Predicting wetting front advance in soils using simple laboratory derived hydraulic parameters

1996 ◽  
Vol 30 (6) ◽  
pp. 1471-1477 ◽  
Author(s):  
P Moldrup ◽  
T Yamaguchi ◽  
D.E Rolston ◽  
J.Aa Hansen
Keyword(s):  
Hydraulic Parameters ◽  
Wetting Front ◽  
Front Advance

Feldspathic sandstone addition and its impact on hydraulic properties of sandy soil

2018 ◽  
Vol 98 (3) ◽  
pp. 399-406 ◽  
Author(s):  
Junchao Jia ◽  
Pingping Zhang ◽  
Xiaofeng Yang ◽  
Xingchang Zhang
Keyword(s):  
Sandy Soil ◽  
Hydraulic Properties ◽  
Field Capacity ◽  
Water Retention Curve ◽  
Hydraulic Parameters ◽  
Wetting Front ◽  
Land Restoration ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Feldspathic Sandstone

Feldspathic sandstone could be used as an effective conditioner to improve the physical quality of sandy soil, and increase the crop yield there. To determine the effects of feldspathic sandstone content on soil hydraulic properties in a sandy soil, the present study added 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% (no sandy soil) of feldspathic sandstone to sandy soil. Changes in hydraulic parameters were investigated and the results showed addition of feldspathic sandstone increased saturated water content by 37%–61% and field capacity by 29%–44%, and decreased saturated hydraulic conductivity from 10.19 to 0.58 cm h−1 of the sandy soil. Further data analysis demonstrated that with increasing content of feldspathic sandstone, the parameter n of soil water retention curve in Van Genuchten model dropped from 1.807 to 1.333. The same decreasing trend is detected in parameter a of infiltration rate (3.841–0.703) in Kostiakov formula (i = at−b) and parameter a1 of wetting front (6.901–1.174) in the empirical equation (X = a1tb1). In terms of hydraulic parameters, 40% feldspathic sandstone and 60% sandy soil, optimally matching indices of loess soil, were the best mixing ratio for sandy land restoration.

The effect of aggregate size on the infiltration behaviour of a slaking soil and its relevance to ponded irrigation

Soil Research ◽  
1979 ◽  
Vol 17 (1) ◽  
pp. 65 ◽  
Author(s):  
N Collis-George ◽  
RSB Greene
Keyword(s):  
Surface Soil ◽  
Aggregate Size ◽  
Surface Region ◽  
Infiltration Rate ◽  
Optical Microscope ◽  
Wetting Front ◽  
Cumulative Infiltration ◽  
Front Advance ◽  
Soil Wetting ◽  
Independent Confirmation

The depth and degree to which columns of aggregates of different sizes of a structurally unstable red-brown earth surface soil slaked when water was ponded on the surface were studied. The slaking affected the subsequent infiltration into the soil. Wetting front advance and cumulative infiltration data indicated that the depth of the zone of slaking increased as the aggregate size increased. However, the effectiveness of the slaked layer in reducing the infiltration rate depended not only on the depth of slaking, but also on the extent to which the different aggregates had slaked into microaggregates and to what extent the microaggregates filled the interaggregate pores, if any. Examination of vertical sections of the slaked surface region using an optical microscope provided independent confirmation of the phenomenon of slaking in the various aggregate sizes.

Innovative In-Situ Determination of Unsaturated Hydraulic Properties in Deep Loess Sediments in North-West Bulgaria

2007 ◽  
Author(s):  
Dirk Mallants ◽  
Doncho Karastanev ◽  
Dimitar Antonov ◽  
Janez Perko
Keyword(s):  
Hydraulic Properties ◽  
Large Scale ◽  
Ground Surface ◽  
Time Domain Reflectometry ◽  
Hydraulic Parameters ◽  
Wetting Front ◽  
Field Scale ◽  
North West ◽  
Infiltration Tests ◽  
Migration Pathways

In the framework of selecting a suitable site for final disposal of low- and intermediate level short-lived radioactive waste (LILW-SL) in Bulgaria, site characterization is ongoing at the Marichin Valog site, North-West Bulgaria. The site is characterized by a complex sequence of loess, clayey gravel, and clay layers, of which the first 30–40 m are unsaturated. Proper knowledge about unsaturated water flow and concomittant radionuclide transport is key input to safety assessment calculations. Constant-head infiltrometer tests were carried out at several meters below ground surface to determine the unsaturated hydraulic properties of silty loess, clayey loess, and clayey gravel layers. Individual infiltrometers were equipped with 0.5-m-long filter sections; the shallowest filter was from 2 to 2.5 m depth, whereas the deepest was from 9.5 to 10 m depth. Infiltration tests provided data on cumulative infiltration and progression of the wetting front in the initially unsaturated sediments surrounding the infiltrometer. A cylindrical time-domain reflectometry TRIME probe was used to measure water content variations with time during progression of the wetting front. Access tubes for the TRIME probe were installed at 0.3 to 0.5 m from the infiltrometer tubes. By means of an inverse optimization routine implemented in the finite element code HYDRUS-2D, field-scale soil hydraulic parameters were derived for all layers. Results show a great consistency in the optimized parameter values, although the test sites were several meters apart. Apparently the size of the affected volume of soil was large enough to reduce the effect of spatial variability and to produce average field-scale hydraulic parameters that are relevant for large-scale predictions of flow patterns and radionuclide migration pathways.

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