical Investigation in Ayankulam Area, South Tamilnadu, India

Abstract

Ayankulam is the trending one recently during the 2021 monsoon of India. Despite a large supply of water from the Nambiar canal for five days, the village's fabled well was unable to fill. When the district collector and IIT team came, they assessed the community and noted that the wells' geological makeup was classified as a karst formation (as per e-news sited in The New Indian Express dated 03/12/2021). There might be some sinking stream that might link this well. Karst topography of calcarenite rocks is the reason for groundwater movement beneath the subsurface for not filling the well. One of the most crucial elements of nature's water supplies is groundwater. Groundwater has to be explored more thoroughly since demand for it rises as the population grows. To determine the existence of usable groundwater for irrigation purposes in the study area Geophysical (Azimuthal square array method and Magnetotelluric method) and Geochemical investigations were done. The Azimuthal Square array method covers 360º coverage of subsurface resulting in fracture orientation of rock to determine the weak/strong zones in different rock types. The Magnetotelluric method scans the subsurface rock and provides information about Geological formation, Weak zone where water oozes out, depth and movement of groundwater. Water samples were collected in and around the “Sinking Stream” origin well and its associated open and tube wells from the study area. The combination of Square Array, MT, Water quality, and quantity study focuses on the Trapped Aquifer system of sinking streams in all water bodies and wells. The movement of groundwater seems to be increasing in Seashore areas such as Uvari and Karikovil are identified relating its water samples from deep bore wells quality and sinking stream water quality. The heavy rainfall and hydrostatic pressure of predominant rock on eroded Calcarenite lime formation create water “Dry fall out” resulting in Sinking streams in the Ayankulam area.