نتایج جستجو برای: wind erosion forms

تعداد نتایج: 379184  

ژورنال: :پژوهش های دانش زمین 0
محمد حسن صادقی روش دانشگاه آزاد اسلامی واحد تاکستان حسن خسروی دانشگاه تهران

از آنجا که پدیده های واقعی همواره فازی، نادقیق و مبهم هستند. آنچه در ارزیابی این پدیده ها مهم به نظر می رسد امتیازدهی صحیح شاخص ها به منظور دستیابی به نتایج قابل استناد می باشد. فرسایش بادی نیز به عنوان یک پدیده واقعی واجد شاخص هایی هست که ساختار کیفی یا ساختار نامشخصی دارند که نمی توانند به دقت اندازه گیری شوند. در چنین مواردی به منظور دستیابی به ماتریس ارزشیابی می توان از اعداد فازی استفاده ک...

2008
A. MAXWELL

Darlit streamlined streaks observed in orbital images of the Western Desert of Egypt are similar in saale and form to craterand knob-related streaks on the martian surfaae. In Egypt, dark streaks form in the lee of topographic highs^ ranging in sise from small hills a few meters across^ to the 60 km wide Uweinat massifs On the surfaae of Mars, streaks may he either lighter or darker in tone tha...

2005
James C. Ascough Lajpat R. Ahuja Dennis C. Flanagan

ABSTRACT. Current challenges in soil erosion research have created demand for integrated, flexible, and easily parameterized sediment transport models. Most of the existing monolithic erosion models (e.g., WEPP and WEPS) are not modular, thus modifications require considerable time, effort, and expense. In this paper, the feasibility and challenges of using the Object Modeling System (OMS) for ...

2006
Nani G. Bhowmik Misganaw Demissie

An excessive amount of bank erosion along a number of waterways in Illinois and surrounding states exists at the present time. Erosion of stream banks attracts public attention, reduces property values, results in the permanent loss of real estate, increases the turbidity of streams, and accelerates the silting of reservoirs and backwater lakes along stream courses. Among the main causes of ban...

2013
Zhiwu Han Wei Yin Junqiu Zhang Shichao Niu Luquan Ren

Plants have numerous active protection strategies for adapting to complex and severe environments. These strategies provide endless inspiration for extending the service life of materials and machines. Tamarisk (Tamarix aphylla), a tree that thrives in raging sandstorm regions, has adapted to blustery conditions by evolving extremely effective and robust erosion resistant characteristics. Howev...

Introduction: Increasing or reducing the production of suspended particles depends on the important climatic and terrestrial characteristics of a region. One of the most important climatic factors affecting soil erosion is wind speed, so if the surface winds speed in a region exceeds the threshold of erosion, soil susceptibility to erosion and dust production increases. In contrast, the most im...

Journal: :مرتع و آبخیزداری 0
طیبه مصباح زاده استادیار گروه احیای مناطق خشک و کوهستانی، دانشکدة منابع طبیعی، دانشگاه تهران حسن احمدی استاد دانشگاه آزاد اسلامی، واحد علوم تحقیقات، تهران غلامرضا زهتابیان استاد گروه احیای مناطق خشک و کوهستانی، دانشکدة منابع طبیعی، دانشگاه تهران فریدون سرمدیان استاد گروه مهندسی خاک، دانشکدة مهندسی خاک، دانشگاه تهران فیروزه مقیمی نژاد کارشناس ارشد مرتعداری، دانشکدة منابع طبیعی، دانشگاه تهران

desertification is specific phenomenon of arid, semi-arid, dry sub humid regions. this phenomenon has a high rate in developing countries such as iran. the main objective of this research was calibration of imdpa model in abuzeidabad (kashan) region with emphasis on land criteria. imdpa model, introduced by iranian researchers to assess desertification intensity in iran. before application, the...

2009
J. B. Sankey

Wind erosion of soil is an appreciable but unstudied event following fires in cold desert. We examined aeolian transport of sediment for 1 year following fire in semi-arid shrub steppe on loess soils in southern Idaho, USA. Sediment collectors were used to determine horizontal mass transport of soil and saltation sensors and anemometers were used to determine saltation activity (fraction of tim...

2010

PM10 concentrations were measured at Nellis Dunes Recreation Area (NDRA), Nevada, USA. NDRA is a desert area located 6 km northeast of the metropolitan area of Las Vegas. Three sources contribute to the dust at the site: local wind erosion, off-road vehicular activity and dust production in the city of Las Vegas. PM10 concentrations were measured during one complete year and stored as 20-min av...

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