Long-term forecast of flow dynamics of Chirchik basin (original) (raw)
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Water, 2020
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Assessment of climate change impact on streamflow in the Chaliyar Basin
2011
The increase in concentration of carbon dioxide and other greenhouse gases in the atmosphere is expected to have a significant effect on hydrological regimes. General Circulation Models (GCMs) are probably the best available tool to evaluate the effects of rising concentrations of greenhouse gases in the atmosphere on rainfall and temperature, through a continuous, three dimensional simulation of various atmospheric, oceanic and cryospheric processes. However the spatial resolution of these models (250km x 250km) is not compatible with that of watershed hydrologic models. To overcome this problem, the output from the GCM is downscaled with the help of Regional Climate Models (RCMs), thereby projecting the output to a finer resolution (25km x 25km). In this study, a general methodology is presented in order to use the downscaled output from a RCM directly in a hydrologic model for evaluating the impact of climate change on water resources. The hydrologic model used is the Soil and Water Assessment Tool (SWAT). The study area is a part of the Chaliyar River Basin in Kerala, India. Outputs from two scenarios, A2 and B2 are used in the RCM to predict future scenarios. The climate variables generated are rainfall and temperature. These are then input to the physically based hydrological model, SWAT to estimate the effect of climate change on streamflow. Calibration and validation of the SWAT are performed using data for a period of 5 years, viz. 1987-91 and 1999-2003, respectively. Goodness-of-fit measures such as the Nash-Sutcliffe efficiency and coefficient of correlation (R 2 ) are evaluated to assess the performance of the model. These values are found to be reasonably high, suggesting that model performance is reasonably good. It is predicted that annual streamflows in the river basin would significantly reduce in both the scenarios considered in this study. Results of the study indicate that hydrology of the basin is very sensitive to projected climate changes.
Impact of climate change on future stream flow in the Dakbla river basin
Journal of Hydroinformatics, 2014
A systematic ensemble high-resolution climate modelling study over Vietnam was performed and future hydrological changes over the small catchment of Dakbla, Central Highland region of Vietnam, were studied. Using the widely used regional climate model WRF (Weather Research and Forecasting), future climate change over the period 2091-2100 was ascertained. The results indicate that surface temperature over Dakbla could increase by nearly 3.5 W C, while rainfall increases of more than 40% is likely. The ensemble hydrological changes suggest that the stream flow over the peak and post-peak rainfall seasons could experience a strong increase, suggesting risks of flooding, with an overall average annual increase of stream flow by 40%. These results have implications for water resources, agriculture, biodiversity and economy, and serve as useful findings for policy makers.
Proceedings of the International Association of Hydrological Sciences, 2018
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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.
Attribution of current trends in streamflow to climate change for 12 Central Asian catchments
Climatic Change, 2023
This study investigates the attribution of climate change to trends in river discharge during six decades from 1955 until 2014 in 12 selected river catchments across six Central Asian countries located upstream of the main rivers. For this purpose, the semi-distributed eco-hydrological model SWIM (Soil and Water Integrated Model) was firstly calibrated and validated for all study catchments. Attributing climate change to streamflow simulation trends was forced by factual (reanalysis) and counterfactual climate data (assuming the absence of anthropogenic influence) proposed in the framework of the ISIMIP (Inter-Sectoral Impact Model Intercomparison Project) or ESM without anthropogenic forcing that were firstly tested and then compared. The trend analysis was performed for three variables: mean annual discharge and high flow (Q5) and low flow (Q95) indices. The results show that trends in the annual and seasonal discharge could be attributed to climate change for some of the studied catchments. In the three northern catchments (Derkul, Shagan, and Tobol), there are positive trends, and in two catchments (Sarysu and Kafirnigan), there are negative streamflow trends under the factual climate, which could be attributed to climate change. Also, our analysis shows that the average level of discharge in Murghab has increased during the historical study period due to climate change, despite the overall decreasing trend during this period. In addition, the study reveals a clear signal of shifting spring streamflow peaks in all catchments across the study area.
2020
Climate change is becoming one of the most debating and threatening issues in terms of global context which alter regional hydrologic conditions and results in a variety of impacts on water resource systems. The aim of this study is to assess the impact of climate change on the stream flow of Dabus Sub-basin which located in upper Blue Nile Basin of Ethiopia. The CORDEX RCM downscaled and bias corrected were used for the climate projection. To estimate the level of impact of climate change, climate change scenarios of precipitation and temperature were divided into three time windows of 25 years as the whole from (2025-2099). Soil and water assessment Tool (SWAT) was calibrated and validated for stream flow simulation using SWAT-CUP with a method of SUFI2. The results showed that the value of calibration and validation reveals a good agreement with R 2 =0.84 during calibration and R 2 =0.82 during validation whereas NSE= 0.75 during calibration and NSE=0.72 during validation. The m...
Environmental Research Letters
An intercomparison of climate change impacts projected by nine regional-scale hydrological models for 12 large river basins on all continents was performed, and sources of uncertainty were quantified in the framework of the ISIMIP project. The models ECOMAG, HBV, HYMOD, HYPE, mHM, SWAT, SWIM, VIC and WaterGAP3 were applied in the following basins: Rhine and Tagus in Europe, Niger and Blue Nile in Africa, Ganges, Lena, Upper Yellow and Upper Yangtze in Asia, Upper Mississippi, MacKenzie and Upper Amazon in America, and Darling in Australia. The model calibration and validation was done using WATCH climate data for the period 1971-2000. The results, evaluated with 14 criteria, are mostly satisfactory, except for the low flow. Climate change impacts were analyzed using projections from five global climate models under four representative concentration pathways. Trends in the period 2070-2099 in relation to the reference period 1975-2004 were evaluated for three variables: the long-term mean annual flow and high and low flow percentiles Q 10 and Q 90 , as well as for flows in three months high-and low-flow periods denoted as HF and LF. For three river basins: the Lena, MacKenzie and Tagus strong trends in all five variables were found (except for Q 10 in the MacKenzie); trends with moderate certainty for three to five variables were confirmed for the Rhine, Ganges and Upper Mississippi; and increases in HF and LF were found for the Upper Amazon, Upper Yangtze and Upper Yellow. The analysis of projected streamflow seasonality demonstrated
Jurnal Pengelolaan Sumberdaya Alam dan Lingkungan (Journal of Natural Resources and Environmental Management)
Beside land use change, future climate change potentially alters streamflow fluctuation of a river basin in Indonesia. We investigated relative impact of changes in climate and land use on the streamflow fluctuation of a watershed in Jambi Province, Indonesia for future condition (2025). To account for the climate change, we simulated future rainfall and temperature scenarios using the downscaled rainfall and mean surface temperature of 24 CMIP5 GCM outputs with moderate scenario of RCP4.5. We used distributed hydrologic model (SWAT) to simulate relative impact of changes in climate and land use on the future streamflow fluctuation. The SWAT model performed well with the Nash-Sutcliff efficiency values of 0.80-0.85 (calibration) and 0.84-0.86 (validation). The results indicated that the climate change caused 32% decrease of the minimum discharge during dry season and 96% increase of the maximum peak discharge during rainy season. Meanwhile, the land use change led to 40% decrease of the minimum discharge in the dry season and 65% increase of the maximum peak discharge in wet season. Both changes indicated significant impact on the extreme events such as discharge and minimum discharge. The impact of the climate change on the increased peak discharge is more significant compared to that of the land use change. Meanwhile, the impact of the land use change on the minimum discharge is more significant compared to that of the climate change. The results of this study pointed out that both climate and land use changes potentially become crucial factors for the future discharge fluctuation in Indonesia.
Journal of Hydrology, 2020
The study analyses the impact of climate change on streamflow regime of the Mahanadi River basin (MRB) in projected climate scenarios obtained from CMIP5 models. Projections from a total of 9 Global Climate Models (GCMs) were utilized. Integrated MIKE 11 NAM-HD, a conceptual hydrological model was employed to simulate the streamflow at Hirakud and Mundali gauging sites of upper Mahanadi River basin (UMRB) and middle Mahanadi River basin (MMRB), respectively. Prior to generating the streamflow regimes for the projected scenarios, GCM simulated precipitation and temperature were bias corrected using India Meteorological Department (IMD) observed gridded precipitation and temperature datasets. Precipitation was corrected using quantile mapping technique employing four different approaches, i.e., seasonal, hybrid, monthly non-hybrid, and monthly hybrid approaches. Hybrid approaches explicitly correct the extreme rainfall using Generalized Extreme Value (GEV) distribution whereas Gamma distribution is used for normal rainfall. Temperature data was corrected using Gaussian distribution on daily basis employing monthwise time series. L-moments based frequency analysis method was used to estimate the 50-year return period rainfall for observed and bias corrected projected time series to assess the efficacy of bias correction methods in correcting the extreme events. Monthly hybrid approach was found to resolve rainfall climatology over both UMRB and MMRB with improved skill in extreme rainfall correction. Though, monthly non-hybrid approach produced the seasonal cycle of rainfall with highest accuracy, it performed poorly in correcting the extremes. Under projected climate scenarios mean annual rainfall is found to be increasing for BCC-CSM1.1(m), HadGEM2-AO, GFDL-CM3, and IPSL-CM5A-LR whereas other GCMs show mixed signal compared to their mean state of historic period (1976-2005). Streamflow regime in projected climate was analyzed using ensemble mean of simulated streamflow from identified GCMs. Mean monthly streamflow were overall found to be increasing towards the end of the century i.e., in far-future defined as 2070-2099. Daily high flows (defined at 5% and 10% exceedance probability) were found to be increasing in their magnitude and frequency in far-future whereas occurrences of low flows (defined at 90% and 95% exceedance probability) were found to be predominantly decreasing under projected climate. precipitation events has increased over most of the areas across the globe (IPCC, 2007). Altering precipitation pattern has a causal effect on water dynamics of a river basin by changing the streamflow regime. To assess the climate change impact on streamflow, projections from Global Climate Models (GCM) such as precipitation and temperature have been widely used as input to the hydrological models (Mirza et al.,