نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشیار گروه علوم مهندسی آب، دانشگاه بینالمللی امام خمینی (ره)، قزوین، ایران.
2 دانشجوی دکتری گروه مهندسی آب، دانشکده کشاورزی و منابع طبیعی، دانشگاه بینالمللی امام خمینی (ره)، قزوین، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Aim: The process of climate change, especially the change in temperature and precipitation, and its effect on the drought phenomenon constitute the most important topic of discussion in environmental sciences. Studying climate change and its effect on the severity and frequency of droughts in the coming decades can considerably contribute to the planning for the proper use of water resources and adapting to the destructive effects of droughts. To this end, based on the SDSM microscale method, precipitation and temperature during the 2020-2100 period were predicted in the present study using the large-scale CanESM2 model, and the effects of climate change on the meteorological drought in Ilam Province were studied using the SPI and RDI indices.
Method: In this study, the required climatic data are obtained through one of the data reporting sites of the IPCC AR5. Twenty one CMIP5 models have been used to predict Precipitation and temperature parameters in the future. The weighting method of observational means was used to investigate the uncertainty caused by using the studied models. Then, using the SDSM model, meteorological data are generated under three scenarios: RCP 2.6, RCP4.5 and RCP8.5 of the CanESM2 model. Model historical data from 1993 to 2005 will be used to analyze the SDSM model using NCEP re-analysis data, and data from 2006 to 2100 will be used to estimate future climate change. The SPI and RDI time series were calculated in three scales of 3, 6 and 12 months for the historical and future period. The intensity, duration and frequency of the drought, according to the run theory for the spi and RDI on scale 3, 6 and 12 months.
Results: According to the results of the uncertainty analysis, the CanESM2 model had the highest weight compared to other models for both temperature and precipitation variables. Analysis of trend in precipitation and temperature data by non - parametric mann - kendall test showed that temperature in scenario rcp8.5 has a significant positive trend ( increasing ) at 0.01 and precipitation has decreasing trend. The results of drought monitoring showed that in both SPI and RDI indices, the frequency of dry period’s decreases with increasing time scale, which is accompanied by an increase in the severity and duration of drought. The RDI index shows higher drought characteristics than SPI due to considering the average temperature in calculating dry periods. The greatest drought in the historical period according to the SPI index on a 12-month scale has an intensity of 38.22 and a duration of 26 months. RDI index on a 12-month scale has an intensity of 39.14 and a duration of 26 months.The study area will experience more severe and longer droughts in the future according to all three scenarios than in the historical period. The severity of droughts produced by RCP4.5 RCP2.6 and RCP8.5 scenarios based on 12-month SPI is 11%, 52% and 65%.
Conclusion: The results of the analysis with the SDSM model and the SPI and RDI drought indices indicated that in the future climatic conditions in the 2020-2100 period, an increase in temperature and a decrease in precipitation are probable. To wit, temperature rises by 3.798 C and precipitation decreases by 6.8%. The results also revealed that the study area will experience more severe and longer droughts in the future than in the historical period under all three RCP2.6, RCP4.5 and RCP8.5 scenarios. As the time scale of the drought index increases, the severity and duration of the drought increases. The RDI index has a high behavioral similarity to the SPI, but the RDI index is sensitive to environmental changes and provides better results.
کلیدواژهها [English]