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Shiang-Jen Wu Yeou-Koung Tung Jinn-Chuang Yang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,21(2):195-212
Occurrence of rainstorm events can be characterized by the number of events, storm duration, rainfall depth, inter-event time and temporal variation of rainfall within a rainstorm event. This paper presents a Monte-Carlo based stochastic hourly rainfall generation model considering correlated non-normal random rainstorm characteristics, as well as dependence of various rainstorm patterns on rainfall depth, duration, and season. The proposed model was verified by comparing the derived rainfall depth–duration–frequency relations from the simulated rainfall sequences with those from observed annual maximum rainfalls based on the hourly rainfall data at the Hong Kong Observatory over the period of 1884–1990. Through numerical experiments, the proposed model was found to be capable of capturing the essential statistical features of rainstorm characteristics and those of annual extreme rainstorm events according to the available data. 相似文献
2.
Risk analysis for flood-control structure under consideration of uncertainties in design flood 总被引：1，自引：0，他引：1
This study presents a risk analysis model to evaluate the failure risk for the flood-control structures in the Keelung River
due to the uncertainties in the hydrological and hydraulic analysis, including hydrologic, hydraulic, and geomorphologic uncertainty
factors. This study defines failure risk as the overtopping probability of the maximum water level exceeding the levee crown,
and the proposed risk analysis model integrates with the advanced first-order and second-moment (AFOSM) method to calculate the overtopping probability of levee system. The proposed model is used to evaluate the effects of the
freeboard and flood-diversion channel on the flood-control ability of the levees in the Keelung River, which were designed
based on the 3-day, 200-year design rainfall event. The numerical experiments indicate that the hydrologic uncertainty factors
have more effect on the estimated maximum water level than hydraulic and geomorphologic uncertainty factors. In addition,
the freeboard and the flood-diversion channel can effectively reduce the overtopping probability so as to significantly enhance
the flood-control capacity of the levee system in the Keelung River. Eventually, the proposed risk analysis successfully quantifies
the overtopping risk of the levee system under a scenario, the increase in the average 200-year rainfall amount due to climate
change, and the results could be useful when planning to upgrade the existing levee system. 相似文献
3.
Coupled 1D–2D hydrodynamic models are widely utilized in flood hazard mapping. Previous studies adopted conceptual hydrological models or 1D hydrodynamic models to evaluate the impact of drainage density on river flow. However, the drainage density affects not only river flow, but also the flooded area and location. Therefore, this work adopts the 1D–2D model SOBEK to investigate the impact of drainage density on river flow. The uncertainty of drainage density in flood hazard mapping is assessed by a designed case and a real case, Yanshuixi Drainage in Tainan, Taiwan. Analytical results indicate that under the same return period rainfall, reduction in tributary drainages in a model (indicating a lower drainage density) results in an underestimate of the flooded area in tributary drainages. This underestimate causes higher peak discharges and total volume of discharges in the drainages, leading to flooding in certain downstream reaches, thereby overestimating the flooded area. The uncertainty of drainage density decreases with increased rainfall. We suggest that modeling flood hazard mapping with low return period rainfalls requires tributary drainages. For extreme rainfall events, a lower drainage density could be selected, but the drainage density of local key areas should be raised.
相似文献4.
Real-time correction of water stage forecast during rainstorm events using combination of forecast errors 总被引：2，自引：2，他引：0
Shiang-Jen Wu Ho-Cheng Lien Che-Hao Chang Jhih-Cyuan Shen 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(4):519-531
This study proposes a real-time error correction method for the forecasted water stage using a combination of forecast errors
estimated by the time series models, AR(1), AR(2), MA(1) and MA(2), and the average deviation model to update the water stage
forecast during rainstorm events. During flood forecasting and warning operations, the proposed real-time error correction
method takes advantage of being individually and continuously implemented and the results not being updated to the hydrological
model and hydraulic routings so as to save computational time by recalibrating the parameters of the proposed methods with
real-time observation. For model validation, the current study adopts the observed and forecasted data on a severe typhoon,
Morakot, collected at eight water level gauges in Southern Taiwan and provided by the flood forecast system FEWS_Taiwan, which is linked with the reliable quantitative precipitation forecast (QPF) at 3 h of lead time provided by the Center Weather
Bureau in Taiwan, as the model validation. The results of numerical experiments indicate that the proposed real-time error
correction method can effectively reduce the errors of forecasted water stages at the 1-, 2-, and 3-h lead time and so enhance
the reliability of forecast information issued by the FEWS_Taiwan. By means of real-time estimating potential forecast error, the uncertainties in hydrology, modules as well as associated
parameters, and physiographical features of the river can be reduced. 相似文献
5.
Natural Hazards - This study aims to develop a probabilistic rainfall threshold estimation model for shallow landslides (PRTE_LS) in order to quantify its reliability while being affected by... 相似文献
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7.
Shiang-Jen Wu Jinn-Chuang Yang Yeou-Koung Tung 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,20(3):171-183
In hydrosystem engineering design and analysis, temporal pattern for rainfall events of interest is often required. In this
paper, statistical cluster analysis of dimensionless rainfall pattern is applied to identify representative temporal rainfall
patterns typically occurred in Hong Kong Territory. For purpose of selecting an appropriate rainfall pattern in engineering
applications, factors affecting the occurrence of different rainfall patterns are examined by statistical contingency tables
analysis through which the inter-dependence of the occurrence frequency of rainfall patterns with respect to geographical
location, rainfall duration and depth, and seasonality is investigated. Furthermore, due to inherent variability of rainfall
mass curves or hyetographs within each classified rainfall pattern, a practical procedure to probabilistically generate plausible
rainfall patterns is described. The procedure preserves the inherent stochastic features of random dimensionless rainfall
hyetograph ordinates, which in general are correlated non-normal multivariate compositional variables. 相似文献
8.
Natural Hazards - This study proposes a risk assessment framework for quantifying the reliability of the rainfall threshold used in flash flood warning, which should be influenced by the... 相似文献
9.
Modeling risk analysis for forecasting peak discharge during flooding prevention and warning operation 总被引：3，自引：3，他引：0
Shiang-Jen Wu Ho-Cheng Lien Che-Hao Chang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(8):1175-1191
This work proposes a risk analysis model to evaluate the risk of underestimating the predicted peak discharge, i.e. the exceedance
of probability due to the uncertainties in rainfall information (rainfall depth, duration, and storm pattern) and the parameters
of the rainfall-runoff model (Sacramento Soil Moisture Accounting model, SAC-SMA) during the flooding prevention and warning operation. The proposed risk analysis model is combined with the multivariate
Monte Carlo simulation method and the Advance First-Order Second-Moment method (AFOSM). The observed rainfall and discharge measured at Yu-feng Basin study area in Shihmen reservoir watershed is used in the
model development and application. The results of the model application indicate that the proposed risk analysis model can
analyze the sensitivity of the uncertainty factors for the predicted peak discharge and evaluates the variation of the probability
of exceeding the predicted peak discharge with respect to the rainfall depth and storm duration. In addition, the result of
risk analysis for a real rainstorm event, Typhoon Morakot, shows that the proposed model successfully explores the risk of underestimating the predicted peak discharge using SAC-SMA and forecasted rainfall information and provides a probabilistic forecast of the peak discharge. 相似文献
10.
Wu Shiang-Jen Chang Che-Hao Hsu Chih-Tsung 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(5):641-667
Stochastic Environmental Research and Risk Assessment - This study develops a real-time error correction model named RTEC_2DIS for two-dimensional (2D) flood-inundation simulations. Inundation... 相似文献
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