Resolution Dependence of Regional Hydro-Climatic Projection: A Case-Study for the Johor River Basin, Malaysia (original) (raw)
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The impact of climate change and uncertainty of climate projections from General Circulation Models (GCMs) from phase 5 of the Coupled Model Intercomparison Project (CMIP5) on streamflow in the Johor River Basin, Malaysia was assessed. Eighteen GCMs were evaluated, and the six that adequately simulated historical climate were selected for an ensemble of GCMs under three Representative Concentration Pathways [RCPs; 2.6 (low emissions), 4.5 (moderate emissions) and 8.5 (high emissions)] for three future time periods (2020s, 2050s and 2080s) as inputs into the Soil and Water Assessment Tool (SWAT) hydrological model. We also quantified the uncertainties associated with GCM structure, greenhouse gas concentration pathways (RCP 2.6, 4.5 and 8.5), and prescribed increases of global temperature (1–6 WC) through streamflow changes. The SWAT model simulated historical monthly streamflow well, with a Nash–Sutcliffe efficiency coefficient of 0.66 for calibration and 0.62 for validation. Under RCPs 2.6, 4.5, and 8.5, the results indicate that annual precipitation changes of 1.01 to 8.88% and annual temperature of 0.60–3.21 WC will lead to a projected annual streamflow ranging from 0.91 to 12.95% compared to the historical period. The study indicates multiple climate change scenarios are important for a robust hydrological impact assessment.
Projected Streamflow in the Kurau River Basin of Western Malaysia under Future Climate Scenarios
Scientific Reports, 2020
Climate change-induced spatial and temporal variability of stremflow has significant implications for hydrological processes and water supplies at basin scale. This study investigated the impacts of climate change on streamflow of the Kurau River Basin in Malaysia using a Climate-Smart Decision Support System (CSDSS) to predict future climate sequences. For this, we used 25 reliazations consisting from 10 Global Climate Models (GCMs) and three IPCC Representative Concentration Pathways (RCP4.5, RCP6.0 and RCP8.5). The generated climate sequences were used as input to Soil and Water Assessment Tool (SWAT) to simulate projected changes in hydrological processes in the basin over the period 2021–2080. The model performed fairly well for the Kurau River Basin, with coefficient of determination (R2), Nash-Sutcliffe Efficiency (NSE) and Percent Bias (PBIAS) of 0.65, 0.65 and –3.0, respectively for calibration period (1981–1998) and 0.60, 0.59 and −4.6, respectively for validation period (1996–2005). Future projections over 2021–2080 period show an increase in rainfall during August to January (relatively wet season, called the main irrigation season) but a decrease in rainfall during February to July (relatively dry season, called the off season). Temperature projections show increase in both the maximum and minimum temperatures under the three RCP scenarios, with a maximum increase of 2.5 °C by 2021–2080 relative to baseline period of 1976–2005 under RCP8.5 scenario. The model predicted reduced streamflow under all RCP scenarios compared to the baseline period. Compared to 2021–2050 period, the projected streamflow will be higher during 2051–2080 period by 1.5 m3/s except in February for RCP8.5. The highest streamflow is predicted during August to December for both future periods under RCP8.5. The seasonal changes in streamflow range between –2.8% and –4.3% during the off season, and between 0% (nil) and –3.8% during the main season. The assessment of the impacts of climatic variabilities on the available water resources is necessary to identify adaptation strategies. It is supposed that such assessment on the Kurau River Basin under changing climate would improve operation policy for the Bukit Merah reservoir located at downstream of the basin. Thus, the predicted streamflow of the basin would be of importance to quantify potential impacts of climate change on the Bukit Merah reservoir and to determine the best possible operational strategies for irrigation release.
Water, 2021
This study introduces a hydro-climatic extremes assessment framework that combines the latest climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) HighResMIP with the Soil and Water Assessment (SWAT) model, and examines the influence of the different climate model resolutions. Sixty-six hydrological and environmental flow indicators from the Indicators of Hydrologic Alteration (IHA) were computed to assess future extreme flows in the Kelantan River Basin (KRB), Malaysia, which is particularly vulnerable to flooding. Results show that the annual precipitation, streamflow, maximum and minimum temperatures are projected to increase by 6.9%, 9.9%, 0.8 °C and 0.9 °C, respectively, by the 2021–2050 period relative to the 1985–2014 baseline. Monthly precipitation and streamflow are projected to increase especially for the Southwest Monsoon (June–September) and the early phase of the Northeast Monsoon (December) periods. The magnitudes of the 1-, 3-, 7-, 30- an...
Hydrological Sciences Journal, 2019
Water scarcity issues in the Johor River Basin (JRB) could affect the populations of Malaysia and Singapore. This study provides an overview of future hydro-meteorological droughts using climate projections from an ensemble of four Coordinated Regional Climate Downscaling Experiments-Southeast Asia (CORDEX-SEA) domain outputs under the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios for the 2021-2050 and 2071-2100 periods. The climate projections were bias-corrected using the quantile mapping approach before being incorporated into the Soil and Water Assessment Tool (SWAT) hydrological model. The Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSI) were used to examine the meteorological and hydrological droughts, respectively. Overall, future annual precipitation, streamflow, maximum and minimum temperature are projected to change by about-44.2 to 24.3%,-88.7 to 42.2%, 0.8 to 3.7ºC and 0.7 to 4.7ºC, respectively. The results show that the JRB is likely to receive more frequent meteorological droughts in the future.
This study assesses the precipitation and maximum temperature under RCP 4.5 scenario in 2030s and 2050s to explore the impacts of climate change to the water-energy-food (WEF) nexus in Peninsula Malaysia. Dynamically downscaled GCM from SEACLID is simulated for the baseline period 1986-2005, 2011-2040 (2030s) and 2041-2070 (2050s) and is overlaid and analysed on regional areas, main granary areas, and dams using ArcGIS, R and SPSS. The anomaly is relative to the baseline period 1986-2005. Results indicate all regions are projected to be warmer than baseline in 2030s and 2050, with anomalies reaching above 1.5°C but below 2°C. Precipitation in 2030s would be increasingly wetter, but 2050s drier. Anomaly wise, all regions in 2050s (mean=109.5mm) is significantly wetter than 2030s (mean=57.45mm). For granary areas in 2011-2070, mean projections in OFF season (33.57°C) is significantly higher than MAIN season (32.76°C). In 2030-2050, the anomaly is between 0.6°C -1.38°C and 0.38°C -1.32°C in MAIN and OFF season, respectively. From 2011-2070 in MAIN season, Selangor IADA ranks the highest (34.25°C) while, MADA (35.24°C) ranks the highest in OFF season. All areas have exceeded the T32opt, except for Penang IADA. RAI and anomaly analyses showed that Kenyir dam catchment is drier in 2030s but wetter in 2050s while Sungai Selangor dam catchment indicates drier period from 2030s progressing to 2050s. The mean distribution of Kenyir in 2050s (146.76mm) is not significantly higher than 2030s (138.96mm), while Sungai Selangor in 2050s (238.39mm) is not significantly higher than 2030s (233.50mm). Future climate projections assessments on WEF nexus is critical with rising vulnerability to additional climate variability, and slow adaptation would threaten the food, water and energy security.
Water, 2017
Potential impacts of climate change on the streamflow of the Bernam River Basin in Malaysia are assessed using ten Global Climate Models (GCMs) under three Representative Concentration Pathways (RCP4.5, RCP6.0 and RCP8.5). A graphical user interface was developed that integrates all of the common procedures of assessing climate change impacts, to generate high resolution climate variables (e.g., rainfall, temperature, etc.) at the local scale from large-scale climate models. These are linked in one executable module to generate future climate sequences that can be used as inputs to various models, including hydrological and crop models. The generated outputs were used as inputs to the SWAT hydrological model to simulate the hydrological processes. The evaluation results indicated that the model performed well for the watershed with a monthly R 2 , Nash-Sutcliffe Efficiency (NSE) and Percent Bias (PBIAS) values of 0.67, 0.62 and −9.4 and 0.62, 0.61 and −4.2 for the calibration and validation periods, respectively. The multi-model projections show an increase in future temperature (t max and t min) in all respective scenarios, up to an average of 2.5 • C for under the worst-case scenario (RC8.5). Rainfall is also predicted to change with clear variations between the dry and wet season. Streamflow projections also followed rainfall pattern to a great extent with a distinct change between the dry and wet season possibly due to the increase in evapotranspiration in the watershed. In principle, the interface can be customized for the application to other watersheds by incorporating GCMs' baseline data and their corresponding future data for those particular stations in the new watershed. Methodological limitations of the study are also discussed.
Dynamics of potential precipitation under climate change scenarios at Cameron highlands, Malaysia
SN Applied Sciences, 2021
Precipitation is sensitive to increasing greenhouse gas emission which has a significant impact on environmental sustainability. Rapid change of climate variables is often result into large variation in rainfall characteristics which trigger other forms of hazards such as floods, erosion, and landslides. This study employed multi-model ensembled general circulation models (GCMs) approach to project precipitation into 2050s and 2080s periods under four RCPs emission scenarios. Spatial analysis was performed in ArcGIS10.5 environment using Inverse Distance Weighted (IDW) interpolation and Arc-Hydro extension. The model validation indicated by coefficient of determination, Nash–Sutcliffe efficiency, percent bias, root mean square error, standard error, and mean absolute error are 0.73, 0.27, 20.95, 1.25, 0.37 and 0.15, respectively. The results revealed that the Cameron Highlands will experience higher mean daily precipitations between 5.4 mm in 2050s and 9.6 mm in 2080s under RCP8.5 s...
Vietnam Journal of Science and Technology, 2018
A top-down approach begins with Global Climate Models (GCMs) is a common method for assessing climate change impacts on water resources in river basins. To overcome the coarse resolution of GCMs, dynamic downscaling by regional climate models (RCMs) with bias-correction procedures is utilized with the aim to reflect the meteorological features at the river basin scale. However, the results still entail large uncertainties. This paper examines the ability to capture the observed baseline temperature and precipitation (1986-2005) in the Ba River Basin from GCM outputs, RCM outputs, bias-corrected GCM outputs and bias-corrected RCM outputs by analyzing statistical indicators between historical simulations and observed data in 4 temperature and 6 rainfall stations. Bias-corrected results of both GCM and RCM have significantly smaller errors compared to the unbias-corrected ones. The uncertainty of future climate projection for the mid and late 21th century of the bias-corrected GCMs and...
FUDMA JOURNAL OF SCIENCES
The complexity of hydrological models has been a setback in their evaluation particularly for long-term simulations. Deficit and constant loss (DCL) method has been introduced in Hydrologic Engineering Center's Hydraulic Modeling System (HEC-HMS) model for continuous based simulations. However, studies on climate change impacts using the method are still very few. This study used the method to evaluate potential impacts of climate change on streamflow at Bernam Basin, Malaysia for 2010-2039, 2040-2069 and 2070-2099 to the baseline period (1976-2005) under two RCP scenarios (RCPs 4.5 and 8.5). The model efficiency during evaluation is found satisfactory. Compared with the baseline period, the predicted streamflow decreased in all future periods during main and off-seasons. However, the changes have become more pronounced during the off-season with a significant decrease of 9.14% under the worst-case scenario (RCP8.5). Therefore, the Basin would likely experience tremendous pres...
Civil and Environmental Engineering
Climate change is a complex and multi-layer issue with global and local entanglement. In this study, Langat River Basin is chosen. Secondary data was used including the historical flood and drought event reports, Standardized Precipitation Index-1 data and Canadian Earth System Model (CanESM2) along with Australian Community Climate and Earth System Simulator Coupled Model (ACCESS CM-2). These data were used to determine the monthly flood and drought precipitation risk based on five regions of Langat River Basin. The CanESM2 and ACCESS CM-2 based on RCP 4.5 and RCP 8.5 scenarios were downscaled and bias corrected for this study. The reliability of these models was then analyzed with Pearson correlation and probability density function (PDF). The future flood and drought risks from year 2020 to 2100 were predicted using the most reliable local climate model local climate hazard thresholds. The CanESM2 RCP 4.5 scenario was identified to have moderate relationship with the historical p...