| چکیده انگلیسی مقاله |
Introduction and Goal
The phenomenon of climate change is the reason for the continued change of the climate pattern in the future in 2016, the Intergovernmental Panel on Climate Change, with the cooperation of various research centers around the world, has started compiling the sixth climate change assessment report CMIP(6). Due to the low spatial resolution of the output of GCM models, it is not appropriate to use them to evaluate the effect of climate change on a local scale. Consequently, it is necessary to scale the output of these models for regional studies using appropriate models or methods. One of the most important effects of climate change is the impact on rainfall and runoff in the watershed, which is effective on meteorological and hydrological droughts. One of the famous rainfall-runoff models that do not require a lot of input data is IHACRES. Researchers have welcomed its use in the last decade. The purpose of this research is to investigate the effects of climate change on meteorological and hydrological drought in the Minab Dam watershed.
Materials and Methods
In this study, climatic and hydrological data related to the region including daily precipitation, mean daily temperature and mean daily discharge were used to model and simulate the daily discharge of the Minab watershed during the statistical period of 1989 to 2018. From the Canadian model of the sixth report and three climate change scenarios SSP-1-2.5, SSP-3-7.5 and SSP-5-8.5, from the IHACRES model for predicting river flow for the future period from 2019 to 2040 and from the LARS-model WG was used for microscale precipitation and temperature. The Standardized Rainfall/Runoff Index (SPI/SRI) was used to study the drought. To analyze the drought trend and its characteristics, the Mann-Kendall test was utilized in both baseline and future periods.
Results and Discussion
Using the mentioned data, the runoff was calibrated using the IHACRES model. After the proper performance of the model in the calibration stage, the model was verified and predicted using three scenarios of the sixth report of runoff for a period in the future. Then, SPI, SRI, and drought characteristics (severity, duration, magnitude, and peak) were estimated for the past and future periods, and their changes compared to the future period. The results showed that the trend of precipitation changes in all three scenarios decreased in autumn and winter. Also, by using three scenarios, it was found that the most changes in the observation period were related to November. Also, regarding the flow of the river, its trend is decreasing due to the decrease of precipitation and these changes are mostly related to the autumn and winter seasons (up to 49% decrease), but its changes in the summer season have an increasing trend compared to the base period. In general, the trend of changes in precipitation and discharge in the entire period has an increasing slope. Investigating the effect of climate and meteorological drought in the study area showed that the hydrological and meteorological drought values have been increasing in the past, but in the future, in most scenarios, the drought trend is decreasing, which generally lacks a statistically significant trend. It is also clearly visible in the characteristics of drought.
Conclusion and Suggestions
Considering the regional changes of drought caused by global climate changes, considering different combinations of scenarios can be useful for early warning of drought as well as water resources management planning. In general, the conditions of drought management and forecasting in many parts of Iran, especially in arid and semi-arid regions, are currently far from the ideal situation. Therefore, it is necessary to be prepared to deal with it. Therefore, in severe droughts, the use of climate change models to predict future conditions can be very useful in evaluating the ability to provide water and the need for auxiliary water sources. |