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

Structurally controlled landscape evolution in Kula badlands, Western Turkey

Badlands are extensively eroded landscapes consisting of weakly consolidated deposits within highly dense drainage systems. Their controlling and shaping factors can differ in relation to various internal and external conditions and processes that are not always well understood. This study focuses on the development of a badland landscape affecting Miocene and Quaternary sand-clay sediments in the extensional tectonic regime of Western Turkey with a multidisciplinary approach. The area between Kula and Selendi towns exhibits a badland topography with extensively eroded surface features, deepened gullies within poorly consolidated, sand clay-sized sediments. The results of structural field mapping and morphometric analyses using a 5 m resolution DEM to study the role of structural control in the development of badlands are presented in this study. Field data analysis supported by the quantitative assessment of longitudinal gully profiles illustrates the role of pre-existing structures as faults, their orientation and geometry in net erosion-sedimentation and the development of deepened gully networks. Representative illustrations, field photographs and block diagrams are presented to show the relationship between the rock structure and badland landscape. The connection between the extensional tectonics, erosional dynamics and geomorphology point to a structurally-controlled landscape in the Kula badlands in Western Turkey

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

Cross-comparison of last glacial radiocarbon and OSL ages using periglacial fan deposits

Two cores from a Weichselian periglacial alluvial fan were dated using 14C and OSL, to verify the reliability of both methods and check the upper dating limit of the 14C method. Both dating methods yielded a similar chronology for core Eerbeek-I, with infinite 14C dates for the lower part where OSL dates indicated ages of over 45 ka. Finite 14C dates were obtained throughout the core for Eerbeek-II, despite stratigraphic and OSL evidence suggesting ages beyond 14C limits. Apparently, additional chemical pre-treatment to remove younger carbon fractions did not work adequately for samples from this core. We hypothesize that this may be related to a larger influence of younger-age humin fractions in the mainly sandy Eerbeek-II deposits compared to those buffered by a thick peat layer of Eerbeek-I. We suggest that (local) stratigraphy, percolation and humification processes may impact 14C ages of organic deposits more than commonly assumed, and should receive more attention. In addition, we introduce a new method to assess robustness and validity of OSL dates and demonstrate the applicability of OSL dating methods in this setting. Our results highlight that the 14C method requires additional verification methods, such as OSL, for deposits older than 30 ka

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)