Isotope techniques to identify recharge areas of springs for rainwater harvesting in the mountainous region of Gaucher area, Chamoli District, Uttarakhand

• Published in: Current science (Bangalore) 2008-04, Vol.94 (8), p.1003-1011
• Main Authors: Shivanna, K., Tirumalesh, K., Noble, J., Joseph, T. B., Singh, Gursharan, Joshi, A. P., Khati, V. S.
• Format: Article
• Language: English
• Subjects: Altitude; Chemical composition; Evaporation; Groundwater; Hydrology; Isotopes; Natural springs; Precipitation; Rain; Sea water
• ISSN: 0011-3891

Environmental isotope techniques have been employed to identify the recharge areas of springs in India, in order to construct artificial recharge structures for rainwater harvesting and groundwater augmentation for their rejuvenation. A model project was taken up in the mountainous region of Gaucher area, Chamoli District, Uttarakhand for this purpose. The springs in this region are seasonal and are derived from seepage waters flowing through the shallow weathered and fractured zone. The chemistry of high-altitude springs is similar to that of precipitation, whereas water–rock interactions contributes to increased mineralization in low-altitude springs. The stable isotopic variation in precipitation suggests that the altitude effect for Gaucher area is −0.55‰ for δ¹⁸O and −3.8‰ for δ²H per 100 m rise in altitude. Based on local geology, geomorphology, hydrochemistry and isotope information, the possible recharge areas inferred for valleys 1, 2 and 3 are located at altitudes of 1250, 1330 and 1020 m amsl respectively. Water conservation and recharge structures such as subsurface dykes, check bunds and contour trenches were constructed at the identified recharge areas in the respective valleys for controlling the subsurface flow, rainwater harvesting and groundwater augmentation respectively. As a result, during and after the following monsoon, the discharge rates of the springs not only increased significantly, but also did not dry up even during the dry period. The study shows that the isotope techniques can be effectively used in identifying recharge areas of springs in the Himalayan region. It also demonstrates the advantage of isotope techniques over conventional methods.