Environmental Erosion Research

fa ارزیابی کمّی فرونشست زمین در بخش شمالی آبخوان کاشمر با استفاده از روش تداخل‌سنجی راداری و شاخص خشکسالی PSI Quantitative evaluation of land subsidence in the northern part of Kashmir aquifer using radar interferometry approach and PSI drought index مدلسازی و تحلیل زمانی و مکانی رخداد انواع مختلف فرسایش محیطی مستخرج از پایان‌نامه / رساله / طرح پژوهشی فرونشست زمین، به عنوان یکی از مخاطرات محیطی، در بسیاری از کشورهای جهان در حال وقوع و رخ دادن است. این پدیده در صورت عدم مدیریت صحیح، می‌تواند خسارت جبران‌ ناپذیر مالی و جانی ایجاد نماید. لذا، به دلیل اهمیت موضوع، این‌‌‌ پژوهش با هدف ارزیابی فرونشست زمین طی سال‌های 1396 تا 1400 در شمال آبخوان کاشمر  به عنوان بخشی از حوضه آبریز ایران مرکزی و با مساحتی در حدود 6340 هکتار انجام شد. جهت پایش تغییرات روند فرونشست زمین از تداخل‌سنجی راداری استفاده شد. ارزیابی خشکسالی آب زیرزمینی با استفاده از شاخص PSI و روند تغییرات خشکسالی با استفاده از آزمون‌های تحلیل سری زمانی من-کندال و پتیت به دست آمد. همچنین جهت محاسبه تراکم چاه‌ها (17 حلقه چاه) از تابع تراکم کرنل و برای بررسی همبستگی مکانی-زمانی شاخص‌ خشکسالی آب زیرزمینی و میزان تغییرات فرونشست زمین از روش آماری-تحلیلی استفاده ‌‌شد. نتایج بررسی تداخل سنجی راداری نشان داد که در مناطق مختلف شمال آبخوان کاشمر  و در بازه زمانیسال‌های 1396 تا 1400، به میزان 46 تا 84 سانتیمتر فرونشست به وقوع پیوسته است. بررسی خشکسالی آب زیرزمینی نیز با استفاده از سری زمانی شاخص خشکسالی PSI نشان داد که تغییرات ناگهانی شاخص آب زیرزمینی PSI در چاه کلاته رحیم و خلیل آباد در سطح احتمال 5 درصد غیرمعنی‌دار و در مابقی چاه‌های آبخوان معنی‌دار بوده است. بررسی روند همبستگی بین شاخص PSI  و فرونشست زمین نشان دهنده ارتباط معنادار بین دو شاخص است. علاوه برآن، بررسی تراکم چاه‌ها نشان داد که بیشترین تراکم چاه در بخش‌های مرکزی و غربی شمال آبخوان کاشمر  بوده که مربوط به اراضی زراعی است و یکی از دلایل مهم فرونشست زمین در بخش‌های مرکزی و غربی آبخوان، مربوط به تراکم چاه‌ها و برداشت بی‌رویه از سفره آب زیرزمینی می‌باشد.     1- Introduction Land subsidence, as one of the environmental hazards, is happening in many countries of the world. This phenomenon, if not properly managed, can cause irreparable damage. In this regard, Iran, as one of the countries that has been facing the risk of land subsidence for several decades, will probably be affected by the damage of this phenomenon in the near future. Damages including; Damage to agricultural lands, buildings, roads, bridges, pipelines, etc. Various activities such as; Mining, excessive extraction of underground water, etc., have intensified the process of land subsidence to the point where it has become one of the most important hazards of geomorphology. Identifying the boundaries, the pattern of land subsidence and estimating its intensity will play a significant role in the management and control of this phenomenon. Therefore, it is necessary to take measures to prevent further problems. Therefore, the important goal of this research is to evaluate the subsidence of the Kashmer plain with the radar interferometry method and its relationship with the groundwater drought. Maybe the results of this research can help the executive managers and planners of land and soil resources in the field of protection and management of water resources to prevent land degradation. 2- Methodology In this research, radar interferometry was used to monitor subsidence, and Kendall and Pettit's time series analysis tests were used to evaluate groundwater drought. Also, to calculate the density of wells, kernel density estimation was used, which transforms and determines the position of points in space in a continuous density function in the studied area. Finally, to determine the correlation coefficient and covariance between the existing rasters, as well as some statistical parameters such as the minimum, maximum, average and standard deviation values for each raster, Band Collection Statistic analyzer, which is considered a part of multi variate analyzers was used. Two SENTINEL satellite images were used to determine the amount of subsidence in the target area: 1- The Master image was taken on 04/04/2017. The variable image of 03/25/2021 Slav was also used with a time span of about 4 years and using Land subsidence was calculated from SNAP software. The PSI index was used to determine the level of groundwater drought. This index can be used for all piezometric levels. 3- Results The results of the radar interferometric analysis showed that the subsidence in the studied area was due to excessive water withdrawal from wells and underground water sources. The cause of subsidence around the wells was due to the lack of equipment and the entry of particles into the well. The results of changes in the time series of the PSI index showed that it is insignificant at the probability level of 5% in Kalate Rahim and Khalil Abad wells and significant in the rest of the wells. In the studied area, the lowest water level drop is related to the wells of Khalil Abad, Kalate Rahim. Khalil Abad well has had a drop in water level from 1996 to 2006, and from 2006 to 2021, the PSI index had an upward trend. The analysis of PSI data up to 2019 showed that the groundwater drought in the Kashmir plain has reached its peak over time, and from 2019 to 2014, the conditions have somewhat returned to normal conditions. In addition, subsidence is developing from the western areas such as Khalilabad, which have been involved in this issue in the past, towards the central areas and the center of Kashmar plain. The highest density of wells in the study area is in the central areas towards the western areas of the plain. The study of the land use map of the region also showed that the majority of the density of wells is related to agriculture and irrigated agriculture, which includes 76% of the exploited wells. 4- Discussion & Conclusions The obtained results showed that in different regions of Kashmir Plain, in the period of 4 years (2017 to 2021), there was about 46 to 84 cm of land subsidence, which means that annually in different areas between 11.5 and 21 cm of subsidence can be observed. On the other hand, the process of subsidence has reached the central areas from the west of the Kashmar plain, and the highest intensity of subsidence can be seen around the city of Kashmar. The time series of PSI groundwater drought index is insignificant in Kalate Rahim and Khalil Abad wells and significant in the rest of the wells. Regarding the relationship between the amount of land subsidence and the severity of groundwater drought, the highest amount of subsidence is located in the areas that are in the minimum historical conditions of the PSI index and include the highest fluctuation of subsidence in the region. As we approach the normal conditions of the region in terms of the PSI index, the amount of subsidence also decreases, which indicates a strong connection between groundwater drought and land subsidence. The future perspective of the dangers caused by this phenomenon is very difficult and even impossible, considering the vast dimensions of the damage it causes to the fields of natural resources. Therefore, the custodian bodies, including the country's natural resources and watershed management organization, the General Directorate of Natural Resources and Watershed Management, the Jihad Agriculture Organization, the Regional Water Company of Khorasan Razavi Province, have a very heavy responsibility in managing the crisis and improving the conditions.   آب زیرزمینی, آزمون من-کندال, تغییر کاربری اراضی, تغییر اقلیم, مخاطرات محیطی. Mann-Kendall test, Land use change, Climate change, Environmental hazards 178 203 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-974-1&slc_lang=fa&sid=1 amin moslemzadeh امین مسلم زاده aminmoslemzadeh@yahoo.com 10031947532846008690 10031947532846008690 Yes Department of watershed, Faculty of Natural Resources. Birjand University. Birjand, Iran. گروه مهندسی آبخیزداری، دانشکده منابع طبیعی، دانشگاه بیرجند، بیرجند، ایران Hadi Memarian هادی معماریان خلیل آباد hadi_memarian@birjand.ac.ir 10031947532846008691 10031947532846008691 No Department of watershed, Faculty of Natural. Birjand University. Birjand, Iran. گروه مهندسی آبخیزداری، دانشکده منابع طبیعی، دانشگاه بیرجند، بیرجند، ایران Seyed Mohammad Tajbakhsh سید محمد تاجبخش فخرآبادی tajbakhsh.m@birjand.ac.ir 10031947532846008692 10031947532846008692 No Department of watershed, Faculty of Natural Resources. Birjand University. Birjand, Iran. گروه مهندسی آبخیزداری، دانشکده منابع طبیعی، دانشگاه بیرجند، بیرجند، ایران Morteza Akbari مرتضی اکبری m_akbari@um.ac.ir 10031947532846008693 10031947532846008693 No Department of Desert Areas Management, Faculty of Natural Resources and Environment. Ferdowsi University of Mashhad. Mashhad, Iran. گروه مدیریت مناطق خشک و بیابانی، دانشکده منابع طبیعی و محیط زیست، دانشگاه فردوسی مشهد، مشهد، ایران