A mass balance model for the hydrologic response of fine-grained hillside soils to rainfall
- New Mexico Inst. of Mining and Technology, Socorro, NM (United States). New Mexico Bureau of Mines and Mineral Resources
For a sloping soil layer of uniform thickness D, length L, and angle of inclination B, slope-normal influx per unit breadth is given by Q[sub in] = R L cos B, where R is net recharge. Slope-parallel discharge is given by Q[sub out] = K D sin B, where K is saturated hydraulic conductivity. If the long-term ratio of discharge to influx is > 1, then the slope is self-draining. If the ratio is < 1, then the slope is self-filling. Self-filling slopes will be more susceptible to failure because they cannot easily dissipate infiltration-induced pore pressure increases. For time-variant recharge, the rate of change in volumetric soil moisture content is given by d[Theta]/dt = (R/D) cos B--(K/L) sin B. Calculations using data from a thin colluvium landslide along the Ohio River give an average annual steady-state value of Q[sub out]/Q[sub in] = 1.06. A finite difference solution of the transient mass balance equation agrees fairly well with observed daily mean pressure heads from spring 1988. Stochastic simulations using temporally uncorrelated rainfall distributions fitted to the observed data tend to produce smoother hydrographs than simulations using observed rainfall values. This is due to a mismatch between the observed and fitted distributions, which caused the frequency of large storms to be underestimated and the frequency of small storms to be overestimated. Long-term trends in the stochastic simulations, however, were self-draining in three out of five trials. The mildly self-draining nature of thin colluvium hillsides along the Ohio River may explain why these slopes are marginally stable to unstable, and the general agreement between observed and simulated values suggests that mass balance models may be useful for assessing the susceptibility of hillside soils to precipitation-induced landsliding.
- OSTI ID:
- 5816249
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
Similar Records
Inventory of landslides in southern Illinois near the New Madrid Seismic Zone and the possible failure mechanism at three sites
Landslide hazard mapping with selected dominant factors: A study case of Penang Island, Malaysia
Related Subjects
OHIO
WATERSHEDS
HYDROLOGY
DRAINAGE
FINITE DIFFERENCE METHOD
FORECASTING
LAND USE
LANDSLIDES
MASS BALANCE
MATHEMATICAL MODELS
PARTICLE SIZE
RAIN
SIZE
SOILS
STORMS
WATER INFLUX
ATMOSPHERIC PRECIPITATIONS
CALCULATION METHODS
DEVELOPED COUNTRIES
DISASTERS
ITERATIVE METHODS
NORTH AMERICA
NUMERICAL SOLUTION
USA
540250* - Environment
Terrestrial- Site Resource & Use Studies- (1990-)