Bromand Salahi; Mahnaz Saber; Abbas Mofidi
Abstract
In this study, the perspective of reference crop evapotranspiration (ETo) in the southern part of the Aras River Basin under climate change condition was drawn using SDSM downscaling. For this purpose, meteorological data of selected synoptic stations located in this basin were used and after receiving ...
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In this study, the perspective of reference crop evapotranspiration (ETo) in the southern part of the Aras River Basin under climate change condition was drawn using SDSM downscaling. For this purpose, meteorological data of selected synoptic stations located in this basin were used and after receiving the downscaling outputs for the parameters required for estimating ETo by Penman-Monteith FAO-56, basin ETo was calculated for the near future (2021-2050). In this regard, daily reanalysis NCEP data and station daily data include: maximum and minimum temperature, wind speed, relative humidity and sunshine hours as well as output data on CanESM2 model under RCPs scenarios were used to generate future station data for estimate Aras Basin ETo. The studied stations included: Ahar, Ardabil, Parsabad, Jolfa, Khoy and Makoo and the base period for the data was considered 1985-2005. First, the efficiency of SDSM in simulating the parameters required for ETo estimation was evaluated by comparing NCEP simulated data with station data. Their comparison indicated the appropriate performance of the model in simulating data. Therefore, climatic parameters were simulated using the CanESM2 model under RCPs scenarios for the future. After calculating their monthly values, in CROPWAT was entered to estimate the basin ETo and trend of the variable for the next three decades were calculated. The results showed that the basin ETo in the future period compared to the base period will increase by an average of about 7 mm per year. In terms of stations, there will be an increase in Parsabad (102 mm) and Jolfa (66 mm). This increase also means an increase in the water needs of plants. Also, the future trends of ETo in Khoy, Makoo, Ahar and Ardabil will be decreasing.
Saeedeh Nateghi; Elham Rafiiei sardooi; Ali Azareh; Farshad Soleimani Sardoo
Abstract
Changes in water cycles in different parts of the world is one of the effects of climate change in recent decades. Evapotranspiration, as the part of the hydrological cycle, will also undergo these changes. Therefore, in the present study, the effect of climate change on potential evapotranspiration ...
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Changes in water cycles in different parts of the world is one of the effects of climate change in recent decades. Evapotranspiration, as the part of the hydrological cycle, will also undergo these changes. Therefore, in the present study, the effect of climate change on potential evapotranspiration changes in Halilrood Watershed, under RCP2.6, RCP 4.5 and RCP 8.5 scenarios using LARS-WG downscaling model and the output of the general circulation model of HadGEM2 in future (2021-2040) was studied and the rate of evapotranspiration at the basin scale was calculated based on the predicted climatic parameters using Tornthwaite method in future. According to the results of the LARS-WG model, in the study area, precipitation will decrease and the temperature will increase under all scenarios in future compared to the baseline period. Evapotranspiration will also increase based on the predicted temperature and precipitation. So that, at the basin scale, evapotranspiration will increase by 3.4, 6.8 and 8.5 under RCP 2.6, RCP 4.5 and RCP 8.5 scenarios in future (2040-2021), respectively. According to the results, the highest increase in temperature and evapotranspiration and the highest decrease in precipitation at the basin scale is related to the RCP 8.5 scenario. The results of this study can be used in studies related to water resources management, agricultural and environmental studies.
Mokhtar Karami; Rasol Sarvestan; Reza Sabouri
Abstract
The purpose of this study was to investigate the effect of climate change on the monthly discharge of Karoon Catchment as the largest basin in the country. In this study, five hydrometric stations (Bamdgeh, Telezang, Gharmaleh, Gotvand and Dezful) and three synoptic stations (Ahwaz, Dezful and Masjed ...
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The purpose of this study was to investigate the effect of climate change on the monthly discharge of Karoon Catchment as the largest basin in the country. In this study, five hydrometric stations (Bamdgeh, Telezang, Gharmaleh, Gotvand and Dezful) and three synoptic stations (Ahwaz, Dezful and Masjed Soleiman) were considered. Using the SDSM software, NCEP data and large-scale data from the general circulation model (HadCM3 for temperature and CgCM3 for water discharge) were scaled parameters under two climate scenarios A1B and A2 in the Karun Basin. Then, the climate change data and the output of the microscale model were applied to the SPSS 19 and Minitab 17 to predict the significance of water discharge for future climate courses (2020-2070) be simulated. Results of climate change analysis showed that under different scenarios, monthly air temperature in the scenario A1B increases by 1.60°C and in the scenario A2 1.58°C, but the average annual rate of stations in the scenario A1B is 19.82 m S-1 in size and 16.27 m S-1 in the A2 scenario. The modified Kendall and age tests were used to identify seasonal and semi-annual seasonal time series trends. Results also showed that under climate scenarios of discharge in spring and first half of the year, there was no significant trend at 95% of confidence, but in other seasons of the second half of the year, there was a significant decrease.
Sima Rahimi Bondarabadi
Abstract
Increasing the greenhouse gases not only has impacts on the weather parameters, but also, has impact on water resources, agriculture, environment, health and economy. Climate change has significant effects on water resources by changing the hydrological cycle. There are several simulation methods for ...
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Increasing the greenhouse gases not only has impacts on the weather parameters, but also, has impact on water resources, agriculture, environment, health and economy. Climate change has significant effects on water resources by changing the hydrological cycle. There are several simulation methods for investigating the effects of climate change on different systems in the future, like climate models. The AOGCM model is able to simulate global climate in an area of some ten dousant km2, but, while they are not suitable for regional scale. For this reason, downscaling methods such as dynamic methods are used. These methods are based on high resolution and analysis of climate models. In this research, the impact of climate change was investigated on the low flow of Karkheh Basin as one the most important basins due to its water product and agricultural point of view. For this purpose, the PRECIS which is exponential dynamics and downscaling model, was used to estimate the temperature and precipitation in the period of 2070 to 2100 under A2 and B2 scenarios. The SWAT model, a comprehensive and continuous hydrological model was also used to estimate the flow discharge for the watershed. After calibration and validation of the SWAT model, the amount of rainfall and temperature used as input for PRECIS model under different climate scenarios and finally the daily flow rate was estimated for sub-basins. Then the indices of low flow rates (Q75, Q90 and Q95) and low flow series frequency analysis of 10 and 30 days were assessed. Results showed that rainfall and flow rate have negative and temperature have positive trend. In general, the results of PRECIS model indicated that this model has a good estimate of temperature and precipitation in the region, but, it is not strong for rainfall in autumn and spring, due to the local nature of the precipitation. The climate change assessment under scenario A2, indicated the rise of low flow rate by 70 percent, and this increase of low flow was more in the northern parts of basin, while under the scenario B2 the low flow rate droped by 50 percent for the period of 2080. But, low flow distribution had no change compared to base period.Thus, sever droughts would happen in the central and some northern parts of basin. It can be concluded that under different scenarios, climate change has different impact on the low flow rate. Therefore, due to the different impacts of climate change on low flow rate under different scenarios, uncertainties of scenarios as well as regional economic and social status should be considered in the management plans.
Jaber Salehpoor; Afshin Ashrafzadeh; Seyed Ali Moussavi
Abstract
In the present study, the effect of climate change on the flow of the Hablehroud River was assessed, using the HadCM3 general circulation model, the LRAS-WG downscaling model, and the SWAT hydrologic model. First, using the LARS-WG model, the output of HadCM3 model in the period of 2011-2040 was downscaled ...
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In the present study, the effect of climate change on the flow of the Hablehroud River was assessed, using the HadCM3 general circulation model, the LRAS-WG downscaling model, and the SWAT hydrologic model. First, using the LARS-WG model, the output of HadCM3 model in the period of 2011-2040 was downscaled and the necessary data for the SWAT model were obtained. The downscaling results showed that there is no meaningful difference between the future precipitation and the precipitation observed in the base period of 1995-2010. It was also observed that in the A2, B1, and A1B emission scenarios, the mean of minimum temperature will increase by 0.59, 0.47, and 0.43 0C, respectively, and the mean of maximum temperature will increase by 0.51, 0.39, and 0.35 0C. In the next stage, the SWAT model was calibrated and validated using the monthly flow data recorded at Bonkouh gaging station located at the outlet of the basin. The values of the coefficient of determination and Nash-Sutcliffe in validation phase were 0.8 and 0.72, respectively. Introducing the downscaled rainfall and temperature data to the SWAT model, the variation of the basin outflow was simulated in the period of 2011-2040. Results showed that in the three scenarios under study, the annual flow will increase 10.66, 17.72, and 17.52% in comparison to the base period.
Abbasali Mohammadian; Ali Talebi; - -; - -
Abstract
Weather generator models are used to predict climate parameters variations caused by climate change phenomenon. It can be used as a downscaling method for hydrological modeling, risk assessments in agriculture etc. Herein this research, HadCm3 model were used. Three different scenarios were considered. ...
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Weather generator models are used to predict climate parameters variations caused by climate change phenomenon. It can be used as a downscaling method for hydrological modeling, risk assessments in agriculture etc. Herein this research, HadCm3 model were used. Three different scenarios were considered. Downscaling were done using LARS-WG model. LARS-WG is a statistical downscaling model. Different climatic parameters such as minimum and maximum monthly temperature, minimum and maximum precipitation were predicted based on A1B, B1 and A2 scenarios. This research was done for Balqur Watershed in Kardeh Dam in Mashhad. Base line period is 1961-2010. Prediction was done for 2046-2065. Results showed that changes in minimum temperature would be higher than maximum in 2046-2065. Generally precipitation would be decreased except for a light increase in A2 scenario. But even if it is considered, it would not be as important as an increase in temperature would increase evaporation too. So, with regard to this fact and be aware of directly and indirectly negative effects of climate change on the environment and other sectors, strategic long-term plans to manage the new situation seems inevitable and necessary.
Behnoush Farrokhzadeh; Sepideh Choobeh; Hamid Nouri; Massoud Goodarzi
Abstract
In addition to climate change, the land use changes as an ancillary factor affects flooding. Thus evaluation of impacts of climate change and land use change (together) on flood situation in the coming decades will open a new way to deal with this phenomenon. In this research, to study the effects of ...
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In addition to climate change, the land use changes as an ancillary factor affects flooding. Thus evaluation of impacts of climate change and land use change (together) on flood situation in the coming decades will open a new way to deal with this phenomenon. In this research, to study the effects of climate change on 2020s in Balighloo Chai Watershed, HadCM3 under A2 and B1 senarios was downscaled with LARS-WG. Results showed an increase between 8.78 to 12.86 percent in average of annual rainfall in 2020s. Average annual temperture increases 0.66 °C in 2020s. After examining past hanges in land use, two scenarios were developed to predict the impact of land use changes on the runoff in the coming decades: the first scenario assumes a constant in current land use and the second scenario assumes continuation of changes rate during past decades in the future. Results showed a decrease between nine percent in rangelands and five percent increase in agricultural lands area respectively in 2020s. In order to simulate the hydrologic system in the coming decades, HEC-HMS model was calibrated and validated using data of past period, and was used with new curve number, impersive area and hytograph estimated for the future decades. Then the coming decades predicted hydrographs were compared to the past ones. Results showed an increase in peak flow and flood volume in April while they will decrease in March, May and June. If land use change occures with climate change, this increase will be intensified.
Mohammadreza Khazaei; Ahmad Sharafati; Hadis Khazaei
Abstract
One of the most important impacts of climate change is the change of snowfall regime, especially extreme snowfalls in the future. Extreme snowfalls will be affected by increasing in extreme rainfalls and temperature oppositely in the future climate while the trend of changes is not clear. In this paper, ...
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One of the most important impacts of climate change is the change of snowfall regime, especially extreme snowfalls in the future. Extreme snowfalls will be affected by increasing in extreme rainfalls and temperature oppositely in the future climate while the trend of changes is not clear. In this paper, climate change impact on extreme daily rainfalls in the Mehrabad station of Tehran is assessed. Future daily precipitation and temperature projections of the CGCM3 model under B1, A2, and A1B emission scenarios are downscaled using IWG stochastic model. Snowfall is simulated using temperature threshold criteria, and climate change impact is assessed on snowfall in 2036-65 period. Results of the validation tests showed that the IWG model have reproduced a broad range of the temperature and precipitation statistics. Also, snowfall statistics specially the annual maximum daily snowfall distribution are well reproduced. The climate change impact assessment results showed that under various emission scenarios, despite increasing in extreme precipitation in the future in the Tehran Mehrabad station, annual maxima daily snowfalls would greatly decrease. So that, maximum daily snowfall with return period of two years would decrease more than 50% under all considered scenarios.
Shahla Tavangar; Hamidreza Moradi; Alireza Massah Bavani; Mahmood Azari
Abstract
Climate is a complex system that changing mostly due to increased greenhouse gases and global warming, leading to intensification of change in climatic factors such as precipitation amount and intensity of extreme precipitation events. In effect of climate change in the future, change amount and volume ...
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Climate is a complex system that changing mostly due to increased greenhouse gases and global warming, leading to intensification of change in climatic factors such as precipitation amount and intensity of extreme precipitation events. In effect of climate change in the future, change amount and volume of the soil erosion is expected which the most important sensitive factor will be the rain fall erosivity. The aim of this study was to determine the effect of climate change on rainfall erosivity factor. For this purpose the HadCM3 model from A1B scenario was used and downscaling with LARS-WG model was used. So monitoring of rainfall erosivity factor for three periods of 2011-2030, 2045-2065, and 2080-2099 in north of Iran was simulated. Results show that rainfall erosivity factor in Sangdeh, Babol, Korkorsar, Anzali, Behshar and Gorgan stations will be increasing during the 2011-2030 period but for stations in Babolsar, Hashtpar, Rasht and Gorgan in the period 2045-2065 and 2080-2099 decreased. According of calculations, maximum changes of the rainfall erosivity factor in future will be occurring during the 2011-2030 and it’s minimum will be occurring period the 2080-2099. So largest rainfall erosivity factor was simulated about 42.6 MJ mm ha-1 h-1 for Hashtpar station during the 2011 to 2030 period. The obtained results show that the erosivity factor increase will be during the current century in the north of Iran.
