U. Karmegam

Study on the hydrogeochemical characteristics in groundwater, post- and pre-tsunami scenario,from Portnova to Pumpuhar, southeast coast of India

Natural hazards cause great damage to humankind and the surrounding ecosystem. They can cast certain indelible changes on the natural system. One such tsunami event occurred on 26 December 2004 and caused serious damage to the environment, including deterioration of groundwater quality. This study addresses the groundwater quality variation before and after the tsunami from Pumpuhar to Portnova in Tamil Nadu coast using geochemical methods. As a part of a separate Ph.D. study on the salinity of groundwater from Pondicherry to Velankanni, water quality of this region was studied with the collection of samples during November 2004, which indicated that shallow aquifers were not contaminated by sea water in certain locations. These locations were targeted for post-tsunami sample collection during the months of January, March and August 2005 from shallow aquifers. Significant physical mixing (confirmed with mixing models) within the aquifer occurred during January 2005, followed by precipitation of salts in March and complete leaching and dissolution of these salts in the post-monsoon season of August. As a result, maximum impact of tsunami water was observed in August after the onset of monsoon. Tsunami water inundated inland water bodies and topographic lows where it remained stagnant, especially in the near-shore regions. Maximum tsunami inundation occurred along the fluvial distributary channels, and it was accelerated by topography to a certain extent where the southern part of the study area has a gentler bathymetry than the north.

Study on the Significance of Temporal Ion Chemistry in Groundwater of Dindigul District, Tamilnadu, India

The demand of water supply is increasing day by day to meet the pace of developments in domestic, agricultural and industrial sectors especially in developing countries like India. Groundwater being a scarce commodity in a hard rock terrain like Dindigul district an attempt has been made in this study brings out the significance of temporal ion chemistry in groundwater by collecting groundwater from 43 different location of the district and analysed for major and minor ions. These ions were then used for the irrigation classification of groundwater and to bring out the mechanisms responsible of the water chemistry of the region during different seasons.

A Comparative Study on the Arsenic Levels in Groundwaters of Gangetic Alluvium and Coastal Aquifers in India

Arsenic contaminated groundwater causes danger to the health of millions of people in India. In this context, a comparative study has been made to evaluate the Arsenic (As) concentration in groundwater of Gangetic alluvium, West Bengal and south eastern coastal aquifer at Kalpakkam, India. The variations of Ar concentration with lithologies, depth of aquifers, sources and distribution of Ar and hydrochemical facies of groundwater has been clearly identified from the two localities. In Gangetic alluvium, As concentrations appear to be mostly low in groundwater from deep aquifers and it is interesting to note that in almost all the formations of coastal aquifer, the concentration increases with increase of depth. The shallow ground water of the southern coastal aquifer reveals the presence of oxidizing conditions and frequently flushing during the monsoonal period, which may also dilute or reduce the concentrations. The poor relationship between As and Fe indicates the As release into the groundwater depends on several processes such as mineral weathering, O2 consumption, and NO3 reduction and is de-coupled from Fe cycling.