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1.
Geoff Kite 《水文研究》1993,7(2):227-233
Using current meters to estimate flows in fast mountain streams is difficult and inaccurate. The salt dilution method offers an easier and more accurate alternative. The method has been used for many years but is time consuming and messy because of the need to mix chemical solutions and measure chemical concentrations in the field. A computer program has been developed which uses a laptop computer to calculate the mixing length and the mass of salt needed. The program controls the conductivity measurements and calculates the streamflow directly in the field. The development of this program is described and examples are presented of the application of the method in the Rocky Mountains of Alberta and British Columbia. 相似文献
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A local-scale model for temperature-dependence of water-retention curves may be applicable to large scales. Consideration of this temperature dependence is important for modeling unsaturated flow and transport in the subsurface in numerous cases. Although significant progress has been made in understanding and modeling this temperature effect, almost all the previous studies have been limited to small scales (on the order of several centimeters). Numerical experiments were used to investigate the possibility of extending a local-scale model for the temperature-dependence of water retention curves to large scales (on the order of meters). Temperature effects on large-scale hydraulic properties are of interest in many practical applications. Numerical experiment results indicate that the local-scale model can indeed be applicable to large-scale problems for special porous media with high air entry values. A typical porous medium of this kind is the porous tuff matrix in the unsaturated zone of Yucca Mountain, Nevada, the proposed geologic disposal site for national high-level nuclear wastes. Whether this finding can approximately hold for general cases needs to be investigated in future studies. 相似文献
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西安翠华山山崩地质遗迹资源保护 总被引:5,自引:3,他引:5
文论述了西安翠华山山崩地质遗迹资源保护的目的,进行了保护分区,将其分为核心保护区、缓冲区和视域保护区三个区,重点分析了核心保护区的保护现状,并在此基础上提出了相应的保护内容和对策,以实现山崩地质遗迹资源的可持续利用和发展。 相似文献
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ZHANGJin MAZongjin RENWenjun LEIYongliang 《大地构造与成矿学(英文版)》2003,27(1):165-178
There are many thrust-related structures occurring in the Paleozoic strata of the Niushou Mountain in the central part of Ningxia Hui Autonomous Region. The fault-related folds are the typical structures in this area. Based on the analysis about these structures and their relationships, the processes by which these structures of the Miboshan Formation were formed are reconstructed, and the strata underwent about three stages of deformation: (1) horizontal shortening, (2) folding, and (3) thrusting. And the fact that the Niushou Mountain is the leading edge of an old thrust sheet was proved, the Niushou Mountain, the Daluo Mountain and the Xiaoluo Mountain together constitute the front part of this old thrust zone, so the Niushou Mountain and the Ordovician strata in the central and southern parts of Ningxia now are likely allochthons. In the period from middle Ordovician to Devonian, the areas of the central and southern Ningxia belonged to the back-arc foreland basin of North Qilianshan orogen, which was adjacent to the continent in the north. In the later part of the early Paleozoic period, the Niushou Mountain was formed after the closure of the back-arc foreland basin. 相似文献
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Yucca Mountain, the proposed site for the high-level nuclear waste repository, is located just south of where the present
water table begins a sharp rise in elevation. This large hydraulic gradient is a regional feature that extends for over 100 km.
Yucca Mountain and its vicinity are underlain by faulted and fractured tuffs with hydraulic conductivities controlled by flow
through the fractures. Close to and parallel with the region of large hydraulic gradient, and surrounding the core of the
Timber Mountain Caldera, there is a 10- to 20-km-wide zone containing few faults and thus, most likely, few open fractures.
Consequently, this zone should have a relatively low hydraulic conductivity, and this inference is supported by the available
conductivity measurements in wells near the large hydraulic gradient. Also, slug injection tests indicate significantly higher
pressures for fracture opening in wells located near the large hydraulic gradient compared to the opening pressures in wells
further to the south, hence implying that lower extensional stresses prevail to the north with consequently fewer open fractures
there. Analytical and numerical modeling shows that such a boundary between media of high and low conductivity can produce
the observed, large hydraulic gradient, with the high conductivity medium having a lower elevation than the water table. Further,
as fractures can close due to tectonic activity, the conductivity of the Yucca Mountain tuffs can be reduced to a value near
that for the hydraulic barrier due to strain release by a moderate earthquake. Under these conditions, simulations show that
the elevation of the steady-state water table could rise between 150 and 250 m at the repository site. This elevation rise
is due to the projected shift in the location of the large hydraulic gradient to the south in response to a moderate earthquake,
near magnitude 6, along one of the major normal faults adjacent to Yucca Mountain. As the proposed repository would only be
200–400 m above the present water table, this predicted rise in the water table indicates a potential hazard involving water
intrusion.
Received: 7 June 1996 / Accepted: 19 November 1996 相似文献
8.
1 INTRODUCTION Sitting in the central part of the Pearl River Delta, Guangzhou is one of the cities in China that are most polluted by acid rain. Broad attention has been brought to the problem. Since the early 1980s, a series of observation and studies h… 相似文献
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贡嘎山东坡亚高山不同林地土壤水分特性与生态环境效应 总被引:2,自引:0,他引:2
森林土壤水分特性,包括水分的渗透与蒸发、保持与贮存等对森林生态环境都有重要意义。本文研究了长江上游贡嘎山亚高山不同森林类型土壤的水分特征及其生态环境作用,结果表明:成熟林、过熟林土壤在储水、渗透、容水、蒸发和持水特性等多数方面利于保持和改善生态环境,次生或林分单一森林类型次之,林木皆伐后最差。研究区以成熟林和过熟林为主,生态环境保护较好。尽管该区与长江上游其它地区一样同具自然地理条件差、生态环境脆弱的特征,但由于该区森林植被和环境得到了有效保护,土壤水分特性好,促进了森林生态系统的良性循环,生态环境问题得到进一步改善。 相似文献