نتایج جستجو برای: steep slope

تعداد نتایج: 62486  

Journal: :desert 2008
m. jafari m. souri h. azarnivand m. makhdom v. etemad

soil salinity is one of the problems threatening agricultural lands. parts of this phenomenon are related to geologic formations and saltpans, while some major factors are resulted from irrelevant agricultural activities, issue of irrigation, and improper cultivation systems which lead to increase in soil salinity. to avoid such consequences that would end up with ecosystem degradation, suitabl...

2017
Ahmad Solgi Ramin Naghdi Petros A. Tsioras Ulrik Ilstedt Ali Salehi Mehrdad Nikooy

Harvest traffic with heavy equipment causes damage to forest soils. Whereas increased soil damage has been reported with increasing harvest equipment traffic and on increasing slope gradients, it is unclear how much soil damage is caused by different directions of skidding. We examined the effects of traffic frequency, skid trail slope and skidding direction on the dry bulk density and total po...

2013
Yun - Yao Chi

In this paper, a study of slope failures along the Alishan Highway is carried out. An innovative empirical model is developed based on 15-year records of rainfall-induced slope failures. The statistical models are intended for assessing the volume of landslide for slope failure along the Alishan Highway in the future. The rainfall data considered in the proposed models include the effective cum...

Journal: Desert 2007
H. Azarnivand M. Aghayi M. Jafari, M. Makhdom M. Souri V. Etemad

Soil salinity is one of the problems threatening agricultural lands. Parts of this phenomenon are related to geologic formations and saltpans, while some major factors are resulted from irrelevant agricultural activities, issue of irrigation, and improper cultivation systems which lead to increase in soil salinity. To avoid such consequences that would end up with ecosystem degradation, suitabl...

ژورنال: علوم آب و خاک 2014

Modernization of irrigation canals as an operation improvement tool is essential to promote the performance of canal networks and indeed requires control systems. Proportional integral derivative (PID) algorithms have more applications than the other controllers in different places of the world, but tuning these controllers for different hydraulic conditions of canals is considered as a major p...

ژورنال: علوم آب و خاک 2014

To study the effects of irrigation durations and land slopes on wetting pattern dimensions, some experiments were performed using an emitter with constant discharge of 4 liters per hour by 2, 4, and 6 hours irrigation durations. Experiments were conducted on lands with the slopes of 0, 5, 15 an 25 percent, with silty loam soil texture in 3 replications in Fathali region, Mogan plain, Iran. Resu...

2005
R. Johannesson V. Pavlushkov V. V. Zyablov

In this paper several rate R = 2/5 convolutional encoding matrices with four states are used to illustrate how unequal error protection can be achieved for the different positions in the code sequences as well as in the information sequences. Free outputand input-distances and active burst outputand input-distances are computed. Typically a single code cannot combine a large free outputor input...

Journal: :Physical review letters 2002
Semion Sukoriansky Boris Galperin Nadejda Dikovskaya

The Kolmogorov-Batchelor-Kraichnan (KBK) theory of two-dimensional turbulence is generalized for turbulence on the surface of a rotating sphere. The energy spectrum develops considerable anisotropy; a steep -5 slope emerges in the zonal direction, while in all others the classical KBK scaling prevails. This flow regime in robust steady state is reproduced in simulations with linear drag. The co...

2012
Roman A. DiBiase Arjun M. Heimsath Kelin X Whipple

Hillslopes are thought to poorly record tectonic signals in threshold landscapes. Numerous previous studies of steep landscapes suggest that large changes in long-term erosion rate lead to little change in mean hillslope angle, measured at coarse resolution. New LiDAR-derived topography data enables a finer examination of threshold hillslopes. Here we quantify hillslope response to tectonic for...

Journal: :تحقیقات آب و خاک ایران 0
الهام درویشی دانشجوی دکتری سازه های آبی، گروه مهندسی آبیاری و آبادانی، دانشکدة مهندسی و فناوری کشاورزی، دانشگاه تهران صلاح کوچک زاده استاد گروه مهندسی آبیاری و آبادانی، دانشکدة مهندسی و فناوری کشاورزی، دانشگاه تهران جان فنتون استاد دانشگاه فنی وین، اتریش عبدالحسین هورفر استاد گروه مهندسی آبیاری و آبادانی پردیس کشاورزی و منابع طبیعی دانشگاه تهران

the assumptions considered in developing the saint-venant equations limit their application in many practical situations. the modified boussinesq equation was presented to overcome the limitation imposed by saint-venant equation due to the presence of non-hydrostatic pressure distribution and steep slope. in this paper a computational model was developed for solving the modified and the traditi...

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