Drought trends projection under future climate change scenarios for Iran region

significantly. So that, for most of the stations, this trend is significant in the level of 0.01. The highest downward trend for a large number of stations is observed in the A2 scenario. Thus, it can be declared that the amount of SPEI will drop sharply over time and this decrease under the A2 scenario will be the most intensive. As a consequence, it can be inferred that the A2 scenario predicts the most serious drought in comparison to other scenarios. Moreover, since the survey of [36] demonstrated that the certainty of the predicted PET values under the A2 scenario is higher than the other scenarios, the results of the A2 scenario were examined for extracting the characteristics of SPEI based on the Run theory,. Findings are provided in Table 7 for each station for the next 102 years. As an overall trend, comparing the number of dry periods for all the stations indicate that the proportion of dry periods in humid and cold regions is more than warm climate. For instance, 288 dry months are expected for Gorgan, in comparison to 218 dry months for Zahe- dan. However, in regard to long dry periods, the longest dry periods are expected to be observed in warmer stations; 8 in Gorgan compared to 25 in Zahedan. The maximum deficit can also be seen in warm climates such as Zahedan, with 27.36. This consequence can be seen Table 7. Characteristics of dry and wet periods based on SPEI under the A2 scenario. Station Dry period Wet period Number of periods Longest period Maximum deficit Total deficit Number of periods Longest period Maximum surplus Total surplus

Ahvaz 210 24 22.73 501.43 211 15 14.55 508.67 Arak 246 20 24.43 506.77 252 14 12.28 512.99 Ardebil 271 15 16.1 497.68 268 8 11. 504.91 Bandar abas 266 16 17.7 488.75 263 19 16.4 503.50 Birjand 250 18 17.26 500.57 251 15 14.81 508.13 Bojnoord 269 16 14.84 504.92 264 8 9.8 510.39 Boshehr 281 14 12.06 494.97 275 17 19.36 505.15 Esfahan 217 21 21.01 506.28 222 15 16.99 512.71 Ghazvin 216 21 19.53 514.54 223 12 13.14 519.73 Ghom 232 22 22.69 503.45 240 16 16.86 509.59 Gorgan 286 8 8.50 504.00 285 8 9.67 510.38 Hamedan 253 22 21.58 507.41 252 12 14.37 512.47 Ilam 233 17 19.34 504.62 231 20 20.41 510.20 Karaj 258 10 11.12 507.75 260 12 12.78 512.45 Kerman 216 19 22.02 505.28 224 31 30.31 510.99 Kermanshah 234 16 17.41 506.19 237 10 11.51 511.46 Khoramabad 231 19 16.38 511.63 241 18 20.71 514.76 Mashhad 231 25 21.52 503.20 244 14 13.11 508.52 Oroomie 253 19 16.03 500.67 246 18 14.98 507.71 Rasht 303 19 17.24 502.56 309 6 6.77 509.73 Sanandaj 225 14 14.72 506.03 228 15 11.82 513.01 Semnan 228 14 13.71 504.03 232 20 20.01 510.36 Shahrekord 232 24 13.87 508.38 245 23 21.94 514.23 Shiraz 229 18 19.18 512.50 225 26 24.86 515.82 Tabriz 274 10 12.07 510.63 265 12 10.53 516.59 Tehran 242 20 24.93 ( 505.32 247 10 11.3 510.95 Yasooj 242 12 12.12 507.48 240 19 16.07 515.50 Yazd 225 22 23.04 504.55 227 22 21.71 508.28 Zahedan 218 25 27.36 507.67 216 20 16.97 513.33

Zanjan 241 21 23.60 501.38 242 11 11.70 506.53 https://doi.org/10.1371/journal.pone.0290698.t007 PLOS ONE Drought trends projection under future climate change scenarios for Iran region PLOS ONE | https://doi.org/10.1371/journal.pone.0290698 November 9, 2023 19 / 24