Coastal vulnerability assessment for Chennai, east coast of India using geospatial techniques

Abstract

The geochemistry of a coastal aquifer was assessed using statistical and geospatial analysis tools for the pre-monsoon, rainy and post-monsoon seasons. Data were obtained from both the field and laboratory analysis of water samples. Statistical methods such as correlation coefficients, piper plots, factor analysis and mixing index were used to gain insights into the geochemistry, while geospatial tools were used to create contours to understand the spatial distribution of the measured groundwater parameters of the coastal aquifer. The measured groundwater levels ranged from-0.84 to 30.08 m above mean sea level. The Electrical Conductivities and Total Dissolved Solids values were observed to have perfectly correlated with each other. Groundwater salinities were generally high, as over 94% of the water samples tested exceeded the WHO drinking water limit of 750 lS/cm and 500 mg/l, respectively. The groundwater pH was generally slightly alkaline but could be slightly acidic in the rainy season. The Na ? , K ? , Mg 2? , Cl-and SO 4 2-were observed to have high impacts on the geochemistry and also had tendencies to form similar trends. EC, TDS and NaCl values above 1000 mg/l in the groundwater were observed to generally skew towards the ocean during the rainy season. The principal process influencing the geo-chemistry was found to be seawater intrusion, while mineral dissolutions and rainwater percolation play lesser roles. The aquifer predominantly comprises Na-Cl waters of marine origin. The study shows the growing importance and applicability of integrated statistical and geospatial approaches for better understanding of groundwater and geochemistry of aquifers.

Coastal vulnerability assessment of Puducherry coast, India, using the analytical hierarchical process

“…The assignment of vulnerability scores is performed using a 1-4 scale. This is contrary to the practice of using a scale of 1-3 or 1-5 in the case of other vulnerability studies (Rao et al, 2008;Kumar and Kunte, 2012). The choice of this scale is purely based on the opinion of the experts.…”

“…There is a considerable amount of subjectivity involved in the case of categorical classes; however, they can be used as indicators in the case of vulnerability assessment. The quantitative classes have been decided based on the expert judgments, literature information (Rao et al, 2008;Kumar et al, 2010;Kumar and Kunte, 2012) and the spectrum of values of the data set considered specific to the region. All these methodologies of classification depict site-specific relative vulnerability thresholds and thus are appropriate for regions with similar environmental conditions.…”

“…The vulnerability to multiple hazard scenarios along the coast of Cuddalore-Villupuram was assessed by Mahendra et al (2011) by incorporating storm surge parameters along with other physical factors. Kumar et al (2012) did a vulnerability assessment of the Chennai coast using geo-spatial technologies. In a majority of these studies the CVI is expressed as the square root of the product of the ranking factors divided by the number of parameters considered (Thieler and Hammer-Klose, 2000).…”

“…The rationale behind using this value is that this estimate is consistent with the global estimate reported in the Third assessment report of IPCC (Unnikrishnan and Shankar, 2007). In their paper Kumar and Kunte (2012) assigned this value as a medium vulnerability class for their study area of Chennai. As the scoring in our case varies between 1-4, we have classified it as a high vulnerability class with a ranking of 3.…”

Assessment of Coastal Vulnerability to combined effects of Socio-Economical Factors and Erosion on Karnataka Coast with the aid of Integrated Remote Sensing and GIS Techniques

“…December 2004 tsunami has brought the importance for scientific study of the natural hazards and coastal processes of the Indian coast [13]. Vulnerabilities associated with the various coastal states of India are being studied in recent times using afore mentioned approaches [9,6,11,21,29,18,13,12,14].…”