Pilot basin study (PBS) integrated water resoures management (IWRM) in Tawi river basin, JK

Abstract

Flow regime of a river is an important factor on the basis of which development of water resources of a river for various beneficial uses is thought of. During recent decades, concerns about the impacts of climate change / landuse on water resources have created social and political tensions from local to national and international levels. Major concerns focus on consequences of these changes for water supply and demand, for local and downstream hydrological hazards, and for biodiversity conservation. Also, the increased competition for water and alterations in land use in the upstream of many rivers, are argued to have contributed to change in hydrological regimes and consequently, the river ecology of many rivers. Under the 12th Five Year Plan (2012-17), National Institute of Hydrology (NIH) has proposed to initiate few Pilot Basin Studies (PBS) across India for Integrated Water Resources Management (IWRM) planning. As part of the IWRM studies taken up from different regional centres of NIH on different sub-basins, Western Himalayan Regional Centre (WHRC), Jammu has identified the Tawi basin for its first PBS study. The important role of Tawi River for sustaining the most populous cities in the region, Jammu and Udhampur has been considered while selecting the basin. The Tawi River has a very high social impact as it is the only major source of water for drinking, agricultural and industrial needs and serving to the almost 20% population of the whole J&K State. The river Tawi is endowed with vast water resources with irrigation, domestic water and hydropower potential which are yet to be assessed in details. Since last four decades, few minor schemes for irrigation, hydropower and domestic water supply have come up. Tawi river is the major source of water supply to the Jammu and Udhampur cities. Recently, one project for recreational activity is also coming up on Tawi river at Jammu. The increasing demand of the development of Tawi river for beneficial uses of the population of Jammu, Udhampur and Doda districts calls for the systematic hydrological studies for the river. All these issues point towards an integrated hydrological approach, but, the lack of research quality data required for developing an Integrated Water Resources Management Plan is hampering the development and management of water resources of Tawi river. In this connection, the present study has been envisaged to cover the aspects: (i) Ruoff simulation for assessment of water resources availability under the present and future scenarios; (ii) Assessment of water demands in the basin under the present and future scenarios; (iii) Preparation of water resources management plan in terms of water allocation to different sectors in the Tawi basin; (iv) To carry out capacity building and mass awareness; (v) To formulate the institutional coordination mechanism. The summary of the study and conclusions drawn with respect to these aspects have been elaborated in the following sections: The ArcSWAT model has been calibrated for the period from 1983 to 1992 and validated for the years from 1993 to 1997. The LULC map pertaining to the year 1995 has been used for the calibration and validation. The model simulated the discharge of Tawi catchment upto Jammu satisfactorily with Coefficient of Correlation (CC) and Nash–Sutcliffe efficiency (NSE) as 0.715 and 0.453 during calibration and 0.855 and 0.835 respectively during validation. Statistical downscaling module SDSM 4.2.1 was used in the study to downscale the future climatic parameters viz. rainfall and temperature from the HadCM3 GCM model outputs for A2 and B2 Scenarios. It uses the principle of multiple linear regression (MLR) to develop a relationship between the pretictand and the predictors and assume that this relation remain valid for the future as well as. Five out of total 26 largescale predictor variables have been selected for downscaling. The SDSM model showed a good agreement between the observed and estimated monthly average and annual statistics of rainfall during calibration and validation period. values of coefficient of determination during calibration and validation were estimated as 0.776 and 0.799 respectively between observed and estimated in both the cases. It can be concluded that the performance of SDSM model using MLR is good on monthly basis for future estimation of rainfall under HadCM3-A2 and B2 emission scenarios.