Upscaling Catchment Processes for Sustainable Water Management in Peninsular India

Economic development and population growth in Peninsular India have resulted in rapid changes to land-use, land-management and water demand which together are seriously impacting and degrading water resources. Urbanization, deforestation, agricultural intensification, shifts between irrigated agriculture and rain-fed crops, increased groundwater use, and the proliferation of small-scale surface water storage interventions, such as farm-level bunds (usually to conserve soil moisture in fields) and check-dams (to replenish local aquifers) all have contributed to significant changes in the hydrological functioning of catchments. The impact of such changes and interventions on local hydrological processes, such as streamflow, groundwater recharge and evapotranspiration, are poorly constrained, and our understanding of how these diverse local changes cumulatively impact water availability at the broader basin-scale is very limited. Focussing on the highly contentious inter-state Cauvery River basin (with an area of c.80,000 km2, the Cauvery is one of India's largest river basins) our study addresses the key scientific challenge of representing the many local, small-scale interventions in Peninsular India at larger scales. Using observations from established experimental catchments in both rural and urban settings, the project will first explore how changes in land-use, land-cover, irrigation practices and small-scale water management interventions locally affect hydrological processes. In tandem we will then develop novel upscaling methods to represent the improved process-understanding in models at the larger sub-basin (Kabini, ~10,000 km2) and basin (Cauvery) scales. In so doing, the project will demonstrate the capability to generically represent the cumulative impact of abundant small-scale changes in basin-wide integrated water resources management models. The impact of local-scale interventions will further be modelled alongside projections of population growth, climate- and land-use-change and water demand to assess future impacts on water security across the basin. Key stakeholders are involved throughout the different stages of the project to ensure that project outputs reflect their interests and concerns and provide useful input to their decision making.

Our research tackles one of the most pressing natural resource issues in Peninsular India: how rapid economic development and population growth impacts water security through widespread changes in land-use, water management and water demand. Currently our understanding of the impact of such changes on hydrological processes is limited despite water degradation and depletion being a major issue in many Peninsular India. The Cauvery River Basin form the focus of our research. Shared between the states of Tamil Nadu and Karnataka, the river has long presented water management challenges at the local, regional and basin scale. Urbanization, deforestation, agricultural intensification and shift from rain fed crops to irrigated agriculture are all major influences in different parts of the Cauvery basin and small scale interventions such as the construction of farm-level bunds to conserve soil moisture continue to proliferate. Our research will take a multi-scale approach to understand the impact of anthropogenic changes in the hydrological system of Peninsular India.
The project will develop novel methods for upscaling the improved process understanding from rural and urban experimental catchments and will demonstrate the capability to assess the cumulative impact of abundant small scale changes across larger basins. Integrated process understanding will inform modelling from the field to basin scale to quantify interactions between different anthropogenic catchment modifications and their integrated impact on surface and groundwater resources at the basin scale.
There are a number of beneficiaries of the research:
Local water users. The field scale research of the impact of small scale interventions on the local hydrological conditions is of direct benefit to the farmers and communities using water and managing land. By building on ATREE's existing Water Literacy campaign we will ensure that the new knowledge and understanding is quickly and appropriately communicated. Within the urban environment of Bangalore we have support from both the Bangalore Water Supply and Sewerage Board and a local NGOs involved in water rejuvenation within the city. Both will directly benefit from the research by being given a better understanding of the feedbacks between groundwater, surface water and the built environment and forecasts of future trends.
Basin Authorities. A major outcome from this research is to upscale the key small scale processes to inform how the hydrological system functions at a basin scale. The beneficiaries from this research include the State Authorities such as the Cauvery River Authority and Karnatak Government's Watershed Development Department, both of which have offered support to our project.
National Institutes. At a national scale, a major impact from the project will be improved hydrological modelling frameworks for large-scale Indian catchments. Our project's whole systems approach will deliver methods which allow the representation of cumulative local scale interventions within larger catchment models. As such, the project outputs will be particularly useful to the Central Groundwater Board and the National Water Development Agency, both of whom have expressed their willingness to participate in the project.
Academic Community. The research will benefit researchers in hydrology, environmental modelling and the growing community investigating linkages between society and the water-food-energy nexus. It will provide an impetus and mechanism for increased India-UK academic collaboration, and benefit both communities through increased exchange. The research team has a strong international academic track record and are involved in academic and professional networks which will increase uptake of within the broader academic community, such as UNESCO supported networks GRAPHIC, G-WADI, HELP and the scientific communities of IAHS and IAH.