Embedding isochronous cells overland flow module into MODFLOW     

Bo Zhang  Mei Hong  Zuhao Zou  Tian‐Chyi Jim Yeh  Pin Cheng 《水文研究》2013,27(26):3833-3841

This study integrates a simple overland flow module (isochronous cells model) with the river module of MODFLOW such that temporal and spatial interactions between stream flow and groundwater can be simulated using net rainfall data of a watershed. The isochronous cells model is an efficient travel time runoff approach based on geographic information system (GIS) that considers both spatial and temporal variations of net rainfall through hill slope of the watershed. This overland module is easily coupled with MODFLOW river routing module. Specifically, the stream flow from the isochronous cells model is directly assigned to both sides of river cells of the MODFLOW model. Such an integration of MODFLOW and isochronous cells model is especially useful in watersheds where river flow data are limited. The feasibility of this integrated model was demonstrated using a case study in the middle and downstream regions of the Yitong River watershed, China. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Soil water balance model for precipitation-induced shallow landslides   总被引：3，自引：2，他引：1  

Hsin-Fu Yeh  Cheng-Haw Lee 《Environmental Earth Sciences》2013,70(6):2691-2701

Precipitation infiltration is one of the most significant triggering factors for slope failure occurrence in many places around the world. Knowledge of the mechanisms leading to precipitation-induced slope failures is of great importance to the management of landslide hazard. In this study, a soil water balance model is developed to estimate soil water flux during the process of infiltration from rainfall data, with consideration of storm periods and non-storm periods. Two important assumptions in this study are given: (1) instantaneous uniform distribution of the degree of saturation and (2) a linear relationship between evapotranspiration and the related degree of saturation. For storm periods, the Brooks and Corey model estimates both the soil water retention curve and soil water parameters. The infiltration partition is employed by an infinite-series solution of Philip in conjunction with the time compression approximation. For none-storm periods, evapotranspiration can be derived for the moisture depletion of soil water. This study presents a procedure for calculating the safety factor for an unsaturated slope suffering from precipitation infiltration. The process of infiltration into a slope due to rainfall and its effect on soil slope behavior are examined using modified Mohr–Coulomb failure criterion in conjunction with a soil water balance model. The results indicate that the matric suction, which is closely related to slope stability, is affected by the degree of saturation controlled by rainfall events.  相似文献   

红树林湿地植被生物量的雷达遥感估算   总被引：19，自引：0，他引：19  

黎夏  叶嘉安  王树功  刘凯  刘小平  钱峻屏  陈晓越  何执兼  覃朝锋 《遥感学报》2006,10(3):387-396

根据雷达后向散射系数建立了红树林湿地植被生物量的估算模型,并运用遗传算法确定其中非线性模型的最优参数.对比分析表明,雷达后向散射系数模型比NDVI模型在植被生物量估算中有更高的精度.使用NDVI指数有可能导致某些植被类型的生物量估算出现较大的误差.这是因为一些具有密集冠层的草本植被（例如互花米草等）有比红树林高得多的NDVI值.而雷达遥感所具有的侧视特点及一定的穿透能力能有效地获取植被的垂直信息,大大减低植被生物量估算的误差.  相似文献   

Performance of the experimental HWRF in the 2008 Hurricane Season   总被引：1，自引：1，他引：0  

Kao-San Yeh  Xuejin Zhang  Sundararaman Gopalakrishnan  Sim Aberson  Robert Rogers  Frank Marks  Robert Atlas 《Natural Hazards》2012,63(3):1439-1449

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The Impact on the Positioning Accuracy of the Frequency Reference of a GPS Receiver     

Ta-Kang Yeh  Chieh-Hung Chen  Guochang Xu  Chuan-Sheng Wang  Kwo-Hwa Chen 《Surveys in Geophysics》2013,34(1):73-87

Despite the pervasive use of the global positioning system (GPS) as a positioning technology for its high efficiency and accuracy, several factors reduce its performance. This study examines to which extent the frequency offset and the frequency stability of the internal quartz oscillator or of an externally supplied rubidium oscillator have an influence. Observations were made at the Taiwan Ching Yun University (TCYU) tracking station, where a quartz oscillator and a rubidium oscillator were applied alternatively on a monthly basis throughout a 16-month period. Moreover, the accuracy of the local oscillator used in this study was calibrated by the National Standard Time and Frequency Laboratory, Taiwan. The frequency offset and frequency stability calculated via the remote method at the TCYU station were compared with values (uncertainty is 3.0E?13) measured directly at the National Standard Time and Frequency Laboratory, Taiwan. Analytical results show that the two methods vary by 1.4E?10 in terms of frequency offset and by 6.5E?12 in terms of frequency stability, demonstrating that the remote method can yield computational results almost as accurate as direct measurement. Positioning precision results also show that rubidium oscillator accuracy improved by 5, 11, and 15 % for short-, medium-, and long-baseline positioning, respectively, indicating that clock quality is more influential for long-baseline GPS relative positioning and that the frequency stability of a receiver clock is far more critical than the frequency offset. On the other hand, the positioning performance noted is essentially independent (max. 15 % change) of the reference frequency stability, which indeed differed by 4 orders of magnitude.  相似文献   

The 11 March 2011 East Japan Earthquake and Tsunami: Tsunami Effects on Coastal Infrastructure and Buildings     

Harry Yeh  Shinji Sato  Yoshimitsu Tajima 《Pure and Applied Geophysics》2013,170(6-8):1019-1031

The 11 March 2011 East Japan Earthquake and Tsunami caused unprecedented damage to well-engineered buildings and coastal structures. This report presents some notable field observations of structural damage based on our surveys conducted along the Sanriku coast in April and June 2011. Engineered reinforced concrete buildings failed by rotation due to the high-velocity and deep tsunami inundation: entrapped air in the buildings and soil liquefaction by ground shaking could have contributed to the failure. The spatial distribution pattern of destroyed and survived buildings indicates that the strength of tsunami was affected significantly by the locations of well-engineered sturdy buildings: weaker buildings in the shadow zone tended to survive while jet and wake formations behind the sturdy buildings enhanced the tsunami forces. We also found that buildings with breakaway walls or breakaway windows/doors remained standing even if the surrounding buildings were washed away or destroyed. Several failure patterns of coastal structures (seawalls) were observed. Flow-induced suction pressure near the seawall crown could have caused the failure of concrete panels that covered the infill. Remarkable destruction of upright solid-concrete type seawalls was closely related with the tsunami induced scour and soil instability. The rapid decrease in inundation depth during the return-flow phase caused soil fluidization down to a substantial depth. This mechanism explains severely undermined roads and foundations observed in the area of low flow velocities.  相似文献   

A Rupture Model for the 1999 Chi-Chi Earthquake from Inversion of Teleseismic Data Using the Hybrid Homomorphic Deconvolution Method     

Boi-Yee Liao  Tian-Wei Sheu  Yeong-Tien Yeh  Huey-Chu Huang  Lien-Shiang Yang 《Pure and Applied Geophysics》2013,170(3):391-407

This study investigates the kinematics of the rupture process of the M _L 7.3 Chi–Chi, Taiwan, earthquake on September 21, 1999. By applying the proposed hybrid homomorphic deconvolution method to deconvolve teleseismic broadband P-wave displacement recordings of the earthquake, this study derives the apparent source time functions (ASTFs) at ten stations located around the epicenter. To further characterize the fault, the kinematic history of the rupture was inverted from ASTFs using a genetic algorithm, coupled with nonlinear iterative technique. The calculated ASFTs reveal that the total rupture event lasted for approximately 27 s. Static slip distribution images indicate that most slip occurred at shallower portions of the fault plane, especially 20–55 km north of the epicenter. The maximum slip reached 20 m at 45 km north of the epicenter, and the average slip throughout the observed rupture area was approximately 2 m. Large asperities on the fault appeared at 25–35 km and 40–50 km north of the hypocenter, and coincided with relatively high rupture velocity. This suggests that the earthquake’s energy may have been released quickly. The rupture velocity decreased upon encountering an asperity, and increased again after passing the asperity. This implies that the rupture required more time to overcome the resistances of the asperities. The maximum rupture velocity was 3.8 km/s, while the average rupture velocity was approximately 2.2 km/s. The rise time distribution suggests that larger slip amplitudes generally correspond to shorter rise times on the subfaults.  相似文献   

Development of a global flood risk index based on natural and socio-economic factors   总被引：1，自引：0，他引：1  

Yuko Okazawa  Pat J.-F. Yeh  Shinjiro Kanae 《水文科学杂志》2013,58(5):789-804

Abstract

A global flood risk index (FRI) is established, based on both natural and social factors. The advanced flood risk index (AFRI) is the expectation of damage in the case of a single flood occurrence, estimated by a linear regression-based approach as a function of hazard and vulnerability metrics. The resulting equations are used to predict potential flood damage given gridded global data for independent variables. It is new in the aspect that it targets floods by units of events, instead of a long-term trend. Moreover, the value of the AFRI is that it can express relative potential flood risk with the process of flood damage occurrence considered. The significance of this study is that not only the hazard parameters which contribute directly to flood occurrence, but vulnerability parameters which reflect the conditions of the region where flood occurred, including its residential and social characteristics, were shown quantitatively to affect flood damage.

Citation Okazawa, Y., Yeh, P., Kanae, S. & Oki, T. (2011) Development of a global flood risk index based on natural and socioeconomic factors. Hydrol. Sci. J. 56(5), 789–804.  相似文献   

Characterization of slip zone associated with the 1999 Taiwan Chi-Chi earthquake: X-ray CT image analyses and microstructural observations of the Taiwan Chelungpu fault     

Tetsuro Hirono  Masumi Sakaguchi  Kenshiro Otsuki  Hiroki Sone  Koichiro Fujimoto  Toshiaki Mishima  Weiren Lin  Wataru Tanikawa  Masaharu Tanimizu  Wonn Soh  En-Chao Yeh  Sheng-Rong Song 《Tectonophysics》2008,449(1-4):63-84

To characterize the fault-related rocks within the Chelungpu fault, we performed X-ray computed tomography (CT) image analyses and microstructural observations of Hole B core samples from the Taiwan Chelungpu-fault Drilling Project. We identified the slip zone associated with the 1999 Chi-Chi earthquake, within the black gouge zone in the shallowest major fault zone, by comparison with previous reports. The slip zone was characterized by low CT number, cataclastic (or ultracataclastic) texture, and high possibility to have experienced a mechanically fluidized state. Taking these characteristics and previous reports of frictional heating in the slip zone into consideration, we suggested that thermal pressurization was the most likely dynamic weakening mechanism during the earthquake.  相似文献   

Optimization of landfill leachate treatment by microwave oxidation using the Taguchi method     

C.-J. Yeh  S.-L. Lo  J. Kuo  Y.-C. Chou 《International Journal of Environmental Science and Technology》2018,15(10):2075-2086

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