Effects of soil porosity on slope stability and debris flow runout at a weathered granitic hillslope

Muhammad Mukhlisin, Ken'ichirou Kosugi, Yoshifumi Satofuka, Takahisa Mizuyama

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Accurate models of rainfall infiltration are needed for analysis and prediction of slope failure induced by heavy rainfall. In this study, a numerical model was developed to simulate two-dimensional rainwater infiltration into an unsaturated hillslope, the formation of a saturated zone, and the resultant changes in slope stability. This model was subsequently used to analyze the effects of soil porosity parameters (i.e., saturated soil water content θs and effective soil porosity [ESP]) on the occurrence of slope failure, the moisture conditions of the displaced material, and the movement of debris flow on weathered granitic hillslopes. We conducted the simulations by imposing various conditions of rainfall, initial wetness of the slope, soil thickness, and slope gradient. Results showed that when the surface soil of a slope has a relatively large ESP value, it has a greater capacity for holding water and therefore delays deeper water infiltration into the subsurface. Consequently, the increase in pore water pressure in the subsurface at a greater depth is also delayed. In this manner, the greater ESP value contributes to delaying slope failure. Under small storm conditions, slope failure tends not to occur when the surface soil has a relatively large ESP value. However, a greater ESP tends to increase the water content of the displaced matter, which results in faster and longer travel distances, and more deposition of debris flow, thus increasing the risk of damage in downstream regions.

Original languageEnglish
Pages (from-to)283-295
Number of pages13
JournalVadose Zone Journal
Volume5
Issue number1
DOIs
Publication statusPublished - Feb 2006
Externally publishedYes

Fingerprint

slope stability
hillslope
debris flow
porosity
slope failure
soil
infiltration
rain
infiltration (hydrology)
rainfall
soil surface
water content
phreatic zone
effect
rainwater
water holding capacity
porewater
travel
soil depth
deep water

ASJC Scopus subject areas

  • Soil Science

Cite this

Effects of soil porosity on slope stability and debris flow runout at a weathered granitic hillslope. / Mukhlisin, Muhammad; Kosugi, Ken'ichirou; Satofuka, Yoshifumi; Mizuyama, Takahisa.

In: Vadose Zone Journal, Vol. 5, No. 1, 02.2006, p. 283-295.

Research output: Contribution to journalArticle

Mukhlisin, Muhammad ; Kosugi, Ken'ichirou ; Satofuka, Yoshifumi ; Mizuyama, Takahisa. / Effects of soil porosity on slope stability and debris flow runout at a weathered granitic hillslope. In: Vadose Zone Journal. 2006 ; Vol. 5, No. 1. pp. 283-295.
@article{36199fb19fc04f48956fa78d2694fd6b,
title = "Effects of soil porosity on slope stability and debris flow runout at a weathered granitic hillslope",
abstract = "Accurate models of rainfall infiltration are needed for analysis and prediction of slope failure induced by heavy rainfall. In this study, a numerical model was developed to simulate two-dimensional rainwater infiltration into an unsaturated hillslope, the formation of a saturated zone, and the resultant changes in slope stability. This model was subsequently used to analyze the effects of soil porosity parameters (i.e., saturated soil water content θs and effective soil porosity [ESP]) on the occurrence of slope failure, the moisture conditions of the displaced material, and the movement of debris flow on weathered granitic hillslopes. We conducted the simulations by imposing various conditions of rainfall, initial wetness of the slope, soil thickness, and slope gradient. Results showed that when the surface soil of a slope has a relatively large ESP value, it has a greater capacity for holding water and therefore delays deeper water infiltration into the subsurface. Consequently, the increase in pore water pressure in the subsurface at a greater depth is also delayed. In this manner, the greater ESP value contributes to delaying slope failure. Under small storm conditions, slope failure tends not to occur when the surface soil has a relatively large ESP value. However, a greater ESP tends to increase the water content of the displaced matter, which results in faster and longer travel distances, and more deposition of debris flow, thus increasing the risk of damage in downstream regions.",
author = "Muhammad Mukhlisin and Ken'ichirou Kosugi and Yoshifumi Satofuka and Takahisa Mizuyama",
year = "2006",
month = "2",
doi = "10.2136/vzj2005.0044",
language = "English",
volume = "5",
pages = "283--295",
journal = "Vadose Zone Journal",
issn = "1539-1663",
publisher = "Soil Science Society of America",
number = "1",

}

TY - JOUR

T1 - Effects of soil porosity on slope stability and debris flow runout at a weathered granitic hillslope

AU - Mukhlisin, Muhammad

AU - Kosugi, Ken'ichirou

AU - Satofuka, Yoshifumi

AU - Mizuyama, Takahisa

PY - 2006/2

Y1 - 2006/2

N2 - Accurate models of rainfall infiltration are needed for analysis and prediction of slope failure induced by heavy rainfall. In this study, a numerical model was developed to simulate two-dimensional rainwater infiltration into an unsaturated hillslope, the formation of a saturated zone, and the resultant changes in slope stability. This model was subsequently used to analyze the effects of soil porosity parameters (i.e., saturated soil water content θs and effective soil porosity [ESP]) on the occurrence of slope failure, the moisture conditions of the displaced material, and the movement of debris flow on weathered granitic hillslopes. We conducted the simulations by imposing various conditions of rainfall, initial wetness of the slope, soil thickness, and slope gradient. Results showed that when the surface soil of a slope has a relatively large ESP value, it has a greater capacity for holding water and therefore delays deeper water infiltration into the subsurface. Consequently, the increase in pore water pressure in the subsurface at a greater depth is also delayed. In this manner, the greater ESP value contributes to delaying slope failure. Under small storm conditions, slope failure tends not to occur when the surface soil has a relatively large ESP value. However, a greater ESP tends to increase the water content of the displaced matter, which results in faster and longer travel distances, and more deposition of debris flow, thus increasing the risk of damage in downstream regions.

AB - Accurate models of rainfall infiltration are needed for analysis and prediction of slope failure induced by heavy rainfall. In this study, a numerical model was developed to simulate two-dimensional rainwater infiltration into an unsaturated hillslope, the formation of a saturated zone, and the resultant changes in slope stability. This model was subsequently used to analyze the effects of soil porosity parameters (i.e., saturated soil water content θs and effective soil porosity [ESP]) on the occurrence of slope failure, the moisture conditions of the displaced material, and the movement of debris flow on weathered granitic hillslopes. We conducted the simulations by imposing various conditions of rainfall, initial wetness of the slope, soil thickness, and slope gradient. Results showed that when the surface soil of a slope has a relatively large ESP value, it has a greater capacity for holding water and therefore delays deeper water infiltration into the subsurface. Consequently, the increase in pore water pressure in the subsurface at a greater depth is also delayed. In this manner, the greater ESP value contributes to delaying slope failure. Under small storm conditions, slope failure tends not to occur when the surface soil has a relatively large ESP value. However, a greater ESP tends to increase the water content of the displaced matter, which results in faster and longer travel distances, and more deposition of debris flow, thus increasing the risk of damage in downstream regions.

UR - http://www.scopus.com/inward/record.url?scp=34547915535&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34547915535&partnerID=8YFLogxK

U2 - 10.2136/vzj2005.0044

DO - 10.2136/vzj2005.0044

M3 - Article

AN - SCOPUS:34547915535

VL - 5

SP - 283

EP - 295

JO - Vadose Zone Journal

JF - Vadose Zone Journal

SN - 1539-1663

IS - 1

ER -