نوع مقاله : مقاله علمی پژوهشی
نویسندگان
1 گروه پژوهشی جغرافیا، مرکز پژوهشی علوم جغرافیایی و مطالعات اجتماعی، دانشگاه حکیم سبزواری، سبزوار، ایران
2 گروه ژئومورفولوژی، دانشکده جغرافیا و علوم محیطی، دانشگاه حکیم سبزواری، سبزوار، ایران
3 گروه سنجش‌ازدور، دانشکده جغرافیا و علوم محیطی، دانشگاه حکیم سبزواری، سبزوار، ایران
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Considering the persistence of drought and its destructive effects on various socio-economic sectors of Khorasan-Razavi province, this study is aimed at investigating the spatial-temporal changes of drought risk in the province and assessing the vulnerability to it. For this purpose, from the set of meteorological data during the 70-year period (1950-2020) and drought indices such as Standard Precipitation Index (SPI), Rainfall Index (RAI) and Z-Index (ZSI) in order to evaluate the drought situation of the region in four-time scales. 3, 6, 12 and 24 months were used. Then, drought risk and vulnerability were evaluated using four drought risk indices (DHI), drought exposure index (DEI), drought vulnerability index (DVI) and combined drought risk index (DRI). According to the results of the DHI index, severe and very severe droughts correspond to the eastern, central and southern parts, which can be due to the increase in water consumption due to population development, agricultural and industrial development, as well as climate change. According to the results of DVI and DRI indicators, the regions correspond to severe and very severe droughts in the southern, western and central parts. The DEI index showed that in the central, eastern and southern parts of the province, the agricultural sector is the first sector to be affected by the destructive effects of drought due to excessive dependence on soil moisture reserves. Drought risk maps indicate the possibility of the region facing very dry conditions and affecting the water resources of the region in the short and medium term.
Extended Abstract
Introduction
Drought is a natural disaster that occurs slowly and can continue for a long time and involve large parts of the land. This phenomenon can occur in all climatic regions, and only its characteristics are different from one region to another. Compared to other natural disasters, this natural disaster is very important in terms of intensity and frequency, spatial extent, and the amount of damage it causes. The purpose of the present research is 1- to determine and analyze the intensity and duration of dry and wet periods using standard precipitation indices (SPI), rainfall index (RAI), and index (ZSI), 2- analysis of the risk of drought and damage, adaptability using four indexes such as (DHI), (DEI), (DVI), and (DRI).
Methodology
In the present study, after reviewing the statistics and information of 226 rain gauge and synoptic stations received from the National Meteorological Organization, the rainfall statistics of 176 stations were used during the common statistical period of 70 years (1950-2020). After determining the common statistical period, the meteorological data were analyzed using SPSS software, and the statistical defects were reconstructed using the difference and ratios method. Then, SPI, RAI, and ZSI indices were exerted to determine the drought status of the province using DIP software, and a map of areas affected by drought was prepared using interpolation in ArcGIS software. To quantify and prepare the drought risk index, weight is given to each class of drought in such a way that the class of normal drought is given a weight of one, and a very severe drought, which creates the most significant risk when it occurs, is given a weight of four. Then, the severity map of the drought classes is classified into four classes based on the percentage probability of drought using the natural breakdown method.
Results and discussion
The comparison of SPI index values in 3, 6, 12, and 24 months shows that a significant change in rainfall occurred in 56% of the study period. The values of the RAI index in 3 and 6 months show that in all stations, the number of normal periods is more than wet and dry periods, and the number of dry events is more than wet events. The values of the ZSI index in 3 and 6-month periods show that the severity and frequency of drought in the northern and eastern regions is more than in the western regions of the province. According to the DHI drought risk map, the probability of a severe 3-month drought is less in the southwestern regions (Khalilabad, Ferdous, and Gonabad basins), as well as parts of the center (Torbet Heydarieh and Kashmar basins) and the east of the province (Torbat Jam and Taybad basins) are exposed to severe drought. DEI's drought risk assessment shows that a 12-month severe drought generally includes the eastern regions (Torbat Jam and Taibad basins) and the southeast (Khaf and Rashtkhar basins) and has the highest probability of drought and the northwestern regions (basin Quchan and Chenaran), northeast (Kalat and Sarkhs basins) to parts of the center (Mashhad and Freeman basins) have the lowest probability of 12-month severe drought. Also, the scattered parts from the northwest to the southeast have the highest probability and the parts from the west and east to the northeast have the lowest probability of an average drought of 12 months. The spatial distribution of the index (DVI) in a 3-month time step shows that parts of the province from the north to the northeast have the highest and the west and southwest parts have the lowest 3-month drought risk index. The spatial distribution of the drought risk index in a 12-month time step shows that there is the highest risk from west to east, and the northeastern parts of the region have the lowest risk of a 12-month drought. The index (DRI) evaluation indicates that the highest percentage of severe drought occurs in the southern and eastern parts of the province, and the lowest percentage of severe drought occurs in the western part. In general, the areas prone to severe drought are mainly concentrated in the central part of the province, and the western and northeastern areas are prone to
severe drought.
Conclusion
The results of using drought indices show that these three indices do not differ much from each other in determining drought periods. However, the ZSI index has a significant difference in trend with them, which is probably due to considering the median of the data instead of their average, which the results of Karimi et al.'s study (2010) regarding the low correlation of this index with other drought indices are consistent. Risk assessment with the DHI drought risk index showed that very severe drought (38%) is reserved for the east, center, and south of the province, and the rest of the basins of the province have experienced less than 21% of severe drought periods. The DEI drought risk index shows that the drought in the south, northeast, southeast, and southwest parts is more than 18%, and the northern regions of the province have experienced more than 60% of the entire average drought period. According to the DVI index, very severe droughts are observed in the center and south of the province. Then there is the
east, southeast, center, and northeast, where the maximum number of severe droughts in the entire period is 36 percent. Therefore, according to the spatial zoning of the intervals, it can be concluded that the east, northeast, south, southeast, and center of the province had the most severe and moderate droughts.
Funding
There is no funding support.
Authors’ Contribution
Authors contributed equally to the conceptualization and writing of the article. All of the authors approved thecontent of the manuscript and agreed on all aspects of the work declaration of competing interest none.
Conflict of Interest
Authors declared no conflict of interest.
Acknowledgments
We are grateful to all the scientific consultants of this paper
کلیدواژه‌ها [English]
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