@article { author = {Saberi, Aref and Soltani-Gerdefaramarzi, Somayeh and Miryaghoubzadeh, Mirhasan}, title = {Study of drought using meteorological and remote sensing data (Azarbaijan province)}, journal = {Journal of the Earth and Space Physics}, volume = {44}, number = {2}, pages = {439-461}, year = {2018}, publisher = {Institute of Geophysics, University of Tehran}, issn = {2538-371X}, eissn = {2538-3906}, doi = {10.22059/jesphys.2018.239626.1006927}, abstract = {In recent years, drought has created a destructive impact on the ecology, water resources management, and ecological processes. In this context, appropriate and appropriate method for predicting and monitoring the drought could have a significant impact in neutralizing the effect of this natural phenomenon. In this research, drought monitoring and evaluation of data from MODIS images were used in the extraction of NDVI and DVI indices. The study area of West Azarbaijan province is one of the northwest provinces of the country. In this study, images of meteorological index of drought or wet year have been used. ArcGIS 9.3 has been used to prepare and perform the necessary corrections on the images, as well as to prepare the vegetation cover index (NDVI) and vegetation difference index (DVI) using ENVI 4.5 software, to classify the results and output in the formg images. The aim of this study was to evaluate meteorological droughts using SPI and ZSI as monthly intervals and also determine the correlation between vegetation and meteorological droughts that happened in this area. The results of SPI and ZSI indices indicate that in the first three months of the year, the vegetation is moderate in the prevailing region, and in the second quarter of the year, the maps indicate weak and uncoated vegetation, because the rainfall is very limited in this time. On the other hand, in these months of the year, overgrazing has caused plant degradation. Vegetation in the first three months of the year seems to have had more favorable conditions due to the melting of snow and winter and autumn rainfall of the previous year. Percentage of vegetation coverage in the study area for the wet years 1383, 1385, 1390 and 1393, was respectively reported as 19.85%, 19.5%, 19.6% and 19.5% and also in the drought years 1384, 1387, and 1389 it was calculated as 18.71%, 18.7% and 19% respectively. The results of SPI and ZSI indices indicate that in the first three months of the year, the vegetation is moderate in the prevailing region, and in the second quarter of the year, the maps indicate weak and uncoated vegetation because the rainfall is very limited at this time. On the other hand, in these months of the year, overgrazing has caused plant degradation. Should be cautious about further action beacause One NDVI index is correlated with meteorological drought indices SPI and ZSI which is varied with respect to the short-term and long-term interval respectively. The result confirmed that NDVI and SPI indices were appropriate for monitoring and assessment of drought. The highest correlation values between NDVI and DVI was observed for short term intervals of SPI and ZSI (1, 2 and 3 months). Generally the highest correlation values during the statistical period between NDVI and SPI was obtained as well as in the year when normal drought conditions were reported. In addition, the determination of trends of the indices using the Man Kendall test indicated that there exist a downward trend in all indices and there was an increase in drought and vegetation decline during the statistical period.}, keywords = {Meteorological drought,index,remote sensing,correlation,MODIS}, title_fa = {مطالعه خشک‌سالی با استفاده از شاخص‌های هواشناسی و داده‌های سنجش‌ازدور (استان آذربایجان غربی)}, abstract_fa = {در سال­های اخیر خشک­سالی تأثیر مخربی در بیشتر بخش­های اکولوژی، مدیریت منابع آب، و فرآیند­های زیست­محیطی برجا گذاشته است. در این تحقیق جهت ارزیابی خشک­سالی از اطلاعات حاصله از تصاویر سنجندهMODIS  در استخراج شاخص NDVI و DVI استفاده شده ­است. هدف از این تحقیق بررسی خشک­سالی­های هواشناسی در منطقه با استفاده از دو شاخص هواشناسی SPI و ZSI به‌صورت دوره­های ماهانه و همچنین بررسی رابطه بین شاخص پوشش گیاهی با خشک­سالی­های هواشناسی می­باشد. درصد کل پوشش در منطقه مورد مطالعه برای سال­های ترسالی 1383، 1385،1390 و 1393 به‌ترتیب 85/19، 5/19، 6/19 و 5/19 درصد بوده و در سال­های خشک‌سالی 1384، 1387، 1389 به‌ترتیب 71/18، 7/18 و 19 درصد محاسبه شد. بیشترین همبستگی بین شاخص NDVI و  DVIبا دوره­های کوتاه‌مدت (1، 2 و 3 ماهه) شاخص­های SPI و ZSI وجود دارد. همچنین همبستگی معنی‌دار بین شاخص­های پوشش گیاهی و دوره‌های بلندمدت شاخص­های هواشناسی مشاهده نشد. به‌طورکلی بیشترین میزان همبستگی در طول دوره آماری بین شاخص­های SPI و NDVI و همچنین در سالی که شرایط خشک‌سالی نرمال گزارش شد، به دست آمد. علاوه بر این تعیین روند شاخص­های مورد مطالعه با استفاده از روش من-کندال نشان از وجود روند نزولی در همه شاخص­ها و افزایش خشک‌سالی و کاهش پوشش گیاهی در طول دوره آماری می­باشد.}, keywords_fa = {خشک‌سالی هواشناسی,شاخص,سنجش‌ازدور,همبستگی,مودیس}, url = {https://jesphys.ut.ac.ir/article_64869.html}, eprint = {https://jesphys.ut.ac.ir/article_64869_2b75f4fec49d6bb754c5f790d9f54a7d.pdf} }