Abstract:
Groundwater utilization has increased dramatically in developing cities of the world over last few decades. The present study was taken up for assessing the sustainability of water resources in a subtropical mountainous Watershed of Dehradun District, Uttarakhand. The study area is the Suswa watershed situated in Dehradun district of North India between 77° 57' and 78° 10' East longitudes and 30° 08' and 30° 27' North latitudes. The study has indicated that the rate of urbanization has increased phenomenally in the study area in the recent decade. The surface runoff estimated for the study area by employing the well known NRCS-CN method is around 22% of annual rainfall in the study area, with the minimum surface water resources availability being about 63 million-eper annum. Ground water estimation for 2005-06 was carried out by using the mass balance based methodology of ground water budgeting practiced by the Groundwater Agencies in India. The stage of groundwater development in the command and non-command areas was found to be 19% and 38% respectively, thus placing the Suswa Watershed under 'Safe' category of development.
A synoptic assessment of ground water quality was carried out by evaluating a groundwater quality index (GWQI) following the approach of Melloul and Collin (1998). For estimating GWQI, seven water quality parameters were selected viz. cadmium, nickel, chromium, total hardness, sulfate, total dissolved solids and total alkalinity.
The relative weights of these parameters were computed by using an analytical hierarchy process. The GWQI contour maps have indicated that, the groundwater of the study area is generally fit for drinking purpose except in few patches of the watershed. For evaluation of sustainability parameters, it was observed that, the deforestation rate in the period of 10 years from 1990 to 2000 was faster than that during the preceding duration of 18 years (from 1972 to 1990). With respect to the water barrier index, computations have indicated that the Suswa
Watershed can be put in 'absolute scarcity' category whereas on the basis of IWSS score, the watershed can be classified as 'moderately stressed' to 'highly stressed'. It was found that the ground water resources development is becoming unsustainable in the watershed as well as in the Dehradun city. This study has resulted in formulation of viable guidelines for assessment of sustainability of water resources and is likely to be of the benefit to the planners, hydrologists and decision makers.
