نتایج جستجو برای: in many arid and semi

تعداد نتایج: 21768044  

Journal: :سنجش از دور و gis ایران 0
سیدجواد ساداتی نژاد دانشگاه تهران محمدرضا شکاری دانشگاه کاشان

the importance of groundwater as a source of water supply in arid, semi –arid areas in recent years due to the uncontrolled exploitation of groundwater have been doubled. uncontrolled exploitation has been caused a drop in the water table in many areas of the country, including this region. with replace methods of modern irrigation instead of traditional irrigation methods can prevent drop the ...

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 ...

Journal: :desert 2008
a. khalili h. rahimi z. agha shariatmadari

depth of frost penetration is one of the main indices in agriculture, civil and transportation engineering. soil temperature is a function of several factors including: topography, solar radiation, air temperature, moisture content and other physical properties of soil such as thermal capacity, coefficient of heat conductivity, and specific heat. the main objective of the present paper is to de...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده ریاضی 1390

the main objective in sampling is to select a sample from a population in order to estimate some unknown population parameter, usually a total or a mean of some interesting variable. a simple way to take a sample of size n is to let all the possible samples have the same probability of being selected. this is called simple random sampling and then all units have the same probability of being ch...

In the arid and semi-arid area's rainfall have considerable changes in terms of time and amount that make the water resource management an important issue. In this research, using both Boolean and Fuzzy logic were zoned potentiality suitable areas for construction of underground dams. The study area is located in the central region of Ardabil province with 7461 km2 area and semi-arid climate. F...

Journal: :desert 2015
amir reza keshtkar

knowledge about low flow statistics is essential for effective water resource planning and management in ungauged orpoorly gauged catchment areas, especially in arid and semi-arid regions such as iran. we employed a data set of 20 riverflow time-series from the iranian central plateau river basin, iran to evaluate the low-flow series using several frequencyanalysis methods and compared the resu...

Journal: :journal of rangeland science 2014
mohsen sharafatmandrad adel sepehry hossein barani

in arid and semi-arid rangelands, grazing as one of the natural or human induced processes has direct and indirect effects on structure and dynamics of plant community and ecosystems. a study was done to analyze the effects of grazing on plant species diversity and plant functional types‘ (pfts) diversity of arid and semi-arid rangelands. we analyzed plant richness and diversity data from 75 sa...

Journal: :journal of rangeland science 2012
sedigheh zare kia hossein arzani mohammad jafari seyyed akbar javadi ali ashraf jafari

this study aims to assess the effect of grazing intensity on vegetation structure, soil nutrient concentrations and soil physical properties. the study was carried out in steppe rangelands of saveh, markazi province, iran. four sites with four grazing intensities including very high, high, moderate and non-grazed with the same ecological conditions were selected. to study various vegetation and...

Urbanism directly affects the hydrological cycle. One of the ways to manage runoffs in urban areas that is considered nowadays is green roof creation. Green roof is mainly created in humid and semi-humid areas, and efficiency of green roofs in arid and semi-arid areas has attracted less attention. In the current study, to evaluate the effect of green roof in arid and semi-arid to reduce runoff,...

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