نتایج جستجو برای: irrigation channel embankment and hydraulic conductivity coefficient

تعداد نتایج: 16898008  

Journal: :Journal of environmental quality 2013
Ethan M Lineberger A Borhan M Badruzzaman M Ashraf Ali Matthew L Polizzotto

Across Bangladesh, dry-season irrigation with arsenic-contaminated well water is loading arsenic onto rice paddies, leading to increased arsenic concentrations in plants, diminished crop yields, and increased human health risks. As irrigation water flows through conveyance channels between wells and rice fields, arsenic concentrations change over space and time, indicating that channels may pro...

Journal: :Remote Sensing 2015
Joseph Mtamba Rogier van der Velde Preksedis Ndomba Zoltán Vekerdy Felix Mtalo

Vegetation resistance influences water flow in floodplains. Characterization of vegetation for hydraulic modeling includes the description of the spatial variability of vegetation type, height and density. In this research, we explored the use of dual polarized Radarsat-2 wide swath mode backscatter coefficients (σ°) and Landsat 5 TM to derive spatial hydraulic roughness. The spatial roughness ...

Journal: :آب و خاک 0
رضا لاله زاری سعید برومند نسب هادی معاضد علی حقیقی

introduction: groundwater is the largest resource of water supplement and shortages of surface water supplies in drought conditions that requires an increase in groundwater discharge. groundwater flow dependson the subsurface properties such as hydraulic gradient (water table gradient or head loss in artesian condition) and hydrodynamic coefficients. the flow treatment is analyzed with an accur...

2008
M. Berli A. Carminati T. A. Ghezzehei

[1] Prediction of water flow and transport processes in soils susceptible to structural alteration such as compaction of tilled agricultural lands or newly constructed landfills rely on accurate description of changes in soil unsaturated hydraulic conductivity. Recent studies have documented the critical impact of aggregate contact characteristics on water flow rates and pathways in unsaturated...

Journal: :Waste management 2009
B Celik R K Rowe K Unlü

Leakage rates are evaluated for a landfill barrier system having a compacted clay liner (CCL) underlain by a vadose zone of variable thickness. A numerical unsaturated flow model SEEP/W is used to simulate the moisture flow regime and steady-state leakage rates for the cases of unsaturated zones with different soil types and thicknesses. The results of the simulations demonstrate that harmonic ...

1999
Alex S. Mayer Changlin Huang

The coupled ̄ow-mass transport inverse problem is formulated using the maximum likelihood estimation concept. An evolutionary computational algorithm, the genetic algorithm, is applied to search for a global or near-global solution. The resulting inverse model allows for ̄ow and transport parameter estimation, based on inversion of spatial and temporal distributions of head and concentration meas...

2003
F. Abbasi

While inverse parameter estimation techniques for determining key parameters affecting water flow and solute transport are becoming increasingly common in saturated and unsaturated zone studies, their application to practical problems, such as irrigation, have received relatively little attention. In this article, we used the Levenberg–Marquardt optimization algorithm in combination with the HY...

Journal: :desert 2008
h. motaghian j. mohammadi a. karimi

soil hydrau-physical data are important for many hydrological modelings. they are the main variables controllingthe key processes such as water and chemicals movement and transport in the soil profiles. this study was conductedin order to analyze the spatial distribution of selected soil hydrau-physcial characteristics including infiltration rate(ir), saturated hydraulic conductivity (ks), bulk...

Journal: Geopersia 2016

IInfiltration rate and hydraulic conductivity are immensely important parameters for evaluating the hydrology of subsurface environments. Specifically, in disposal wells schemes and in artificial recharge plans both properties must be correctly assessed to better analyze the performance of these installations. In a new research, tanker water and rainfall runoff were injected into a 22.5 m deep ...

2010
Xiao-Wei Jiang Li Wan Tian-Chyi Jim Yeh Xu-Sheng Wang Liang Xu

Multi-scale heterogeneity of geological formations is a rule, which consists of random (local-scale) and systematic (large-scale) variability of hydraulic conductivity. The random variability and depth–decaying trend, a systematic variability, have different effects on subsurface flow, thus on groundwater discharge into tunnels. Little research has examined this problem in the past. Using Monte...

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