[U-04] Geospatial Applications for Societal Benefits

[U04-08] SIMULATI0N OF UPPER BERNAM RIVER BASIN STREAMFLOW USING SWAT MODEL AND CMIP6 PROJECTION SCENARIOS IN MALAYSIA

*MUAZU DANTALA ZAKARI¹, Rowshon MD Kamal¹, Norulhuda M Ramli¹, Balqis M Rehan¹, Mohd Syazwan F Mohd², Franklin A Kondum¹ (1.UNIVERSITI PUTRA MALAYSIA, 2.River Basin Research Centre, National Water Research Institute of Malaysia)

Keywords:Climate change, Streamflow predictions, CMIP6 projections, Agro-hydrological basin.

This study examines the possible effect of climate change on streamflow in the Upper Bernam River in Malaysia (UBRB). Given the critical problems that climate change presents to water resources management, it is vital to comprehend future changes in streamflow patterns to develop effective planning and adaptation methods. This study used the Soil and Water Assessment Tool (Q-SWAT 2012), a hydrological model to predict the changes in streamflow patterns across different Climate Model Intercomparison Project phase 6 (CIMP6) projection scenarios (SSP245, SSP460, and SSP585) on UBRB after calibrating and validating the model. This study collected daily climatic data for various periods: the baseline period (1985-2020), which was then divided into two sub-periods: 1991-2005 and 2006-2020; the future periods of the 2030s (2021-2035), 2040s (2036-2050), 2050s (2051-2065), 2070s (2066-2080), and 2080s (2081-2095). The variables were derived from 10 global climate models (GCMs) and were determined based on three shared socioeconomic paths (SSPs) scenarios (SSP245, SSP460, and SSP585). The climate variables were downscaled to a specific local station using the Climate-Smart Decision Support System (CSDSS) in the MATLAB environment. The statistical analysis of the model evaluation in the Bernam watershed, conducted during both the calibration and validation phases, indicated that the QSWAT model performed “GOOD’. The p-factor, r-factor, R2, NSE, PBIAS, and KGE values obtained during the calibration and validation periods were as follows: 0.82, 0.88, 0.72, 0.70, -1.1, and 0.85; and 0.8, 1.04, 0.75, 0.65, -6.6, and 0.79, respectively. The assessment and study of current and future streamflow for the UBRB indicate that water availability will vary, with expected changes under various climate scenarios. The historical streamflow was observed as 1,231.59mm (1991 – 2005) and 1,214.69 (2006 – 2020); while for the future are 786.04mm, 743.38, 751.3 against SSP245, SSP460, and SSP585 respectively for 2021 – 2035; similarly, 755.77mm, 726.06mm, 726.11mm for 2036 – 2050; 783.26mm, 756.66mm, 753.06mm for 2051 – 2065; 793.67mm, 743mm, 694.96mm for 2066 – 2080; and 893.85mm, 767.8mm, and 695.49mm for the period 2081 – 2095. An analysis is conducted on the simulation results to evaluate alterations in the pattern and variability of streamflow across several CMIP6 scenarios. Furthermore, the study examines the consequences of these alterations on the management of water resources and the sustainability of the ecosystem in the Upper Bernam River Basin and recommends a provision for a water reservoir for off-season agricultural requirements. The research findings provide valuable insights into the region's potential hydrological consequences of climate change, assisting decision-makers in formulating adaptive policies to alleviate future water-related hazards.