Downscaling GCM data for climate change impact assessments on rainfall: a practical application for the Brahmani-Baitarani river basin
R. J. Dahm1, U. K. Singh2, M. Lal2, M. Marchand1, F. C. Sperna Weiland1, S. K. Singh3, and M. P. Singh31Deltares, Boussinesqweg 1, P.O. Box 177, 2600 MH Delft, the Netherlands 2RMSI, A-8 Sector 16, NOIDA 201 30, India 3Central Water Commission, R.K. Puram, New Delhi 110 066, India
Received: 16 Nov 2015 – Accepted for review: 10 Dec 2015 – Discussion started: 15 Jan 2016
Abstract. The delta of the Brahmani-Baitarani river basin, located in the eastern part of India, frequently experiences severe floods. For flood risk analysis and water system design, insights in the possible future changes in extreme rainfall events caused by climate change are of major importance. There is a wide range of statistical and dynamical downscaling and bias-correction methods available to generate local climate projections that also consider changes in rainfall extremes. Yet the applicability of these methods highly depends on availability of meteorological observations at local level. In the developing countries data and model availability may be limited, either due to the lack of actual existence of these data or because political data sensitivity hampers open sharing.
We here present the climate change analysis we performed for the Brahmani-Baitarani river basin focusing on changes in four selected indices for rainfall extremes using data from three performance-based selected GCMs that are part of the 5th Coupled Model Intercomparison Project (CMIP5). We apply and compare two widely used and easy to implement bias correction approaches. These methods were selected as best suited due to the absence of reliable long historic meteorological data. We present the main changes – likely increases in monsoon rainfall especially in the Mountainous regions and a likely increase of the number of heavy rain days. In addition, we discuss the gap between state-of-the-art downscaling techniques and the actual options one is faced with in local scale climate change assessments.
Dahm, R. J., Singh, U. K., Lal, M., Marchand, M., Sperna Weiland, F. C., Singh, S. K., and Singh, M. P.: Downscaling GCM data for climate change impact assessments on rainfall: a practical application for the Brahmani-Baitarani river basin, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2015-499, 2016.