ارزیابی تغییرات فرسایش بادی متاثر از فرین‌های بارشی در جلگه غربی مکران

فرسایش را می توان به عنوان یک تعادل مبتنی بر اقلیم و مدیریت زمین در نظر گرفت. درک چگونگی تاثیرپذیری فرسایش از تغییرات آب و هوایی، برای توسعه استراتژی‌های مدیریتی مناسب، حیاتی است. هدف از این پژوهش، مطالعه تاثیرپذیری شدت فرسایش بادی از فرین‌های بارشی به عنوان یکی از وقایع حدی اقلیمی است. داده‌های پژوهش، شاخص‌های رطوبت خاک و انبوهی پوشش گیاهی تصاویر ماهواره‌ای مودیس، داده‌های بارش و نیز داده‌های ژئومورفولوژیک و ویژگی‌های سطح زمین است. علاوه بر مدل اریفر از نرم‌افزارهای arc gis و اکسل به عنوان ابزار استفاده شد. ضمن گردآوری نتایج مطالعات ژئومورفولوژی منطقه، محدوده به واحدهای همگن مطالعاتی تقسیم شد. در هر واحد، با استفاده از مدل اریفر به ارزیابی شدت فرسایش بادی اقدام شد. با اخذ آمار بارش ایستگاه سینوپتیک بندرجاسک به‌عنوان تنها ایستگاه معیار منطقه، فرین‌های بارشی در طول دوره آماری مشخص شد. ازآنجایی‌که از بین 9 معیار اریفر 7 معیار آن با زمان تغییر زیادی نمی‌کند، این معیارها ثابت فرض شد. دو معیار مستقیماً از بارش تاثیر می‌پذیرند، معیار رطوبت خاک و معیار انبوهی پوشش گیاهی. این معیارها به کمک تصاویر ماهواره‌ای (شاخص‌های ndvi و ndmi) و روابط آماری تبدیل به معیارهای اریفر شد. با فرض ثابت بودن سایر عوامل، شدت فرسایش بادی در 10، 20 و 30 روز پس از وقوع فرین‌های بارشی مورد محاسبه قرار گرفت. بر اساس نتایج تحقیق، متوسط شدت فرسایش بادی در جلگه غربی مکران، محدوده جلگه ساحلی سیریک و جاسک، 11.4 تن بر هکتار در سال است که در طبقه متوسط قرار می‌گیرد. نتایج نشان می‌دهد که فرین‌های بارشی با افزایش رطوبت خاک و انبوهی پوشش گیاهی، کاهش مقطعی فرسایش بادی را سبب شده‌اند. به نظر می‌رسد دلیل عدم تداوم کاهش فرسایش، موقتی بودن رویش گونه‌های یکساله تروفیت است. این گونه‌ها ماندگاری چندانی نداشته و دوره رویشی آن‌ها وابستگی تامّی به شرایط اقلیمی دارد. 

assessing impact of extreme precipitation events on wind erosion intensity: western region of makran coastal plain, iran

1- introductionerosion is a delicate balance influenced by climate and land management practices. understanding the impact of climate change on erosion is crucial for developing effective management strategies. while wind erosion is a global phenomenon, its severity depends on the natural environment’s support (chorley et al., 2000). particularly in arid and semi-arid regions, wind erosion is a significant challenge leading to desertification (jebali & zare chahouki, 2021); in these areas, the natural environment has contributed and wind has become the main factor of desertification (yan, 2004). dust storms resulting from wind erosion not only degrade soil but also deteriorate air quality in downwind areas (jiang et al., 2018). given the detrimental effects of wind erosion on food security and human health, accurately simulating and predicting this process in arid regions is essential (wang et al, 2020).  this study aims to investigate the impact of extreme precipitation events on wind erosion intensity.the research area encompasses the western plain of makran, including jask and sirik counties in hormozgan province, southern iran, covering an area of 366,879 square kilometers. this low-lying coastal region is characterized by frequent intense winds, especially during the summer, contributing to various erosion processes, including wind and coastal erosion. the region’s climate is arid, with low rainfall concentrated in the winter months. the average temperature is 27 degrees celsius, with the highest rainfall occurring in january. the region experiences a dry period all months annually, with humidity ranging from 60-80%. the warmest month is july, with temperatures below 34°c.3- methodologythe research data include soil moisture indicators, vegetation abundance from modis’s satellite images, precipitation data, and geomorphological features. the irifr model, arcgis, and excel software were utilized for analysis. homogeneous study units were established based on geomorphological characteristics. the irifr model was employed to assess wind erosion intensity in each unit. precipitation data from the jask synoptic station were used to determine rainfall patterns. extreme precipitation events were identified and extracted. since most irifr criteria are constant, soil moisture and vegetation density measures were derived from satellite images and statistical relationships. wind erosion intensity was calculated at 10, 20, and 30 days post-extreme precipitation events.3- results the average wind erosion intensity in the western plain of makran, specifically sirik and jask, is 11.4 tons per hectare per year, indicating moderate erosion levels. extreme rainfall events temporarily reduce wind erosion by enhancing soil moisture and vegetation abundance. meteorological data demonstrated that extreme precipitation events have a significant impact on mitigating wind erosion in the region.according to the meteorological data of jask station, the average rainfall of the region during the statistical period is 110 mm per year. the lowest amount of annual rainfall is 79 mm and the highest amount of annual rainfall during the statistical period under review is 188.6 mm. for the study of precipitation events, the upper 60% of the rainfall statistics of the region were considered as precipitation. the results showed that extreme presentations have improved the condition of ndvi and ndmi indices. this situation continued for 20 days after the rainy event, but with time, the moisture conditions of the soil and its surface vegetation returned to the previous situation.4- discussion & conclusionsthe results showed that extreme precipitations have caused a decrease in wind erosion by increasing soil moisture and dense vegetation; however, this reduction did not permanent and the intensity of wind erosion gradually increased. it seems that apart from the amount of precipitation in an extreme event, the season of its occurrence is also important. it seems that these extreme precipitations, although in a certain period, have caused a great reduction in the intensity of wind erosion in the region, their effect does not last. the reason for the non-continuity of erosion reduction is the growth of ephemeral species (terophytes) after rainfall. terophytes have a short life and are limited to the wet period of the year (jalili sehbardan et al., 2021). with more rainfall and a more suitable rainy season in terms of temperature and intensity of radiation, a higher percentage of them grow and increase the number of plants. the ombrothermic diagram shows that the end of winter is a suitable season for growth in the region, so the effect of the rain showers of this period on the abundance of vegetation has been greater.