Antecedent Moisture Content and Aging Duration Effects on Seal Formation and Erosion in Smectitic Soils

Abstract This study was based on a rainstorm that happened in Beijing on 20 July 2016. We analyzed the characteristics of rainfall and runoff during this rainstorm, compared it to rainstorm 721, and investigated why no surface runoff was observed during this rainstorm. A runoff plot experiment showed that almost all runoff consisted of deep interflow (40–60 cm). For runoff plots with identical vegetation, the slope was smaller, and the lag time of the deep interflow relative to the process of rainfall was shorter. The runoff yield of the deep interflow was inversely proportional to the slope. Compared to plots with pure tree forest and shrub forest, the interflow process curve of plots with coniferous and broad-leaved mixed forest was relatively gentle during the rainfall process. Thick litter layers, low antecedent moisture content of the soil, high gravel content of the soil, and the short duration of high intensity rainfall are the causes for the observed lack of surface runoff. To simultaneously prevent flooding and waterlogging, we propose to utilize vegetation to improve water storage at the reservoirs and to replenish the groundwater during cumulative rainstorms with a stable rain tendency.

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Laboratory experiments on rainfall-induced flowslide from pore pressure and moisture content measurements

Natural Hazards and Earth System Sciences Discussions ◽

10.5194/nhessd-3-1575-2015 ◽

2015 ◽

Vol 3 (2) ◽

pp. 1575-1613 ◽

Cited By ~ 7

Author(s):

M. R. Hakro ◽

I. S. H. Harahap

Keyword(s):

Moisture Content ◽

Pore Pressure ◽

Sandy Soil ◽

Laboratory Experiments ◽

Slope Failure ◽

Rainfall Intensity ◽

Mass Movement ◽

Sudden Increase ◽

Antecedent Moisture ◽

Type Of Failure

Abstract. During or immediately after rainfall many slope failures have been observed. The slope failure occurred due to rainfall infiltration that rapidly increase the pore pressure and trigger the slope failure. Numerous studies have been conducted to investigate the rainfall-induced slope failure, but the mechanism of slope failure is still not well clarified. To investigate mechanism of rainfall-induced slope failure laboratory experiments have been conducted in flume. The slope was prepared with sandy soil in flume with constant inclination of 45°, because most of rainfall-induced slope failure occurred in sandy soil and on steep slope. The hydrological parameters such as pore pressure and moisture content were measured with piezometers and advanced Imko TDRs respectively. The slope failure occurred due to increase in moisture content and rise in pore pressure. During the flowslide type of slope failure the sudden increase in pore pressure was observed. The higher moisture content and pore pressure was at the toe of the slope. The pore pressure was higher at the toe of the slope and smaller at the upper part of the slope. After the saturation the run-off was observed at the toe of the slope that erodes the toe and forming the gullies from toe to upper part of the slope. In the case antecedent moisture conditions the moisture content and the pore pressure increased quickly and producing the surface runoff at the horizontal part of the slope. The slope having less density suffer from flowslide type of the failure, however in dense slope no major failure was occurred even at higher rainfall intensity. The antecedent moisture accompanied with high rainfall intensity also not favors the initiation of flowslide in case of dense slope. The flowslide type of failure can be avoided by controlling the density of soil slope. Knowing such parameters that controls the large mass movement helpful in developing the early warning system for flowslide type of failure.

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Interrill erosion, runoff and sediment size distribution as affected by slope steepness and antecedent moisture content

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-7-6447-2010 ◽

2010 ◽

Vol 7 (4) ◽

pp. 6447-6489 ◽

Cited By ~ 10

Author(s):

M. B. Defersha ◽

S. Quraishi ◽

A. Melesse

Keyword(s):

Soil Erosion ◽

Size Distribution ◽

Sediment Yield ◽

Rainfall Intensity ◽

Black Soil ◽

Slope Steepness ◽

Sediment Size ◽

Antecedent Moisture ◽

Runoff Rate ◽

Antecedent Moisture Content

Abstract. Soil erosion is a two-phase process consisting of the detachment of individual particles and their transport by erosive agents such as flowing water. The rate at which erosion occurs depends upon the individual as well as interactive effects of different parameters responsible for soil erosion. The study discusses results of a laboratory analysis and evaluates the effect of slope steepness and antecedent moisture content on sediment yield (wash) and runoff rate. Interrill sediment yield, splash detachment, runoff, and sediment size distribution were measured in laboratory erosion pans under simulated total duration of 90 min. Rainfall intensity at 120 mm/hr, 70 mm/hr, and 55 mm/hr were applied sequentially at 9, 25, and 45% slope steepness for three soils (Alemaya Black soil, Regosols, and Cambisols) varied from clay to sandy clay loam in texture with wet and dry antecedent water contents. As slope steepness increased from 9 to 25% splash increased for five treatments and decreased for the remaining treatment; washed sediment increased for all treatments. As slope increased from 25 to 45% splash decreased for five treatments but increased for one treatment, and washed sediment increased for three treatments but decreased for the other three treatments. Pre-wetting decreased splash detachment for all soil treatments and rate of reduction was high for the highly aggregated soil, Alemaya Black soil and low for the less aggregated soil Regosols. Splash sediment and sediment yield was not correlated. Change in splash with increase in slope steepness was also not correlated with change in sediment yield. Change in runoff rate with increase in slope steepness was correlated (r=0.66) with change in sediment yield. For Alemaya Black soil and Regosols, splashed sediment size distribution was correlated with washed sediment size distribution. Interrill erosion models that include runoff and rainfall intensity parameters were a better fit for these data than the rainfall intensity based model. The exponent term, b, values in (E=a Ib) model did not approach 2.00 for all treatments. For the same slope steepness factor, both rainfall and rainfall-runoff based models provided different erodibility coefficients at different levels of slope and moisture contents.

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