Assessment of Climate Change Effects on Meteorological Variables and Maximum Precipitation under New RCP Emission in Watershed

Subject Areas : Water Resource Management

Mohammadreza Goodarzi ¹ (Associate Professor, Department of Civil Engineering, Yazd University, Iran)
Atiyeh Fatehifar ² (M.S Student of Civil Engineering, Water and Hydraulic Structures, Ayatollah Ozma Boroujerdi University, Iran)

Received: 2018-11-26 Accepted : 2019-08-26 Published : 2022-06-22

Keywords: Climate Change, Statistical down scaling, RCP, SDSM, CanESM2,

Abstract :

Background and Objective: Today, the excessive use of fossil fuels has increased the emissions of greenhouse and climate change. Climate change not only affects changes in the mean of variables such as temperature and total precipitation, but also increases the incidence of maximum events. Therefore, the impact of climate change on temperature and precipitation parameters as well as extreme precipitation can be very important for future planning. Analysis methodology: In this study, to investigate the effect of climate change on temperature and precipitation parameters, CanESM2 general circulation model, according to assessment report fifth (AR5) of the intergovernmental panel on climate change used of new scenarios Representative Concentration Pathways (RCP) Contains RCP2.6, RCP4.5 and RCP8.5 and Statistical down scaling model (SDSM) for down scaling Large scale data GCM for simulation has been used during the period 2030-2059. Then the efficiency of the model will be evaluated with three indicators: root mean square error (RMSE), coefficient of determination (R2) and nash–sutcliffe efficiency (NSE). Findings: The results of the research in the first stage of downscaling with the SDSM model show the good efficiency of the model. The R2 and NSE coefficients for the calibration period of the Azarshahr station are 0.99, 0.99 for temperature and 0.95, 0.95, precipitation and for the Ghermezigol station is 0.91, 0.86. The results indicate the minimum and maximum temperature increase, especially in the month of April to July in this basin, with the highest increase relative to RCP8.5 at 0.26 ° C. Also, precipitation in the Azarshahr station increased by 7.44% under RCP 2.6 and at the Ghermezigol station decreased by 7.57%, under RCP8.5. The decreasing trend of precipitation can be seen in the scenarios, so that the most pessimistic scenario (RCP8.5) shows the greatest decrease. The results of the investigation of extreme rainfalls showed that despite the climate changes and the decrease of precipitation and increase in temperature and consequently the increase of evaporation and the lack of water resources and drought, one should not ignore floods and extreme rainfalls. Discussion and Conclusions: In general, the results have shown an increase in the amount of maximum rainfall in the future. With such simulations, it can be seen that climate change has caused an increase in the amount and frequency of extreme rainfall, even in basins that have brought about a decrease in average annual rainfall. In the present study, in the stations where the amount of rainfall increases in different seasons, the increase in the amount of rainfall will increase the risk of flooding, so it is necessary to pay special attention to the management of water resources and flood control of the basin.

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