ARSENIC VULNERABILITY ASSESSMENT AND MAPPING

Abstract

Groundwater arsenic vulnerability assessment is an important aspect of determining the risk to groundwater contamination and for developing management options to preserve the quality of groundwater resources. Contamination has been found in Argentina, Mexico, Chile, Bangladesh and India. Central ground water board investigated and revealed that West Bengal, Uttar Pradesh, Assam, Bihar, Chhattisgarh, Manipur are being affected by arsenic contamination. Also, the surface water sources are more amenable to pollution, it has become necessary to use groundwater at an increasing rate. As there is no proof regarding natural emission of arsenic in groundwater and yet to be established hence this study aims to provide a spatial and statistical analysis of the prevailing subsurface, hydrochemical parameters and environmental conditions under which groundwater may get polluted due to arsenic for a study area. Usage of secondary data by reviewing and analyzing it, has proved to provide a cost effective way of conducting the correlation studies and helped in portraying the present condition. In the present work, it was envisaged to review the methods currently available for assessment of groundwater vulnerability and quality and to develop the appropriate framework, suitable for this condition using multi criterion decision making model. The arsenic vulnerability index has been developed and mapping has been done using GIS for finding out the vulnerable zones of groundwater contamination in Ballia district of Uttar Pradesh Attempts were made to develop a multipurpose database in GIS environment, and to validate the developed method by comparing its finding against the data for arsenic concentration of the region. The integrated vulnerability map exhibit the high risk imposed on the southern region of the Ballia district due to deep ground water level, low elevation, high silicate concentration and terrace alluvial plain while the elevated western and northern region falls in “Low” vulnerability zone. Higher arsenic concentration in groundwater is observed in the southern and north east region which pertains to moderate to high vulnerability zone and moderate to very high risk zone. Further, a good correlation between INDEX value and Arsenic map has been also observed in the study area. The GIS technique has provided an efficient environment for analyses and handling of large spatial data. The developed groundwater vulnerability and risk map may assist in decision making and future planning of sustainable water resources development.