نتایج جستجو برای: Sand dunes

تعداد نتایج: 29226  

2018
Baoli Fan Allen David McHugh Shujiang Guo Quanlin Ma Jianhui Zhang Xiaojuan Zhang Weixing Zhang Juan Du Qiushi Yu Changming Zhao

Calligonum mongolicum is a successful pioneer shrub to combat desertification, which is widely used for vegetation restoration in the desert regions of northwest China. In order to reveal the limitations to natural regeneration of C. mongolicum by asexual and sexual reproduction, following the process of sand dune stabilization, we assessed clonal shoots, seedling emergence, soil seed bank dens...

2013
Golan Bel Yosef Ashkenazy

Golan Bel and Yosef Ashkenazy Department of Environmental Physics, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel (Dated: May 11, 2014) Abstract Psammophilous plants are special plants that flourish in sand moving environments. There are two main mechanisms by which the wind affects these plants: (i) sand drift exposes roots and cov...

Journal: :مرتع و آبخیزداری 0
اصغر توکلی فرد کارشناس ارشد بیابان‏ زدایی، دانشکده منابع طبیعی و علوم زمین، دانشگاه کاشان علی اکبر نظری سامانی دانشیار دانشکده منابع طبیعی، دانشگاه تهران ناصر مشهدی استادیار مرکز تحقیقات بین‏ المللی همزیستی با کویر، دانشگاه تهران هدی قاسمیه استادیار دانشکده منابع طبیعی و علوم زمین، دانشگاه کاشان مجتبی هدایی آرانی کارشناس ارشد ژئومورفولوژی، دانشکده جغرافیا، دانشگاه تهران

kashan erg is one of the most important sand dunes complexes in iran. it is included the most important various type of sand dunes in iran. this study was performed to compare the granulometry of aeolian sediments in different sand dunes and also from plinth to crest of transverse dunes that located in kashan erg’s north. in order to determining different statistical variables, aeolian sediment...

Grain size is one of the most obvious characteristics in many studies of Aeolian erosion, Ergs, moving of sand dune, etc. Comparison of Grain size and morphoscopy between new and old sand dunes in an Erg, help us to identify the sources sand and control reactivity sand dunes. This study, as first step, by aerial photography and satellite imagery attempting to identify areas were sedimented. The...

2008

Endemic species are those that exist at only one location or area on Earth. They tend to be more numerous in habitats that are distinctly different from the surrounding areas. The Great Sand Dunes harbor at least seven endemic species of insects. Many of the insects here are ‘sand obligates’, meaning that they are adapted uniquely for sandy habitats. Currently, just over 1,000 different kinds o...

Journal: Desert 2007
G. Feghhi H. Ahmadi M. Ekhtesasi N. Mashhadi, S. Feiznia

Wind regime and sand grain size are two of the factors that determine the morphology and dynamics of sand dunes in desert areas. Regarding the importance of wind effects on sand dunes especially in Iran, in this study, Khartooran Erg was analyzed to determine wind direction and to detect sand source sites. Khartooran Erg is located on eastern north of Iran and lies in Khorasan Razavi and Semnan...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2007
Eric J R Parteli Hans J Herrmann

We apply a model for sand dunes to calculate formation of dunes on Mars under the present Martian atmospheric conditions. We find that different dune shapes as those imaged by Mars Global Surveyor could have been formed by the action of sand-moving winds occurring on today's Mars. Our calculations show, however, that Martian dunes could be only formed due to the higher efficiency of Martian win...

Journal: :desert 2008
n. mashhadi h. ahmadi m. r. ekhtesasi s. feiznia g. feghhi

wind regime and sand grain size are two of the factors that determine the morphology and dynamics of sand dunes in desert areas. regarding the importance of wind effects on sand dunes especially in iran, in this study, khartooran erg was analyzed to determine wind direction and to detect sand source sites. khartooran erg is located on eastern north of iran and lies in khorasan razavi and semnan...

2013
Hans J. Herrmann

We apply a model for sand dunes to calculate formation of dunes on Mars under the present Martian atmospheric conditions. We find that different dune shapes as those imaged by Mars Global Surveyor could have been formed by the action of sand-moving winds occuring on today’s Mars. Our calculations show, however, that Martian dunes could be only formed due to the higher efficiency of Martian wind...

2016
Ying Pan Hao Zhang Xu Li Yonghong Xie

Sedimentation is recognized as a major factor determining the ecosystem processes of lake beaches; however, the underlying mechanisms, especially in freshwater sand dunes, have been insufficiently studied. To this end, nine belt transects from nine freshwater sand dunes, classified into low (<23.7 m), medium (25.4-26.0 m), and high-elevation groups (>28.1 m) based on their elevations in 1972, w...

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