**Participatory Modelling of Surface and Groundwater to Support Strategic Planning in the Ganga Basin in India**

**Marnix van der Vat 1,\*, Pascal Boderie 1, Kees C. A. Bons 1, Mark Hegnauer 1, Gerrit Hendriksen 1, Mijke van Oorschot 1, Bouke Ottow 1, Frans Roelofsen 1, R. N. Sankhua 2, S. K. Sinha 3, Andrew Warren <sup>1</sup> and William Young <sup>4</sup>**


Received: 13 August 2019; Accepted: 18 November 2019; Published: 21 November 2019

**Abstract:** The Ganga Basin in India experiences problems related to water availability, water quality and ecological degradation because of over-abstraction of surface and groundwater, the presence of various hydraulic infrastructure, discharge of untreated sewage water, and other point and non-point source pollution. The basin is experiencing rapid socio-economic development that will increase both the demand for water and pollution load. Climate change adds to the uncertainty and future variability of water availability. To support strategic planning for the Ganga Basin by the Indian Ministry of Water Resources, River Development and Ganga Rejuvenation and the governments of the concerned Indian states, a river basin model was developed that integrates hydrology, geohydrology, water resources management, water quality and ecology. The model was developed with the involvement of key basin stakeholders across central and state governments. No previous models of the Ganga Basin integrate all these aspects, and this is the first time that a participatory approach was applied for the development of a Ganga Basin model. The model was applied to assess the impact of future socio-economic and climate change scenarios and management strategies. The results suggest that the impact of socio-economic development will far exceed the impacts of climate change. To balance the use of surface and groundwater to support sustained economic growth and an ecologically healthy river, it is necessary to combine investments in wastewater treatment and reservoir capacity with interventions that reduce water demand, especially for irrigation, and that increase dry season river flow. An important option for further investigation is the greater use of alluvial aquifers for temporary water storage.

**Keywords:** integrated water resources management; river basin planning; Ganga River; India; participatory modelling; conjunctive water use; hydrologic modelling
