TY - JOUR
T1 - Probabilistic modelling of overflow, surcharge and flooding in urban drainage using the first-order reliability method and parameterization of local rain series
AU - Thorndahl, Søren
AU - Willems, Patrick
PY - 2007/7/31
Y1 - 2007/7/31
N2 - Failure of urban drainage systems may occur due to surcharge or flooding at specific manholes in the system, or due to overflows from combined sewer systems to receiving waters. To quantify the probability or return period of failure, standard approaches make use of the simulation of design storms or long historical rainfall series in a hydrodynamic model of the urban drainage system. In this paper, an alternative probabilistic method is investigated: the First Order Reliability Method (FORM). To apply this method, a long rainfall time series was divided in rain storms (rain events), and each rain storm conceptualized to a synthetic rainfall hyetograph by a Gaussian shape with the parameters: rain storm depth, duration and peak intensity. Probability distributions were calibrated for these three parameters and used on the basis of the failure probability estimation, together with a hydrodynamic simulation model to determine the failure conditions for each set of parameters. The method takes into account the uncertainties involved in the rain storm parameterization. Comparison is made between the failure probability results of the FORM method, the standard method using long-term simulations, and alternative methods based on random sampling (Monte Carlo Direct Sampling and Importance Sampling). It is concluded that without crucial influence on the modelling accuracy, the First Order Reliability Method is very applicable as an alternative to traditional long-term simulations of urban drainage systems.
AB - Failure of urban drainage systems may occur due to surcharge or flooding at specific manholes in the system, or due to overflows from combined sewer systems to receiving waters. To quantify the probability or return period of failure, standard approaches make use of the simulation of design storms or long historical rainfall series in a hydrodynamic model of the urban drainage system. In this paper, an alternative probabilistic method is investigated: the First Order Reliability Method (FORM). To apply this method, a long rainfall time series was divided in rain storms (rain events), and each rain storm conceptualized to a synthetic rainfall hyetograph by a Gaussian shape with the parameters: rain storm depth, duration and peak intensity. Probability distributions were calibrated for these three parameters and used on the basis of the failure probability estimation, together with a hydrodynamic simulation model to determine the failure conditions for each set of parameters. The method takes into account the uncertainties involved in the rain storm parameterization. Comparison is made between the failure probability results of the FORM method, the standard method using long-term simulations, and alternative methods based on random sampling (Monte Carlo Direct Sampling and Importance Sampling). It is concluded that without crucial influence on the modelling accuracy, the First Order Reliability Method is very applicable as an alternative to traditional long-term simulations of urban drainage systems.
KW - Urban drainage modelling
KW - Combined sewer overflow
KW - Flooding
KW - First order Reliability Method (FORM)
KW - Uncertainties
KW - Monte Carlo Sampling
KW - Urban drainage modelling
KW - Combined sewer overflow
KW - Flooding
KW - First order Reliability Method (FORM)
KW - Uncertainties
KW - Monte Carlo Sampling
U2 - doi:10.1016/j.watres.2007.07.038
DO - doi:10.1016/j.watres.2007.07.038
M3 - Journal article
SN - 0043-1354
VL - 42
SP - 455
EP - 466
JO - Water Research
JF - Water Research
IS - 1-2
ER -