A Method for Evaluation of Artificial Recharge Through Percolation Tanks Using Environmental Chloride

For meeting the growing demand on ground water in hard rock areas of India, man-made percolation tanks have become important structures for augmenting ground-water recharge. Keeping in view their increasing number and cost involved in their construction and their temporal variation in percolation due to silting or desilting operations if undertaken, it is vital to develop proper methodology to evaluate the performance of these structures. A method employing the mass balance of environmental chloride in the tank has been developed for this purpose. The results obtained using this method at one experimental site indicate that an average of 30–35% of impounded water is recharged through this structure situated in granitic gneissic terrain of a semiarid region of India. The remainder is lost through evaporation. The method developed is simple, inexpensive, and sensitive enough to observe the temporal variation in the recharge rate through such tanks.