نتایج جستجو برای: spatial and temporal variation

تعداد نتایج: 16930333  

2015
Daisy Brickhill Peter GH Evans Jane M Reid

Understanding population dynamics requires spatio-temporal variation in demography to be measured across appropriate spatial and temporal scales. However, the most appropriate spatial scale(s) may not be obvious, few datasets cover sufficient time periods, and key demographic rates are often incompletely measured. Consequently, it is often assumed that demography will be spatially homogeneous w...

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The growing population led to greater human need to use natural resources such as sand and gravel mines. Direct removal of sands from the bed river leads to increase suspended sediment concentrations in downstream of harvested area and creates other problems viz. filling reservoirs, change in hydraulic characteristics of the channel and environmental damages. However, the range of temporal and ...

2012
Jerry L. Hatfield John H. Prueger

Evapotranspiration represents the combined loss of soil water from the earth’s surface to the atmosphere through evaporation of water from the soil or plant surfaces and transpiration via stomates of the plant. In agricultural production systems these two losses of water represent a major component of the water balance of the crop. If we examine evapotranspiration over time throughout a growing...

Journal: :international journal of environmental research 2015
m.v. kumarasamy

prediction of spatial and temporal variation of water quality is vital for managing pollutantsdisposal into the rivers. depletion of dissolved oxygen (do) takes place due to the consumption of oxygen bymicrobes to digest bio-degradable pollutants which enter a water course. reaeration takes place in a specificrate depending on do deficit. many investigators have formulated models as an alternat...

Fatemi , M.R., Jamili, Sh., Mokhayer , Z., Mousavi Nadushan , R., Rabbaniha, M., Safavi, S.E.,

Coastal ecosystems of Bushehr are shallow environments subject to human impacts, including shrimp aquaculture and urban expansion activities. A spatial-temporal study was conducted in order to assess the actual ecological status of the creeks, estuary and marine sites on the basis of their taxonomic composition and density of mesozooplankton. Zooplankton species distribution and abundance data ...

Journal: :Genetics 1978
P W Hedrick

The spatial model of Levene (1953) was examined in a finite population and compared to a temporal model. The spatial model was much more effective in retaining genetic variation in a finite population. Furthermore, the haploid spatial model was more effective in retaining genetic variation than the analogous diploid absolute dominance model. This is the opposite from that found for the temporal...

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...

Journal: :international journal of environmental research 2011
a. kavian y. fathollah nejad m. habibnejad k. soleimani

there is a need to analyze and map rainfall erosivity to assess soil erosion at the regional scale. the objectives of this study were to develop a regional model to estimate seasonal erosivity from seasonal rainfall data and to study temporal and spatial distribution of rainfall erosivity for the gorganrood drainage basin in the northeast of iran. six gauging stations with a high temporal reso...

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