Browsing by Author "You, L. W."

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Assessing curve number uncertainty for green roofs in a stochastic environment
(2018-01-01)
Huang, W. S. C.
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You, L. W.
;
Tung, Y. K.
;
Yoo, C. S.
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防災與水環境研究中心
Curve number (CN) is well-known by hydrologists for estimating rainfall induced runoff from a catchment. It can also be used as an indicator for measuring the impact of engineering or non-engineering measures on the runoff production in a catchment. In this study, a method is presented to quantify the uncertainty of CN for hydrologic performance of a green roof system. Latin hypercube sampling approach, coupled with the antithetic variate technique, is used to achieve efficient and accurate quantification of the uncertainty features of CN for a green roof system. Elements in green roofs subject to uncertainty considered are rainfall characteristics (i.e. amount and inter-event dry period), soil-plant-climate factors (i.e. field capacity, wilting point, interception, evapotranspiration rate), and model error in SCS I-a-S relation. Numerical study shows that model error in SCS I-a-S relation has the dominant effect on the uncertainty features of CN for green roof performance.
Sensitivity and uncertainty analyses of retention performance of green roofs considering aleatory and epistemic uncertainties
(2018-01-01)
You, L. W.
;
Tung, Y. K.
;
Yoo, C. S.
;
防災與水環境研究中心
;
Disaster Prevention and Water Environment Research Center
A methodological framework is presented to integrate epistemic uncertainties into an aleatory-based probabilistic green roof model. In doing so, the sensitivity and uncertainty of the mean and standard deviation of retention ratio are assessed. Regression-based global sensitivity analysis showed that the first-order effect of model parameters plays the dominant role over the higher-order effect in contributing the overall uncertainty of statistical moments of retention ratio from the probabilistic green roof model used. Inclusion of epistemic uncertainties allows comprehensive evaluation of uncertainty associated with the performance of a green roof system, which further facilitates risk-based design of green roof systems.