三峡工程对长江流域可持续发展的影响

可持续发展观念应该正确理解,研究可持续发展不能脱离国家或地区的发展水平。在分析长江流域可持续发展的限制因子（频繁的洪水灾害、偏低的防洪能力、落后的社会经济水平及脆弱的生态环境）的基础上,从三峡工程的防洪作用、发电效益、航运效益以及三峡工程效益发挥的可持续性方面,研究了三峡工程对长江流域可持续发展的促进作用。同时论述了三峡工程的建设对长江中上游地区生态环境综合治理及库区社会经济发展的带动作用。认为三峡工程的建设符合我国当今可持续发展战略,是全面促进长江流域社会经济环境可持续发展的关键性工程。     

The development of private sheltered housing in Scotland: a changing market

The provision of sheltered housing for sale in Scotland has experienced rapid growth since the opening of the first scheme in 1982. Development has been geographically concentrated in a small number of inner city and rural (coastal) areas. The expectation of continued rapid expansion is unlikely if recent trends of slower growth continue. This paper uses evidence from interviews with developers and owners of sheltered and mainstream housing, to examine the possible future contribution of the private market. On the basis of such evidence it raises questions about the relevance of some existing planning policies.     

MFAM模型在河流水质污染模拟及预测中的应用

文中以时间序列分析为基础，介绍了均值生成函数这一崭新概念，并且经成份因子提取分析推导建立了模拟序列的数字模型（简记为MFAM），经对黄河下游花园口断面的1988-1989年实测水质污染指标溶解氧（DO），氨氧，化学耗氧量（COD），五日生化需氧量（BOD5）等序列模拟，结果表明MFAM模型能较好地模拟河流水质污染指标的变化趋势，拟合平均误差只有5.2-6.4%，MFAM模型应用于预测1990-1991年水质污染指标变化，结果表明预测精度达85%以上，文中最后得出结论：MFAM模型应用于河流污染模拟和预测，是完全可行且十分方便。     

The case for free market environmentalism

Environmental Ethics is the ethics of how we humans are to relate to each other about the environment we live in. The best way to adjust inevitable differences among us in this respect is by private property. Each person takes the best care of what he owns, and ownership entails the free market, which enables people to make mutually advantageous trades with those who might use it even better. Public regulation, by contrast, becomes management in the interests of the regulators, or of special interests, such as lovers of rare species-not the people they're supposed to be serving.     

环保执法难点浅析

环保执法是贯彻实施我国环境保护这一基本国策的重要保证。但是，在基层环保执法工作中常常遇到诸如被执法企业受地方保护主义的庇护、公众的环保意识薄弱、环保执法队伍自身素质差、执法水平低、执法力量薄弱、技术装备落后等问题。为维护环保法的尊严，严肃执法程序，确保环保执法顺利进行，分析研究这些问题的实质和存在的背景条件是必要的，并为解决这类问题作有益的探讨。     

黄河断流与黄河的水资源承载力

分析了黄河断流的时空特征、根源和危害，提出了水资源承载力的概念。黄河的水资源承载力即指在生态系统良性循环的条件下，黄河对人类取用水资源的最大承受能力。只有建立起水资源承载力的概念，人类才会谨慎地取用水资源，小心地保护水资源。     

泗阳县黄河故道滩区综合开发模式研究和实践

1989年以来,泗阳县运用系统工程的方法,对黄河故道滩区洪涝沙碱旱的综合治理和滩区三荒资源的综合开发利用进行了研究和实践,创立了黄河故道滩区综合开发模式,缩短了开发周期,提高了开发效益,为黄淮流域季节性沙土河道滩区的治理开发树立了一个典范。本文将扼要介绍模式的提出、建立和实施效果。     

A composite medium approximation for unsaturated flow in layered sediments

Saturated-unsaturated flow in strictly layered sediments proceeds via conductors in parallel in the direction parallel to bedding, and via resistors in series in the direction perpendicular to bedding. On sufficiently small scales of space and time, flow in such media will be subject to approximate capillary equilibrium locally, which provides a basis for approximating the effective hydraulic conductivity of a composite multi-layer medium in terms of the conductivities of the individual layers. Equations for the hydraulic conductivity tensor in "composite medium approximation" (COMA) are given in a coordinate system aligned with bedding. Hydraulic conductivity parallel to bedding is generally larger than in the perpendicular direction. The anisotropy depends on the spread of the conductivity distribution, and tends to increase for dryer conditions. The COMA model was implemented in a multi-phase flow simulator and tested by comparison with high-resolution simulations in which all layering heterogeneity is resolved explicitly. Under favorable conditions, COMA is found to accurately represent sub-grid scale flow and transport processes, providing a practical method for simulating field-scale flow and transport in layered media. The approximation improves when layers are thinner, and when flow rates are smaller.     

Forced migration, processes of return and livelihood construction among pastoralists in northern Sudan

The Hawaweer, a nomadic, pastoralist group in northern Sudan, were seriously affected by the drought in the Sahel during the mid-1980s. Their experience illustrates the connection between internally displaced people, normal mobility, forced migration, dilemmas and opportunities of return and how new livelihoods can be successfully constructed based on traditional rights, strong local institutions and external resources. Some displaced Hawaweer got the chance to return to their homeland as new livelihood opportunities were established; others did not get this opportunity nor would they have returned if they had been given the chance. In both situations, the processes of displacement and return had an impact on the sense of belonging and identity.     

春季连阴雨对江苏省夏收作物产量的影响

分析了江苏省40年(1960～1999)春季连阴雨的发生概率、发展趋势及其时空分布规律。研究发现,春季连阴雨累计日数、总雨量与夏粮产量呈显著负相关关系,且累计日数≥30d时,夏粮减产非常明显,这种情况的发生概率达59．1％。