نتایج جستجو برای: genuchten

تعداد نتایج: 254  

ژورنال: علوم آب و خاک 2007
جانب‌اله نیازی اردکانی, , سید حمید احمدی, ,

In this paper, the effect of irrigation water salinity levels on seed germination, dry matter weight of seedlings at eight-leave stage, and the salt tolerance of 8 rapeseed cultivars was investigated. Relative yield reduction in saline and non saline conditions, salt sensitivity index and Van Genuchten-Hoffman methods were used to determine the salt tolerance of the cultivars. Results showed th...

روابط آب و خاک به قدری پیچیده هستند که پیشرفتهترین مدلهای ریاضی نیز به سختی قادر به شبیهسازی دقیق آنها میباشند. منحنی رطوبتی و هدایتهیدرولیکی غیراشباع، از جمله عوامل مهم در بررسی حرکت آب در خاک هستند. بهعلت تغییرپذیری بالا و پیچیدگی خاک، بدست آوردن ویژگیهای هیدرولیکی خاکبهطور مستقیم دشوار، وقتگیر و هزینهبر بوده و بنابراین لازم است با استفاده از روشهای غیرمستقیم تخمین زده شوند. هدف از این پژوهش،...

1995
Glenn A. Williams Michael D. Tocci

Capillary pressure-saturation-relative permeability relations described using the van Genuchten and Mualem models for non-uniform porous media lead to numerical convergence diiculties when used with Richards' equation for certain auxiliary conditions. These diiculties arise because of discontinuities in the derivative of speciic moisture capacity and relative permeability as a function of capil...

2014
Rajiv K. Giri Krishna R. Reddy

In bioreactor landfill, the leachate flow and moisture distribution depend upon saturated and unsaturated hydraulic properties of municipal solid waste (MSW). The effects of unsaturated parameters have not been studied because of scarcity of the data and variation in unsaturated parameters due to MSW heterogeneity, degree of decomposition, and pore structure. In this study, a numerical two-phas...

2012
N. Fajraoui

Drainage experiments are commonly conducted to determine soil hydraulic parameters. Experiments generally measure the temporal evolution of the cumulative outflow as well as pressure heads and water contents at several levels in the column. Then the analysts try to calibrate the model by fitting the model response to the data series. The aim of the present work is to investigate the quality of ...

Journal: :پژوهش آب در کشاورزی 0
سعید سعادت استادیار مؤسسه تحقیقات خاک و آب. مهدی همایی استاد گروه خاکشناسی دانشگاه تربیت مدرس.

plant response to salinity varies at different growth stages. information on plant response to salinity at various growth stages can be used in managing saline waters for irrigation. in order to measure the quantitative response of salinity on germination of sorghum (sorghum bicolor l. moench), a greenhouse experiment was conducted in a natural saline sandy loam soil, using plastic pots with 15...

ژورنال: علوم آب و خاک 2014
جعفری, سیروس, خلیلی مقدم, بیژن, قربانی دشتکی, شجاع, مرادی, فرزاد,

Soft computing techniques have been extensively studied and applied in the last three decades for scientific research and engineering computing. The purpose of this study was to investigate the abilities of multilayer perceptron neural network (MLP) and neuro-fuzzy (NF) techniques to estimate the soil-water retention curve (SWRC) from Khozestan sugarcane Agro-Industries data. Sensitivity analysi...

Journal: :Rona Teknik Pertanian 2021

Abstract. The application of large manure on the agricultural lands that derived from Concentrated Animal Feeding Operations (CAFOs) could cause excess nutrients such as nitrogen and phosphorus transport to groundwater through vadose (unsaturated) zone. objective this study is follows: (1) compare in zone at different Land Management Units (LMUs) for three consecutive years (2004-06) using HYDR...

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