Masterplan for riverbank filtration in India to mitigate climate change effects and groundwater over exploitation

Abstract

The water sector in India is highly dynamic and spatially heterogeneous such that there is a complex interlinkage with the other resources of energy, land and the climate. With climate change exerting additional pressures and uncertainties on these interlinkages, the consequent unprecedented levels of resource depletion have catalyzed increasing scarcity and conflicts across the country, necessitating urgent research and policy interventions. Bank/ riverbank filtration (BF/RBF), which is an element of managed aquifer recharge (MAR), is a proven and sustainable natural water treatment technology, where surface water is infiltrated to an aquifer through river or lake banks resulting in water quality improvements. MAR, including BF, is recognized as an increasingly important water management strategy in areas faced with changing climate, rising intensity of climate extremes or overexploitation of groundwater resources, in order to maintain, enhance and secure stressed groundwater systems and to protect and improve water quality. Despite these advantages, RBF is intentionally used only at some places in India resulting in a low portion (<0.1 %) of drinking water produced thereof. On the other hand, there is a large potential to secure at least 5 % of India’s drinking water supply by RBF. This can be achieved by the preparation of a science-based masterplan for RBF water supply, which is one of the aims of an Indo-German RBF network project funded by the Federal Ministry of Education and Research of Germany from July 2020 to June 2023. The project consortium comprising 7 German and 8 Indian partners will collaborate to expand the R&D activities of the Indo-German Competence Centre for Riverbank Filtration that was established by the National Institute of Hydrology Roorkee and the University of Applied Sciences Dresden in 2011. The masterplan will be based on the R&D activities to develop RBF demonstration sites in Haridwar, Agra, North East India and Goa and a constructed wetland demonstration site in Varanasi. Thereby the diverse hydro-climatic and geological conditions are incorporated.The development of the masterplan includes scientific procedures based upon results from research and interlinked with relevant policy. Hydrogeological, water quality and numerical groundwater flow modelling investigations will be highlighted for a few selected RBF sites along with information, education and communication measures used to develop the concept for the masterplan. Measures to implement the masterplan and associated scientific investigations to explore potential RBF sites will be highlighted based on some of the demonstration sites such as in Haridwar. Experiences from some of these demonstration sites have shown that to implement a RBF masterplan on the ground, the division of RBFcompetency within India must be absolutely clear because the water supply practitioners need robust scientific results from R&D/ academic institutes and competent consulting and engineering firms in the private sector to provide planning and construction services. More over a clear and specific policy on RBF and a body to oversee and monitor the progress of the RBF masterplan in India is advantageous.