Open Access

ARTICLE

Trends in Rainfall-Temperature Projections in Upper Bernam River Basin Using CMIP6 Scenarios in Malaysia

Muazu Dantala Zakari^1,2,*, Md. Rowshon Kamal^1,*, Norulhuda Mohamed Ramli¹, Balqis Mohamed Rehan³, Mohd Syazwan Faisal Bin Mohd⁴

1 Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, 43400, Malaysia
2 Agricultural and Environmental Engineering Department, Faculty of Engineering, Bayero University, Kano, PMB 3011, Nigeria
3 Department of Civil Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, 43400, Malaysia
4 River Basin Research Centre, National Water Research Institute of Malaysia, Seri Kembangan, 43300, Malaysia

* Corresponding Authors: Muazu Dantala Zakari. Email: ; Md. Rowshon Kamal. Email:

(This article belongs to the Special Issue: Resource and Environmental Information Modeling)

Revue Internationale de Géomatique 2025, 34, 487-511. https://doi.org/10.32604/rig.2025.065835

Received 22 March 2025; Accepted 30 June 2025; Issue published 29 July 2025

Abstract

Understanding trends in rainfall and temperature projections is critical for assessing climate change impacts, managing water resources, mitigating disaster risks, and guiding sustainable agricultural and infrastructure planning. This study investigates projected changes in temperature and rainfall in the Upper Bernam River Basin (UBRB), Malaysia, using ten Global Climate Models (GCMs) from CMIP6 across four scenarios (SSP126, SSP245, SSP370, and SSP585). Downscaling was conducted with the Climate-Smart Decision Support System (CSDSS) for the baseline period (1985–2014) and for future periods: 2020s, 2040s, 2060s, and 2080s. Results indicate a consistent warming trend, with maximum temperatures projected to increase from 1.4°C (2020s, SSP126) to 4.66°C (2080s, SSP585), and minimum temperatures from 1.97°C to 5.70°C over the same period and scenarios. Rainfall projections reveal high variability and inter-scenario uncertainty, with average monthly rainfall changes ranging from −17.6% (2020s, SSP585) to +6.6% (2080s, SSP370). Extremes analysis shows intensifying wet and dry spells, with 95th percentile rainfall rising to 7.87% and significant increases in 90th percentile temperatures, reaching nearly 20% under SSP585 by 2080s. Seasonal shifts include reduced rainfall from January to April and potential increases in main-season (July–August) flooding. These findings highlight the importance of adaptive strategies such as flood control, off-season (January–June) water storage, and climate-resilient infrastructure. The study underscores inter-scenario uncertainties and provides critical insights for climate-resilient water resource planning and disaster risk mitigation in UBRB.

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