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Thesis (M.S.)--Oregon State University, 1974. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis--M. Sc.(Eng.), University of Hong Kong. / Mimeographed.

The fluvial soils of the Kelantan plain, mainly cropped for rubber and paddy were studied along six transacts. Field examinations were made at fixed intervals and pedo-unit samples were collected for analysis. The transact data are presented as isopleth diagrams and analysed numerically. The variations in low chroma colours, red colours, structure, texture, segregation/concretions of Fe and Rn-oxides from the levees to the basin are systematic and predictable, being largely controlled by topography. Low chrome colours are useful for separating surface and ground water effects while red colours indicate the degree of aerobisa. m-oxides occur irregularly but they are always absent from the soil in depressions. Numerical analyses show that. 1. colour indices and structure discrMnate the soils while Mn-oxides do not, 2, lateral variations are continuous but there is a soil toposequence from the levees to the depressions, 3. the existing soil boundaries are usually valid as are most of the originally mapped soil series.Soil formation is sequential, following each sedimental accretion, The important soil characteristics are inherited, whether formed naturally or under paddy cultivation. The mineralogy and stratification are inherited; low chroma and red colours develop from the yellow brown sediments; soil coatings and mass transported materials are common; matrix anisotropism changes along the toposequenoe; Fe illuviation is weak but Mn illuviation is pronounced.Paddy cultivation promotes playing and the formation off strong brown mottles and microlaminations within the plough layer. Clay particles become disorientated and some are lost through suspension in the water. Although hydromorphism,:strongly influence the soils, natural biological activity causes some homogenisation. A redefinition of the series is proposed and the classification of the soils is discussed.

This study provides information about six representative Cambisols in North Central Portugal. The study area is part of the drainage basin of the river Vouga, where Cambisols are most extensive. Their general characterization includes the estimation of pH, loss-on-ignition, organic carbon, total nitrogen, cation exchange capacity, exchangeable cations and percent base saturation, particle-size analysis, "free" Fe, Si and Al, mineralogy of the clay fraction, heavy mineralogy of the fine sand fraction and micromorphology. These preliminary investigations revealed some distinctive features in these soils on which particular attention was focussed, namely their polycyclic character, the unique characteristics of the upper horizons and the presence of gibbsite. Finally, UV autofluorescence was observed in weathering products of aluminosilicates, which were identified as gibbsite by electron-probe microanalysis and scanning electron microscopy and compared to standard minerals. The potential of this technique in soil micromorphological studies was assessed.

The salient points of the thesis are summarised as follows: Chapter one: The geographical features including the location of the site, the discussion of subtropical climates, the world pattern of aridity, climatic changes in the tropics, and finally the topography, drainage and the vegetation of the area are reviewed. Chapter two: A general review of the geology, hydrogeology, hydrology, and geomorphology IS of the area ~~ covered. The geomorphic history of the area and its relation // to land formation, and the origin and development of domed and boulder inselbergs are generally discussed. A brief classification and illustrations of the geomorphic units in Kordofan provinces are given. Chapter three: In this chapter a review of the literature concerning the soils of arid and semi-arid regions is presented. The factors of soil formation, especially the climate, topography and parent material, are given.- The soil fo~ming.processes, in particular the weathering and formation of deep profiles are discussed. Accumulation of organic matter in the tropics and ~ the development of horizons such as gypsic, calcic, ~atric, salic, argillic and sesquioxides are reviewed. r,hap~er four: In this chapter a review of the work carried out in Western Sudan and the relationship of soils to the geomorphology is given. A brief account of soil conservation and m~nagement is also considered especially concerning water movement, erosion, and evapc~ranspiration. Chapter five: The detailed soil survey of the clayey pediplain soils carried out in 1973 is described together with their chemical and physical properties. - GL~l Some results on the water movement through the soils~also included. The soils generally showed neutral to alkaline reaction in their property with increasing alkalinity with depth. The soluble salts at the surface are mainly of calcium, sodium and magnesiUm. In the lower horizons the sodiumcalcium and magnesium chlorides and sulphates are dominant. The water movement through the soil is rapid when the soil is dry decreasing to very slow when wet. This might perhaps be due to the increase in the concentration of salts of sodium when reacting with water causing dispersion. Chapter six: While carrying out the laboratory investigations given in chapter six certain discrepancies in the results became obvious; in particular, particle size analysis, cations excahangeable capacity and exchangeable cations. Therefore some experiments were performed to determine the best me'thod for such soils. For the particle size analysis the pipette method gave high results for the clay fraction, so did wet sieving followed by the hydrometer method. The Bouyocos (1927) method gave very low values for the clay. Chapter seven: A detailed pedological characterisation of selected "Gardud" soils is described. Profiles 1, 2, 3 on the slope show similar morphological features, the coiour is yellowish red at the surface changing slightly to dark yellowi~h brown then to dark brown in the lower horizons. The lower profile No. (4) in the depression is dark yellowish brown in colour. The texture is uniform sandy clay loam in soils on the slope changing to sandy clay in the depressions. The chemical analyses are similar to those that have been described in chapter four, except that the C.E.C. is mod~rately high ranging between 15 and 30 meq/100 g soil. The organic matter and CIN ratios are lower and the soil reaction is neutral to alkaline. In the later work carried out in 1976 there is a slight increase in Clay in almost all the profiles and also a lesser amount of soluble salts which may be due to the sheet erosion, both the clay and soluble salts being washed horizontally by seasonal water. Chapter eight: The detailed results of the micromorphological and mineralogical properties are given. All the soils except the Vertisol (profile No 4) have similar properties, viz. compact.alveolar structure with strong anisotropic soil matrix and abundant domains and aureoles. The subangular and subrounded quartz grains indicate that they are pedisediments. Although some well rounded quartz grains indic~te that there is some wind blown sand.This strong anisotropic soil matrix might be the reason for soil hardness and the alveolar structure. A few whole soil coatings occur indicating that tne soil has undergone several cycles of expansion and contraction. Profile No. (4) has a massive to wedge structure with many calcite carbonate concretions, and some gypsum crystals occur observed at depth. The mineralogical studies confirmed that the soils are highly weathered and have been derived from metamorphic and igneous parent materials. The quartz dominates the light minerals followed by a little biotite, calcite, feldspar and sometimes muscovite. The heavy minerals were dominated by the opaques followed by a little rutile, zircon, kyanite, tourmaline and others. The scanning electron microscope results showed clearly tha~ the soil matrix is well organized overlapping clay sheets and that the quartz grains are well embedded in it. Chapter nine: A discussion of the results· and final conclusions are given. Finally there are four appendices containing results

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Many previous studies have been focused on the behaviour homogeneous granular soils under the quasi-static loading, however, various soil types exist in the field. Therefore, based on the evaluation of these previous studies, an extensive study has been addressed to expose the dynamic behaviour of cohesive-frictional soils associated with the effects of fines content, the effect of moisture content and the type of impact regime. The proposed study mainly investigates the behaviour of sand – clay mixtures to impact loading, both from a loaded plate dropped from different heights and one dropped repeatedly from a fixed height. The Aberdeen beach sand and the Teuchan clay were used for the study and mixed in different proportions to create soils of varying proportions. The six soil samples used have known volumetric proportions of sand : clay and the tests were carried out under the dry condition and two other moisture contents. The results determine the optimal percentage of fines content and its related moisture condition to obtain more stable performance of the granular soils under dynamic compaction. It can be implemented to enhance the quality of ground improvement techniques for the construction. A Soil Model Tester for 2-Dimension program (SM2D) [Chan (1988)] was used to modify the existing material model before being used for Finite Element simulation. The impact test results were used to verify the numerical model developed using an explicit u-w schemebased finite element program, GLADYS2E [Chan et al. (1992, 1994)]. Such use of explicit schemes requires the use of time step lengths which are smaller than a critical value, in order that stability and accuracy of solution are ensured. A semi-empirical formula has been developed for the critical time step determination using MATLAB.

The main aim of this thesis is to develop an integrated approach that can be used to evaluate or support policy and management decisions for potentially vulnerable areas in Europe. The EUSES (European System for the Evaluation of Substances) model was selected for this work. The methodology is based in the adaptation of the models contained in EUSES to use more realistic regional environmental data. The thesis aims to extend the current functionality of EUSES by providing users with the means of visualising and understanding the spatial component of the risk associated with a particular substance. The development environment for this approach is the ESRI ArcView GIS software and associated modules. EUSES was reimplemented in Excel to understand all the equations of the model. In order to understand the drivers of the model, screenings experiments were performed. As a result a set of graphs showing the relationship between the parameter considered and the outputs of the model was produced. A further stage focused on linking EUSES to GIS adding a spatial component. From available datasets the main drivers of the model were extracted. Using ArcView GIS and ArcView Spatial Analyst, these data were overlayed and processed to obtain GIS maps of Europe at different scales. On the basis of the screening experiments, a set of mathematical equations were extrapolated and used to perform new computations to calculate the variation of the regional PECs due to changing in different parameters. These new computations were certificated with EUSES and a very good correspondence was found. These new computations were used in ArcView GIS; as a result a set of GIS maps were created showing potential vulnerable areas at different scales. This approach was also used to perform some scenario analyses useful to assess the impact of changing conditions on PEC values.