Adaptive adjustment of channel geometry

This paper constructs a model of channel geometry composed of three subsections: a steady-state submodel, a gradedstate submodel, and a stochastic error submodel. With the aid of this representation of the morphology of channels, the at-a-point changes in geometry can be reproduced by a simple recursive equation of autoregressive, moving-average form which is derived from methods used in the statistical analysis of time series. A set of height loss data for three Japanese rivers derived from Yatsu's (1955) paper is used to determine the effect of bed material changes on adaptations within the graded-state submodel of the channel. The results of analyzing the autocorrelation function, spectrum, and adaptive parameter shifts within this model can be used to infer that significant changes in the amplitude of height change variation, and a shift to higher frequency oscillations of bed forms are associated with the shift in bed material conditions.     

Mathematical simulation of stable and equilibrium river bed profiles and slopes

Two approaches to the simulation of stable and equilibrium longitudinal profiles and slopes are considered. The first one deals with a solution to the equation of solid matter (sediment) continuity in the equilibrium case and the second approach deals with the application of variational principles. The approaches considered and results obtained can be used in hydroengineering construction for designing stable and equilibrium longitudinal profiles of water streams and slopes.     

外辐射带区域新建地磁场经验模型的定量研究

准确的磁场模型对于辐射带粒子环境研究至关重要.本文利用美国Van Allen Probes（VAP）在2012至2018年期间测量的磁场数据和GOES15在2011至2017年期间测量的磁场数据,定量地评估了三个较新的外磁场经验模型（TS05、TA15和TA16）对外辐射带区域（3~6.6R_E）磁场的描述性能.本文选择预测效率（Prediction Efficiency,PE）作为评估指标,定量分析各模型在不同空间范围（Lm值）、不同地磁活动水平（Kp）以及不同磁地方时（MLT）下的性能表现,并且计算了观测磁场与模型磁场的夹角θ,以评估模型的磁场方向预测能力.结果表明：PE随Lm值增大,随地磁扰动增强而下降;θ随Lm值增大,随地磁扰动增强而增大.在Lm=5~6.5R_E范围内,PE呈现晨昏不对称性,MLT=12-21时的PE值小于MLT=0-9时的值,说明三个磁场模型可以较好地描述晨侧磁场的强度,但它们并不能很好地反映下午至昏侧磁场的大小;在地球同步轨道附近（Lm~6.6R_E）,PE呈现昼夜不对称性,MLT=9-15时的PE值大于其他时区的值,说明三个磁场模型可以很好地反映昼侧磁场大小,但在夜侧可能存在较大的误差.θ在MLT=6-12时的值小于其他时区的值,呈现昼夜不对称性,说明三个磁场模型可以较好地描述昼侧磁力线的分布位型,但在夜侧存在较大的方向描述误差.在外辐射带3~6.5R_E内,TA16模型与VAP磁场观测数据最为接近,PE均大于0.7,θ均小于3°;在地球同步轨道高度（6.6R_E）,TS05模型与GOES15卫星磁场观测数据最为接近,PE约为0.75,θ约为7°.相关的研究结果可以为我国星载高能粒子探测器探测数据的在轨交叉定标、辐射带高能粒子动态模型研究和相关的磁层环境理论/应用研究提供地磁场模型选择方面的参考.     

西天山阿吾拉勒二叠纪陆相长英质火山岩铜银矿矿床模式

通过对西天山二叠纪陆相火山岩及成矿作用的研究,指出铜银矿床与长英质火山岩一石英钠长斑岩有直接关系,并从成矿构造背景、产出地质环境、矿床地质特征等方面总结出二叠纪陆相长英质火山岩铜银矿床矿床模式。     

Capture zone,travel time,and solute-transport predictions using inverse modeling and different geological models

Six regional-scale flow models are compared to gain insight into how different representations of hydraulic-conductivity distributions affect model calibration and predictions. Deterministic geological models were used to define hydraulic-conductivity distributions in two steady-state flow models that were calibrated to heads and baseflow estimates using inverse techniques. Optimized hydraulic-conductivity estimates from the two models were used to calculate layer and model mean hydraulic-conductivity values. Despite differences in the two geological models, inverse calibration produced mean hydraulic-conductivity values for the entire model domain that are quite similar. The layer and model mean hydraulic-conductivity values were used to generate four additional flow models and forward runs were performed. All of the models adequately simulate the observed heads and total baseflow. The six flow models were used to predict the steady-state impact of a proposed well field, and the flow solutions were used in simulating particle tracking and solute transport. Results of the predictive simulations show that, for this example, simple models of heterogeneity produce capture zones similar to more complex models, but with very different travel times and breakthroughs. Inverse modeling combined with different geological models can provide a measure of capture zone and breakthrough reliability.

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Resumen Se compara seis modelos de flujo a escala regional para conocer cómo afecta a la calibración y a la predicción del modelo diversas representaciones de la distribución de la conductividad hidráulica. Se ha utilizado modelos geológicos deterministas para definir las distribuciones de la conductividad hidráulica en dos modelos de flujo permanente, calibrados mediante técnicas inversas con niveles piezométricos y estimaciones del flujo de base. Se ha adoptado estimaciones optimizadas de la conductividad hidráulica de los dos modelos para calcular las cotas de las capas y sus conductividades hidráulicas medias. A pesar de las diferencias entre ambos modelos geológicos, con la calibración inversa se obtiene valores similares de conductividad hidráulica en todo el dominio. Estos valores de las capas y de las conductividades hidráulicas medias han servido para generar cuatro modelos adicionales de flujo y realizar predicciones. Todos los modelos simulan de forma adecuada los niveles observados y los caudales de base. Los seis modelos han sido aplicados a la predicción del impacto estacionario de un campo de pozos, y las soluciones del flujo permiten simular el transporte de partículas y de solutos. Los resultados de estas predicciones muestran que, para este ejemplo, los modelos sencillos de la heterogeneidad dan lugar a zonas de captura similares a las generadas por modelos más complejos, pero aparecen grandes diferencias en los tiempos de tránsito y en las curvas de llegada. Una combinación de modelación inversa y de modelos geológicos diferentes puede proporcionar una medida de la fiabilidad de la zona de captura y de las curvas de llegada.

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Résumé Six modèles d'écoulement à l'échelle régionale sont comparés afin d'avoir un aperçu de la manière dont les différentes représentations de la distribution de la conductivité hydraulique affectent la calibration et les prédictions de modèles. Des modèles géologiques déterministes ont été utilisés pour définir les distributions de la conductivité hydraulique dans deux modèles d'écoulement en régime permanent qui ont été calibrés avec des estimations des charges et des écoulements de base faites par des techniques inverses. Les estimations optimisées de la conductivité hydraulique de ces deux modèles ont servi à calculer les valeurs de conductivité hydraulique moyenne des couches et du modèle. Malgré des différences entre les deux modèles géologiques, la calibration inverse a donné des valeurs de conductivité hydraulique moyenne pour le domaine complet du modèle qui sont complètement semblables. Les valeurs de la conductivité moyenne des couches et du modèle ont été utilisées pour générer quatre modèles d'écoulement supplémentaires et des traitements ont été effectués. Tous les modèles simulent correctement les charges observées et l'écoulement de base total. Les six modèles ont servi à prédire l'impact en régime permanent d'un champ captant projeté et les solutions d'écoulement ont été utilisées dans une simulation par suivi de particules et de transport de soluté. Les résultats de simulations prédictives montrent que, pour cet exemple, de simples modèles d'hétérogénéité fournissent des zones de capture semblables aux modèles plus complexes, mais pour des temps de parcours et des restitutions très différents. Une modélisation inverse combinée à différents modèles géologiques peut assurer une mesure de la zone de capture et une fiabilité de la restitution.

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Solute transport in a single fracture with negligible matrix permeability: 1. fundamental mechanisms

This report describes the fracture-scale mechanisms acting on solute transport in fractured aquifers under natural-flow conditions. It focuses on low-permeability rocks where advection in the matrix is negligible compared with that in fractures. The relevant transport mechanisms detailed have been identified by experimental and theoretical studies over the past 30 years: advection and hydrodynamic dispersion, channeling effects, matrix diffusion, and sorption reactions. This review is intended to emphasize the fundamental concepts and to draw up a reader's guide through an extensive bibliography by linking key problems to key papers. These concepts might be integrated into transport models, but their influence at the large scale, however, remains an open question that is not dealt with in this review.

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Resumen Este informe describe los mecanismos que actúan a escala de fractura en el transporte de solutos en acuíferos fracturados, bajo condiciones de flujo natural. Se centra en rocas de baja permeabilidad en las que la advección en la matriz es despreciable en relación con la advección en las fracturas. Los mecanismos de transporte relevantes han sido identificados mediante estudios experimentales y teóricos realizados en los últimos 30 años. Consisten en advección y dispersión hidrodinámica, influencia de los canales, difusión en la matriz y reacciones de sorción. Esta revisión pretende enfatizar en los conceptos fundamentales y generar una guía para el lector por medio de una bibliografía abundante que relaciona los problemas clave con artículos clave. Estos conceptos podrían ser integrados en modelos de transporte, pero su influencia a gran escala es todavía un tema no resuelto, el cual no se aborda en este trabajo.

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Résumé Ce rapport décrit les mécanismes agissant sur le transport de soluté dans les aquifères fissurés en régime d'écoulement naturel. L'accent est mis sur les roches peu perméables, où le transport par convection dans la matrice est négligeable devant la convection dans les fractures. Les mécanismes de transport sont analysés à l'échelle de la fracture: convection et dispersion hydrodynamique, chenalisation, diffusion dans la matrice et réactions de sorption. L'objectif de ce travail est double: d'une part, mettre en avant les concepts fondamentaux pouvant être intégrés dans les modèles de transport, et d'autre part, établir un "guide" permettant au lecteur de s'orienter à travers une bibliographie abondante, en reliant chaque sujet abordé à quelques articles clés. Notons que l'influence de ces mécanismes sur le transport à grande échelle reste un problème clé qui ne sera pas abordé ici.

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Double Material Segment as the Model of Irregular Bodies

We propose a new, simple model to describe the gravity field of irregular, nonspherical celestial bodies, like small moons or minor asteroids. The simple idea of Duboshin to use a material straight segment for such bodies is extended by combining two perpendicular segments of different lengths and masses. In typical situations, when the longest axis of the body coincides with one segment, the remaining segment must have an imaginary length. The potential remains a real function even if one segment is imaginary. The new model is confronted with the exact form of an ellipsoid's potential and with two alternative simple models for a two-axial and a three-axial ellipsoid.     

Simulation of Surface Air Temperature by GCMs,Statistical Downscaling and Weather Generator: Higher-Order Statistical Moments

The third and fourth statistical moments, that is, skewness and kurtosis, are compared for daily maximum temperature in summer and daily minimum temperature in winter between observations, outputs of two global climate models, four versions of statistical downscaling, and weather generator. The comparison is performed at six stations in central Europe. None of the simulation models can be considered as superior to the others. Causes of a good correspondence with and differences from observations are identified e.g. in the treatment of physics in the models, imperfections in physical parameterizations, or a linear transfer of properties from predictors onto predictands in statistical downscaling.     

Combining Sample and Census Data in Small Area Estimates: Iterative Proportional Fitting with Standard Software*

The combination of detailed sample data with less detailed but fully enumerated marginal subtotals is the focus of a wide range of research. In this article we advocate careful modeling of sample data, followed by Iterative Proportional Fitting (IPF). The modeling aims to estimate accurately the interaction or odds ratios of complex tables, which is information not contained in the marginal subtotals. IPF ensures consistency with the subtotals. We advance this work in three practical ways. First, we show that detailed small‐area estimates of both counts and proportional distributions usually gain accuracy by combining data for larger areas containing the small areas, and we illustrate the multilevel framework to achieve these estimates. Second, we find that a general classification or socioeconomic typology of the small areas is even more associated with the within‐area interactions than is membership of the larger area. Third, we show how the Statistical Package for the Social Sciences (SPSS) can be used for IPF in any number of dimensions and with any structure of constraining marginal subtotals. Throughout, we use an example taken from the 1991 U.K. Census. These data allow us to evaluate various methods combining 100 percent tabulations and the Samples of Anonymised Records.     

Volcanic Eruption Induced Floods. A Rainfall-Runoff Model Applied to the Vesuvian Region (Italy)

Explosive events are commonly accompanied or followed byheavy rains. These eruption-induced storms together with thedeposition of large amounts of ash contribute to destabilise thehydrological cycle in the areas affected by volcanic eruptions.Flooding of the region surrounding the active volcano can easilyfollow, increasing the complexity of the volcanic crisis and itsmanagement. This is particularly true in the case of Vesuvius,that is not only characterized by a dramatic volcanic hazard, butit is also located within an area that is normally prone to flood hazard. A complete assessment of the impact associated with explosive volcaniceruptions should involve a flood hazard assessment for the region.This work represents a first attempt to address the problem: atopographically based rainfall-runoff model was here applied to theVesuvian area where two main sub-basins were analysed. The modelwas applied to evaluate the role of selected parameters on the totaldischarge at the basins' outlet. These parameters were chosen amongthose likely to be affected by an explosive event and were variedthrough a reasonable range. Results confirm that the deposition oflarge amounts of ash can affect the temporal evolution of the dischargeand its maximum value, for a given precipitation event. The simulationspresented outline the need for a detailed flood forecasting study for theVesuvian area, that should be included within the hazard mitigation strategies.