Volume 16, Issue 1 (3-2026)
J Watershed Manage Res 2026, 16(1): 14-26 |
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Yahyavi Dizaj A, Akbari Azirani T, Javan K. (2026). Evaluation of the Climate Change Effect on Minimum and Maximum Temperatures and the Reference Evapotranspiration in the Lake Urmia Basin Using CMIP6 Models. J Watershed Manage Res. 16(1), 14-26. doi:10.61186/jwmr.2024.1269
URL: http://jwmr.sanru.ac.ir/article-1-1269-en.html
URL: http://jwmr.sanru.ac.ir/article-1-1269-en.html
1- Department of Physical Geography, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran
2- Department of Geography, Faculty of Literature and Humanities, Urmia University, Urmia, Iran
2- Department of Geography, Faculty of Literature and Humanities, Urmia University, Urmia, Iran
Abstract: (813 Views)
Extended Abstract
Background: Climate change as an influential phenomenon causes changes in climate systems, increasing both the temperature and the moisture capacity of the atmosphere so that the increase in global temperature has increased the evaporation from the surface and the atmosphere water content. Therefore, an increase in temperature and the moisture capacity of the air, when there is a moisture source, increases the specific humidity of the air and decreases relative humidity. This causes the total water vapor in the atmosphere to rise, and water vapor, as a greenhouse gas, causes global warming. In this regard, one of the most important consequences of climate change is its influence on factors affecting the hydrological status of basins, such as temperature, precipitation, and reference evapotranspiration (ET). Therefore, knowing the rate of evapotranspiration in each point, especially in arid and semi-arid regions such as Iran, and more specifically in the Lake Urmia basin, where its activities are mainly related to agriculture, is very important for determining the water needs of plants and managing water resources, hence the study of ET is more necessary under the influence of climate change. Therefore, climate change is a phenomenon affecting reference ET as the most important part of the hydrological cycle because climate changes can have significant effects on the biosphere.
Methods: In this research, the effect of climate change on minimum and maximum temperatures and average reference evapotranspiration in the Lake Urmia basin was evaluated on a monthly scale with CMIP6 climate models in mm per month using the observation data of Urmia, Tabriz, and Saghez synoptic stations. The minimum and maximum temperatures on a monthly scale and for the statistical period of 1975 to 2014 were received from the IRAN Meteorological Organization (IRIMO). The second category is the data of CMIP6 climate models in the historical period of the model, which have a common period with the observation period (1975-2014), the periods of the near future (2020-2059), and the far future (2060-2099). Sixth report models were obtained from historical and future periods on a monthly scale. Two climate models (CESM2 and IPSL-CM6A-LR) under the optimistic SSP1-2.6 and pessimistic SSP5-8.5 scenarios in the near future (2020-2059) and far future (2060-2099) were used to investigate the effects of climate change and predict minimum and maximum temperature changes as well as changes in reference ET on a monthly scale. Downscaling was done using the LS method, and climate models were validated using R2 and MAE statistics. Finally, the crop reference ET was calculated for basic, near, and far future by Makkink and Turc methods.
Results: In the present study, the results of CESM2 and IPSL-CM6A-LR models using R2 and MAE for the future period compared to the base period showed that the optimistic scenario would perform better in the near future in both models. In the mentioned models and in Urmia, Tabriz, and Saghez stations, the optimistic scenario showed the proper performance of the models with a high R2 (0.99, 0.99, and 0.99 for Tmin and 0.99, 0.99, and 1.00 for Tmax) and a low MAE (1.48, 1.27, and 1.37 for Tmin and 1.54, 1.49, and 1.55 for Tmax), respectively. The results of examining the changes in minimum and maximum temperatures and reference ET were presented in different tables and graphs. Accordingly, the minimum and maximum temperature ranges and, accordingly, the reference ET obtained from the Makkink and Turc methods will increase in optimistic and pessimistic scenarios and in the near and far future periods in Urmia, Tabriz, and Saghez stations. According to the results, the average minimum and maximum temperatures will increase in future periods and under both scenarios. Moreover, the average minimum and maximum temperatures will increase in the investigated stations according to optimistic and pessimistic scenarios. An effect of climate change is the increase in temperature, and one of its consequences is the increase in ET and the water requirement of plants. Furthermore, the main part of activities in the Lake Urmia basin is focused on agriculture and plays an important role in the employment and economy of this region. Therefore, climate change will cause many environmental problems by affecting the temperature and reference ET in the coming years.
Conclusion: To know the average minimum and maximum temperature changes and reference ET in the study area, the effect of climate change on minimum and maximum temperatures and reference ET in the Lake Urmia basin was evaluated using CMIP6 models. The mentioned variables were predicted using the observation data of Urmia, Tabriz, and Saghez stations as well as CESM2 and IPSL-CM6A-LR models of the sixth report. Downscaling was done by the LS method during the base period (1975-2014) and two future periods (2020-2059 and 2060-2099) under optimistic and pessimistic scenarios. R2 and MAE statistics were used to validate climate models. Finally, the Makkink and Turc methods were used to calculate reference ET. The results indicate that the minimum temperature will increase from 0.05 to 3.02 and 0.60 to 4.31 ℃, and the maximum temperature will increase from 0.25 to 3.84 and 0.55 to 5.41 ℃ in the near and far future compared to the base period, respectively. Moreover, the average reference ET will increase from 0.72 to 4.68 and 0.08 to 4.80 mm/month by the Makkink method and from 0.24 to 5.23 and 0.71 to 5.59 mm/month by the Turc method in the near and far future, respectively.
Background: Climate change as an influential phenomenon causes changes in climate systems, increasing both the temperature and the moisture capacity of the atmosphere so that the increase in global temperature has increased the evaporation from the surface and the atmosphere water content. Therefore, an increase in temperature and the moisture capacity of the air, when there is a moisture source, increases the specific humidity of the air and decreases relative humidity. This causes the total water vapor in the atmosphere to rise, and water vapor, as a greenhouse gas, causes global warming. In this regard, one of the most important consequences of climate change is its influence on factors affecting the hydrological status of basins, such as temperature, precipitation, and reference evapotranspiration (ET). Therefore, knowing the rate of evapotranspiration in each point, especially in arid and semi-arid regions such as Iran, and more specifically in the Lake Urmia basin, where its activities are mainly related to agriculture, is very important for determining the water needs of plants and managing water resources, hence the study of ET is more necessary under the influence of climate change. Therefore, climate change is a phenomenon affecting reference ET as the most important part of the hydrological cycle because climate changes can have significant effects on the biosphere.
Methods: In this research, the effect of climate change on minimum and maximum temperatures and average reference evapotranspiration in the Lake Urmia basin was evaluated on a monthly scale with CMIP6 climate models in mm per month using the observation data of Urmia, Tabriz, and Saghez synoptic stations. The minimum and maximum temperatures on a monthly scale and for the statistical period of 1975 to 2014 were received from the IRAN Meteorological Organization (IRIMO). The second category is the data of CMIP6 climate models in the historical period of the model, which have a common period with the observation period (1975-2014), the periods of the near future (2020-2059), and the far future (2060-2099). Sixth report models were obtained from historical and future periods on a monthly scale. Two climate models (CESM2 and IPSL-CM6A-LR) under the optimistic SSP1-2.6 and pessimistic SSP5-8.5 scenarios in the near future (2020-2059) and far future (2060-2099) were used to investigate the effects of climate change and predict minimum and maximum temperature changes as well as changes in reference ET on a monthly scale. Downscaling was done using the LS method, and climate models were validated using R2 and MAE statistics. Finally, the crop reference ET was calculated for basic, near, and far future by Makkink and Turc methods.
Results: In the present study, the results of CESM2 and IPSL-CM6A-LR models using R2 and MAE for the future period compared to the base period showed that the optimistic scenario would perform better in the near future in both models. In the mentioned models and in Urmia, Tabriz, and Saghez stations, the optimistic scenario showed the proper performance of the models with a high R2 (0.99, 0.99, and 0.99 for Tmin and 0.99, 0.99, and 1.00 for Tmax) and a low MAE (1.48, 1.27, and 1.37 for Tmin and 1.54, 1.49, and 1.55 for Tmax), respectively. The results of examining the changes in minimum and maximum temperatures and reference ET were presented in different tables and graphs. Accordingly, the minimum and maximum temperature ranges and, accordingly, the reference ET obtained from the Makkink and Turc methods will increase in optimistic and pessimistic scenarios and in the near and far future periods in Urmia, Tabriz, and Saghez stations. According to the results, the average minimum and maximum temperatures will increase in future periods and under both scenarios. Moreover, the average minimum and maximum temperatures will increase in the investigated stations according to optimistic and pessimistic scenarios. An effect of climate change is the increase in temperature, and one of its consequences is the increase in ET and the water requirement of plants. Furthermore, the main part of activities in the Lake Urmia basin is focused on agriculture and plays an important role in the employment and economy of this region. Therefore, climate change will cause many environmental problems by affecting the temperature and reference ET in the coming years.
Conclusion: To know the average minimum and maximum temperature changes and reference ET in the study area, the effect of climate change on minimum and maximum temperatures and reference ET in the Lake Urmia basin was evaluated using CMIP6 models. The mentioned variables were predicted using the observation data of Urmia, Tabriz, and Saghez stations as well as CESM2 and IPSL-CM6A-LR models of the sixth report. Downscaling was done by the LS method during the base period (1975-2014) and two future periods (2020-2059 and 2060-2099) under optimistic and pessimistic scenarios. R2 and MAE statistics were used to validate climate models. Finally, the Makkink and Turc methods were used to calculate reference ET. The results indicate that the minimum temperature will increase from 0.05 to 3.02 and 0.60 to 4.31 ℃, and the maximum temperature will increase from 0.25 to 3.84 and 0.55 to 5.41 ℃ in the near and far future compared to the base period, respectively. Moreover, the average reference ET will increase from 0.72 to 4.68 and 0.08 to 4.80 mm/month by the Makkink method and from 0.24 to 5.23 and 0.71 to 5.59 mm/month by the Turc method in the near and far future, respectively.
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