Algunos ejemplos de relación entre agregación, capacidad de infiltración y erosión en suelos mediterráneos

[Resumen] Este trabajo tiene por objeto evaluar la influencia de la agregación sobre la capacidad de infiltración y la tendencia a la erosión de suelos mediterráneos sobre litología caliza. Se identifican algunas variables de agregación que influyen de una manera importante en la infiltración y la erosión, aunque es en combinación con otras características del suelo cuando estas variables explican mejor dichos parámetros. Se consiguen una serie de modelos de ecuaciones de regresión múltiple basadas en variables indicadoras de la agregación de los suelos y otras características (cobertura vegetal, materia orgánica, pedregosidad y humedad del suelo) que explican bastante bien la capacidad de infiltración, la concentración de sedimentos y la erosión de los suelos en las zonas de estudio.[Abstract] The objective of this work is to evaluate the influence of soil aggregation on soil infiltration capacity and erosion in mediterranean soils developed on limestones. Sorne key-variables related to soil aggregation which play an important role on soil infiltration capacity and erosion are identified. Especially the combination of these variables with other soil characterisitics give the most satisfactory results explaining soil infiltration and erosiono Sorne models of multiple regression equations based in variables related to aggregation and other soil characteristics (vegetation cover, organic matter, stoniness and soil moisture) are obtained. They explain quite well the infiltration capacity, the sediment concentration and the erosion in the study zones

Influencia de la estructura y usos del suelo en las características de retención hídrica de suelos mediterráneos sobre litología caliza

[Resumen] Se investigan las diferencias entre la capacidad de retención hídrica de suelos mediterráneos sobre litología caliza sometidos a diferentes usos: incendiados y bajo pastoreo intensivo. En estos mismos suelos se valoran las relaciones entre estructura del suelo y capacidad de retención hídrica a diversos puntos de la curva de retención. Agregados de pequeño tamaño y materia orgánica influyen positivamente y de manera considerable en la capacidad de retención en casi todos los puntos de la curva de retención determinados. Agregados de gran tamaño y microagregados estables en agua influyen negativamente. La combinación de agregados de tamaño 1-0,105 mm y el contenido en materia orgánica predicen bastante bien la capacidad de retención a niveles bajos de succión (pF 0,4 YpF 1).[Abstract] The differences between the water holding capacity of Mediterranean soils developed on limestones and under different land uses (burnt and overgrazed soils) are investigated. The relationships between soil structure and soil moisture characteristic at different levels of the water retention curve in these same soils are evaluated. Organic matter and small sized aggregates are positively related to the water holding capacity. Large sized aggregates and waterstable microaggregates are negatively related to the water holding capacity of the soils. The combination of aggregates at 1-0,105 mm and organic matter content predict quite well the water retention capacity at lower suction levels (pF 0,4 and pF 1)

Епідигматичний модус англійських числівників

У статті розглядаються англійські числівники, денумеративи та їх епідигматичний модус. Семантична структура порівнюваних груп розглядаються на векторах їх походження та модифікації. Частиномовна представленість досліджується на просторах їх граматичного, семантичного і словотворчого буття. Визначаються перспективи подальшого дослідження. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/30551В статье исследуются английские числительные, денумеративы, а также их эпидигматичекие аспекты. Семантическая структура сравниваемых единиц изучается на векторах семантики, грамматики и словотворчества. Намечаются перспективы дальнейшего исследования. При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/30551The article in question deals with the English numerals, denumerals and their epidigmatic tendencies. The semantic structures of both groups are being focused upon. The words under analysis are viewed in terms of their initial and secondary grounds. The item of part of speech charge is being considered in terms of grammatical, semantic and epidigmatic aspects. Thus, the modus of the paradigmatic groups have been considered wide perspectives for further investigation. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3055

Mass-Movement Causes: Changes in Slope Angle

This chapter discusses and illustrates how changes in slope angle can cause mass movement. Several processes can cause removal of lateral or underlying support of a slope, and most of the time multiple processes are acting together on a landscape. Slow and sudden processes causing changes in slope angle are differentiated, and several examples and illustrations of each are given. In addition, this chapter reviews current literature on landscape evolution modeling in which researchers try to incorporate these geomorphological processes in the analysis and simulation of current and future landscapes

Quantitative Modeling of Landscape Evolution

This chapter reviews quantitative modeling of landscape evolution – which means that not just model studies but also modeling concepts are discussed. Quantitative modeling is contrasted with conceptual or physical modeling, and four categories of model studies are presented. Procedural studies focus on model experimentation. Descriptive studies use models to learn about landscapes in general. Postdictive and predictive try to correctly simulate the evolution of real landscapes, respectively in the past (with calibration) or in the future (with calibrated models). The geomorphic process is a central concept in landscape evolution modeling. We discuss problems with the field-based definition of these processes from a modelling perspective. After the classification of 117 landscape evolution studies in these categories, we find that descriptive studies are most common, and predictive studies are least common. In the remainder of the chapter, we list and review the 117 studies. In procedural studies, attention has been focussed at production methods for digital landscapes, spatial resolution and the role of sinks and depressions. Descriptive studies focussed mainly on surface–tectonic interactions, sensitivity to external forcing, and the definition of crucial field observations from model results. Postdictive and predictive studies operate mainly in time-forward mode and are sometimes validated (postdictive studies of soil redistribution over centennial to millennial timescales). Finally, we look ahead to the future of landscape evolution modeling, arguing for a larger role for complexity research, predictive studies and uncertainty analysis, process definition and feedbacks to and from other fields (including ecology)

Two decades of numerical modelling to understand long term fluvial archives: Advances and future perspectives

The development and application of numerical models to investigate fluvial sedimentary archives has increased during the last decades resulting in a sustained growth in the number of scientific publications with keywords, 'fluvial models', 'fluvial process models' and 'fluvial numerical models'. In this context we compile and review the current contributions of numerical modelling to the understanding of fluvial archives. In particular, recent advances, current limitations, previous unexpected results and future perspectives are all discussed. Numerical modelling efforts have demonstrated that fluvial systems can display non-linear behaviour with often unexpected dynamics causing significant delay, amplification, attenuation or blurring of externally controlled signals in their simulated record. Numerical simulations have also demonstrated that fluvial records can be generated by intrinsic dynamics without any change in external controls. Many other model applications demonstrate that fluvial archives, specifically of large fluvial systems, can be convincingly simulated as a function of the interplay of (palaeo) landscape properties and extrinsic climate, base level and crustal controls. All discussed models can, after some calibration, produce believable matches with real world systems suggesting that equifinality - where a given end state can be reached through many different pathways starting from different initial conditions and physical assumptions - plays an important role in fluvial records and their modelling. The overall future challenge lies in the development of new methodologies for a more independent validation of system dynamics and research strategies that allow the separation of intrinsic and extrinsic record signals using combined fieldwork and modelling