Hyderabad: Over the years, governments have been relying on groundwater recharge methods like rain water harvesting pits. But new research now suggests that in semi-arid areas, like Hyderabad, such pits contribute little to aquifer recharge.
Experts say that recharge techniques such as percolation pits work only during heavy rainfall when water stress is virtually non-existent.
Scientists from the Indo French Centre for Groundwater Research at the National Geophysical Research Institute have studied aquifer recharge from a percolation pit built in Maheshwaram near Hyderabad. Dr Shakeel Ahmed, team leader at IFCGR, said, “We have been using these techniques to recharge groundwater. But people just build them and nobody knows what happens later and how much groundwater is getting recharged.”
Groundwater recharge techniques such as rain water harvesting and percolation pits have been used by governments. The master plan for ‘Managed Aquifer Recharge’ proposed the construction of 3,800 percolation pits and 11,167 check dams.
“There is a lack of strong evidence concerning the impact of those structures on the water balance,” Dr Ahmed explained. The erstwhile Andhra Pradesh government had also set a goal of increasing aquifer recharge from nine per cent of the total rainfall under natural conditions to 15 per cent by 2020.
Scientists argue that while these structures have been extensively proposed to be used, their performance dips drastically during weak monsoon years due to high evaporation, but works normally during strong monsoon years.
The study says that water harvesting in the semi-arid region of South India may also be a ‘part of the problem’, instead of being the solution.
However, municipal authorities say the water can’t go anywhere else but into the ground. S. Harikrishna, additional commissioner, GHMC said, “Where else will the water go? I am not sure about their study, but we have had good experiences. The pits worked well.”
