Hydrometeorological feedback and changes in water storage and fluxes in northern Indian basins

The Gangetic Plain is a large fertile area at the foot of the Himalayas, covering most of northern India. Home to around 400 million inhabitants, it is one of the most densely inhabited regions in South-East Asia. With its fertile soils, monsoon precipitation and vast groundwater aquifers, the plains have been at the heart of the Indian agricultural revolution. Over the last 4 decades, the introduction of new fertilisers and crops, and the construction of large-scale irrigation systems have been major drivers of socio-economic development in the region. These practices have, however, also led to severe groundwater decline and strains on other water resources. Changing feedbacks of water and energy between the land-surface and atmosphere may have even altered the local climate system. A strong economic development is expected to continue these trends in the near future and future climate change is also expected to increase the pressure on local water resources systems.

Identifying the major causes of observed historical changes in water availability and predicting the future impact of local water management strategies under climate change are particularly challenging, yet indispensable for the sustainable management of water resources. For example: assessing the sustainability of groundwater aquifers requires knowledge of global climate influences, but also of the influence of land-use, abstractions and soil moisture dynamics; furthermore, the unprecedented scale of land-use changes and increased irrigation are expected to have influenced local climate through feedbacks of water and energy. In order to unravel and quantify the impact of different drivers of change, a fully integrated analysis of the major water fluxes in the Gangetic Plain is needed.

This study would be the first to analyse changes in the main water fluxes and feedbacks of the Gangetic Plain in a fully integrated modelling set-up. The approach will enable the separation of the impact of local and regional land use change from that of global climate drivers. We will develop a custom-built coupled hydrological model for the region using available groundwater and surface water modelling toolboxes. This model will be calibrated and tested using a variety of different sources of information, from local measurements, satellite observations and global climate (reanalysis) datasets. Subsequently, we will run the model with different land-use and water extraction scenarios. This will allow us to quantify the impact of land-use change and extraction on the main hydrological fluxes and water resources.

At the same time, the hydrological model will generate high-resolution data about soil moisture changes resulting from historical land-use, as well as different hypothetical scenarios. By feeding these scenarios into a global climate model, we will study the potential feedbacks of large-scale changes in soil moisture on the Indian monsoon system. A pair of state-of-the-art global climate models will be used: the UK MetOffice Unified Model (MetUM) and the NCAR Community Atmosphere Model (CAM4).

In a final step, the superimposed impact of climate change will be assessed and future predictions of water availability will be generated. For this purpose, we will use the new CMIP5 ensemble of climate models. Using a statistical approach, these models will be downscaled to a level useful for application over the Gangetic Plains. The integrated hydrological model can then be run with these future climate projections to assess the impact of future climate change on regional and local water availability. Two local case studies will address the usefulness of such projections and their uncertainties in a local ecosystem-oriented management setting.

The work will impact on several distinct, but interconnected communities at a local, national and international scale.

At a local scale the assessments and modelling carried out in specific areas of the basin will have direct relevance to local populations and civil society. The project's initial results will supplement directly the Ganga River Basin Management Plan, due to be drafted during 2011, in which Co-I's Sinha and Ojha are theme coordinators.

At a national scale, a major deliverable from the project will be the downscaled probabilistic hydrologic scenarios accounting for climate change. These projections will be useful for many agencies such as State Water Resources Departments, the Ministries of Environment and Forests, Irrigation, Earth Sciences, Energy and Water Resources (including the Central Water Commission and the Central Groundwater Board) in developing management strategies. Other groups interested include the Indian Agricultural Research Institute (IARI), Indian Society of Hydraulics, Indian Water Resources Society, and the Indian Association of Hydrogeologists who will all benefit from the outcome of the projects.

At the wider scale the results will be of direct relevance to the climate modelling community, who will be able to use the outcomes of the project to improve the hydrological components of, and feedback within, future generations of climate models. Particular users we identify are the India Meteorological Department (IMD), the India National Centre for Medium Range Weather Forecasting (NCMRWF) and the UK Met Office for model improvement and prediction purposes. NCMRWF also shares usage of the Met Office Unified Model.

We will interact with these beneficiaries using a wide range of tools.

At the local level, a workshop will be organised by IIT Roorkee or Kanpur. This workshop will address resource managers, NGOs and others interested in the direct application of the research to local issues in the Gangetic plain. Invitations to the workshop will target as wide an audience as practical. While the project will focus on the Gangetic plains, the models and methodologies developed will be useful in other parts of the country, and linkages with the Ministry of Water Resource's India Hydrology Project, which focuses on catchments outside the Ganga, will be used to invite as wide a range of practitioner hydrologists as possible.

Project websites will be developed. These will be mirrored, as appropriate, between the UK and India. The websites will be designed to supplement the information disseminated at the workshop for local stakeholders, while also containing more technical information, including reports and published papers.

We will join the relevant GEWEX working groups as well as the UNESCO G-WADI network. Contacts already exist through project partner Howard Wheater. Both networks are an excellent communication channel to reach international institutes and NGOs. Through Co-I Bhanu Neupane, direct links will exist with the UNESCO International Hydrological Programme. Finally, links exist with the CGIAR/International Water Management Institute.

We identify several indicators and milestones to assess the efficiency of our dissemination strategies. The dissemination workshop organised by IIT Roorkee or Kanpur will be a major milestone in the project. The success of this workshop can be assessed directly by the number of participants, and their feedback. Website publication, number of weblog articles and statistics on visitors will also be a major indicator of the success of our dissemination. Finally, the number of publications, both peer-reviewed and outreach, as well as the number of downloads on their respective websites, will be a good indicator.