عنوان مقاله [English]
Climate change and its impacts stand as the most important challenge to the world. One of the fundamental issues that have emerged in recent decades is the limited water resources. Because of the high dependence on precipitation, water resources are heavily susceptible to damage from climate change. Projection the effects associated with climate change is a major part of strategic planning in the current century. Cold climate regions are the main reservoir and feeding source for surface and underground water and a vital supplier of hydroelectric power in Iran. Any change in the seasonal precipitation situation will have severe outcomes for the status of water resources in cold regions. The purpose of this study is to investigate the impacts of climate change on seasonal precipitation in cold regions of Iran based on the outputs of new CMIP5 models and radiative forcing (RCP) scenarios.
Alongside this, changes were first observed for the period 1980-2005. Afterwards, the data for the upcoming period up to the 2090 horizon were processed using the models BCC-CSM1.1, HadGEM2-ES, GFDL-CM3, MIROC-ESM and GISS-E2-R from the series of CMIP5 models of the MarksimGCM database based on the radiative forcing scenarios RCP8.5 and RCP4.5. The data were subsequently validated based on weighing method and RMSE, MAE, MBE and R2 evaluation criteria. The results of the processing were drawn on the digital elevation layer (DEM) of cold climate regions of Iran in the form of temporal-spatial seasonal precipitation distribution. Is
The results showed that based on the weighing method and applying statistical indices on the output of CMIP5 models, the output of the HadGEM2.ES general circulation model is accompanied by fewer simulation errors in illustrating the climate change of the future period than the observation or baseline period. In fact, based on the evaluation criteria or errors, this model showed a higher compliance with observational data. In the monthly pattern in cold regions of Iran during the cold months, especially in the autumn and winter months, the precipitation parameter indicates a slight increase from 10-20 mm relative to the baseline period. This small increase in precipitation over the coming decades, based on the structure of the models, cannot be stable because of increasing temperature and evapotranspiration. However, in the annual and normal long-term pattern, the precipitation level will be less than the preceding period such that in the 2020-2055 period in the annual pattern, precipitation decreases by 54 mm, equivalent to 20.1% decrease. Seasonal precipitation will decrease in winter, autumn, and summer of the upcoming period up to the 2090 horizon, according to radiative forcing scenarios. Precipitation reduction in the summer will be more severe than in other seasons. Only in spring season will the amount of precipitation in the coming period increase slightly compared to the baseline period. Most of the spatial variations in precipitation distribution will occur in the cold climate regions of Iran in the high-altitude areas of the middle Alborz and especially in high Zagros regions.
The center of areas with maximum precipitation in cold regions will mainly move to higher latitudes. In fact, the regions with substantial precipitation will become smaller, whereas areas with low rainfall will be extended. Therefore, climate change will have an impact on the temporal-spatial distribution of precipitation in the cold climate regions of Iran and will face with a future with less and variable precipitations.