Chala sime - Academia.edu (original) (raw)

Papers by Chala sime

Applied and Environmental Soil Science, Sep 2, 2022

Sediment movement is the most critical problem in Ethiopia, notably in the Ketar River watershed,... more Sediment movement is the most critical problem in Ethiopia, notably in the Ketar River watershed, which is located in the Rift Valley Basin. e Ketar River ows through rugged terrain with steep slopes and high sediment movement. e purpose of the study is to evaluate the Soil and Water Assessment Tool's (SWAT) ability to simulate sediment and to identify areas that are vulnerable to soil erosion. is will aid water resource planners in determining the appropriate corrective action. In SWAT sediment sensitivity analysis, the USLE soil erodibility factor (USLE-K) is found to be the most sensitive sediment parameter. e SWAT model sediment simulation performance is evaluated using the coe cient of determination (R 2) and Nash-Sutcli e E ciency (NSE). e model performance results in R 2 and NSE values of 0.69 and 0.55 for calibration and 0.73 and 0.51 for validation, respectively, using the SWAT Calibration and Uncertainty Program (SWAT-CUP). e sediment-prone area subbasins have steep slopes and were mostly covered by cultivated land. Annual sediment yield from cultivated land was approximately 1872.12 t/y, while yield for moderately cultivated grassland was 171.45 t/y. Woodland and forest land have less soil erosion rate. e subbasin highly covered by Eutric Nitisols is found in very high soil erosion-prone areas. Sediment yield from a slight slope is almost zero, whereas sediment yield from steep and very steep slopes is very high. e slope of the subbasin is an important factor in determining sediment yield, followed by land cover and soil types. e very high sediment yield rate area accounted for 39.64% of the total subbasin and it needs soil conservation planning.

Research Square (Research Square), Aug 30, 2022

Hydrological measurements are vital for Water Resources Planning and Management. Modeling rainfal... more Hydrological measurements are vital for Water Resources Planning and Management. Modeling rainfallrunoff may be used to understand the impact of future hydrological changes such as ooding, soil loss, and sedimentation effect on lakes and reservoirs for irrigation and hydropower. But the di cult one is the selection of the best models. All hydrological models may not be equally performed due to being in uenced by input data and over models system that will be used for the analysis. Therefore, two hydrological models; Soil and Water Assessment Tool (SWAT), and Hydrologic Engineering Centers Hydrological Modeling System (HEC-HMS) models to simulate rainfall runoff. These models were calibrated and validated using daily observed stream ow data. The R 2 and NSE were used to check the performance of the models and the result indicates that during HEC-HMS model calibration and validation, R 2 of 0.6 and 0.61, NSE of 0.55 and 0.53, generated respectively. During the SWAT model accuracy assessment, the values of model performance indicators were R 2 of 0.69 and 0.68, NSE of 0.58 and 0.52 for calibration and validation respectively. This indicates both SWAT and HEC-HMS models have been satis ed in stream ow simulations. The SWAT model overestimated the daily stream ow more than the observed and HEC-HMS simulated stream ow. These models overestimated peak stream ow during both the calibration and validation period. The curve number grid generated by HEC-GeoHMS was slightly lower than the curve number simulated by the SWAT model.

Sediment movement is the most critical problem in Ethiopia, notably in the Ketar river watershed,... more Sediment movement is the most critical problem in Ethiopia, notably in the Ketar river watershed, which is located in the Rift Valley Basin. The Ketar River flows through rugged terrain with steep slopes and high sediment movement. The purpose of this research is to check Soil and Water Assessment Tool (SWAT) in simulating sediment yield and to identify soil erosion-prone sites. The SWAT model sediment simulation performance was evaluated using the coefficient of determination (R2) and Nash-Sutcliffe Efficiency (NSE), with R2 and NSE values of 0.69 and 0.55 for calibration and 0.73 and 0.51 for validation, respectively using SWAT Calibration and Uncertainty Program (SWAT-CUP). The sub-basins located at the upstream of the watershed have a high sediment yield rate. The sediment-prone area sub-basins have steep slopes and were mostly covered by cultivated land. Annual sediment yield from cultivated land was approximately 1872.12 t/y, while grass land with moderately cultivated yield w...

Arabian Journal of Geosciences

Climate change and its impacts continue and become a major challenge if proper mitigation measure... more Climate change and its impacts continue and become a major challenge if proper mitigation measures are not taken. This study aimed to analyze and predict the impact of climate change on crop yield under two Representative Concentration Pathways (RCPs), high (RCP8.5) and medium (RCP4.5) emission global warming scenarios of rainfall and temperature data derived from the Coordinated Regional Climate Downscaling Experiment (CORDEX) Africa, Regional Climate Models (RCMs). The performance of REgional MOdel (REMO2009), High-Resolution Hamburg Climate Model 5 (HIRAM5), Climate Limited-Area Modeling Community (CCLM4-8), and Rossby Center Regional Atmospheric Model (RCA4) RCMs were evaluated using observed rainfall and temperature data of (1985–2005), and the results proved that the ensemble of these models performed well as compared to the performance of individual models. Bias-corrected RCMs ensemble rainfall and temperature projected data of RCP8.5 and RCP4.5 for the future period of (2030–2050) were used as an input in artificial neural network (ANN) to predict sorghum, maize, teff, and wheat yield. Analysis of the projected data shows that under RCP8.5 scenarios, the maximum temperature will increase up to 2.84 °C while the minimum temperature is expected to increase in the range of 1.36–2.2 °C. Under RCP4.5, the minimum temperature increases in the range of 0.38–1.83 °C. The projected rainfall shows that there would be a shift in maximum rainfall from July to August. Under RCP8.5 temperature scenarios, the sorghum, wheat, and teff yield would decrease within the range of 2.64–8.42%, 4.47–8.35%, and 1.77–9.77% respectively. In the RCP8.5 rainfall scenario, maize and wheat yield are expected to increase, but teff and sorghum to decrease. In the future period of 2030–2050 years, the change in temperature will have a greater impact on crop yield than the change in rainfall.

Sustainable Water Resources Management, 2021

SWAT and HEC-HMS models are widely used hydrological models for runoff simulation. The performanc... more SWAT and HEC-HMS models are widely used hydrological models for runoff simulation. The performance of these models varies based on spatial and hydro-metrological characteristics of the watershed; These models are not applied on Toba watershed for daily runoff simulation. Therefore, the ultimate objective of this research is to check the performance of SWAT and HEC-HMS models in daily runoff simulation of Toba watershed which is located in Abbay River Basin, Ethiopia using the same input data set and methods. Land Use/Land cover (LU/LC), Soil, Digital Elevation model (DEM) and daily hydro-metrological data were the input data for both models. Therefore, the daily observed stream flow-data were used for both model calibration and validation. The statistical metrics used to measure the performance of both models were, R2, NSE, PBIAS, and RMSE. The respective values for HEC-HMS were 0.85, 0.805, 33.7%, 22.7 m3/s during calibration, and 0.87, 0.84, 2.71%, 20.7 m3/s during validation. For SWAT model, the respective values were 0.69, 0.61, − 26.1%, 31.85 m3/s, and 0.62, 0.54, − 18.3, 35.24 m3/s during calibration and validation period. These values are at an acceptable level of accuracy. Therefore, both SWAT and HEC-HMS models well performed in the runoff simulation of Toba watershed. The overestimation of peak discharge and average runoff for dominantly cultivated land gives insight about the LU/LC characteristics of the watershed. The study can be used as a baseline scenario for future assessment of LU/LC and runoff potential.

Modeling Earth Systems and Environment, 2020

Streamflow modeling is essential in developing long-term water resource management plans. Especia... more Streamflow modeling is essential in developing long-term water resource management plans. Especially in the inaccessible area like Toba sub-watershed, Ethiopia, modeling is an alternative means of obtaining streamflow data. Knowing of the hydrological response of a watershed would help to resolve potential water resources problems associated with floods, droughts, and availability of water for irrigation, hydropower, domestic and industrial use, and to develop the adaptation and preparedness strategies to meet these challenges, in case of their occurrence. In the present study, the Soil and Water Assessment Tool (ArcSWAT version 2012) model was used to simulate streamflow from Toba sub-watershed located in the southwest part of Ethiopia. The model Sensitivity analysis, calibration, and validation made using a sequential uncertainty fitting (SUFI-2) method of the ArcSWAT Calibration Uncertainty program known as SWAT-CUP2012. Groundwater delay (GW_DELAY) and curve number (CN2) were the first and the second most sensitive parameters. Calibration and validation results indicated a good much between the measured and simulated streamflow data with R 2 , 0.82 and 0.70 and NSE, 0.72, and 0.68, respectively. The mean monthly stream simulated at Toba station was 58.71m 3 /s and 55.91m 3 /s during calibration and validation, respectively, and the mean annual runoff of the Toba river was 434.38 mm.

Journal of Sedimentary Environments, 2020

Surface runoff is a critical input in watershed management. Runoff is a driving force for soil er... more Surface runoff is a critical input in watershed management. Runoff is a driving force for soil erosion which causes sedimentation of reservoirs located at downstream of watersheds. The present study aimed to model surface runoff using the Soil and Water Assessment Tools (SWAT) model in Ketar watershed, Ethiopia. Ketar river crosses mountainous steep slope areas. High surface runoff from the Ketar watershed flows to Lake Ziway. The Ketar watershed was delineated into 35 sub-basins and 147 Hydraulic Response Units (HRUs). In this work, surface runoff was simulated using 36 years (1980–2015) meteorological data as input. The model was calibrated and validated for streamflow using sequential uncertainty fitting-2 (SUFI_2) of the SWAT Calibration and Uncertainty Programs (SWAT_CUP). The model calibrated using 12-year measured streamflow data (1988–1997) and validated using 7-year streamflow data (1998–2004). The coefficient of determination (R2) and Nash–Sutcliffe (NSE) were used to measure the performance of the model. R2 and NSE were 0.82 and 0.7 during calibration and 0.78 and 0.71 during validation, respectively. The results show that there was an excellent relation between monthly observed and simulated streamflow during both calibration and validation. Simulated average monthly surface runoff of the watershed was 112.82 mm per month. The southwest part of the watershed, which was characterized by highest annual surface runoff, covers 27% of the total area.

Journal of Hydrometeorology, 2003

Probable maximum precipitation (PMP) is the conceptual construct that defines the magnitude of ex... more Probable maximum precipitation (PMP) is the conceptual construct that defines the magnitude of extreme storms used in the design of dams and reservoirs. In this study, the value and utility of applying multifractal analysis techniques to systematically calculate physically meaningful estimates of maximum precipitation from observations in the eastern United States is assessed. The multifractal approach is advantageous because it provides a formal framework to infer the magnitude of extreme events independent of empirical adjustments, which is called the fractal maximum precipitation (FMP), as well as an objective estimate of the associated risk. Specifically, multifractal (multiscaling) behavior of maximum accumulated precipitation at daily (327 rain gauges) and monthly (1400 rain gauges) timescales, as well as maximum accumulated 6-hourly precipitable water fluxes for the period from 1950 to 1997 were characterized. Return periods for the 3-day FMP estimates in this study ranged from 5300 to 6200 yr. The multifractal parameters were used to infer the magnitude of extreme precipitation consistent with engineering design criterion (e.g., return periods of 10 6 yr), the design probable maximum precipitation (DPMP). The FMP and DPMP were compared against PMP estimates for small dams in Pennsylvania using the standard methodology in engineering practice (e.g., National Weather Service Hydrometeorological Reports 51 and 52). The FMP estimates were usually, but not always, found to be lower than the standard PMP (FMP/PMP ratios ranged from 0.5 to 1.0). Furthermore, a high degree of spatial variability in these ratios points to the importance of orographic effects locally, and the need for place-based FMP estimates. DMP/PMP ratios were usually greater than one (0.96 to 2.0), thus suggesting that DPMP estimates can provide a bound of known risk to the standard PMP.

Journal of Climate, 2013

This study evaluates the ability of 10 regional climate models (RCMs) from the Coordinated Region... more This study evaluates the ability of 10 regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX) in simulating the characteristics of rainfall patterns over eastern Africa. The seasonal climatology, annual rainfall cycles, and interannual variability of RCM output have been assessed over three homogeneous subregions against a number of observational datasets. The ability of the RCMs in simulating large-scale global climate forcing signals is further assessed by compositing the El Niño–Southern Oscillation (ENSO) and Indian Ocean dipole (IOD) events. It is found that most RCMs reasonably simulate the main features of the rainfall climatology over the three subregions and also reproduce the majority of the documented regional responses to ENSO and IOD forcings. At the same time the analysis shows significant biases in individual models depending on subregion and season; however, the ensemble mean has better agreement with observation than ind...

Applied and Environmental Soil Science, Sep 2, 2022

Sediment movement is the most critical problem in Ethiopia, notably in the Ketar River watershed,... more Sediment movement is the most critical problem in Ethiopia, notably in the Ketar River watershed, which is located in the Rift Valley Basin. e Ketar River ows through rugged terrain with steep slopes and high sediment movement. e purpose of the study is to evaluate the Soil and Water Assessment Tool's (SWAT) ability to simulate sediment and to identify areas that are vulnerable to soil erosion. is will aid water resource planners in determining the appropriate corrective action. In SWAT sediment sensitivity analysis, the USLE soil erodibility factor (USLE-K) is found to be the most sensitive sediment parameter. e SWAT model sediment simulation performance is evaluated using the coe cient of determination (R 2) and Nash-Sutcli e E ciency (NSE). e model performance results in R 2 and NSE values of 0.69 and 0.55 for calibration and 0.73 and 0.51 for validation, respectively, using the SWAT Calibration and Uncertainty Program (SWAT-CUP). e sediment-prone area subbasins have steep slopes and were mostly covered by cultivated land. Annual sediment yield from cultivated land was approximately 1872.12 t/y, while yield for moderately cultivated grassland was 171.45 t/y. Woodland and forest land have less soil erosion rate. e subbasin highly covered by Eutric Nitisols is found in very high soil erosion-prone areas. Sediment yield from a slight slope is almost zero, whereas sediment yield from steep and very steep slopes is very high. e slope of the subbasin is an important factor in determining sediment yield, followed by land cover and soil types. e very high sediment yield rate area accounted for 39.64% of the total subbasin and it needs soil conservation planning.

Research Square (Research Square), Aug 30, 2022

Hydrological measurements are vital for Water Resources Planning and Management. Modeling rainfal... more Hydrological measurements are vital for Water Resources Planning and Management. Modeling rainfallrunoff may be used to understand the impact of future hydrological changes such as ooding, soil loss, and sedimentation effect on lakes and reservoirs for irrigation and hydropower. But the di cult one is the selection of the best models. All hydrological models may not be equally performed due to being in uenced by input data and over models system that will be used for the analysis. Therefore, two hydrological models; Soil and Water Assessment Tool (SWAT), and Hydrologic Engineering Centers Hydrological Modeling System (HEC-HMS) models to simulate rainfall runoff. These models were calibrated and validated using daily observed stream ow data. The R 2 and NSE were used to check the performance of the models and the result indicates that during HEC-HMS model calibration and validation, R 2 of 0.6 and 0.61, NSE of 0.55 and 0.53, generated respectively. During the SWAT model accuracy assessment, the values of model performance indicators were R 2 of 0.69 and 0.68, NSE of 0.58 and 0.52 for calibration and validation respectively. This indicates both SWAT and HEC-HMS models have been satis ed in stream ow simulations. The SWAT model overestimated the daily stream ow more than the observed and HEC-HMS simulated stream ow. These models overestimated peak stream ow during both the calibration and validation period. The curve number grid generated by HEC-GeoHMS was slightly lower than the curve number simulated by the SWAT model.

Sediment movement is the most critical problem in Ethiopia, notably in the Ketar river watershed,... more Sediment movement is the most critical problem in Ethiopia, notably in the Ketar river watershed, which is located in the Rift Valley Basin. The Ketar River flows through rugged terrain with steep slopes and high sediment movement. The purpose of this research is to check Soil and Water Assessment Tool (SWAT) in simulating sediment yield and to identify soil erosion-prone sites. The SWAT model sediment simulation performance was evaluated using the coefficient of determination (R2) and Nash-Sutcliffe Efficiency (NSE), with R2 and NSE values of 0.69 and 0.55 for calibration and 0.73 and 0.51 for validation, respectively using SWAT Calibration and Uncertainty Program (SWAT-CUP). The sub-basins located at the upstream of the watershed have a high sediment yield rate. The sediment-prone area sub-basins have steep slopes and were mostly covered by cultivated land. Annual sediment yield from cultivated land was approximately 1872.12 t/y, while grass land with moderately cultivated yield w...

Arabian Journal of Geosciences

Climate change and its impacts continue and become a major challenge if proper mitigation measure... more Climate change and its impacts continue and become a major challenge if proper mitigation measures are not taken. This study aimed to analyze and predict the impact of climate change on crop yield under two Representative Concentration Pathways (RCPs), high (RCP8.5) and medium (RCP4.5) emission global warming scenarios of rainfall and temperature data derived from the Coordinated Regional Climate Downscaling Experiment (CORDEX) Africa, Regional Climate Models (RCMs). The performance of REgional MOdel (REMO2009), High-Resolution Hamburg Climate Model 5 (HIRAM5), Climate Limited-Area Modeling Community (CCLM4-8), and Rossby Center Regional Atmospheric Model (RCA4) RCMs were evaluated using observed rainfall and temperature data of (1985–2005), and the results proved that the ensemble of these models performed well as compared to the performance of individual models. Bias-corrected RCMs ensemble rainfall and temperature projected data of RCP8.5 and RCP4.5 for the future period of (2030–2050) were used as an input in artificial neural network (ANN) to predict sorghum, maize, teff, and wheat yield. Analysis of the projected data shows that under RCP8.5 scenarios, the maximum temperature will increase up to 2.84 °C while the minimum temperature is expected to increase in the range of 1.36–2.2 °C. Under RCP4.5, the minimum temperature increases in the range of 0.38–1.83 °C. The projected rainfall shows that there would be a shift in maximum rainfall from July to August. Under RCP8.5 temperature scenarios, the sorghum, wheat, and teff yield would decrease within the range of 2.64–8.42%, 4.47–8.35%, and 1.77–9.77% respectively. In the RCP8.5 rainfall scenario, maize and wheat yield are expected to increase, but teff and sorghum to decrease. In the future period of 2030–2050 years, the change in temperature will have a greater impact on crop yield than the change in rainfall.

Sustainable Water Resources Management, 2021

SWAT and HEC-HMS models are widely used hydrological models for runoff simulation. The performanc... more SWAT and HEC-HMS models are widely used hydrological models for runoff simulation. The performance of these models varies based on spatial and hydro-metrological characteristics of the watershed; These models are not applied on Toba watershed for daily runoff simulation. Therefore, the ultimate objective of this research is to check the performance of SWAT and HEC-HMS models in daily runoff simulation of Toba watershed which is located in Abbay River Basin, Ethiopia using the same input data set and methods. Land Use/Land cover (LU/LC), Soil, Digital Elevation model (DEM) and daily hydro-metrological data were the input data for both models. Therefore, the daily observed stream flow-data were used for both model calibration and validation. The statistical metrics used to measure the performance of both models were, R2, NSE, PBIAS, and RMSE. The respective values for HEC-HMS were 0.85, 0.805, 33.7%, 22.7 m3/s during calibration, and 0.87, 0.84, 2.71%, 20.7 m3/s during validation. For SWAT model, the respective values were 0.69, 0.61, − 26.1%, 31.85 m3/s, and 0.62, 0.54, − 18.3, 35.24 m3/s during calibration and validation period. These values are at an acceptable level of accuracy. Therefore, both SWAT and HEC-HMS models well performed in the runoff simulation of Toba watershed. The overestimation of peak discharge and average runoff for dominantly cultivated land gives insight about the LU/LC characteristics of the watershed. The study can be used as a baseline scenario for future assessment of LU/LC and runoff potential.

Modeling Earth Systems and Environment, 2020

Streamflow modeling is essential in developing long-term water resource management plans. Especia... more Streamflow modeling is essential in developing long-term water resource management plans. Especially in the inaccessible area like Toba sub-watershed, Ethiopia, modeling is an alternative means of obtaining streamflow data. Knowing of the hydrological response of a watershed would help to resolve potential water resources problems associated with floods, droughts, and availability of water for irrigation, hydropower, domestic and industrial use, and to develop the adaptation and preparedness strategies to meet these challenges, in case of their occurrence. In the present study, the Soil and Water Assessment Tool (ArcSWAT version 2012) model was used to simulate streamflow from Toba sub-watershed located in the southwest part of Ethiopia. The model Sensitivity analysis, calibration, and validation made using a sequential uncertainty fitting (SUFI-2) method of the ArcSWAT Calibration Uncertainty program known as SWAT-CUP2012. Groundwater delay (GW_DELAY) and curve number (CN2) were the first and the second most sensitive parameters. Calibration and validation results indicated a good much between the measured and simulated streamflow data with R 2 , 0.82 and 0.70 and NSE, 0.72, and 0.68, respectively. The mean monthly stream simulated at Toba station was 58.71m 3 /s and 55.91m 3 /s during calibration and validation, respectively, and the mean annual runoff of the Toba river was 434.38 mm.

Journal of Sedimentary Environments, 2020

Surface runoff is a critical input in watershed management. Runoff is a driving force for soil er... more Surface runoff is a critical input in watershed management. Runoff is a driving force for soil erosion which causes sedimentation of reservoirs located at downstream of watersheds. The present study aimed to model surface runoff using the Soil and Water Assessment Tools (SWAT) model in Ketar watershed, Ethiopia. Ketar river crosses mountainous steep slope areas. High surface runoff from the Ketar watershed flows to Lake Ziway. The Ketar watershed was delineated into 35 sub-basins and 147 Hydraulic Response Units (HRUs). In this work, surface runoff was simulated using 36 years (1980–2015) meteorological data as input. The model was calibrated and validated for streamflow using sequential uncertainty fitting-2 (SUFI_2) of the SWAT Calibration and Uncertainty Programs (SWAT_CUP). The model calibrated using 12-year measured streamflow data (1988–1997) and validated using 7-year streamflow data (1998–2004). The coefficient of determination (R2) and Nash–Sutcliffe (NSE) were used to measure the performance of the model. R2 and NSE were 0.82 and 0.7 during calibration and 0.78 and 0.71 during validation, respectively. The results show that there was an excellent relation between monthly observed and simulated streamflow during both calibration and validation. Simulated average monthly surface runoff of the watershed was 112.82 mm per month. The southwest part of the watershed, which was characterized by highest annual surface runoff, covers 27% of the total area.

Journal of Hydrometeorology, 2003

Probable maximum precipitation (PMP) is the conceptual construct that defines the magnitude of ex... more Probable maximum precipitation (PMP) is the conceptual construct that defines the magnitude of extreme storms used in the design of dams and reservoirs. In this study, the value and utility of applying multifractal analysis techniques to systematically calculate physically meaningful estimates of maximum precipitation from observations in the eastern United States is assessed. The multifractal approach is advantageous because it provides a formal framework to infer the magnitude of extreme events independent of empirical adjustments, which is called the fractal maximum precipitation (FMP), as well as an objective estimate of the associated risk. Specifically, multifractal (multiscaling) behavior of maximum accumulated precipitation at daily (327 rain gauges) and monthly (1400 rain gauges) timescales, as well as maximum accumulated 6-hourly precipitable water fluxes for the period from 1950 to 1997 were characterized. Return periods for the 3-day FMP estimates in this study ranged from 5300 to 6200 yr. The multifractal parameters were used to infer the magnitude of extreme precipitation consistent with engineering design criterion (e.g., return periods of 10 6 yr), the design probable maximum precipitation (DPMP). The FMP and DPMP were compared against PMP estimates for small dams in Pennsylvania using the standard methodology in engineering practice (e.g., National Weather Service Hydrometeorological Reports 51 and 52). The FMP estimates were usually, but not always, found to be lower than the standard PMP (FMP/PMP ratios ranged from 0.5 to 1.0). Furthermore, a high degree of spatial variability in these ratios points to the importance of orographic effects locally, and the need for place-based FMP estimates. DMP/PMP ratios were usually greater than one (0.96 to 2.0), thus suggesting that DPMP estimates can provide a bound of known risk to the standard PMP.

Journal of Climate, 2013

This study evaluates the ability of 10 regional climate models (RCMs) from the Coordinated Region... more This study evaluates the ability of 10 regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX) in simulating the characteristics of rainfall patterns over eastern Africa. The seasonal climatology, annual rainfall cycles, and interannual variability of RCM output have been assessed over three homogeneous subregions against a number of observational datasets. The ability of the RCMs in simulating large-scale global climate forcing signals is further assessed by compositing the El Niño–Southern Oscillation (ENSO) and Indian Ocean dipole (IOD) events. It is found that most RCMs reasonably simulate the main features of the rainfall climatology over the three subregions and also reproduce the majority of the documented regional responses to ENSO and IOD forcings. At the same time the analysis shows significant biases in individual models depending on subregion and season; however, the ensemble mean has better agreement with observation than ind...