تاثیر فرآیندهای اقلیمی بر حساسیت پذیری فرسایش بادی (مطالعه موردی استان اصفهان)

فرسایش بادی در مناطق خشک و نیمه‌خشک جهان از جمله ایران از نظر کمی و کیفی حائز اهمیت بسیار است. در سطح کشور کل مساحت مناطق تحت تاثیر فرسایش بادی در حدود 20 میلیون هکتار است. وقوع طوفان‌های گردوغبار شدید و پایین آمدن کیفیت هوا، افزایش مشکلات تنفسی و افزایش بیماری‌ها و بیابان‌زایی از اثرات فرسایش بادی می‌باشد. در این مطالعه تاثیر فرآیندهای اقلیمی بر حساسیت پذیری فرسایش بادی در دوره مشاهداتی (1990-2017) و دوره آینده (2020-2100) در استان اصفهان برسی گردید. جهت بررسی تاثیر فرآیندهای اقلیمی بر حساسیت پذیری فرسایش بادی از دو عامل اقلیمی چپیل و فائو استفاده شد. نتایج عامل اقلیمی چپیل برای دوره مشاهداتی نشان داد که حساسیت پذیری فرسایش بادی از فرآیندهای اقلیمی در ایستگاه‌های اصفهان، داران، نائین و نطنز از ابتدای دوره روند افزایشی داشته در سال 2016 به بیشترین مقدار رسیده است. درحالیکه در ایستگاه خور و بیابانک بین سال‌های 1994-2014 روند نزولی داشته سپس افزایش یافته و در سال 2016 به بیشترین مقدار رسیده است. نتایج حاصل از عامل اقلیمی فائو برای دوره مشاهداتی نشان داد که حساسیت پذیری فرسایش بادی در تمامی ایستگاه ها افزایش یافته و در سال 2016 به بالاترین حد خود رسیده است. نتایج حاصل از عامل‌های اقلیمی فرسایش بادی چپیل و فائو نشان داد که مقادیر میانگین حساسیت پذیری فرسایش بادی در دوره آینده نسبت به دوره مشاهداتی کاهش خواهد یافت.با توجه به اینکه تاثیر افزایش بارندگی و کاهش سرعت باد در دوره آینده بر عامل‌های اقلیمی بیشتر از تاثیر افزایش دما بر عامل‌ها بوده، حساسیت پذیری فرسایش بادی در دوره آینده نسبت به دوره مشاهداتی کاهش خواهد یافت. به طور کلی تاثیر فرآیندهای اقلیمی بر حساسیت پذیری فرسایش بادی در دوره مشاهداتی روند افزایشی و در دوره آینده به طور میانگین نسبت به دوره مشاهداتی کاهش خواهد داشت.

the effect of climatic processes on wind erosion sensitivity (case study of isfahan province)

1. introductionarid and semi-arid areas due to unfavorable environmental conditions affected by geology and climate along with human activities have made the ground for wind erosion very favorable. in the past few decades, the increase of greenhouse gases in the atmosphere caused by the expansion of industry and the increase in fossil fuel consumption and land use change has caused the stagnation of the trend of climate variables, especially the temperature of the earth (ipcc, 2014). climatic parameters are one of the most effective factors of wind erosion, which are included in wind erosion models in the form of climate factor. due to the fact that climatic parameters are exposed to many changes over time, therefore climatic changes can have an effect on soil erodibility. in this research, the effect of climatic parameters on wind erosion sensitivity is evaluated in the prevailing climate factor in the present and future.2- materials and methodsin this research, climate processes affecting wind erosion have been investigated. in order to investigate the effect of climatic processes on wind erosion sensitivity, two climatic factors, chapil and fao, were used. the chapil climate factor calculates the sensitivity of the wind erosion climate factor using the parameters of temperature, precipitation and wind speed using the chapil climate factor equation, and the fao climate factor calculates the sensitivity using the parameters of temperature, precipitation, wind speed and evaporation and transpiration. wind erosion is calculated using the fao climate factor equation. in the following, the equations for calculating the climatic factor of chapil and fao are stated. the evaluation of wind erosion changes for the observation period (1992-2017) and the future (2100-2020) is evaluated by calculating the climate factor of each of the chapil and fao relationships separately, and the wind erosion changes are calculated for each equation. the obtained climatic factors show the sensitivity of wind erosion in the observation period and in the future.3- resultsthe results of the evaluation of chapil’s climate factor in the observation period showed that wind erosion has high fluctuations in all studied stations. based on the results of this factor, erosion has been on the rise in the observation period. the results of chapil factor in daran station showed that the highest amount of erosion will occur in the future period under the rcp8.5 scenario and in 2073. the results of chapil factor in isfahan station showed that wind erosion had an upward trend between 2005 and 2008, then decreased and increased again since 2009. the results of the climatic factor of wind erosion of chapil station of khor and biyabank in the observation period showed that there was a downward trend between 1994 and 2014 and it has increased since 2014. the results of the climatic factor of wind erosion of nain station in the observation period showed that erosion in this area has been on the rise since 2004. also, the results for this station showed that the highest amount of erosion will occur in the future period under the rcp8.5 scenario in 2093. the results of the climate factor of wind erosion in natanz station chapil showed that wind erosion has increased in the observation period since 2005. the results of fao wind erosion climatic factor of station operators in the observation period showed that wind erosion had an upward trend between 2006 and 2009 and decreased between 2011 and 2014. also, in the future, the highest amount of erosion will occur in 2059 under the rcp2.6 scenario. the results of wind erosion climate factor of fao station in isfahan during the observation period showed that since 2005, the amount of wind erosion in this station has increased during the observation period. in the future period, the highest amount of wind erosion according to the fao climate factor will occur in 2078 under rcp2.6. the results of fao wind erosion climatic factor of khor and biabank stations in the observation period showed that between 2008 and 2015, the amount of wind erosion in this station decreased during the observation period and then increased in 2016. the results of the climatic factor of wind erosion of nain station in the observation period showed that since 2005, the amount of wind erosion in this station has increased in the observation period. in the future period, the highest amount of wind erosion according to the fao climate factor will occur in 2079 under rcp8.5. the results of wind erosion factor of fao natanz station in the observation period showed that between 2002 and 2007 the amount of wind erosion in this station increased during the observation period and then decreased in 2008.4- discussion and conclusionthe results of this survey for the observation period showed that the sensitivity of wind erosion has been increasing since the beginning of the period and reached its highest value in 2016. in recent years, due to many droughts, rainfall had a decreasing trend and wind speed and average temperature had an increasing trend, as a result, the sensitivity of wind erosion in the observation period has an increasing trend. the results of wind erosion climatic factors of chapil and fao showed that the average values of wind erosion sensitivity will decrease in the future period compared to the observation period. changes in climate parameters in the future period showed that under the rcp scenarios, rainfall and temperature parameters will increase and wind parameters will decrease. in general, the results showed that the effect of increasing rainfall and decreasing wind speed in the future period on climate factors is greater than the effect of temperature increase on the factors and the sensitivity of wind erosion in the future period will decrease compared to the observation period.