نتایج جستجو برای: water scarcity in arid and semi
تعداد نتایج: 21812805 فیلتر نتایج به سال:
The objective of this paper is to provide an overview of the primary results of the Semi-Arid Land–Surface–Atmosphere (SALSA) Program in the context of improvements to our overall understanding of hydrologic, ecologic, and atmospheric processes and their interactions in a semi-arid basin. The major findings and future research needs associated with the different core components of the program a...
Hypotheses about the origin of vegetation pattern formation in semi-arid areas around the world almost all include a common feature of semi-arid areas: the presence of a positive feedback between plant density and water infiltration. We investigate whether this positive feedback and the spatial redistribution of runoff water are sufficient to explain vegetation pattern formation. For this purpo...
the purpose of this study was to evaluate the species-environment relationships in arid and semi-arid rangelandsof nodushan, yazd. the plant species cover and the environmental variables were measured at 9 sites. soil sampleswere taken for measurement of 12 attributes in 0-10 cm and 10-80 cm layers. vegetation was classified using twowayindicator species analysis (twinspan). data was analyzed u...
The ever-increasing problem of water scarcity in arid and semi-arid regions of Iran has necessitated the demand to replacement of sugar beet plantation by more water-use efficient plants. Sweet sorghum is one of the sugars plants with low water requirements that potentiates cost-effective sugar production in different regions. However, physiological aspects of sugar yield in this plant is not c...
a field study was conducted to evaluate the possibility of using water table control techniques in the semi arid region of iran with special attention to its salinity management. the wtm consisted of three subirrigation treatments with water table controls set at 0.3, 0.5 and 0.7 m from the soil surface and a free drainage (fd) treatment. the electrical conductivity (ec) of water was 1.5 ds/m. ...
Water scarcity is an urgent issue for social and economic development in arid semi-arid areas. Constructing long-distance pressurized water supply projects a commonly used measure to solve problems these With the increasing complexity of projects, hammer protection has become more prominent. Air chambers have been widely accidents. In this paper, we propose novel air chamber with adjustable cen...
Sloping farmlands are the major sources of soil, water and nutrient losses in arid and semi-arid regions. Information about the impacts of different tillage practices on soil erosion, nutrient loss and crop nutrient uptake on the sloping farmland of semi- arid soil is, however, limited. This study was carried out to investigate the effects of tillage direction on soil, water, nitrogen and phosp...
abstract sensitive and precise voltammetric methods for the determination of trace amounts of furaldehydes, mainly as furfural (f) and 5-hydroxymethyl-2-furaldehyde (hmf), in waste waters and other matrices is described. determination of total furaldehyde at < ?g g-1 levels in alkaline buffered aqueous media was individually investigated. by the use of ordinary swv and adsorptive square wave ...
a semi-empirical mathematical model for predicting physical part of ignition delay period in the combustion of direct - injection diesel engines with swirl is developed . this model based on a single droplet evaporation model . the governing equations , namely , equations of droplet motion , heat and mass transfer were solved simultaneously using a rung-kutta step by step unmerical method . the...
salinity tolerance is one of the most important affecting factors on agricultural production in arid and semi-arid areas. in order to study the effects of saline and fresh water irrigation with application of organic and npk fertilizers on cumin, a split plot experiment based on randomized complete block design was carried out with three replications during 2011 and 2012, at the research farm o...
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