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Fan J.-C.,National Taiwan University | Yang C.-H.,National Taiwan University | Liu C.-H.,National Science and Technology Center for Disaster Reduction 9F | Huang H.-Y.,National Taiwan University
Paddy and Water Environment | Year: 2013

By using CLIGEN and long-term meteorological data, consecutive daily rainfall data can be simulated. At present, the applicability of CLIGEN to regions other than the United States remains to be tested. In this study, CLIGEN was first applied in a subtropical monsoon climate region. Rainfall data from 1961 to 1990 at three weather stations in northern Taiwan were collected, and rainfall parameters and patterns were validated. The results showed no significant difference in the mean and distribution patterns between observed and simulated values for rainfall parameters including precipitation for each month, wet days for each month, precipitation on wet days for each month and standard deviation of daily precipitation for each month. Regarding rainfall pattern, after re-calibration of storm pattern coefficients, the accuracy of the simulated storm duration was greatly enhanced. However, the simulated daily maximum 5- and 30-min peak intensities were overestimated, and there is room for improvement. © 2011 Springer-Verlag. Source

Fan J.-C.,National Taiwan University | Huang H.-Y.,National Taiwan University | Liu C.-H.,National Science and Technology Center for Disaster Reduction 9F | Yang C.-H.,National Taiwan University | And 3 more authors.
Environmental Earth Sciences | Year: 2015

This study focuses on the effects of physiographic factors, such as landslide area, on the occurrence of debris flows in central Taiwan. Four physiographic factors were selected for their significance to the occurrence of debris flows, including landslide ratio (the ratio of landslide area over watershed area), average steepness of the streambed, effective watershed area, and form factor. Two quantifying methods of factors were performed and compared: one using genuine values of factors and another one using values converted by degree of membership from fuzzy theory. Then the logistic regression method was applied for building a model to assess the occurrence probability of debris flows from five variables: four physiographic factors and one hydrologic factor. The model is consistent with the mechanism of debris flow occurrence, with all physiographic and hydrologic factors positively correlated with the occurrence probability. In addition, the accuracy of the model was validated with randomly selected historical events and demonstrated fairly satisfactory validity, ranging from 70 to 80 %. It was found that adopting the degree of membership made the model more stable and more reliable. In addition, the model also shows that reducing the landslide area can significantly reduce the occurrence probability of debris flows. The results show that the model built in this study has the potential to be well applied and fully integrated into current or future warning systems. © 2015, Springer-Verlag Berlin Heidelberg. Source

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