Numerical modeling of coupled fluid flow and thermal and reactive biogeochemical transport in porous and fractured media     

Gour-Tsyh Yeh  Yilin Fang  Fan Zhang  Jiangtao Sun  Yuan Li  Ming-Hsu Li  Malcolm D. Siegel 《Computational Geosciences》2010,14(1):149-170

Subsurface contamination problems of metals and radionuclides are ubiquitous. Metals and radionuclides may exist in the solute phase or may be bound to soil particles and interstitial portions of the geologic matrix. Accurate tools to reliably predict the migration and transformation of these metals and radionuclides in the subsurface environment enhance the ability of environmental scientists, engineers, and decision makers to analyze their impact and to evaluate the efficacy of alternative remediation techniques prior to incurring expense in the field. A mechanistic-based numerical model could provide such a tool. This paper communicates the development and verification of a mechanistically coupled fluid-flow thermal-reactive biogeochemical-transport model where both fast and slow reactions occur in porous and fractured media. Theoretical bases, numerical implementations, and numerical experiments using the model are described. A definition of the “rates” of fast/equilibrium reactions is presented to come up with a consistent set of governing equations. Two example problems are presented. The first one is a reactive transport problem which elucidates the non-isothermal effects on heterogeneous reactions. It also demonstrates that the rates of fast/equilibrium reactions are not necessarily greater than that of slow/kinetic reactions in the context of reactive transport. The second example focuses on a complicated but realistic advective–dispersive–reactive transport problem. This example exemplifies the need for innovative numerical algorithms to solve problems involving stiff geochemical reactions. It also demonstrates that rates of all fast/equilibrium reactions are finite and definite. Furthermore, it is noted that a species-versus-time curve cannot be used to characterize the rate of homogeneous fast/equilibrium reaction in a reactive transport system even if one and only one such reaction is responsible for the production of this species.  相似文献   

Reply to Comment on “Analysis of pumping test data for determining unconfined-aquifer parameters: Composite analysis or not?”: paper published in Hydrogeology Journal (2009) 17:1133–1147, by Hund-Der Yeh and Yen-Chen Huang     

Hund-Der Yeh  Yen-Chen Huang 《Hydrogeology Journal》2010,18(8):1979-1981

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The effect of the variation of river water levels on the estimation of groundwater recharge in the Hsinhuwei River,Taiwan   总被引：1，自引：1，他引：0  

Jung-Wei Chen  Hsun-Huang Hsieh  Hsin-Fu Yeh  Cheng-Haw Lee 《Environmental Earth Sciences》2010,59(6):1297-1307

Land subsidence is a serious problem in Taiwan’s Yunlin area due to groundwater overpumping. There are safety risks in the high-speed railway structures in the areas of Siluo, Huwei, Tuku, and Yuanchang towns that run from north to south in the Yunlin area. Therefore, it is important to increase the groundwater recharge and to remedy the land subsidence in this area. The purpose of this study is to use the stream-flow estimation model (SF) and the groundwater flow numerical software MODFLOW (MF) to estimate the stream infiltration with consideration to the variation of the river water level in the Hsinhuwei River. The Ferris analytical model (FA) and MF are used to estimate the increased stream infiltration after the water level of the river rises. The hydraulic parameters required for each model are obtained from field observations and laboratory experiments. The results indicate that the assessment of the stream infiltration obtained through the SF and MF models are 264.2 × 10⁴ and 170.9 × 10⁴ m³/year, respectively. When the river water level increases by about 2.5 m, the annual stream infiltration obtained through the FA and MF models significantly increases by 31.6 × 10⁴ and 26.4 × 10⁴ m³/year, respectively. Taken together, the stream storages estimated using these two models indicate that an increasing efficiency of groundwater recharge is within the range of 10.0–18.5%.  相似文献   

On the relationship between the Bowen ratio and the near-surface air temperature   总被引：1，自引：0，他引：1  

Jaeil Cho  Taikan Oki  Pat J.-F. Yeh  Wonsik Kim  Shinjiro Kanae  Kyoichi Otsuki 《Theoretical and Applied Climatology》2012,108(1-2):135-145

The sensitivity of land surface energy partitioning to near-surface air temperature (T _a) is a critical issue to understand the interaction between land surface and climatic system. Thus, studies with in situ observed data compiled from various climates and ecosystems are required. The relations derived from such empirical analyses are useful for developing accurate estimation methods of energy partitioning. In this study, the effect of T _a on land surface energy partitioning is evaluated by using flux measurement data compiled from a global network of eddy covariance tower sites (FLUXNET). According to the analysis of 25 FLUXNET sites (60 site-years) data, the Bowen ratio is found to have a linear relation with the bulk surface resistance normalized by aerodynamic and climatological resistance parameters in general, of which the slope and intercept are dependent on T _a. Energy partitioning in warmer atmosphere is less sensitive to changes in land surface conditions. In addition, a negative relation is found between Bowen ratio and T _a, and this relation is stronger above less vegetated surface and under low vapor pressure deficit and low received radiative energy condition. The empirical results obtained in this study are expected to be useful in gaining better understanding of alternating surface energy partitioning under increasing T _a.  相似文献   

Galaxies with supermassive binary black holes: (I) a possible model for the centers of core galaxies     

Ing-Guey Jiang  Li-Chin Yeh 《Astrophysics and Space Science》2014,349(2):881-893

The dynamics of galactic systems with central binary black holes is studied. The model is a modification from the restricted three body problem, in which a galactic potential is added as an external potential. Considering the case with an equal mass binary black holes, the conditions of existence of equilibrium points, including Lagrange Points and additional new equilibrium points, i.e. Jiang-Yeh Points, are investigated. A critical mass is discovered to be fundamentally important. That is, Jiang-Yeh Points exist if and only if the galactic mass is larger than the critical mass. The stability analysis is performed for all equilibrium points. The results that Jiang-Yeh Points are unstable could lead to the core formation in the centers of galaxies.  相似文献   

An Application of Hydraulic Tomography to a Large‐Scale Fractured Granite Site,Mizunami, Japan          下载免费PDF全文

Yuanyuan Zha  Tian‐Chyi J. Yeh  Walter A. Illman  Tatsuya Tanaka  Patrick Bruines  Hironori Onoe  Hiromitsu Saegusa  Deqiang Mao  Shinji Takeuchi  Jet‐Chau Wen 《Ground water》2016,54(6):793-804

While hydraulic tomography (HT) is a mature aquifer characterization technology, its applications to characterize hydrogeology of kilometer‐scale fault and fracture zones are rare. This paper sequentially analyzes datasets from two new pumping tests as well as those from two previous pumping tests analyzed by Illman et al. (2009) at a fractured granite site in Mizunami, Japan. Results of this analysis show that datasets from two previous pumping tests at one side of a fault zone as used in the previous study led to inaccurate mapping of fracture and fault zones. Inclusion of the datasets from the two new pumping tests (one of which was conducted on the other side of the fault) yields locations of the fault zone consistent with those based on geological mapping. The new datasets also produce a detailed image of the irregular fault zone, which is not available from geological investigation alone and the previous study. As a result, we conclude that if prior knowledge about geological structures at a field site is considered during the design of HT surveys, valuable non‐redundant datasets about the fracture and fault zones can be collected. Only with these non‐redundant data sets, can HT then be a viable and robust tool for delineating fracture and fault distributions over kilometer scales, even when only a limited number of boreholes are available. In essence, this paper proves that HT is a new tool for geologists, geophysicists, and engineers for mapping large‐scale fracture and fault zone distributions.  相似文献   

Copula‐based flood frequency (COFF) analysis at the confluences of river systems     

Cheng Wang  Ni‐Bin Chang  Gour‐Tsyh Yeh 《水文研究》2009,23(10):1471-1486

Many civil infrastructures are located near the confluence of two streams, where they may be subject to inundation by high flows from either stream or both. These infrastructures, such as highway bridges, are designed to meet specified performance objectives for floods of a specified return period (e.g. the 100 year flood). Because the flooding of structures on one stream can be affected by high flows on the other stream, it is important to know the relationship between the coincident exceedence probabilities on the confluent stream pair in many hydrological engineering practices. Currently, the National Flood Frequency Program (NFF), which was developed by the US Geological Survey (USGS) and based on regional analysis, is probably the most popular model for ungauged site flood estimation and could be employed to estimate flood probabilities at the confluence points. The need for improved infrastructure design at such sites has motivated a renewed interest in the development of more rigorous joint probability distributions of the coincident flows. To accomplish this, a practical procedure is needed to determine the crucial bivariate distributions of design flows at stream confluences. In the past, the copula method provided a way to construct multivariate distribution functions. This paper aims to develop the Copula‐based Flood Frequency (COFF) method at the confluence points with any type of marginal distributions via the use of Archimedean copulas and dependent parameters. The practical implementation was assessed and tested against the standard NFF approach by a case study in Iowa's Des Moines River. Monte Carlo simulations proved the success of the generalized copula‐based joint distribution algorithm. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

The characteristics of signal versus noise sst variability in the north pacific and the tropical pacific ocean     

Sang-Wook Yeh  Ben P. Kirtman 《Ocean Science Journal》2006,41(1):1-10

Total sea surface temperature (SST) in a coupled GCM is diagnosed by separating the variability into signal variance and noise variance. The signal and the noise is calculated from multi-decadal simulations from the COLA anomaly coupled GCM and the interactive ensemble model by assuming both simulations have a similar signal variance. The interactive ensemble model is a new coupling strategy that is designed to increase signal to noise ratio by using an ensemble of atmospheric realizations coupled to a single ocean model. The procedure for separating the signal and the noise variability presented here does not rely on any ad hoc temporal or spatial filter. Based on these simulations, we find that the signal versus the noise of SST variability in the North Pacific is significantly different from that in the equatorial Pacific. The noise SST variability explains the majority of the total variability in the North Pacific, whereas the signal dominates in the deep tropics. It is also found that the spatial characteristics of the signal and the noise are also distinct in the North Pacific and equatorial Pacific.  相似文献   

Data quality check procedures of an operational coastal ocean monitoring network     

Dong Jiing Doong  Shen Hsien Chen  Chia Chuen Kao  Beng Chun Lee  Sun Pei Yeh 《Ocean Engineering》2007,34(2):234-246

Field oceanographic and meteorological data are required for ocean engineering. In response to the requirement of field data, an operational coastal ocean monitoring network was established around Taiwan coast, including nine deep-water data buoys, one shallow-water pile station, 10 coastal weather stations and 10 tide stations. Data quality check procedures are necessary to ensure the accuracy of measurements. This paper presents the data quality check procedures on ocean wave data which includes automatic and manual check procedures. The checking criteria are derived using statistical theory in this paper. In addition, a sea-state-dependent algorithm is presented in this study in order to derive checking criteria of time-continuity check. It is showed to have better performance of picking up suspicious data than using fixed threshold process. This data quality check program is now used on the operational monitoring network.  相似文献   

Determination of the parameter pattern and values for a one-dimensional multi-zone unconfined aquifer     

Ya-Chi Chang  Hund-Der Yeh  Yen-Chen Huang 《Hydrogeology Journal》2008,16(2):205-214

In an aquifer, heterogeneity plays an important role in governing groundwater flow. Hence, aquifer characterization should involve both the pattern and values of the hydrogeological parameters. A new analytical solution describing the one-dimensional groundwater flow in a multi-zone unconfined aquifer is presented, and a methodology developed from the analytical solution and a heuristic approach for determining the pattern and values of the aquifer parameters are proposed. The analytical solution demonstrates that the hydraulic head varies spatially and is influenced by aquifer heterogeneity. Simulated annealing, a heuristic approach, is incorporated with the solution to simultaneously identify the pattern and values of the hydraulic conductivity for a horizontal multi-zone unconfined aquifer. This approach may be used to give an approximate result for a two-dimensional problem by dividing the model area into a number of transects along the transverse direction, identifying the parameter values along the longitudinal direction for each transect, and then smoothing the identified results.  相似文献