Evaluation of Rainfall Interception by Vegetation Using a Rainfall Simulator

Interception by vegetation is one of the main variables controlling hydrological and geo-environmental problems such as erosion, landslides and floods. Interception, along with precipitation and evapotranspiration, is required for the modeling of infiltration, percolation and runoff. Unfortunately, the measurement of interception in the field is time consuming, burdensome and subject to testing parameters with relatively high variability. In this context, experiments using rainfall simulators (RSs) have the potential to provide an alternative approach that addresses most of the limitations of field experiments. This paper presents a new approach to evaluate interception that combines a RS and the monitoring of the wetting front using pore-water pressure instrumentation at specific locations of the specimen. Two specimens are required, one with and another without vegetation. The proposed approach was applied to Paspalum notatum (bahiagrass) and a tropical soil. The results indicated an average interception of 5.1 mm of the simulated rainfall for a slope at 15 degrees, rainfall intensity of 86 mm h−1, and duration of 60 min. Furthermore, the vegetation decreased the surface runoff that contributes to erosion. The proposed method will enable studies on the interception mechanisms and the various involved variables, with benefits to the modeling of soil-vegetation-atmosphere interaction.

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Response of Soil Suction to Heavy Rainfalls in a Tailings Dam

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.250-253.1681 ◽

2011 ◽

Vol 250-253 ◽

pp. 1681-1685 ◽

Cited By ~ 1

Author(s):

Rui Chen ◽

Ben Zhuo Zhang ◽

Wei Dong Lei ◽

Wen Bin Luo

Keyword(s):

Rainfall Intensity ◽

Pore Water Pressure ◽

Water Pressure ◽

Shallow Landslide ◽

Rainfall Infiltration ◽

Tailings Dam ◽

Wetting Front ◽

Tailings Dams ◽

The Impact ◽

Heavy Rainfalls

Rainfall is a significant factor leading to failure of tailings dams. The impact of rainfall on the instability of dams is mainly reflected in the variation of negative pore-water pressure (i.e. matric suction) during rainfall infiltration. However, there is a lack of study on the effects of rainfall on suction in tailings dams. In this study, the response of suction to artificial heavy rainfalls in a tailings dam was investigated. The effects of rainfall intensity and surface vegetation conditions on the response of suction were studied. It is found that suctions at a certain depth in the tailing dam were kept constant until the wetting front reached this depth. Once suctions were altered, the values dropped rapidly. The magnitude of suction change generally decreased with depth. Rainfall infiltration mainly occurred above the depth of 40 to 80 cm when subjected to rainstorm and heavy rainstorms. Larger rainfall intensity leads to shorter response time and to larger depth affected by rainfall, implying that the tailings dam is more susceptible to shallow landslide failure under larger rainfall intensity. The existing vegetation increases infiltrability significantly and then produces an adverse effect on the stability of the tailings dam. On the other hand, it is observed that the presence of vegetation greatly prevented surface erodibility and then decreases the possibility of debris flow.

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Numerical Analysis to Assess the Vertical Drainage Within Flexible Pavement.

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.20.25856 ◽

2018 ◽

Vol 7 (4.20) ◽

pp. 95

Author(s):

Aqeel Al-Adili ◽

Rasha H. Abdul-Amir ◽

Osamah Hassan Chfat

Keyword(s):

Cross Section ◽

Rainfall Intensity ◽

Pore Water Pressure ◽

Water Pressure ◽

Water Flux ◽

Flexible Pavement ◽

Laboratory Model ◽

Typical Structure ◽

Rainy Period ◽

Vertical Drainage

In this research the work methodology include the software program SEEP/W routine of the GEOSLOPE 2012; which was used to simulate and analyze the vertical drainage of the pavement cross section using steady-state and transient analysis. A laboratory model consisting of typical structure layers of flexible pavement was considered in this research with a 2% slope with the influence of three different rain intensities (30mm/min, 60mm/min and 90mm/min); in which each one has a duration differs from the other. The results indicated that the value of the pore-water pressure in the surface layer resulting from 90 mm/min rainfall intensity is 83.65% greater than the pressure generated by the 60mm/min intensity of rain and 91.076% greater than the pressure produced from 30mm/min intensity. The average of accumulation water produced by the 30mm/min rainfall intensity in the pavement structure is 44.73 % greater than the average of accumulation of water from the 60mm/min intensity and 77.85% higher than the 90mm/min intensity of rain. The water flux through the pavement cross section during the rainy period of 30 mm/min was 8.42% higher than the water flux of 60 mm/min and 49.82% of the water flux of 90 mm/min intensity of rain.

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Seepage Analysis on the Surface Layer of Multistage Filled Slope with Rainfall Infiltration

Advances in Civil Engineering ◽

10.1155/2020/8879295 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Bingxiang Yuan ◽

Zengrui Cai ◽

Mengmeng Lu ◽

Jianbing Lv ◽

Zhilei Su ◽

...

Keyword(s):

Rainfall Intensity ◽

Pore Water Pressure ◽

Water Pressure ◽

Rainfall Infiltration ◽

Feature Points ◽

Saturation State ◽

Seepage Analysis ◽

Safety Coefficient ◽

Infiltration Model ◽

Saturation Region

Based on the theory of rainfall infiltration, the surface infiltration model of multilevel filled slope was established by using the SEEP/W module of GeoStudio. The changes of the volumetric water content (VWC) and pore water pressure (PWP) in the surface of the slope during the rainfall infiltration were analyzed, and the influence of the change of the rainfall conditions on the VWC and PWP was considered. The analysis showed that VWC and PWP increased when the rain fell, and the growth rate of the higher feature point was higher. The affected area was concentrated on the upper part of the surface about 0.75 m. With the increasing of rainfall intensity, the slope surface getting to transient saturation state was quick, and the time of the PWP increasing to 0 among the feature points of same elevation was shortened. Meanwhile, the PWP presented a positive value, and as the infiltration depth increased, the transient saturation region expanded. The safety coefficient of the multistage filled slope was continuously reduced; after the stop of rainfall, the VWC and the PWP decreased, and the decline rate of the higher feature points was higher. In addition, the PWP of the lower part increased, and the safety factor of the slope presented a trend of rebound.

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Study on Slope Instability Disciplinarian on the Condition of Rainfall

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.654 ◽

2013 ◽

Vol 353-356 ◽

pp. 654-658

Author(s):

Nan Tong Zhang ◽

Xiao Chun Zhang ◽

Hua Rong Wang ◽

Chen Yan

Keyword(s):

Slope Stability ◽

Tensile Stress ◽

Rainfall Intensity ◽

Pore Water Pressure ◽

Water Pressure ◽

Road Construction ◽

Slope Instability ◽

Slope Surface ◽

Large Area ◽

Break Zone

Slope stability is one of the problems of road construction which should be faced with and solve. Rainfall can reduce the shear strength of slope soil and raise the underground water level which can lead to increase slope soil pore water pressure. The influence of rainfall infiltration on slop is mainly to change the slope seepage field, increase dynamic and hydrostatic water load on the slope soil and decrease of soil shear parameters. More abundant rainfall of typhoon area could make the road slope stability more fragile. Based on Matoushan Mountain along 104 state roads in Taizhou city, Zhejiang province, slope instability disciplinarian on the condition of rainfall is studied using the method of numerical simulation in this paper. As the results, when the rainfall intensity was 0.006 m/h and continuous rain was in 24 hours, the slope surface compressive stress tends to zero which began to appear tensile stress area on the condition of self-weight. And when the rainfall intensity was 0.01 m/h and continuous rain was in 24 hours, the large area of the slope surface was tensile stress area which means to appear break zone in slope surface and likely to landslide at the same time.

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A suitable methodology for assessing impacts of successive rainfalls infiltration on road slope stability

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.184.1-2.171 ◽

2013 ◽

Vol 184 (1-2) ◽

pp. 171-181

Author(s):

Hugues Georges Rameau ◽

Claude Prepetit ◽

Jean-Claude Verbrugge

Keyword(s):

Slope Failure ◽

Pore Water Pressure ◽

Water Pressure ◽

Rainfall Simulation ◽

Wetting Front ◽

Rainfall Events ◽

Simulation Techniques ◽

Apparent Cohesion ◽

National Road ◽

The Relationship

Abstract Water precipitation in road slopes, pavements, and shoulders may cause disturbances such as erosion, increase of the water table level, decrease of the carriageway bearing capacity, and so on. Roads are normally equiped with drainage systems that are sized and implemented in accordance with the rules of art. These equipments are used for the collection and quick evacuation of water precipitation estimated on the basis of the return period that is taken into account. Despite that, rainwater can still infiltrate unprotected cut or fill slopes, and pavements for repeated and intense rainfalls, which may cause a raise in pore-water pressure and a decrease of the factor of safety of road slopes. Using laboratory rainfall simulation techniques, infiltration measurements were made on intact samples to determine with respect to soil properties, how cumulative rainfalls cause decrease in apparent cohesion and lead to slope failure. This paper focuses on describing the relationship between the rainfall characteristics, the changes in soil water profile, and the changes in apparent cohesion for sandy clay samples collected on the national road RN3 located in Haiti. For a set of consecutive rainfall events at around an interval of 24 hours, the results prove that when wetting front depth approaches 2 meters or more, the risk of landslide is proportionally high in a soil with apparent cohesion (Ca) initially high and an effective cohesion (c′) relatively low.

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Post-Evaluation of Slope-Cutting on Loess Slopes Under Long-Term Rainfall Based on Model Test

10.21203/rs.3.rs-770649/v1 ◽

2021 ◽

Author(s):

Guodong Liu ◽

Shiqiang Xu ◽

Zhijun Zhou ◽

Tao Li

Keyword(s):

Model Test ◽

Pore Water Pressure ◽

Water Pressure ◽

Pressure Sensors ◽

In Situ Stress ◽

Shaanxi Province ◽

Wetting Front ◽

Loess Slope ◽

Post Evaluation ◽

Steady Stage

Abstract Failures of treated slope occurring in China are at a consistently increasing rate, leaving the huge number of treated loess slopes calling for post-evaluation, however, no mature technique is in place. Depended on an loess slope in Shaanxi province treated by slope-cutting, indoor geotechnical and model tests were conducted, revealing the rainwater infiltration characteristics and pressure varying characteristics inside the slope, the results of which were then adopted to perform the post-evaluation of the treated slope. The results showed that the rainwater scouring effect on the loess slope surface attenuates gradually, and enters a steady stage after the first year of rainfall. The rainwater preferentially penetrates the platforms with gradually attenuating rates, however the wetting front can not be deemed as the boundary between the saturated and unsaturated areas, as the most parts of the model slope were indicated unsaturated by the pore water pressure sensors. Caused by the in-situ stress release, the soil pressures don’t increase but decrease sharply at the start of the rainfall. The displacements mainly occurs in the first two years of rainfall, following by steady periods. The model test results and investigation results were then used to conduct the post-evaluation of the prototype slope, which formed a post-evaluation frame relevant to other slope post-evaluations.

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Laboratory Experiment and Numerical Analysis on the Precursory Hydraulic Process of Rainfall-Induced Slope Failure

Advances in Civil Engineering ◽

10.1155/2020/2717356 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Joon-Young Park ◽

Young-Suk Song

Keyword(s):

Numerical Modeling ◽

Laboratory Test ◽

Water Content ◽

Pore Water ◽

Slope Failure ◽

Pore Water Pressure ◽

Water Pressure ◽

Volumetric Water Content ◽

Wetting Front ◽

Artificial Rainfall

A combined analysis involving a laboratory test and numerical modeling was performed to investigate the hydraulic processes leading to slope failure during rainfall. Through a laboratory landslide test in which artificial rainfall was applied to a homogeneous sandy slope, the timing and configurations of multiple slides were identified. In addition, volumetric water content was measured in real time through the use of monitoring sensors. The measured volumetric water content data were then used to validate the relevance of the numerical modeling results. The validated numerical modeling of the laboratory-scale slope failures provided insight into the hydraulic conditions that trigger landslides. According to the numerical modeling results, the miniaturized slope in the laboratory test was saturated in a manner so that the wetting front initially progresses downward and then the accumulated rainwater at the toe of the slope creates a water table that advances toward the crest. Furthermore, each of the five sequential failures that occurred during this experiment created slip surfaces where the pore-water pressure had achieved full saturation and an excessive pore-water pressure state. The findings of this study are expected to help understand the hydraulic prerequisites of landslide phenomena.

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Monitoring soil retention properties in a riverbank susceptible to fluvial erosion

10.5194/egusphere-egu21-6233 ◽

2021 ◽

Author(s):

Carmine Gerardo Gragnano ◽

Guido Gottardi ◽

Elena Toth

Keyword(s):

Pore Water Pressure ◽

Water Pressure ◽

Growth Cycle ◽

Po River ◽

Vegetation Growth ◽

Fluvial Erosion ◽

Plant Soil ◽

Soil Atmosphere ◽

Atmosphere Interaction ◽

Fluvial Ecosystem

<p>One of the principal source of vulnerability for riverbanks is given by slopes instabilities, which is triggered on the riverside by fluvial erosion. In order to mitigate such erosion, the establishment of a dense herbaceous cover aims at promoting the slope protection and reducing the likelihood of embankment failure. In fact, the aerial parts of vegetation reduce the mechanical impact of river level fluctuations and rainfall on the embankment and retain sediment transported, while the belowground parts reinforce mechanically the materials forming the top of the embankment, facilitating drainage in the topmost layers and promoting plant water uptake, thus contributing to the regulation of the drying/wetting cycle.</p><p>Plating deep-rooting perennial, herbaceous species on earth embankments therefore represent a sustainable, green intervention for the protection of a riverbank susceptible to fluvial erosion, contributing to the preservation of the fluvial ecosystem environment and avoiding a wide use of grey solutions. The European research project OPERANDUM is testing also this typology of NBS, with an experimental site selected on the river Panaro, one of the main tributary of the main Po River, Italy. To investigate the effect of vegetation on the riverbank soil, a monitoring system has been installed at shallow depths. The system estimates soil water content, matric suction and pore water pressure, in order to quantify the effects of the growth of different vegetation species, which have been recently seeded on site, for analyzing the plant-soil-atmosphere interaction. The work will present the site preparation and the system implementation. The analysis of the first collected data and the outcomes of the preliminary investigations, including site and laboratory experiments, will then be discussed. Monitoring data collected along the entire vegetation growth cycle, that is expected to take around two years, will allow to quantify the influence of vegetation in the soil-atmosphere interaction processes and, on the long-term, verify its effective contribution in riverbank protection.</p>

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Slope Monitoring System at a Slope Behind an Important Cultural Asset

Journal of Disaster Research ◽

10.20965/jdr.2011.p0070 ◽

2011 ◽

Vol 6 (1) ◽

pp. 70-79 ◽

Cited By ~ 4

Author(s):

Kazunari Sako ◽

◽

Ryoichi Fukagawa ◽

Tomoaki Satomi ◽

◽

...

Keyword(s):

Field Measurement ◽

Slope Failure ◽

Rainfall Intensity ◽

Pore Water Pressure ◽

Numerical Models ◽

Water Pressure ◽

Measurement Data ◽

Warning System ◽

Set Up ◽

Relationship Of

Rainfall-induced slope failure has been responsible for great death and destruction in Japan. This is thus a primary consideration in preserving Japan’s many cultural important temples, palaces, and similar structures, especially in the ancient capital of Kyoto, where many important cultural assets are located on hillsides and near mountains. Our objective is to construct a slope-disaster warning system using real-time field measurement data, in-situ and laboratory testing, and numerical models. We set up field monitoring on a slope behind an important cultural asset in July 2004 to measure pore-water pressure, temperature, and rainfall intensity [1]. We firstly introduce our slope-disaster warning concept and field measurement results for the slope behind the important cultural asset in Kyoto. And then we discuss the relationship of rainfall intensity, seepage behavior, and slope failure based on monitoring data and model test results using a soil box apparatus.

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Research of Slope Stability Analysis Considering Rainfall Infiltration

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.204-208.487 ◽

2012 ◽

Vol 204-208 ◽

pp. 487-491

Author(s):

Jian Hua Liu ◽

Zhi Min Chen ◽

Wei He

Keyword(s):

Slope Stability ◽

Pore Water ◽

Rock Slope ◽

Rainfall Intensity ◽

Pore Water Pressure ◽

Water Pressure ◽

Rainfall Infiltration ◽

Safety Coefficient ◽

Rainfall Duration ◽

Unsaturated Seepage

Based on the saturated-unsaturated seepage theory and considering soil-hydraulic permeability coefficient characteristic curves of rock slope, the variation of suction in unsaturated region and transient saturated zone formation of rock slope were analyzed. Combined with engineering example, the strength reduction methods were adopted to analyzing the rock slope stability influence factors considering unsaturated seepage with different rainfall intensity and duration. The results show that the flow domain owing to rainfall infiltration mainly appears surface layer region of slope. The rainfall infiltration caused the groundwater level rise, the rising of transient pore water pressure and the fall of suction in unsaturated region caused the slope stability decrease. The rainfall intensity and duration have obvious influence on slope stability, and in the same rainfall duration condition, the safety coefficient of slope decreases with the accretion of rainfall intensity. With the rainfall duration increasing, the water in soil has more deep infiltration, the water content and pore water pressure was higher in the same high position, the decreasing of suction caused the safety coefficient of slope has more reduce.

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