ABSTRACT
ABSTRACT: Arsenic beyond permissible limit from tube-well water has been reported from Yamuna sub-basin, which was initially giving potable water. Locating safe water tube-wells using MODFLOW software can give long-term remedy. Hydrostratigraphy of the study domain is conceptualized up to a depth of 140 m and three principal sediment groups were defined viz., Clay, Sand, and Sand and Gravel. This study indicates that the arsenic concentration in sediment and groundwater does not reveal depth-wise trend. Deviation Factor (DF) indicates irregular trend of concentration levels in sediment as well groundwater depth-wise. Statements on acquisition of arsenic free groundwater are site-specific. These necessitate modeling based decision making for safe well location. Secondly, all the DF values are negative, which means that arsenic in sediments is depleted with respect to their world average values. To locate safe drinking water wells in the Yamuna sub-basin, the modeler should incorporate depth specified hydro-stratigraphy and field constraints. This will be followed by calibration of other hydrological parameters to simulate observed arsenic spreading responsible for its sporadic nature.
