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Frontiers of Environmental Science & Engineering 2012年第2期6卷 255-264页

作者： daniel p.loucks Haifeng JIA Civil and Environmental Engineering Comell UniversityIthaca NY 14853USA School of Environment Tsinghua UniversityBeijing 100084China

Water is essential for life. In spite of the entire engineering infrastructure devoted to the treatment, regulation and beneficial uses of water, occasionally sufficient quantities and qualities of water become scarce. When this happens, just how do we decide how much less water to allocate to all of us and the activities we engage in to sustain and enhance our quality of life？ This paper addresses some of the complexities of answering such a question, especially as society increasingly recognizes the need to provide flow regimes that will maintain healthy aquatic and floodplain ecosystems that also impact the economic, physical and even the spiritual quality of our lives. For we depend on these ecosystems to sustain our wellbeing. We are indeed a part of our ecosystems. We depend upon on aquatic ecosystems to moderate river flow qualities and quantities, reduce the extremes of floods and droughts, reduce erosion, detoxify and decompose water- borne wastes, generate and preserve flood plain soils and renew their fertility, regulate disease carrying organisms, and to enhance recreational benefits of river systems. This question of deciding just how much water to allocate to each water user and for the maintenance of viable aquatic ecosystems, especially when there is not enough, is a complex, and largely political, issue. This issue is likely to become even more complex and political and contentious in the future as populations grow and as water quantities and their qualities become even more variable and uncertain.

关键词： water stress aquatic ecosystems sustainablewater resource allocations ecosystem water requirements

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为可持续生计管理水资源(英文)

为可持续生计管理水资源(英文)

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北京论坛（2008）文明的和谐与共同繁荣——文明的普遍价值和发展趋向

作者： daniel p.loucks Civil and Environmental Engineering Cornell University IthacaNY 14850 USA

Water is essential for all forms of life and a viable *** is also essential for food and a quality *** adequate food and a quality environment and supporting ecosystem,life and the economy will *** water is scarce,just how do we decide how much water to allocate to all competing uses of water that enhance a sustainable quality of life? This paper addresses some of the complexities of answering such a question,especially related to environmental flow *** relatively recently have we all begun to recognize the importance of not only keeping we humans from becoming too thirsty,but also of maintaining healthy functioning ecosystems as indeed these ecosystems what we depend on to sustain our own *** are indeed a part of our *** depend upon our environment and ecosystems to sustain the quality of our lives,if not life itself. Balancing water demand allocations,especially when the demands exceed supplies,is a complex, and largely political,*** is likely to become even more complex and political and contentious in the future as populations grow and as water quantities and their qualities become even more variable and *** at least the political process of making allocations should be informed by scientific studies of the likely impacts of alternative allocation decisions, especially with respect to environmental flow demands. How do we allocate scarce water supplies optimally among all demands that impact on the quality of,or even on the existence of,life - both human and ecosystem life - in times of critical water scarcity? The temptation is to ignore environmental flow *** decisions can be at the expense of maintaining a sustainable place to live and prosper.

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On the Importance of the Stokes-Brinkman Equations for Computing Effective permeability in Karst Reservoirs

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Communications in Computational physics 2011年第10期10卷 1315-1332页

作者： Marcin Krotkiewski Ingeborg S.Ligaarden Knut-Andreas Lie daniel W.Schmid physics of Geological processes University of OsloP.O.Box 1048 BlindernNO-0316 OsloNorway SINTEF ICT Department of AppliedMathematicsP.O.Box 124 BlindernNO-0314 OsloNorway Center of Mathematics for Applications University of OsloP.O.Box 1053 BlindernNO-0316 OsloNorway

Cavities and fractures significantly affect the flow paths in carbonate reservoirs and should be accurately accounted for in numerical ***,we consider the problem of computing the effective permeability of rock samples based on high-resolution 3DCT scans containingmillions of *** use the Stokes-Brinkman equations in the entire domain,covering regions of free flow governed by the Stokes equations,porous Darcy flow,and transitions between *** presence of different length scales and large(ten orders of magnitude)contrasts in permeability leads to highly ill-conditioned linear systems of equations,which are difficult to *** obtain a problem that is computationally tractable,we first analyze the relative importance of the Stokes and Darcy terms for a set of idealized 2D *** find that,in terms of effective permeability,the Stokes-Brinkman equations are only applicable for a special parameter set where the effective free-flow permeability is less than four orders of magnitude different from the matrix *** other cases can be accurately modeled with either the Stokes or the Darcy end-member flows,depending on if there do or do not exist percolating free-flow *** insights obtained are used to perform a direct computation of the effective permeability of a rock sample model with more than 8 million cells.

关键词： Upscaling Stokes equation Brinkman equation porous media

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