Ground water Pollution

Ground water pollution is caused by the diverse activities of people. The major cause is from the agricultural sources. The fertilisers and pesticides mix with the water and percolate down to the aquifer. Toxic bioaccumulation of chemical fertilisers and pesticides in water and soil has a cumulative non-linear adverse effect on water quality, soil productivity and human and animal health, the latter through the food chain.

The ground water in the areas adjoining the industrial areas of Patancheru, Bollarum and Visakhapatnam is moderate to heavily polluted. As some of the industries directly release the effluents on the ground, they percolate down to the earth polluting the ground water.

Study SoundS Warning bells on drinking water sources for City

A study on the impact of urbanisation on catchment areas warned that if the present trend of depletion of inflows continued, Osmansagar and Himayatsagar two of the main drinking water sources for the City, will go defunct in the next 30 to 40 years.

The study by Dr. B.Venkateswara Rao, Associate Professor, Centre for Water Resources, Jawaharlal Nehru Technological University and Mr. N. Srinivasa Rao, analysed 36 years (1961-1996) of rainfall record of the catchment areas and inflows into these two reservoirs. It was found that there has been continuous decrease of inflows, though the rainfall remained more or less normal. The reduction of inflows has been attributed to the tapping of both surface and groundwater in the catchment areas, along with the physiological, morphological, agriculture and land use changes owing to urbanisation of the city.

The study revealed that there was no correlation between rainfall intensities in the catchments and inflows reaching the reservoirs over the past 36 years. They observed three distinct regimes of conservation of rainfall into inflows - 1961-73, 1973-83, 1983-96 for Osmansagar and 1961-73, 1973-84, 1984-96 for Himayatsagar. In the case of Osmansagar, the percentage of conversion has decreased from 12.1 in the first region to 6.9 in the last one. As for Himayatsagar, it reduced from 8 to four percent. A zero inflow year for both these reservoirs is predicted, in 2040 AD for Osmansagar and in 2036 AD for Himayatsagar, if the same trend of decrease in inflows continued.

They said the analysis held good only if the city continued to grow more and more and if catchments remained suppliers of agricultural produce. The catchments being close to the city are bound to become urbanised centres. As urbanisation and resultant paving of surface extends to these catchments, the reservoirs might receive inflows but of polluted water. A classic example is Hussainsagar in the midst of the city, whose catchment has been producing polluted water.

Whatever be the outcome of either reservoir turning dry if catchments are not urbanised or reservoir getting polluted if catchments are urbanised, in both cases, the reservoirs are going to be defunct as drinking water sources in the next 30 to 40 years, if remedial measures are not taken.