تحلیل فضایی تنش‌های گیاهی و فرسایش مرتبط با بافت خاک و اقلیم مبتنی براصول سنجش دور و روش‌های تجربی(مورد مطالعه: شهرستان مراوه تپه)

فرسایش به ویژه فرسایش آبی، یکی از مسائل مهم و اصلی تخریب منابع زیست محیطی است. جلوگیری از فرسایش، مستلزم شناخت ابعاد مختلف آن است. تنش به مفهوم تغییر شرایط طبیعی و بهینه فیزیولوژی گیاه است که به کاهش رشد و نمو آن منجر می شود. از کاربردهای مهم تصاویر ماهواره ای تحلیل سری های زمانی گیاهی است. در بعضی مواقع از خود تصاویر ماهواره ای یا داده های ثانویه استخراج شده مثل شاخص ها و مولفه های تصویر در تحلیل های سری زمانی استفاده می شود که این داده ها خود نیازمند پیش پردازش ها و یکسان سازی از لحاظ سیستم مختصات یا حتی نیازمند پردازش های مجدد برای استخراج پارامتر های آماری مثل میانگین، مینیموم، ماکزیمم، تغییر پذیری و آنومان ها است. هدف این پژوهش، تحلیل فضایی تنش های گیاهی و فرسایش مرتبط با بافت خاک و اقلیم مبتنی بر سنجش از دور و روش های تجربی است؛ بدین منظور ابتدا با بررسی داده های ماهواره مودیس، محاسبه آنامالی های گیاهی در هر پیکسل بر اساس توزیع z انجام شد. سپس با استفاده از پارامترهای موثر در تنش گیاهی همچون رطوبت، تبخیر و تعرق، دما و بارش با بازه زمانی 26 ساله، آنالیز سری زمانی ها به روش منکندال انجام شد. در این مطالعه از تارنمای earthdata، تصاویر ماهواره‌ مودیس با کد (mod13q1) از سال 2010 تا 2017 دریافت و پیش‌پردازش و پردازش‌های لازم بر روی آن انجام‌ شد. همچنین به‌منظور آشنایی با شهرستان و برنامه‌ریزی صحیح و اصولی، برای مطالعات فرسایش از منطقه مراوه‌تپه بازدید و در نهایت، برای محاسبه فرسایش به استفاده از روش‌ تجربی همچون epm در منطقه موردمطالعه اکتفا شد. نتایج این تحقیق نشان داد که به علت عدم رعایت مسائل چرای دام و منع بهره‌برداری از مناطق حساس به فرسایش به‌خصوص تبدیل روبه رشد تغییر کاربری به زراعت و از بین رفتن پوشش مرتعی، فشرده شدن حتی به بروز هرز آب‌ها و شسته شدن خاک سطح مراتع منجر شد و تشدید آن به نحوی بود که دامنه‌ها به‌طورکلی تخریب و فرسایش‌های شیاری خیلی شدیدی در اکثر نقاط نمایان شد. روند تغییرات پوشش گیاهی با استفاده از تصاویر ماهواره ای و ارتباط آن با بارندگی در جنوب و شمال شرقی مراوه تپه نیز نشان داد که بین پوشش گیاهی و میزان بارندگی همبستگی معناداری وجود داشت.

Spatial Analysis of Plant Stresses and Erosion Related to Soil and Climate Textu (Case Study: Maraveh Tappeh City)

1 IntroductionErosion, especially soil erosion by water, is one of the most important issues in the destruction of environmental resources. To prevent erosion, we need to know its various dimensions. Erosion is a natural and calm phenomenon that has led to the formation of landscapes that are currently considered suitable environmental resources for human life. However, in terms of natural resources, erosion has destroyed fertile soils and has had many negative effects on lives of inhabitants. Soil erosion is the most important cause of land degradation and leads to water and soil wastage. Plants, like other living organisms, are affected by various stresses, including stresses caused by salinity, drought, cold, frost, high temperatures, heavy metals, flooding conditions, UV radiation, and damages caused by deficiency or excess. Soil dryness and water shortages in the city of Maraveh Tappeh, which plays a vital role in ecology, agriculture, industry, tourism and health of the residents, highlight the importance of monitoring this phenomenon. Drought is an irregular rainfall pattern that leads to changes in vegetation, because water is a required factor in plant growth. On the other hand, changes in green cover levels play a dynamic role in balancing energy and water levels. Plants have developed a variety of mechanisms to adapt to dehydration. Molecular genetic aspects have allowed them to respond appropriately and adapt themselves to this stress.2 MethodologyThe present study, due to the nature of the issue and the subject under investigation, has a descriptiveanalytical design and is of the type of applied studies with an emphasis on quantitative methods. Wet and drought phenomena were used as the key isseues to be examined. The purpose of this study was to measure and analyze the time series of droughtbased plant stresses by using remote sensing data and climatic indicators. For this purpose, first by calculating the data of Modis satellite and Telos sensor, the estimation of Vegetation analysis in each pixel was performed based on z distribution. Then, by using parameters involved in plant stress such as humidity, evapotranspiration, temperature and precipitation with a period of 26 years, the reserachers performed time series validation (Mankendal) method. In this study, MODIS satellite images with code (MOD13Q1) from 2010 to 2017 were received from the EarthData website and preprocessing and other necessary processing such as geometric and radiometric corrections were performed on them. The Kendall Man test is one of the most common and widely used nonparametric methods that can be used to analyze the trend of time series. In order to get acquainted with the study area and conduct a correct principled planning for erosion studies, the MaravaheTappeh area was visited and. finally, by using EPM experimental method the erosion rate in the studied area was estimated. 3 Results The results show that the quality of erosion varies in different coatings, but with the influence of other factors, the effectiveness of this factor also changes. The highest rate of erosion in the region, according to the studied model, is estimated in the southeast, north and northeast of the basin. In general, it can be said that due to the topographic conditions of Maraveh Tappeh region and also due to the importance of agriculture in this region, plain lands and slopes have been allocated to agricultural lands that have had an effective role in sediment production. The existing rangelands, which form the bulk of the area, have eroded in steep and erosionprone areas contrary to the expectations. Due to nonobservance of grazing issues and prohibition of exploitation of erosion in sensitive areas, especially the growing conversion of land use to agriculture and loss of rangeland cover, compaction has even caused water wastage and intensified washing of leaf and soil. Consequently, the slopes are completely bare and very severe groove erosions are visible in most places, which has created a very bad secneray and unfavorable shapes. Finally, it should be said that most nonbiological stresses such as water stress and temperature stress affect plant cells.4 Discussion ConclusionsThe results of this study showed that the evaluated climatic indicators can be consdidred as strong parameters in the analysis of plant stresses. Remote sensing indicators have good accuracy in monitoring plant stress. Extractable plant indicators have been developed from satellite imagery to assess plant stress status by using remote sensing data. Most of these indicators are based on the measurement of spectral reflectances in different bands and can be calculated in each pixel. These indicators had several advantages over other climatic indicators, including covering a large area of land.