Assessment of Groundwater Potential and Its Potability in Sukhatal Area,Nainital, Uttaranchal Estimated Using Electrical Resistivity Techniques

摘要

Nainital hill resort faces acute shortage of groundwater in peak period of tourist season. In search of an alternative reservoir for fresh groundwater, geophysical survey was conducted in Sukhatal depression which remains dry throughout the summer, acts as seasonal lake and is situated slightly on higher elevation than Nainital town in Nainital district, Uttaranchal. The objective of the survey was to configure the fresh and potable groundwater aquifer. Resistivity survey depicted a zone 30 to 55 m thick having resistivity of 50-125 Ohm-m of saturated sand layer which was interpreted as fresh water zone lying at depth of 4-8 m bgl. The lateral extent of the aquifer was 200 m in east-west and 50 m in north-south direction. Assuming the formation resistivity factor for medium to clean sand to be between 3 and 3.5, it was estimated that the amount of total dissolved solid (TDS) in that aquifer may be very less and of the order of 100-180 mg/1 NaCl equivalent which is well within the permissible limit as per the standards of World Health Organization (WHO). A drill hole was recommended in the middle of the area where the aquifer thickness was found to be maximum. It has been reported that substantial amount of potable water is being extracted through the tubewell from Sukhatal.