Suspended sediment dynamics in a steep,glacier‐fed mountain stream,Place Creek,Canada

This study examined suspended sediment concentration (SSC) during the ablation seasons of 2000 and 2001 in Place Creek, Canada, a steep, glacier‐fed mountain stream. Comparison of stream flow in Place Creek with that in an adjacent, almost unglacierized catchment provided a rational basis for separating the ablation seasons into nival, nival–glacial, glacial and autumn recession subseasons. Distinct groupings of points in plots of electrical conductivity against discharge supported the validity of the subseasonal divisions in terms of varying hydrological conditions. Relationships between SSC and discharge (Q) varied between the two study seasons, and between subseasons. Hysteresis in the SSC–Q relationship was evident at both event and weekly time‐scales. Some suspended sediment released from pro‐glacial Place Lake (the source of Place Creek) appeared to be lost to channel storage at low flows, especially early in the ablation season, with re‐entrainment at higher flows. Multiple regression models were derived for the subseasons using predictor variables including Q, Q², the change in Q over the previous 3 h, cumulative discharge over the ablation season, total precipitation over the previous 24 h and SSC measured at 1500 hours as an index value for each day. The models produced adjusted R² values ranging from 0·71 to 0·91, and provided tentative insights into the differences in SSC dynamics amongst subseasons. Introduction of the index value of SSC significantly improved the model fit during the nival–glacial and glacial subseasons for both years, as it adjusts the model to the current condition of sediment supply. Copyright © 2003 John Wiley & Sons, Ltd.     

1988年1月云南威信墨黑山地灾害

这次山地灾害由岩崩、滑坡和泥石流三类灾害组成。在我国西南,隆冬少雨季节出现这类山地灾害是罕见的。这次山地灾害正是发生于1988年1月,具有一定的特殊性。究其原因是,当地某些较为特殊的自然条件和采煤不当,促使山体岩崩崩积物逐年加载,进而引起滑坡、泥石流的发生。灾害造成的直接经济损失合人民币58.6万元。对此种山地灾害宜采取以避害为主的防治措施。     

MULTICOMPONENT DETERMINATIONS BY A MEMBRANE-DISCRIMINATED GAS PHASE ANALYZER AND SUCCESSIVE REGRESSION IN THE FIDUCIARY REGION

A membrane-discriminated gas phase analyzer is proposed for multicomponent determinations. Nitrogengas flows countercurrent through outer and inner channels in a tube-in-tube arrangement. The onlycommunication between the two channels occurs through a 500μm aperture covered by a porous PTFEmembrane. A mixture of organic compounds (up to four components) is injected into the inner channelby a heated backflushed injector and the sample components diffusing into the outer channel aremonitored by a flame ionization detector (FID). A calibration set, consisting of pure components, binary,ternary and quaternary mixtures (a total of 64 samples), provides the known data base: temporal profilesof the FID output as a function of sample composition, Although the overall response behavior is nota linearly additive function of individual analyte concentrations, the use of successive inverse multiplelinear regression (while continually altering the choice of the calibration samples considered for theforward regression, on the basis of the most recent values of the predicted unknown sample composition)is shown to yield analytical results for unknown samples that are in good agreement with their true values.     

陕西省岚皋县城关镇泥石流形成条件及其防治

本文论述了陕西省岚皋县城关镇一带近年来所爆发的泥石流的形成条件、发育特征和发展趋势。据此文中提出了区内小白虎崖泥石流的发育过程模式和对区内泥石流的防治原则和措施。     

庐山羊角岭红色泥砾泥石流成因质疑——与施雅风、邓养鑫商榷

作者根据庐山羊角岭红色泥砾的岩性特征,从地形和堆积物的宏观和微观特征进行分析研究,得出庐山有第四纪冰川。     

A New Interpretation of Centimetre-scale Variations in the Progress of Infiltration-driven Metamorphic Reactions: Case Study of Carbonated Metaperidotite, Val d'Efra, Central Alps, Switzerland

Progress () of the infiltration-driven reaction, 4olivine +5CO₂ + H₂O = talc + 5magnesite, that occurred during Barrovianregional metamorphism, varies at the cm-scale by a factor of3·5 within an 3 m³ volume of rock. Mineral and stableisotope compositions record that X_CO2, ¹⁸O_fluid, and ¹³C_fluidwere uniform within error of measurement in the same rock volume.The conventional interpretation of small-scale variations in in terms of channelized fluid flow cannot explain the uniformityin fluid composition. Small-scale variations in resulted insteadbecause (a) reactant olivine was a solid solution, (b) initiallythere were small-scale variations in the amount and compositionof olivine, and (c) fluid composition was completely homogenizedover the same scale by diffusion–dispersion during infiltrationand subsequent reaction. Assuming isochemical reaction, spatialvariations in image variations in the (Mg + Fe)/Si of the parentrock rather than the geometry of metamorphic fluid flow. Ifinfiltration-driven reactions involve minerals fixed in composition,on the other hand, spatial variations in do directly imagefluid flow paths. The geometry of fluid flow can never be determinedfrom geochemical tracers over a distance smaller than the oneover which fluid composition is completely homogenized by diffusion–dispersion. KEY WORDS: Alpine Barrovian metamorphism; diffusion; metamorphic fluid composition; metamorphic fluid flow; reaction progress     

An integrated linear/non-linear flow model for the conduit-fissure-pore media in the karst triple void aquifer system

Most karstic aquifer media may be characterized as the triple-void media with highly-varied hydraulic properties, including matrix pore, fissure and conduit, in which liner flow may co-exist with non-linear flow. In this paper, an attempt is made to couple linear flow with non-linear flow in a single unified flow governing equations by introducing the concept of equivalent hydraulic conductivity (EHC) and deriving a general Darcys law for various flow. The expression of EHC in the karst conduit and fissure are also derived. The procedures of numerical implementation are demonstrated via an ideal model and a case study of karst aquifer system in the Beishan Ore Formation area, Guangxi Autonomous Region, China.     

地质体三维可视化建模的技术方法研究

地质体三维可视化模型具有形象、直观、动态、准确、信息丰富等特点,在指导地质找矿和矿山开发等方面具有很大的优势及实用价值。文章对地质体三维可视化建模的整个技术方法流程作了总结性阐述,并分析其技术关键,同时还进一步探讨了模型的分类及其应用。     

河南省马山口镇青山河泥石流灾害区首期治理工程竣工

针对河南省内乡县马山口镇青山河泥石流灾害防治工程的泥石流灾害现状、治理工程设计依据、工程设计标准、治理措施、工程效益等方面进行了论述。该项工程的竣工取得了较为显著的社会效益,成为中国地质调查局“典型地质灾害勘查与治理示范”工程。     

Computing residence times for flow towards a pumping well: nomograph solution and validity of the small draw-down approximation

A recent analytical model developed to compute the residence time of fluid flowing in an unconfined aquifer towards a single pumping well is examined. The solution is scaled and presented practically as a nomograph showing the relationship between the residence time, flow length and draw-down. In addition, a similar scaling process is undertaken for the same problem occurring in a confined aquifer so that the error introduced by approximating an unconfined system as a confined system can be understood over a wide range of conditions.

---

Resumen Se examina un modelo analítico, recientemente desarrollado, para calcular el tiempo de residencia de un fluido, el cual está fluyendo dentro de un acuífero libre hacia un pozo de bombeo único. La solución después de ser ajustada, se presenta prácticamente como un nomograma, mostrando la relación entre el tiempo de residencia, la longitud del flujo y el abatimiento. Adicionalmente, un proceso similar de ajuste fue realizado para el mismo problema, pero bajo condiciones de acuífero confinado, por tanto el error causado por hacer la aproximación de un sistema libre como si fuera un sistema confinado, puede llegar a ser entendido para un rango amplio de condiciones.

---

Résumé On analyse un modèle analytique récent pour calculer le temps de résidence dun fluide pendant son écoulement vers un puits de pompage dans une nappe libre. La solution a été mise-à-léchelle et présenté dune manière pratique, comme une nomogramme qui exprime la relation entre le temps de résidence, la distance de l› écoulement et le rabattement. De plus, on a utilisé un procédé similaire de mise-à-léchelle pour le même problème dans une nappe captive affin que lerreur introduite par lapproximation dune nappe libre par une nappe captive peut être interprétée pour une grande classe de conditions.