نتایج جستجو برای: arid and rainfall in arid and semi

تعداد نتایج: 21762861  

2005
S. Vetter

This paper reviews the predictions and management implications of two current paradigms in the ecology and management of arid and semi-arid rangelands. The equilibrium model stresses the importance of biotic feedbacks such as density-dependent regulation of livestock populations and the feedback of livestock density on vegetation composition, cover and productivity. Range management under this ...

ژورنال: علوم آب و خاک 2017

Modified Universal Soil Loss Equation (MUSLE) is one of soil loss estimation models which has been developed based on the runoff characteristics in the event scale. However, it needs to be evaluated in the plot scale for the semi-arid rainfall events. With this aim, a field study was designed using twenty one plots. Runoff and soil loss were measured using 5-min samples under seven rainfall int...

2012
M. MOYO P. DORWARD

Farmers in semi-arid Zimbabwe prioritise climate variability as their major agricultural productivity-reducing problem. This paper raises the importance of considering local farmers’ perceptions on climate risk, as this greatly influences on-farm investments and decision-making in agricultural management and production in semiarid Zimbabwe. A study was conducted in two districts of semi-arid Zi...

Journal: :مدیریت خاک و تولید پایدار 0
مارال خدادادی دانشجوی دکتری/دانشگاه تهران منوچهر گرجی دانشیار/ دانشگاه تهران محمد قنادی مراغه پژوهشگاه علوم و فنون هسته ای، سازمان انرژی اتمی ایران علی سامانی بهرامی پژوهشگاه علوم و فنون هسته ای، سازمان انرژی اتمی ایران میر حسین میر سید حسینی دانشیار/ گروه مهندسی و علوم خاک، پردیس کشاورزی و منابع طبیعی، دانشگاه تهران قوام الدین زاهدی امیری دانشیار/ دانشکده جنگلداری و اقتصاد جنگل، پردیس کشاورزی و منابع طبیعی، دانشگاه تهران معین مفتاحی

over the past decades, the fallout radionuclides 137cs, 210pbex and 7be are increasingly being used to quantify soil erosion and sedimentation rates. although studies using 137cs and to some extent 210pbex are now well-documented, there is a need for further work aimed at exploring the use of 7be, particularly in arid and semi-arid areas. investigating soil erosion processes occurring over shor...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه 1377

the methods which are used to analyze microstrip antennas, are divited into three categories: empirical methods, semi-empirical methods and full-wave analysis. empirical and semi-empirical methods are generally based on some fundamental simplifying assumptions about quality of surface current distribution and substrate thickness. thses simplificatioms cause low accuracy in field evaluation. ful...

2001
Andreas Güntner Jonas Olsson Ann Calver Beate Gannon

Rainfall data of high temporal resolution are required in a multitude of hydrological applications. In the present paper, a temporal rainfall disaggregation model is applied to convert daily time series into an hourly resolution. The model is based on the principles of random multiplicative cascade processes. Its parameters are dependent on (1) the volume and (2) the position in the rainfall se...

ژورنال: علوم آب و خاک 2011
ابراهیم پذیر, , داود نیک‌کامی, , محمد حسین مهدیان, , نازیلا خرسندی, ,

Rainfall erosivity force as on important factor in soil erosion and sediment yield has been introduced in different indexes. The objective of this study was to determine suitable rainfall erosivity indices for two climates of semi-arid in Maravetape and very humid in Sangdeh, both in Khazar watershed, by correlation between rainfall erosivity indices and sediment outflow from erosion plots. F...

Journal: :آب و خاک 0
موسوی موسوی رئیسی رئیسی

abstract earthworms are an important component of soil fauna, and play a crucial role in the improvement of soil properties. however, very little is known of the interactive influence of earthworms and organic materials on soil enzyme activities, particularly in arid and semi-arid soils. the low organic matter content and the significant role of earthworms in stimulating microbiological and bio...

Journal: :desert 2010
h. memarian khalilabad s. feiznia k. zakikhani

abstract erosion and sedimentation are the most complicated problems in hydrodynamic which are very important in water-related projects of arid and semi-arid basins. for this reason, the presence of suitable methods for good estimation of suspended sediment load of rivers is very valuable. solving hydrodynamic equations related to these phenomenons and access to a mathematical-conceptual model ...

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