TY - JOUR

T1 - Conditional expectation for evaluation of risk groundwater flow and solute transport

T2 - One-dimensional analysis

AU - Liou, Tai Sheng

AU - Yeh, Hund-Der

PY - 1997/12/10

Y1 - 1997/12/10

N2 - A one-dimensional groundwater transport equation with two uncertain parameters, groundwater velocity and longitudinal dispersivity, is investigated in this paper. The analytical uncertainty of the predicted contaminant concentration is derived by the first-order mean-centered uncertainty analysis. The risk of the contaminant transport is defined as the probability that the concentration exceeds a maximum acceptable upper limit. Five probability density functions including the normal, lognormal, gamma, Gumbel, and Weibull distributions are chosen as the models for predicting the concentration distribution. The risk for each distribution is derived analytically based on the conditional probability. The mean risk and confidence interval are then computed by Monte Carlo simulation where the groundwater velocity and longitudinal dispersivity are assumed to be lognormally and normally distributed, respectively. Results from the conditional expectation of an assumed damage function show that the unconditional expectation generally underestimates the damage for low risk events. It is found from the sensitivity analysis that the mean longitudinal dispersivity is the most sensitive parameter and the variance of longitudinal dispersivity is the least sensitive one among those distribution models except the gamma and Weibull distributions.

AB - A one-dimensional groundwater transport equation with two uncertain parameters, groundwater velocity and longitudinal dispersivity, is investigated in this paper. The analytical uncertainty of the predicted contaminant concentration is derived by the first-order mean-centered uncertainty analysis. The risk of the contaminant transport is defined as the probability that the concentration exceeds a maximum acceptable upper limit. Five probability density functions including the normal, lognormal, gamma, Gumbel, and Weibull distributions are chosen as the models for predicting the concentration distribution. The risk for each distribution is derived analytically based on the conditional probability. The mean risk and confidence interval are then computed by Monte Carlo simulation where the groundwater velocity and longitudinal dispersivity are assumed to be lognormally and normally distributed, respectively. Results from the conditional expectation of an assumed damage function show that the unconditional expectation generally underestimates the damage for low risk events. It is found from the sensitivity analysis that the mean longitudinal dispersivity is the most sensitive parameter and the variance of longitudinal dispersivity is the least sensitive one among those distribution models except the gamma and Weibull distributions.

KW - Ground water

KW - Monte Carlo analysis

KW - Risk assessment

KW - Sensitivity analysis

KW - Solute transport

UR - http://www.scopus.com/inward/record.url?scp=0343118147&partnerID=8YFLogxK

U2 - 10.1016/S0022-1694(97)00025-5

DO - 10.1016/S0022-1694(97)00025-5

M3 - Article

AN - SCOPUS:0343118147

VL - 199

SP - 378

EP - 402

JO - Journal of Hydrology

JF - Journal of Hydrology

SN - 0022-1694

IS - 3-4

ER -