Fi John Chang
National Taiwan University
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Publication
Featured researches published by Fi John Chang.
Hydrology and Earth System Sciences | 2011
C.-H. Chung; Yen-Ming Chiang; Fi John Chang
Evaporation is an essential reference to the management of water resources. In this study, a hybrid model that integrates a spatial neural fuzzy network with the kringing method is developed to estimate pan evaporation at ungauged sites. The adaptive network-based fuzzy inference system (ANFIS) can extract the nonlinear relationship of observations, while kriging is an excellent geostatistical interpolator. Three-year daily data collected from nineteen meteorological stations covering the whole of Taiwan are used to train and test the constructed model. The pan evaporation (Epan) at ungauged sites can be obtained through summing up the outputs of the spatially weighted ANFIS and the residuals adjusted by kriging. Results indicate that the proposed AK model (hybriding ANFIS and kriging) can effectively improve the accuracy of Epan estimation as compared with that of empirical formula. This hybrid model demonstrates its reliability in estimating the spatial distribution of Epan and consequently provides precise Epan estimation by taking geographical features into consideration.
Science of The Total Environment | 2016
Su Ting Cheng; Edwin E. Herricks; Wen Ping Tsai; Fi John Chang
Theory predicts that the number of fish species increases with river size in natural free-flowing rivers, but the relationship is lost under intensive exploitation of water resources associated with dams and/or landscape developments. In this paper, we aim to identify orthomorphic issues that disrupt theoretical species patterns based on a multi-year, basin-wide assessment in the Danshuei River Watershed of Taiwan. We hypothesize that multiple human-induced modifications fragment habitat areas leading to decreases of local fish species richness. We integrally relate natural and anthropogenic influences on fish species richness by a multiple linear regression model that is driven by a combination of factors including river network structure controls, water quality alterations of habitat, and disruption of channel connectivity with major discontinuities in habitat caused by dams. We found that stream order is a major forcing factor representing natural influence on fish species richness. In addition to stream order, we identified dams, dissolved oxygen deficiency (DO), and excessive total phosphorus (TP) as major anthropogenic influences on the richness of fish species. Our results showed that anthropogenic influences were operating at various spatial scales that inherently regulate the physical, chemical, and biological condition of fish habitats. Moreover, our probability-based risk assessment revealed causes of species richness reduction and opportunities for mitigation. Risks of species richness reduction caused by dams were determined by the position of dams and the contribution of tributaries in the drainage network. Risks associated with TP and DO were higher in human-activity-intensified downstream reaches. Our methodology provides a structural framework for assessing changes in basin-wide fish species richness under the mixed natural and human-modified river network and habitat conditions. Based on our analysis results, we recommend that a focus on landscape and riverine habitats and maintaining long-term monitoring programs are crucial for effective watershed management and river conservation plans.
Journal of Hydrology | 2015
Wen Ping Tsai; Fi John Chang; Li Chiu Chang; Edwin E. Herricks
Journal of Hydrology | 2013
Fi John Chang; Wen Ping Tsai; Hung kwai Chen; Rita Sau Wai Yam; Edwin E. Herricks
Journal of Hydrology | 2008
Fi John Chang; Meng-Jung Tsai; Wen Ping Tsai; Edwin E. Herricks
Hydrology and Earth System Sciences | 2010
Yen-Ming Chiang; Li-Chiu Chang; Ming-Da Tsai; Yi-Fung Wang; Fi John Chang
Journal of Water Resources Planning and Management | 2009
Jian Ping Suen; Wayland J. Eheart; Edwin E. Herricks; Fi John Chang
Journal of Hydrology | 2009
Fi John Chang; Tzu Ching Wu; Wen Ping Tsai; Edwin E. Herricks
Journal of Hydrology | 2011
Fi John Chang; Wen Ping Tsai; Tzu Ching Wu; Hung kwai Chen; Edwin E. Herricks
Ecological Engineering | 2016
Wen Ping Tsai; Fi John Chang; Edwin E. Herricks