fa الگوی فضایی تغییر روند شاخص‌های خشکسالی در استان گیلان تخصصي Special پژوهشي Research <span style="font-size:12pt"><span style="line-height:normal"><span style="direction:rtl"><span style="unicode-bidi:embed"><span style="font-family:Calibri,sans-serif"><b><span lang="FA" style="font-size:13.0pt"><span b="" lotus="" style="font-family:">چکیده </span></span></b></span></span></span></span></span><br> <span style="font-size:12pt"><span style="direction:rtl"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><span bold="" class="T2Char" new="" roman="" style="font-family:" times=""><span style="font-weight:bold"><span b="" lang="AR-SA" lotus="" style="font-family:">هدف:</span></span></span><span b="" lang="AR-SA" lotus="" style="font-family:"> یکی از پیامدهای تغییر دما و بارش، خشکسالی است که تداوم در تکرار آنها با اثرات مخرب زیست محیطی همراه</span><span b="" lang="FA" lotus="" style="font-family:"> است</span><span b="" lang="AR-SA" lotus="" style="font-family:">. در این پژوهش مهم‌ترین پیامد تغییر دما و بارش یعنی خشکسالی مورد بررسی قرار می‌گیرد.</span><span dir="LTR" style="font-size:10.0pt"></span></span></span></span></span><br> <span style="font-size:12pt"><span style="direction:rtl"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><span bold="" class="T2Char" new="" roman="" style="font-family:" times=""><span style="font-weight:bold"><span b="" lang="AR-SA" lotus="" style="font-family:">مواد و روش :</span></span></span><span b="" lang="AR-SA" lotus="" style="font-family:"> ابتدا داده‌های مورد نیاز از مرکز اروپایی پیش‌بینی میان‌مدت جو (</span><span dir="LTR" style="font-size:10.0pt">ECMWF</span><span b="" lang="AR-SA" lotus="" style="font-family:">) با تفکیک مکانی </span><span cambria="" lang="AR-SA" math="" style="font-family:">〖</span><span b="" lang="AR-SA" lotus="" style="font-family:">0.25</span><span cambria="" lang="AR-SA" math="" style="font-family:">〗</span><span b="" lang="AR-SA" lotus="" style="font-family:">^</span>&deg;<span b="" lang="AR-SA" lotus="" style="font-family:">&times;</span><span cambria="" lang="AR-SA" math="" style="font-family:">〖</span><span b="" lang="AR-SA" lotus="" style="font-family:">0.25</span><span cambria="" lang="AR-SA" math="" style="font-family:">〗</span><span b="" lang="AR-SA" lotus="" style="font-family:">^</span>&deg;<span b="" lang="AR-SA" lotus="" style="font-family:"> بمدت 44 سال (1980 تا 2023) دریافت گردید. سپس وجود روند در شاخص‌های </span><span dir="LTR" style="font-size:10.0pt">SPI</span><span b="" lang="AR-SA" lotus="" style="font-family:"> و </span><span dir="LTR" style="font-size:10.0pt">RDI</span><span b="" lang="AR-SA" lotus="" style="font-family:"> با استفاده از آزمون من کندال تعیین و از آماره </span><span dir="LTR" style="font-size:10.0pt">I</span><span b="" lang="AR-SA" lotus="" style="font-family:"> موران محلی (</span><span dir="LTR" style="font-size:10.0pt">ALMI</span><span b="" lang="AR-SA" lotus="" style="font-family:">) برای شناسایی نوع الگوی مکانی آنها استفاده شد.</span><span lang="FA" style="font-family:"B Lotus""></span></span></span></span></span><br> <span style="font-size:12pt"><span style="direction:rtl"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><span bold="" class="T2Char" new="" roman="" style="font-family:" times=""><span style="font-weight:bold"><span b="" lang="AR-SA" lotus="" style="font-family:">یافته‌ها :</span></span></span><span b="" lang="AR-SA" lotus="" style="font-family:"> نتایج نشان داد که شاخص </span><span dir="LTR" style="font-size:10.0pt">RDI</span><span b="" lang="AR-SA" lotus="" style="font-family:"> در ماه‌های مارس، می، ژوئن و </span><span b="" lang="FA" lotus="" style="font-family:">اوت </span><span b="" lang="AR-SA" lotus="" style="font-family:">دارای روند منفی کاهشی بوده است. </span><span lang="FA" style="font-family:"B Lotus""></span></span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:normal"><span style="direction:rtl"><span style="unicode-bidi:embed"><span style="font-family:Calibri,sans-serif"><span bold="" class="T2Char" new="" roman="" style="font-family:" times=""><span style="font-weight:bold"><span lang="AR-SA" style="font-size:11.0pt"><span b="" lotus="" style="font-family:">نتیجه‌گیری:</span></span></span></span><span b="" lang="AR-SA" lotus="" style="font-family:"> علاوه بر وجود روند منفی در میانگین شاخص </span><span dir="LTR" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">RDI</span></span><span b="" lang="AR-SA" lotus="" style="font-family:">ی ماه‌های مارس، می، ژوئن و اوت، روند منفی در شاخص </span><span dir="LTR" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">RDI</span></span><span b="" lang="AR-SA" lotus="" style="font-family:">ی تک‌تک یاخته‌های این ماه‌ها تایید گردید. در این راستا، تحلیل فضایی آزمون روند شاخص خشکسالی </span><span dir="LTR" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">RDI</span></span><span b="" lang="AR-SA" lotus="" style="font-family:"> و </span><span dir="LTR" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">SPI</span></span><span b="" lang="AR-SA" lotus="" style="font-family:"> نشان داد که الگوی خوشه بالا-بالا (</span><span dir="LTR" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">HH</span></span><span b="" lang="AR-SA" lotus="" style="font-family:">) و پایین-پایین (</span><span dir="LTR" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">LL</span></span><span b="" lang="AR-SA" lotus="" style="font-family:">) در ماه‌های مارس، می، ژوئن و اوت در بخش‌های مختلف استان اعم از جلگه تا کوهستان و از شرق تا غرب بصورت هسته‌های جدا از هم شکل گرفته است. در نتیجه رفتار غیرتصادفی بر الگوی توزیع مکانی شاخص </span><span dir="LTR" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">RDI</span></span><span b="" lang="AR-SA" lotus="" style="font-family:"> و </span><span dir="LTR" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">SPI</span></span><span b="" lang="AR-SA" lotus="" style="font-family:"> حاکم است.</span><span dir="LTR" style="font-size:10.0pt"><span style="font-family:"Times New Roman",serif"></span></span></span></span></span></span></span><br> &nbsp; <div dir="rtl" style="text-align: left;"></div><span style="font-size:12pt"><span style="line-height:normal"><span style="direction:rtl"><span style="unicode-bidi:embed"><span style="font-family:Calibri,sans-serif"><b><span dir="LTR" style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">Introduction</span></span></b><span dir="LTR" style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: One of the consequences of changes in temperature and precipitation is drought, the persistence and recurrence of which are associated with destructive environmental impacts. This study investigates drought as the most significant outcome of temperature and precipitation variations.</span></span></span></span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:normal"><span style="direction:rtl"><span style="unicode-bidi:embed"><span style="font-family:Calibri,sans-serif"><b><span dir="LTR" style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">Materials and Methods:</span></span></b><span dir="LTR" style="font-size:11.0pt"><span new="" roman="" style="font-family:" times=""> Initially, the required data were obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) with a spatial resolution of 0.25&deg; &times; 0.25&deg; over a period of 44 years (1980 to 2023). The presence of trends in the Standardized Precipitation Index (SPI) and the Reconnaissance Drought Index (RDI) was determined using the Mann-Kendall test. Additionally, the Local Moran&rsquo;s I statistic (ALMI) was applied to identify the spatial pattern of these indices.</span></span></span></span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:normal"><span style="direction:rtl"><span style="unicode-bidi:embed"><span style="font-family:Calibri,sans-serif"><b><span dir="LTR" style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">Results:</span></span></b><span dir="LTR" style="font-size:11.0pt"><span new="" roman="" style="font-family:" times=""> The results showed that the RDI exhibited a significant decreasing (negative) trend in the months of March, May, June, and August.</span></span></span></span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:normal"><span style="direction:rtl"><span style="unicode-bidi:embed"><span style="font-family:Calibri,sans-serif"><b><span dir="LTR" style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">Conclusion:</span></span></b><span dir="LTR" style="font-size:11.0pt"><span new="" roman="" style="font-family:" times=""> In addition to the negative trend in the mean RDI values during March, May, June, and August, a negative trend was also confirmed at the individual grid cells for these months. Spatial analysis using the trend test and Local Moran&rsquo;s I of the drought indices (RDI and SPI) revealed distinct high-high (HH) and low-low (LL) clusters in various parts of the province, ranging from plains to mountainous areas and from east to west, forming separate cores. This indicates a non-random spatial distribution pattern for the RDI and SPI indices.</span></span></span></span></span></span></span><br> &nbsp; روند, I موران محلی, SPI, RDI, استان گیلان : Trend, Local Moran’s I, SPI, RDI, Gilan Province 71 94 http://geographical-space.iau-ahar.ac.ir/browse.php?a_code=A-10-3941-1&slc_lang=fa&sid=1 leila haghparast لیلا حق پرست Leila.haghparast@iau.ac.ir 100319475328460023378 100319475328460023378 No bahman ramzani بهمن رمضانی Bahman.ramzani@iau.ac.ir 100319475328460023379 100319475328460023379 Yes atoosa bigdeli آتوسا بیگدلی bigdeli1350@iau.ac.ir 100319475328460023380 100319475328460023380 No yousef zeinolabedin یوسف زین العابدین Yousef.zeinolabedin@iau.ac.ir 100319475328460023381 100319475328460023381 No