Zoning and Monitoring of Meteorological Drought in Arid Desert Areas using SPI, SIAP and PN indices (Case Study: Zahedan Plain)

Drought is one of the most destructive weather events that cause great damage to human societies every year. Therefore, drought indices can indicate the natural limits of droughts. In this way, they make it possible for us to evaluate at different time and place scales. In this regard, in the present study, zoning and monitoring of meteorological drought in arid desert areas using indices (SPI, SIAP and PN) in Zahedan plain were studied.

In this study, daily rainfall data sets of operating stations in the study area were collected. Due to the low density of stations and severe limitations of data access in arid areas, five stations (refinery, FBI, Khinjak train, Pudeh Chah and meteorological department of Zahedan) were evaluated as suitable during a 30-year joint statistical period (1987-2016). The selected stations had complete time series and no statistical deficiencies during the selected statistical period. After ensuring the quality of the data by using homogeneity, random and discrete tests, the annual SPI, SIAP and PN indices of the annual time scale were extracted using DIP software and also in order to zoning the evaluated indices by distance photo interpolation method in the environment. Arc GIS was used.

By calculating the coefficient of variation from year to year during the census period (1987-2016), the minimum coefficient of variation was 88.7 and the maximum value was 208.8, it was found that Zahedan plain has irregular rainfall and high variability, which indicates the Occurrence of drought in the region. Then, by examining the three indices of SPI, SIAP and PN, it was found that the conditions of Zahedan plain based on SPI indices were 24 normal years, SIAP 25 normal years and PN 25 years of drought were weak. Also, according to all three indices, the most severe meteorological drought that occurred in Zahedan plain during 2003 was related to 2003. The values ​​of each of these indicators for 2003 are -1.49, -1.16 and 25.32, respectively. According to SPI index, during 24 years of normal statistical period, SIAP index has 25 years of normal conditions and according to PN index of Zahedan plain with 6 wet years, 12 normal years and 5 years of weak drought. The annual drought threshold for the three indices is SPI 1-, SIAP -0.25 and PN 80. In addition, monitoring of spatial variations of three indices, SPI, SIAP and PN, showed that during the statistical period, the northern half of Zahedan plain was more affected by drought. Based on the meteorological zoning maps of Zahedan plain, it was determined that based on the SPI index in the years 1999-2005 of the northeastern region, the SIAP index during the years (1987-1989, 1998-2006) of the northern and northeastern parts and based on the PN index during In the years 2003-2006, the southern and western parts of Zahedan plain had more potential in terms of continuity, frequency and severity of meteorological drought.Overall

Considering that the spatial zoning maps of drought indicate the spatial expansion and more intensity of critical zones during the 30-year statistical period studied in the present study, the identification of these vulnerable and endangered areas and The extent of this phenomenon is also necessary for the implementation of management as well as development, economic, social, environmental and agricultural planning by the government of men and policy makers.