Drinking Water Problem in Anathazhchira - A Tank Site in Thiruvananthapuram Midland Belt

摘要

The midland region of Thiruvanathapuram District of Kerala experiences, an acute scarcity of water during summer months. Even though the district receives an average rainfall of 1800 mm in both monsoons, most of the rainwater is going as runoff and it is because of the undulated topography and heterogeneous geological environments. A large tank (15 acres) existing between the valley fills and the laterite hills is the focus of present study. These laterite hills are underlained by tertiary sandstones and clays, which are subjected to laterisation. The deep groundwater levels of 30 m b.g.l are recorded in wells in the laterite-sandstone areas and shallow water table of 5 m b.g.l in the valley fills. An infiltration gallery well (10m dia.) is pumping water from the tank/ chira by Kerala Water Authority through out the year. The infiltration arm of the well is buried 2 m below the ground level from the tank. During summer month, because of the heavy pumping the water level of the tank goes beyond 2 m and hence water could not be supplied to the local public at this tank. Hydrogeological investigations are carried out at the tank site, to assess the subsurface geological features, and to find out the lateral extension of the aquifers in the chira /tank. Specific suggestions are put forth for renovating the tank at Anathazhchira, without disturbing the present Water Supply Scheme and also ways and means to tide over the water scarcity problems of the area.