Uniqueness of India’s Northeast with respect to climate change impact: an assessment of streamflow variation in the Gomati River basin Ashesh Rudra Paul and Rajib Maity * Department of Civil Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302, India *Corresponding author. E-mail: rajib@civil.iitkgp.ac.in RM, 0000-0001-5631-9553 ABSTRACT Impacts of climate change may vary from location to location for various reasons and may exhibit unique features in some regions. In this study, we considered India’s Northeast which is geographically and hydro-meteorologically unique. The Gomati River catchment is the largest and one of the important river catchments in Tripura, a state in the northeastern region of India. Due to changes in climatic conditions over the previous few decades, the flow pattern of this catchment has changed significantly. The study examines the effect of climate change on the climatology of precipitation and streamflow using the simulation output from the Earth System Model (ESM) from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) into two different conceptual hydrological models for streamflow simulation. Findings indicate that water availability is projected to be reduced in the future due to a reduction in the average streamflow volume by approximately 12–30% (varies from model to model and scenario to scenario). Moreover, the water demands for other hydrological processes, i.e., evap- oration/evapotranspiration, are expected to increase due to a significant increase in temperature (∼1.4–2.1 °C). A sustainable management of water resources will benefit from the research outcomes of this study. Key words: climate change impact, HEC-HMS, hydroclimatic conceptual streamflow (HCCS) model, hydroclimatic modelling, India’s North- east, streamflow HIGHLIGHTS • Uniqueness of India’s Northeast with respect to climate change impact is explored for precipitation and streamflow. • Analysis indicates a significant increase in temperature (∼1.4–2.1 °C) along with a large seasonal variation in annual precipitation but a decrease in the future streamflow. • Reduction is due to an increase in water demands for other hydrological processes, i.e., evaporation/evapotranspiration. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/). © 2023 The Authors Journal of Water and Climate Change Vol 00 No 0, 1 doi: 10.2166/wcc.2023.442 corrected Proof Downloaded from http://iwaponline.com/jwcc/article-pdf/doi/10.2166/wcc.2023.442/1182489/jwc2023442.pdf by guest on 10 March 2023