Climate Change and its Impacts on Selected Indian Hydrological Systems using Earth System and High-Resolution Modeling (NORINDIA)

Due to its diversified socio-economic and climatic regions, India is prominently vulnerable to the ensuing climate changes and related impacts. An increase in temperature and changes in the overall precipitation patterns have a profound impact on the water availability. The advent of climate change and its impact on glacier melt may lead to abrupt floods in regions neighboring the Himalayas. Hence, understanding the monsoon variability and the hydrological cycle in the baseline and future time scales would enrich the information available for policy makers and stakeholders for informed decision making - this is the objective of the NORINDIA project. In this article, a discussion of this multi-national project will be made, looking into its structure, first results and challenges.

The NORINDIA Project draws its research activities on an existing partnership between Norway and India with five Norwegian and three Indian collaborators. The project is coordinated by Dr. Michel Mesquita (Uni Research/BCCR) and the Norwegian collaborators of the project are the University of Bergen and Oslo, the Norwegian Institute for Air Research (NILU) and SN Power. The Indian partners are: the Indian Institute of Tropical Meteorology (IITM), the Centre for Mathematical Modelling and Computer Simulation (CMMACS) and The Energy and Resources Institute (IITM). Besides these institutions, the project also brings in contribution from the National Center for Atmospheric Research (NCAR) in the United States, thus drawing on their expertise in hydrological modelling. NORINDIA is therefore a multi-disciplinary and unique project, not only due to the gamut of participant institutions, but also for the state-of-the-art science it develops.

This project has five Work Packages (WP), which deal with large-scale atmospheric processes down to smaller scales. WP1 studies the effect of climate change in the Indian monsoon. WP2 quantifies the role of snow and surface processes on the Indian summer monsoon. WP3 quantifies the role of snow and glacier melt on water resources. WP4 investigates the hydrological changes during monsoon droughts over India. WP5 studies changes in the hydrological cycle in the present and future climate. Hence, all of the WPs in NORINDIA work together to integrate results across spatial and temporal scales to produce a unified understanding on how climate change may affect the monsoon and water availability in India.

Initial results from WP1, using the RCP8.5 scenario, indicate an increase of around 10% in summer rainfall during the period 2076-2096 compared to recent climate in the Indo-Pacific region. In WP2, it was found that cold conditions over a broad region centred on the Himalayan-Tibetan Plateau lower the land-ocean temperature contrast and delay the monsoon onset by about 9 days. Moreover, the study also found a bias in the snow depth from the 20th century reanalysis data, which could mean that the snow-monsoon onset linkage is overestimated. WP3 shows that moisture entering the Indus, Ganges and Brahmaputra basins come from the Arabian Sea, the Bay of Bengal, the Mediterranean and Caspian Seas. MERRA reanalysis data overestimates the amount of snow due to excess and northward shift in the precipitation pattern coming into high-lying areas. WP4.3 found a weakening of the South Asian monsoon circulation and a decrease of monsoon precipitation over the Indian subcontinent in the future decades.

NORINDIA aims at providing a thorough hydrological assessment for India using state-of-the-art modelling - addressing changes in climate based on IPPC AR5 scenarios. It is hoped that it may make a significant contribution to stakeholders and policy-makers, with respect to the future of water resources in India.