A probabilistic model for real‐time flood warning based on deterministic flood inundation mapping     

Jiun‐Huei Jang  Pao‐Shan Yu  Sen‐Hai Yeh  Jin‐Cheng Fu  Chen‐Jia Huang 《水文研究》2012,26(7):1079-1089

Deterministic flood inundation mapping is valuable for the investigation of detailed flood depth and extent. However, when these data are used for real‐time flood warning, uncertainty arises while encountering the difficulties of timely response, message interpretation and performance evaluation that makes statistical analysis necessary. By incorporating deterministic flood inundation map outputs statistically by means of logistic regression, this paper presents a probabilistic real‐time flood warning model determining region‐based flood probability directly from rainfall, being efficient in computation, clear in message, and valid in physical meaning. The calibration and validation of the probabilistic model show a satisfactory overall correctness rate, with the hit rate far surpassing the false alarm rate in issuing flood warning for historical events. Further analyses show that the probabilistic model is effective in evaluating the level of uncertainty lying within flood warning which can be reduced by several techniques proposed in order to improve warning performance. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Simulating effect of anthropogenic activities and climate variation on Liulin Springs discharge depletion by using the ARIMAX model     

Yonghong Hao  Jing Wu  Qingxia Sun  Yuen Zhu  Yan Liu  Zhongtang Li  Tian‐Chyi J. Yeh 《水文研究》2013,27(18):2605-2613

Based on the groundwater development process, and regional economic and social developing history, we divided the spring hydrological process of the Liulin Springs Basin into two periods: pre‐1973 and post‐1974. In the first period (i.e. 1957–1973), the spring discharge was affected by climate variation alone, and in the second period (i.e. 1974–2009), the spring discharge charge was influenced by both climate variation and human activities. A piecewise analysis strategy was used to differentiate the contribution of anthropogenic activities from climate variation on karst spring discharge depletion in the second period. Then, the ARIMAX model was applied to spring flow time series of the first period to develop a model for the effects of climate variation only. Using this model, we estimated the spring discharge in the second period solely under the influence of climate variation. Based on the water budget, we subtracted observed spring discharge from the estimated spring discharge and acquired the contribution of human activities on spring discharge depletion for the second period. The results of the analysis indicated that the contribution of climate variation to the spring discharge depletion is?0.20 m³/s from 1970s to 2000s. The contribution of anthropogenic activities to the spring flow depletion was ?2.56 m³/s in 2000s, which was about 13 times more than that of climate variation. Our analysis further indicates that groundwater exploitation only accounts for 29% of the spring flow depletion due to the effects of human activities. The remaining 71% of the depletion is likely to be caused by other human activities, including dam building, dewatering during coal mining, and deforestation. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Transient solution for radial two‐zone flow in unconfined aquifers under constant‐head tests     

Y. C. Chang  H. D. Yeh  G. Y. Chen 《水文研究》2010,24(11):1496-1503

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Wellbore flow‐rate solution for a constant‐head test in two‐zone finite confined aquifers     

Chi‐Shan Tsai  Hund‐Der Yeh 《水文研究》2012,26(21):3216-3224

The solution describing the wellbore flow rate in a constant‐head test integrated with an optimization approach is commonly used to analyze observed wellbore flow‐rate data for estimating the hydrogeological parameters of low‐permeability aquifers. To our knowledge, the wellbore flow‐rate solution for the constant‐head test in a two‐zone finite‐extent confined aquifer has never been reported so far in the literature. This article is first to develop a mathematical model for describing the head distribution in the two‐zone aquifer. The Laplace domain solutions for the head distributions and wellbore flow rate in a two‐zone finite confined aquifer are derived using the Laplace transform, and their corresponding time domain solutions are then obtained using the Bromwich integral method and residue theorem. These new solutions are expressed in terms of an infinite series with Bessel functions and not straightforward to calculate numerically. A large‐time solution for the wellbore flow rate is therefore developed by employing the relationship of small Laplace variable versus large time variable and L'Hospital's rule. The result shows that the large‐time solution is identical to the steady‐state solution obtained after applying the Tauberian theorem into the Laplace domain solution. This large‐time solution can reduce to the Thiem equation in the case of no skin. Finally, the newly developed solution is used to investigate the effects of outer boundary distance and conductivity ratio on the wellbore flow rate. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Deriving landslide dam geometry from remote sensing images for the rapid assessment of critical parameters related to dam-breach hazards     

Jia-Jyun Dong  Po-Jung Lai  Chung-Pai Chang  Sheng-Hsueh Yang  Keh-Chia Yeh  Jyh-Jong Liao  Yii-Wen Pan 《Landslides》2014,11(1):93-105

Dam-breaches that cause outburst floods may induce downstream hazards. Because landslide dams can breach soon after they are formed, it is critical to assess the stability quickly to enable prompt action. However, dam geometry, an essential component of hazard evaluation, is not available in most cases. Our research proposes a procedure that utilizes post-landslide orthorectified remote sensing images and the pre-landslide Digital Terrain Model in the Geographic Information System to estimate the geometry of a particular dam. The procedure includes the following three modules: (1) the selection of the reference points on the dam and lake boundaries, (2) the interpolation of the dam-crest elevation, and (3) the estimation of dam-geometry parameters (i.e., the height, length, and width), the catchment area, the volumes of barrier lake and landslides dam. This procedure is demonstrated through a case study of the Namasha Landslide Dam in Taiwan. It was shown the dam-surface elevation estimated from the proposed procedure can approximate the elevation derived from profile leveling after the formation of the landslide dam. Thus, it is feasible to assess the critical parameters required for the landslide dam hazard assessment rapidly once the ortho-photo data are available. The proposed procedure is useful for quick and efficient decision making regarding hazard mitigation.  相似文献   

Occurrence of organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in deep-sea fishes from the Sulu Sea     

Ramu K  Kajiwara N  Mochizuki H  Miyasaka H  Asante KA  Takahashi S  Ota S  Yeh HM  Nishida S  Tanabe S 《Marine pollution bulletin》2006,52(12):1827-1832

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Estimation of effective aquifer hydraulic properties from an aquifer test with multi-well observations (Taiwan)   总被引：1，自引：0，他引：1  

Jet-Chau Wen  Cheng-Mau Wu  Tian-Chyi J. Yeh  Chung-Ming Tseng 《Hydrogeology Journal》2010,18(5):1143-1155

The representative anisotropic parameters for an aquifer located at the campus of the National Yunlin University of Science and Technology in Taiwan have been acquired. A constant-rate pumping test was carried out, and drawdown-time data were collected from ten observation wells. Applications of the conventional aquifer test analysis, which assumes aquifer homogeneity for each observed well hydrograph, yielded spatially varying transmissivity and storage coefficient estimates, contradicting the homogeneous assumption. A direct approach and a nonlinear-least squares minimization of distance-drawdown data were then employed to analyze anisotropy of the transmissivity of an equivalent homogeneous aquifer. Results show that the direction and values of anisotropic transmissivities vary with time and the estimates depend on the number of observation wells used. These field results are consistent with results from recent theoretical investigations which questioned the suitability of the conventional aquifer test analysis.  相似文献   

Data analysis on the extrasolar planets using robust clustering     

Ing-Guey Jiang  Li-Chin Yeh  Wen-Liang Hung  Miin-Shen Yang 《Monthly notices of the Royal Astronomical Society》2006,370(3):1379-1392

We use both the conventional and more recently developed methods of cluster analysis to study the data of extrasolar planets (exoplanets). Using the data set with planetary mass M , orbital period P and orbital eccentricity e , we investigate the possible clustering in the  ln  M ,  ln  P ,  ln  P –ln  M ,   e   and ln   P – e spaces. There are two main implications: (1) mass distribution is continuous, and (2) orbital population could be classified into three clusters, which correspond to the exoplanets in the regimes of tidal, ongoing tidal and disc interaction, respectively.  相似文献   

Oxygen and hydrogen isotopes for the characteristics of groundwater recharge: a case study from the Chih-Pen Creek basin,Taiwan   总被引：5，自引：2，他引：3  

Hsin-Fu Yeh  Cheng-Haw Lee  Kuo-Chin Hsu 《Environmental Earth Sciences》2011,62(2):393-402

Assessing the seasonal variation of groundwater recharge is important for effective management of groundwater resources. Stable isotopes of oxygen and hydrogen were used to estimate the sources of groundwater and seasonal contributions of precipitation to groundwater recharge in Chih-Pen Creek basin of eastern Taiwan. Based on the isotopes of precipitation (n = 177), two different local meteoric water regression lines (LMWL) can be obtained for the different seasons: δD = 8.06¹⁸O + 10.08 for wet season precipitation (May through October) and δD = 8.65δ¹⁸O + 17.09 for dry season precipitation (November through April). The slope and intercept of regression line for wet season precipitation are virtually identical to the global meteoric water line (GMWL) of Craig (1961). In contrast to during dry season precipitation due to evaporation effect the intercept of 17.09 is much higher than of the GMWL of 10. The results show the stable isotopes compositions of precipitation decrease with increasing rainfall amount and air temperature, due to the amount effect of precipitation is pronounced. The amount effect is clearly but do not show the temperature effect from January to December 2007. Using a mass-balance equation, a comparison of deuterium excess or d values of precipitation and groundwater indicates the groundwater consist of 76% wet season precipitation and 24% dry season precipitation, representing a distinct seasonal variation of groundwater recharge in study area. About 79% of the groundwater is recharged from the river water of the mountain watershed and 21% is from the rain that falls on the basin.  相似文献   

Modeling spatial fracture intensity as a control on flow in fractured rock     

Chen-Chang Lee  Cheng-Haw Lee  Hsin-Fu Yeh  Hung-I Lin 《Environmental Earth Sciences》2011,63(6):1199-1211

Spatial fracture intensity (P ₃₂, fracture area by volume) is an important characteristic of a jointed rock mass. Although it can hardly ever be measured, P ₃₂ can be modeled based on available geological information such as spatial data of the fracture network. Flow in a mass composed of low-permeability hard rock is controlled by joints and fractures. In this article, models were developed from a geological data set of fractured andesite in LanYu Island (Taiwan) where a site is investigated for possible disposal of low-level and intermediate-level radionuclide waste. Three different types of conceptual models of spatial fracture intensity distribution were generated, an Enhanced Baecher’s model (EBM), a Levy–Lee Fractal model (LLFM) and a Nearest Neighborhood model (NNM). Modeling was conducted on a 10 × 10 × 10 m synthetic fractured block. Simulated flow was forced by a 1% hydraulic gradient between two vertical x–z faces of the cube (from North to South) with other boundaries set to no-flow conditions. Resulting flow vectors are very sensitive to spatial fracture intensity (P ₃₂). Flow velocity increases with higher fracture intensity (P ₃₂). R-squared values of regression analysis for the variables velocity (V/V _max) and fracture intensity (P ₃₂) are 0.293, 0.353, and 0.408 in linear fit and 0.028, 0.08, and 0.084 in power fit. Higher R ² values are positively linked with structural features but the relation between velocity and fracture intensity is non-linear. Possible flow channels are identified by stream-traces in the Levy–LeeFractal model.  相似文献