Dissertations / Theses on the topic 'Soil erosion Computer simulation'
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Gunawardena, E. R. N. "Computer simulation of runoff and soil erosion from small agricultural catchments in Sri Lanka." Thesis, Cranfield University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333925.
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Geng, Guoqiang. "A simulation study of soil erosion by snowmelt and spring rainfall." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28449.
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High rates of runoff and soil loss occur in temperate areas in late winter and early spring. A low-intensity rainfall simulator and a snowmelt simulator were developed to study soil erosion by snowmelt and/or spring rainfall on a sandy loam soil of southern Quebec. Erosive agent, land slope, thaw depth of partly frozen soil, and intensity and duration of the event were studied in the laboratory using the simulators. All these factors had significant effects on soil erosion. Sediment concentration, soil loss rate, and total soil loss increased with increasing land slope, thaw depth, and intensity, duration, and impact energy of the erosive agent. Duration showed a significant interaction with each of the other factors. interaction between thaw depth and intensity of the event was significant under both snowmelt and rainfall simulation, whereas interaction between land slope and intensity was significant under rainfall simulation, but not under snowmelt simulation. Erosive agent also interacted with each of the other factors. All these interactions increased soil loss. The presence of a frozen sublayer interacted with the other factors and greatly increased runoff, sediment concentration and total soil loss. Rainfall caused more soil loss than did snowmelt under the same conditions.
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Bobe, Bedadi Woreka. "Evaluation of soil erosion in the Harerge region of Ethiopia using soil loss models, rainfall simulation and field trails." Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-08022004-141533.
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Parker, Ronald Dean 1948. "The effect of spatial variability on output from the water erosion prediction project soil erosion computer model." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/191165.
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Spatial variability is all that stands between hydrology and science, forcing us to deal in probabilities and averages. Because of scale, we can not consider forces on individual soil particles, water molecules and solute ions when addressing human size problems. We must therefore look at aggregate properties and mean values for parameters and inputs in computer modeling of hydrologic phenomena. This research explores the impact of spatially variable inputs on the Water Erosion Prediction Project soil erosion computer program. Distributions of input variables are generated and assigned randomly to a grid of homogeneous rangeland hillslope elements. Values for runoff volume and sediment loss from each flow path are recorded and averaged to provide a distribution of outputs in the form of a sensitivity analysis. Variabilities of slope, slope length, soil textures, soil characteristics, terrain, convex and concave slopes, soil saturation, rainfall amount and vegetation were examined. Results show that use of mean inputs values in the WEPP representative hillslope model yields very similar outputs to the spatially variable research model using a distribution of inputs in all simulations in the case of totally random bare rangeland soils. When a decreasing trend in soil clay content is introduced in the variable model, the hillslope model using average values as inputs no longer provides a good estimate of the sediment loss. When random vegetation is generated and added to the simulation, runoff volume continues to be similar between the two models, but the sediment loss is much higher in the spatially variable model. In addition, the results of the standard hillslope model are much less responsive to changes in slope than those of the spatially variable model. It is concluded that spatial variability of soils must be considered when there is a linear change in input values with slope position. Likewise spatial variability of vegetation needs to be addressed in order to accurately estimate erosion on the rangeland watersheds considered in this dissertation. It is also found that this type of simulation provides a model for sensitivity analysis of a complex computer programs. Physically related inputs can be generated in such a way as to preserve the desired interrationships and distributions of inputs can be directly compared to generated distributions of outputs.
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Bussen, Patrick. "Analysis of a rapid soil erosion assessment tool." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2351.
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Michaud, Aubert Raymond. "Soil erodibility indices for Southern Quebec soils derived under variable intensity rainfall simulation." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66178.
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Bobe, Bedadi Woreka. "Evaluation of soil erosion in the Harerge region of Ethiopia using soil loss models, rainfall simulation and field trials." Thesis, University of Pretoria, 2004. http://hdl.handle.net/2263/26929.
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Accelerated soil erosion is one of the major threats to agricultural production in Ethiopia and the Harerge region is not exceptional. It is estimated that about 1.5 billion tones of soil is being eroded every year in Ethiopia. In the extreme cases, especially for the highlands, the rate of soil loss is estimated to reach up to 300 t ha-1yr-1 with an average of about 70 t ha -1yr-1 which is beyond any tolerable level. The government have made different attempts to avert the situation since 1975 through initiation of a massive program of soil conservation and rehabilitation of severely degraded lands. Despite considerable efforts, the achievements were far bellow expectations. This study was aimed at assessing the effect of some soil properties, rainfall intensity and slope gradients on surface sealing, soil erodibility, runoff and soil loss from selected sites in the Harerge region, eastern Ethiopia, using simulated rainfall. Soil loss was also estimated for the sites using Soil Loss Estimation Model for Southern Africa (SLEMSA) and the Universal soil Loss Equation (USLE). Moreover, the effectiveness of various rates and patterns of wheat residue mulching in controlling soil loss was also evaluated for one of the study sites, (i.e. Regosol of Alemaya University), under both rainfall simulation and field natural rainfall conditions. For most of the erosion parameters, the interaction among soil texture, slope gradient and rainfall intensity was significant. In general however, high rainfall intensity induced high runoff, sediment yield and splash. The effect of slope gradients on most of the erosion parameters was not significant as the slope length was too small to bring about a concentrated flow. The effect of soils dominated by any one of the three soil separates on the erosion parameters was largely dependent on rainfall intensity and slope gradient. The soils form the 15 different sites in Harerge showed different degrees of vulnerability to surface sealing, runoff and sediment yield. These differences were associated with various soil properties. Correlation of soil properties to the erosion parameters revealed that aggregate stability was the main factor that determined the susceptibility of soils to sealing, runoff and soil loss. This was in turn affected by organic carbon content, percent clay and exchangeable sodium percentage (ESP). Soils with relatively high ESP such as those at Babile (13.85) and Gelemso (7.18) were among the lowest in their aggregate stability (percent water stable aggregates of 0.25 –2.0mm diameter); and have highest runoff and sediment yield as compared to other soils in the study. Similarly, most of those soils with relatively low ESP, high organic carbon content (OC%) and high water stable aggregates such as Hamaressa, AU (Alemaya University) vertisol and AU regosol were among the least susceptible to sealing and interrill erosion. Nevertheless, some exceptions include soils like those of Hirna where high runoff was recorded whilst having relatively high OC%, low ESP and high water stable aggregates. Both the SLEMSA and USLE models were able to identify the erosion hazards for the study sites. Despite the differences in the procedures of the two models, significant correlation (r = 0.87) was observed between the values estimated by the two methods. Both models estimated higher soil loss for Gelemso, Babile, Karamara and Hamaressa. Soil loss was lower for Diredawa, AU-vertisol and AU-Alluvial all of which occur on a relatively low slope gradients. The high soil loss for Babile and Gelemso conforms with the relative soil erodibility values obtained under rainfall simulation suggesting that soil erodibility, among others, is the main factor contributing to high soil loss for these soils. The difference in the estimated soil losses for the different sites was a function of the interaction of the various factors involved. Though the laboratory soil erodibility values were low to medium for Hamaressa and Karamara, the estimated soil loss was higher owing to the field topographic situations such as high slope gradient. SLEMSA and USLE showed different degrees of sensitivities to their input variables for the conditions of the study sites. SLEMSA was highly sensitive to changes in rainfall kinetic energy (E) and soil erodibility (F) and less sensitive to the cover and slope length factors. The sensitivity of SLEMSA to changes in the cover factor was higher for areas having initially smaller percentage rainfall interception values. On the other hand, USLE was highly sensitive to slope gradient and less so to slope length as compared to the other input factors. The study on the various rates and application patterns of wheat residue on runoff and soil loss both in the laboratory rainfall simulation and under field natural rainfall conditions revealed that surface application of crop residue is more effective in reducing soil loss and runoff than incorporating the same amount of the residue into the soil. Likewise, for a particular residue application method, runoff and soil loss decreased with increasing application rate of the mulch. However, the difference was not significant between 4 Mg ha-1 and 8 Mg ha-1 wheat straw rates suggesting that the former can effectively control soil loss and can be used in areas where there is limitation of crop residues provided that other conditions are similar to that of the study site (AU Regosols). The effectiveness of lower rates of straw (i.e. less than 4 Mg ha-1 ) should also be studied. It should however be noted that the effectiveness of mulching in controlling soils loss and runoff could be different under various slope gradients, rainfall characteristics and cover types that were not covered in this study. Integrated soil and water conservation research is required to develop a comprehensive database for modelling various soil erosion parameters. Further research is therefore required on the effect of soil properties (with special emphasis to aggregate stability, clay mineralogy, exchangeable cations, soil texture and organic matter), types and rates of crop residues, cropping and tillage systems, mechanical and biological soil conservation measures on soil erosion and its conservation for a better estimation of the actual soil loss in the study sites. Copyright 2004, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bobe, BW 2004, Evaluation of soil erosion in the Harerge region of Ethiopia using soil loss models, rainfall simulation and field trials, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-08022004-141533 / >Thesis (PhD (Soil Science))--University of Pretoria, 2004.
Plant Production and Soil Science
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Falkingham, Peter Lewis. "Computer simulation of dinosaur tracks." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/computer-simulation-of-dinosaur-tracks(3b3b150d-c05e-4667-96b5-3c17405856e5).html.
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Fossil tracks represent the only direct record of behaviour and locomotion of extinct animals. A computer model using finite element analysis (FEA) has been developed to simulate vertebrate track formation in cohesive substrates. This model has been designed for, and successfully run on, high performance computing (HPC) resources. A number of individual studies were carried out using the computer model to simulate both abstract indenters and virtual dinosaur autopodia. In addition to the simulation studies, two fossil tracks were described, including the first report of bird tracks at the Mammoth Site of Hot Springs, South Dakota (USA) and a re-description of a 'dinosaur tail drag' as the trace of a crocodilian. Using the computer model, it has been shown that in a wet, soft mud the indentation of a non-webbed virtual tridactyl foot created a resultant track with features analogous to 'webbing' between digits. This 'webbing' was a function of sediment deformation and subsequent failure in 3D, specific to rheology. Apparent webbing impressions were clearly developed only within a limited range of sediment conditions and pedal geometry. Indenter (pedal) geometry and morphology affect track depth independently of substrate and loading parameters. More complex morphologies interact with the cohesive substrate creating a lower effective load than that applied. In non-cohesive substrates such as sand, this effect is reversed, and it is the more compact morphologies that indent to a lesser degree. Virtual sauropod tracks were modelled, based on published soft tissue reconstructions of autopodia anatomy, and published mass/centre of mass estimates. It was shown that foot morphology and differential loading between fore- and hind- limbs leads to a range of substrates in which only the manus or pes are able to generate tracks. This offers a new mechanism for the formation of manus-only sauropod trackways, previously interpreted as having been made by swimming dinosaurs. A series of tracks were simulated using input data (loads, pedal morphologies) from four different dinosaurs (Brachiosaurus, Tyrannosaurus, Struthiomimus, and Edmontosaurus). The cohesive substrates used displayed a 'Goldilocks' effect, allowing the formation for tracks only for a very limited range of loads for any given foot. In addition, there was a strong bias toward larger animals, both in homogeneous and theoretically heterogeneous substrates. These findings imply that interpretations from track assemblages must consider that only a small proportion of the total fauna present may be recorded as a track assemblage due to substrate properties. The use of FEA to simulate dinosaur track formation has been shown to be successful, and offers a number of advantages over physical modelling including; consistency between experiments, specific control over input variables, rapid undertaking of repeatable experiments, and the ability to view subsurface deformation non-destructively. It is hoped that this work will lead to an increased interest in modelling tracks, and offer a quantitative method for studying fossil tracks.
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Rezaur, Rahman Bhuiyan. "Studies on interrill sediment delivery and rainfall kinetic energy." Thesis, Click to view the E-thesis via HKUTO, 1999. http://sunzi.lib.hku.hk/hkuto/record/B42575631.
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Bera, Pubalee. "Computer models for simulating pesticide fate and transport in soil." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=78398.
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Two different modeling approaches to simulate pesticide fate and transport in soil were investigated in this study. First, a process-based mathematical model, DRAINMOD-P, was developed by combining the attractive features of DRAINMOD and PESTFADE. While DRAINMOD formed the main component to perform hydrological predictions, PESTFADE's pesticide sub-model was used to simulate pesticide fate. The new model was validated against three years of independently collected field data from southern Ontario. Several statistical parameters were calculated to evaluate model performance.Second, an implicit model, Multivariate Adaptive Regression Splines, MARS, which is also a novel data mining tool, was used to assess pesticide transport. MARS was first validated against the field data on three herbicides, namely, atrazine, metribuzin and metolachlor. DRAINMOD-P and MARS simulations, though impressive, need further validations before they can be recommended for actual real-world use.*
*This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Microsoft Office; Adobe Acrobat.
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Batt, Kenneth Leslie School of Mathematics UNSW. "The observation and modelling of winds over South Eastern Australia." Awarded by:University of New South Wales. School of Mathematics, 2004. http://handle.unsw.edu.au/1959.4/23472.
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This study uses a very high resolution numerical weather prediction (NWP) model to investigate the complex structure and behaviour of cold fronts along the New South Wales coast during the warmer months of the year, the complex interaction between the wind flow and coastlines and elevated areas as well as the lee-trough effect, particularly the way it affects waters off the east coast of Tasmania, The study also investigates the utility of the higher resolution NWP model to better predict wind fields compared to a lower resolution model. The University of New South Wales very high resolution model (HIRES), nested in the Australian Bureau of Meteorology's coarse NWP model (GASP), was run at various horizontal resolutions (from 15 to 25km) in order to investigate the above-mentioned features. It was found to bave very good skill in resolving the features and was also found to be very accurate in the prediction of surface wind fields for various yacht race events out to at least four days ahead. It can be concluded that there is considerable skill in the ability of high-resolution NWP models such as HIRES, to predict the major features of the wind fields over the ocean out to several days ahead. Moreover, it was also able to more accurately simulate the complex structure of the summer-time cool change as it progressed along the NSW coast than the lower resolution model runs. The influence of coastlines, particularly ones with complex topographical features, on the wind flow was demonstrated to a limited extent throughout the study. Finally the following concepts were also verified as a result of the study: - air flow takes the path of least resistance - the shape of topography can help generate local turbulence - the orientation of the wind flow to a mountain range is important in determining turbulent effects. - under certain airflow and stability situations, standing wave activity and a lee trough can be observed in the lee of mountains, hills or even high coastal cliffs.
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Wang, Li. "Simulation of soil water movement model (SWaMM) using the Spider Distributed System." CSUSB ScholarWorks, 2003. https://scholarworks.lib.csusb.edu/etd-project/2419.
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This project implements a real application on the Spider II, which is a simulation of Soil Water Movement Model. The main objectives of this project were to develop a parallel and distributed algorithm for the Soil Water Model; implement the Soil Water Movement Simulation model on the Spider II distributed system and to evaluate the performance of simulating the Soil Water Movement Model on Spider II.
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McCourt, George H. "Acidification and buffering mechanisms in soil ecosystems." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68218.
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The objectives achieved in this thesis are: (1) to develop a new method for measuring the most important acid buffering mechanism within a soil ecosystem-mineral weathering and (2) to test a soil acidification simulation model against actual field data to determine which soil acidifying or buffering mechanisms seem to be understood and which mechanisms need more detailed analysis. First, a new method was developed that allows for quantification of H$ sp+$ consumption due to weathering and H$ sp+$ consumption due to cation exchange. Initial results yield mineral weathering rates that are well within the range of results obtained by other workers. This technique permits the analysis of multiple soil samples in a relatively short time, allowing for better quantification of spatial variability of mineral weathering within a soil ecosystem. Secondly, it was demonstrated that the acid simulation model generally underestimates soil chemistry values for pH, base cation saturation and soil solution base cations, and overestimates soil solution nitrate concentrations. Problems with obtaining accurate measurements of atmospheric dry deposition, a lack of data on cycling of nutrient elements and the absence of a sub-model to deal with the accumulation and mineralization of organic matter are reasons thought to explain the differences between model and field results.
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Chen, Ying 1957. "Soil thermal regime resulting from reduced tillage systems." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41106.
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The soil thermal regime is important to the soil and plant environment, being an influential factor in determining many processes in soil.Changes in soil bulk density, soil surface reflectance and soil temperature changes with depth and time were studied theoretically and experimental as a function of variable soil properties, soil surface state, crop cover and atmospheric conditions.
A field experiment was carried out on sandy and clayey soils with each plot being subjected to a consistent tillage and fertilizer history of either conventional ploughing, reduced energy disking or zero tillage, and fresh dairy manure or manufactured inorganic fertilizer. The measured results and the quantitative models assist hopefully in identifying how soil management affects the soil thermal regime and in making cultivation management decisions.
Soil bulk density for each fertilizer type can be predicted quantitatively from input tillage energy in a linear fashion. The reflectance of the soil surface was estimated as an integrated form of the individual reflectance and the area fractions of the soil surface components, with a soil roughness correction term. This model can cover various surface situations under different schemes of soil management. A simulation model for soil temperature was developed, which can be applied to bare soil, partially crop-covered soil and completely crop-covered soil. The models can also be used as submodels or be linked to other existing models.
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Alvenäs, Gunnel. "Evaporation, soil moisture and soil temperature of bare and cropped soils /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5714-9.pdf.
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Habte, Michael Andebrhan Civil & Environmental Engineering Faculty of Engineering UNSW. "Numerical and constitutive modelling of monotonic and cyclic loading in variably saturated soils." Awarded by:University of New South Wales. Civil and Environmental Engineering, 2006. http://handle.unsw.edu.au/1959.4/24204.
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A fully coupled, effective stress based elasto-plastic model is presented for a rigorous analysis of flow and deformation in variably saturated porous media subjected to monotonic and cyclic loading. The governing equations are derived based on the effective stress concept, equations of equilibrium, and conservation equations of mass and momentum using a systematic macroscopic approach. Both elastic and elasto-plastic constitutive equations are developed. All model coefficients are identified in terms of measurable parameters. The governing equations presented are general in nature, embodying all previously presented formulations in the field. A unified bounding surface plasticity model is developed to describe the stress-strain behaviour of variably saturated soils subjected to monotonic and cyclic loading. The model is formulated incrementally within the critical state framework using the effective stress approach. The model takes into account the effects of both plastic volumetric strain and matric suction on the hardening of the bounding surface. Cyclic behaviour is captured through a new mapping rule in which the point of stress reversal is taken as the centre of projection. The effect of particle crushing at high stresses is considered through a three-segmented critical state and isotropic compression lines. A non-associative flow rule is employed to generalise application of the model to all soils. Solution to the governing equations is obtained numerically using the finite element approach, with the finite difference method employed for the time integration of the rate equations. The elasto-plastic constitutive equations are integrated explicitly using Euler???s forward and the modified Euler integration schemes. Yield surface correction schemes are adopted to improve accuracy of the solution. Essential elements of the proposed model are validated by comparing numerical predictions with experimental data from the literature for fully and partially saturated soils subjected to monotonic and cyclic loadings in drained, undrained, isotropic and deviatoric conditions. The results demonstrate capability of the coupled model to predict essential characteristics of variably saturated soils subjected to monotonic and cyclic loadings in a unified manner.
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Tafazoli, Sara. "Modeling pesticide fate and transport in soils." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79746.
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The work presented in this thesis represents a contribution to the area of modeling of the transport and fate of herbicides applied to cropped fields, and was part of a larger research effort geared towards better management of herbicides. The main objective of this thesis was to develop a graphical user interface (GUI) for PESTFADE, a process-based mathematical model of pesticide transport and degradation, and to provide documentation for the execution of PESTFADE. The model simulates changes in pesticide concentration at different depths in the soil, based on relevant physical, chemical, biological and meteorological factors. PESTFADE is considered to be one of the most comprehensive models of its kind. However, it was, until now, difficult to implement due to absence of a user manual and graphical interface suitable for exploitation in a Windows environment. The author developed the GUI in Visual Basic, created macros to facilitate certain calculations, rewrote the original FORTRAN 77 code and then validated the updated version against field data obtained from an experimental site (Eugene Whelan Farm, Woodslea, Ontario). A preliminary development of an artificial neural network (ANN) to perform the same simulation implicitly, with fewer input parameters and less computational time, was also done.The thesis describes PESTFADE and the GUI, gives guidelines for implementing the package, and presents the results of the field validation of the revised version. During this work, the author discovered that there were problems in the parts of the code dealing with sorption phenomena. This can be solved by conventional kinetics or by Gamble kinetics.
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Hong, Seonggu. "Comparison of 1-D and 2-D modeling approaches for simulating runoff and sediment transport in overload areas." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-08272007-163824/.
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Georgis, Kidane. "The effect of fertiliser management practices on soil organic matter production in the semi-arid areas : a field and modelling approach." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09AFP/09afpg352.pdf.
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Bibliography: leaves 155-169. Studies the effect of nitrogen fertilizer on dry matter production under differing watering regimes. Investigates the accuracy of different crop and soil organic matter models for predicting crop yield, nitrogen uptake and changes in soil organic carbon and nitrogen. Compares the models with data from long-term field experiments on wheat in Australia and sorghum in Ethiopia. Finds that a higher crop yield and better nitrogen and water utilisation can be achieved if addition of nitrogen fertilizer is balanced with soil water.
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Flack, Paul E. 1960. "A method for establishing base-line soil loss rates on surface mine sites." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276985.
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Surface mining operations require a comparison of post-mining erosion rates with pre-mining soil loss to ascertain if remedial measures are needed. In this study the Universal Soil-Loss Equation (USLE) was modified to reflect conditions of western rangelands to develop a procedure for estimating pre-mining soil loss rates. The modification used back-calculation for the C-Factor and an adjusted R-Factor based on storm size. Soil loss simulation based on stochastic precipitation patterns is appropriate to the site--the La Plata mine area in northern New Mexico--and increases the flexibility of the USLE as a soil loss predictor for western rangelands.
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Kim, Jong Hee. "Improvement of geotechnical site investigations via statistical analyses and simulation." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41218.
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The purpose of this study is to improve site investigation in geotechnical engineering via the evaluation and development of statistical approaches for characterizing the spatial variability of soil properties and the development of site investigation simulation software for educational use.
This study consists of four components: statistical characteristics, data measurement, simulation, and educational training. Statistical measures of spatial variability of soil properties were examined for three different geographical areas where soil formation processes differ to assess the influence on the spatial variability of soils. Statistical measures of spatial variability were also calculated for a case history where blasting was used as a method of soil improvement to evaluate the effects of man-made changes to soil structure.
The concept of spatial aliasing was employed to estimate the maximum allowable sampling interval for field data as a function of the spatial correlation properties. Once a maximum statistically allowable sampling interval is determined for a specific soil property, the minimum statistically required number of soundings / borings is calculated to perform an economical site investigation at a specific site.
A simple and efficient simulation technique was proposed to generate correlated, multi-dimensional simulations of soil properties. Based on limited data, the proposed simulation technique generated accurate and correlated simulations of soil properties that are consistent with the observed or proposed correlation structures of soil properties.
Lastly, a geotechnical site investigation simulation program with a wide variety of in situ and laboratory tests was developed to allow students to plan and perform a comprehensive site investigation program. The simulation generates an input file based partly on the statistical characteristics of the spatial variability of soil properties analyzed in this study and partly on traditional values. Spatial variability in soil properties is modeled via correlated random fields, interpolation, and a decomposition method to yield realistic geotechnical data. Via the simulation, students are able to obtain experience and judgment in an essential component of geotechnical engineering practice.
The four components of this research (statistical characteristics, data measurement, simulation, and educational training) focus on the improvement of site investigation performance in geotechnical engineering, thereby improving reliability analysis in geotechnical practice.
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Bélanger, Nicolas 1971. "Investigating the long-term influence of atmospheric acid deposition and forest disturbance on soil chemistry and cation nutrient supplies in a forested ecosystem of southern Quebec." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36542.
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The objective of this thesis was to validate the dynamic model SAFE (Soil Acidification in Forested Ecosystems) in a small deciduous watershed of southern Quebec. SAFE could then be used to: (1) identify which processes are governing acidification, and (2) assess the rates of acidification according to various forest conditions.Soil and soil solution chemistry between unburned and burned zones following fire disturbance seventy-five years ago was examined within the watershed. Results showed two major, statistically significant, differences: (1) higher base status, and (2) lower soil solution N in the burned zone. High quality leaf litter of aspen and birch (burned zone) relative to that of sugar and red maple (unburned zone) has contributed to the enrichment of base cations in the forest floor. The enrichment of the forest floor did not however impoverish the B horizon as seen in other studies. Rather, fire enriched the soil in base cations and buffered the effect of forest regrowth in the B horizon.
The MAKEDEP model was used to reconstruct the time-series input files needed to run SAFE. In MAKEDEP, the availability of N determines tree growth which in turn, affects most of the processes involved in nutrient cycling. Regressions of measured deposition at the Hubbard Brook Experimental Forest and that of simulated deposition at the study site suggest MAKEDEP is suitable to model the deposition trends of all elements except Na.
SAFE was calibrated for the unburned and burned conditions at the study site. Fire disturbance and forest regrowth have produced different soil chemical composition within the zones as discussed above. SAFE was therefore validated at the study site as a function of its ability to reproduce soil chemistry under unburned and burned conditions. The simulated soil chemistry was in close agreement with the measured unburned soil conditions, but some processes would have to be clarified or accounted for with greater accurately, e.g., biological N fixation and N immobilization by myccorhizal fungi, to reproduce more accurately the measured burned soil chemistry. Simulated soil chemistry in the unburned zone reinforced nevertheless the conclusions of a few historical soil chemistry studies supporting the hypothesis that acid-sensitive forest sites of the United States underwent significant acidification during 1930--1980 during major input of acidity from the atmosphere. Model output suggests that cation nutrient deficiencies could occur in the long-term, but future Al phytotoxic responses are unlikely to occur due to a relatively high projected pH. (Abstract shortened by UMI.)
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朱展強 and Chin-keung Chu. "Parallel computation for time domain boundary element method." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31220678.
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Silliman, Stephen Edward Joseph 1957. "Stochastic analysis of high-permeability paths in the subsurface." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/191120.
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Subsurface fluids may travel along paths having a minimum permeabilility greater than the effective permeability of the rock. This may have an important impact on contaminant migration. A stochastic approach related to percolation theory is advanced to address the question of what is the probability that a high permeability path extends across a given volume of the subsurface. The answer is sought numerically through subdividing the volume of interest into a three-dimensional grid of elements and assigning a random permeability to each element. Four permeability processes are considered: 1) Stationary with independence between grid elements; 2) Stationary and autocorrelated; 3) Nonstationary due to conditioning on measured values; and 4) Random rock volume included in grid. The results utilizing data from fractured granites suggest that in large grids, at least one path having a minimum permeability in excess of the "effective" rock permeability will cross the grid. Inclusion of autocorrelation causes an increase in the expected value of the minimum permeability of such a path. It also results in a significantly increased variance of this permeability. Conditioning on field permeabilities reduces the variance of this value over that obtained by unconditional, correlated simulation, but still produces a variance greater than that obtained when independence was assumed. When conditioning is performed, the mean of the minimum permeabilities along these paths is dependent on the principal axis of the path. Finally, including a random rock volume by allowing the length of the grid to be random increases the variance of the minimum permeability.
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Hugot, Alexandre. "Modelisation des ecoulements gravitaires catastrophiques par une approche objet dynamique : Erosion - Transport - Depot." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2000. http://tel.archives-ouvertes.fr/tel-00002677.
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Nous proposons dans cette thèse un modèle mathématique simple adapté à la sédimentation des dépôts gravitaires en eaux profondes. L'écoulement est traité comme un objet géométrique déformable. Les principaux mécanismes physiques pris en compte par le modèle sont : 1. La turbulence ; 2. L'étalement dû aux forces de pressions ; 3. L'incorporation de fluide le long de l'interface suspension-fluide ambiant ; 4. La sédimentation de particules ; 5. L'érosion de particules. Les solutions analytiques asymptotiques du système différentiel non-linéaire montrent la consistance des solutions numériques sur les temps longs. Les tests numériques permettent de quantifier l'impact qualitatif et quantitatif des pramètres physiques du modèle, des conditions initiales et des parmètres de contrôle (pente, granulométrie). Une méthode d'inversion est mise en oeuvre pour l'identification des conditions initiales et/ou des paramètres du modèle. L'inversion partielle (détermination des conditions initiales) appliquée à des modèles réduits expérimentaux montre le bon comportement qualitatif du modèle et cela même hors du domaine de validité strict de ce dernier. L'inversion total (identification des paramètres physiques et détermination des conditions initiales) montre le bon comportement du modèle d'un point de vue quantitatif au niveau des vitesses de l'écoulement et des épaisseurs déposées. La méthode d'inversion est appliquée à l'effondrement de l'aéroport de Nice en 1979 pour tester des scénarios d'écoulement. Contrainte par les ruptures de câbles et/ou les épaisseurs déposées, elle permet, par exemple, d'estimer le volume initial ou les paramètres physiques de l'effondrement (coefficient de friction, nombre de Schmidt turbulent modifié...). Malgré quelques limitations, principalement dues aux simplifications géométriques de l'écoulement, ce modèle simple est un premier pas vers la compréhension quantitative de l'impact des paramètres externes -tel que la nature et la quantité des apports en sédiments, la géométrie du bassin- sur la dynamique des courants turbiditiques et l'organisation des séquences de dépôts résultantes. Grâce à ses faibles temps de calcul sur micro-ordinateur, il est envisageable de simuler des séries d'événements et de former ainsi des séquences de dépôt multi-événementielles. Il peut être utilisé pour reconstruire les processus de sédimentation et les dépôts résultants.
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Zeng, Honghai. "A web-based high performance simulation system for transport and retention of dissolved contaminants in soils." Diss., Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-10082002-144653.
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Schindewolf, Marcus. "Prozessbasierte Modellierung von Erosion, Deposition und partikelgebundenem Nähr- und Schadstofftransport in der Einzugsgebiets- und Regionalskala." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2012. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-86142.
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The process based soil erosion simulation model EROSION 3D is applied on regional scale for the federal state of Saxony/Germany. This survey is aimed on modeling soil loss, sediment transport, deposition resp. the input of particle attached nutrient and pollutant input into surface water bodies for 10years storm event and three land use scenarios. The available region-wide geo-data were preprocessed to be used in the parameterization interface DPROC. This software has been extended to parameterize large areas as well as small catchments. The basis of parameterization is a relational data base consisting of measured or estimated specific model soil parameters. These values have been derived by heavy rainfall simulation experiments below field conditions. The data base has been extended by the new results, which cover different soil tillage practices. The new experiments were conducted with a newly developed methodology. The experimental results show a significant relation of soil loss from the mechanical impact due to soil tillage. Only the non-tillage practice is able to protect soils efficiently from erosional soil losses. In order to describe particle attached nutrient and pollutant transport, soil samples were analyzed determining the element content of different particle fractions. The regional scale simulations identify the Saxonian Loess Belt as hotspot of soil erosion. However considerable amounts can also be expected in certain areas of the low mountain range. Particle attached element inputs into surface water bodies correspond to main sediment delivery areas. The amounts of erosional soil losses could be reduced to 90 % in case of consequently and area-wide transformation to conservation tillage practices. The calculated phosphorous inputs into surface waters on catchment scale are proofed to be valid. Compared to empirical based phosphorous and heavy metal yields the results in this study exceed this findings by a wide range. The differences are caused by lacking an event based consideration, which disregards system maximal impacts. Since erosion is an exclusive non continuous process, those maximal impacts are highly relevant and have to be considered in case of planning and execution of erosion and water protection conceptsIn der vorliegenden Arbeit wird das prozessbasierte Erosionsprognosemodell EROSION 3D flächendeckend auf regionaler Ebene für den Freistaat Sachsen angewendet. Ziel der Untersuchungen ist es, Bodenabtrag, Sedimenttransport und -deposition bzw. den Eintrag partikelgebundener Nähr- und Schadstoffe in Oberflächengewässer für ein 10jähriges Starkniederschlagsereignis und drei verschiedene Landnutzungsszenarien zu beschreiben. Dazu wurden im Vorfeld verfügbare Geo-Basisdaten so aufbereitet, dass sie für die semiautomatische Parametrisierung mit der Software DPROC verwendet werden können. Diese Software wurde so erweitert, dass sowohl größere Einzugsgebiete als auch einzelne Teileinzugsgebiete parametrisiert werden können. Grundlage der Parametrisierung bildet eine relationale Datenbank, die auf Messwerten bzw. davon abgeleiteten Schätzwerten aus Starkregenexperimenten unter Feldbedingungen basiert. Der vorhandene Datenfundus wurde durch neue Ergebnisse zu verschiedenen Verfahren der ackerbaulichen Bodenbearbeitung mittels neu entwickelter Methodik korrigiert und erweitert. Die experimentellen Ergebnisse zeigen eine deutliche Abhängigkeit des Feststoffaustrages von der Eingriffsintensität bei der Bodenbearbeitung. Dabei ist die Direktsaat die einzige Bewirtschaftungsform, die den Boden effektiv vor Erosion schützt. Um den selektiven partikelgebundenen Nähr- und Schadstofftransport prozessbasiert abzuschätzen, wurden die Stoffgehalte für die Partikelfraktionen Sand, Schluff und Ton an Bodenproben bestimmt. Die regionalskalierten Simulationen identifizieren die sächsische Lössregion als Schwerpunkt der Bodenerosion in Sachsen. Beträchtliche Bodenabträge sind darüber hinaus in den sächsischen Mittelgebirgen zu erwarten. Partikelgebundene Stoffeinträge in Oberflächengewässer verteilen sich in Abhängigkeit von den Sedimentliefergebieten. Die Bodenumlagerungsprozesse einschließlich der damit verbundenen partikelgebundenen Stoffeinträge lassen sich bei konsequenter Umstellung auf konservierende Bewirtschaftungsmethoden entsprechend den Modellergebnissen um mehr als 90 % reduzieren. Im Rahmen der Modellvalidierung konnte die Zuverlässigkeit der berechneten Phosphorausträge auf Einzugsgebietsebene belegt werden. Verglichen mit empirisch basierten mittleren jährlichen Abschätzungen sind die in dieser Arbeit berechneten ereignisbezogenen Phosphor- und Schwermetallausträge um ein Vielfaches höher. Zurückzuführen sind diese Unterschiede vor allem darauf, dass bei den rein empirischen Ansätzen, die maximale Belastungsspitzen unberücksichtigt bleiben. Da Erosion stets ein diskontinuierlicher Prozess ist, sind diese Belastungsspitzen im höchsten Maße relevant und bei der Planung und Durchführung von Erosions- und Gewässerschutzkonzepten unbedingt zu berücksichtigen
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Soliday, Stanley Jr. "Limits of limit equilibrium and finite element techniques applied to cracked debris dams on collapsing foundations." PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4428.
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Limits of slope stability, limit equilibrium methods, and of the finite element code FEADAM are reached in the application of these methods to the problem of cracked dams constructed on collapsing soils.
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Nilufar, Fahmida. "Fate and transport of herbicides in soil in the presence of surfactants in irrigation water." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97982.
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In many countries around the world, municipal sewage and industrial wastewaters are typically treated, or sometimes only partially treated, prior to their discharge into surface waters. A major anionic surfactant, Linear Alkyl benzene Sulfonate (LAS), and a degraded product of a non-ionic surfactant, Nonylphenol (NP), are frequently found in municipal wastewaters. When wastewater containing such surfactants and their degraded products is used for irrigation, it can have an effect on the sorption/desorption and movement of pesticides in soils. Therefore, a lysimeter study was conducted, in summer 2004, to assess the effect of LAS and NP on the movement of agricultural herbicides through a sandy loam soil. The degradation of the herbicides was studied in lysimeters over a ninety-day period. Irrigation water with a concentration of 12 mg L -1 of LAS and NP was used to assess their effect on the leaching of atrazine, metolachlor, and metribuzin. Moreover, a laboratory sorption experiment was undertaken to estimate the partition coefficients (kd) of the three herbicides with water containing the same concentrations of LAS and NP. Irrigation water containing low concentrations of surfactants (LAS and NP) did not increase leaching of the three herbicides. Therefore, these results would reduce the concerns regarding pesticide leaching through sandy soil brought on by LAS and NP in wastewaters for irrigation, which is becoming more important due to increasing water scarcity in the dry climate regions of the world.Beside the lysimeter study, mathematical models can be used effectively and economically in a very short period of time for simulating herbicide concentrations into soil. PESTFADE, a one dimensional transient flow model, was used, in this study, to simulate the fate of the three herbicides in sandy soils. Another model, Artificial Neural Network (ANN), was also used over mathematical modeling due to its faster execution period and less input parameter requirements, for predicting the concentrations of the three herbicides in a sandy loam soil. The predicted concentrations, from both models were compared with the experimental results from the lysimeter study. Although slight overestimations and underestimations were observed, both models simulated herbicide concentrations in the soil profile satisfactorily.
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Larsson, Martin. "Quantifying macropore flow effects on nitrate and pesticide leaching in a structured clay soil : field experiments and modelling with the MACRO and SOILN models /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5489-1.pdf.
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Frankfurt, Ricardo. "Simulação de transporte de massa de um soluto em meio poroso com auxílio do CFD (Computer Fluid Dynamics)." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-29012009-162554/.
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Com o avanço dos computadores pessoais, problemas técnicos complexos, antes restritos aos grandes centros de pesquisas internacionais, passam a ser acessíveis pelas mais diversas áreas do conhecimento, como as engenharias e em particular a Engenharia Química. Fenômenos físicos são representados matematicamente por equações diferenciais, que na maioria das vezes não possuem solução analítica possível. O CFD ( Computer Fluid Dynamics) é uma técnica numérica iterativa, que busca a solução destas equações diferenciais através da discretização do domínio estudado e das equações que governam o fenômeno envolvido. Neste trabalho, através de um software especialista de CFD, o ANSYS CFX 11.0, foi simulado o transporte de massa e momento de um soluto traçador, o Cloreto, presente no sal Cloreto de Sódio, em um meio poroso. Em seguida, os resultados desta simulação foram comparados e validados por um experimento de transporte de massa numa caixa de areia.With the advance of the personal computers, complex technical problems, before restricted to the huge centers of international researches, have become more accessible by many areas of the knowledge, like the engineering and in particular the Chemical Engineering. Physical phenomena are represented mathematically by differentials equations, which most of the time do not have possible analytical solution. CFD (Computer Fluid Dynamics) is an iterative numeric technique, which search the solution of these differentials equations through both discretization of the studied domain and the equations that govern the involved phenomenon. In this work, through a CFD\'s specialist software, ANSYS CFX 11.0, it was simulated the mass and momentum transport of a solute tracer, Chloride, present in Sodium Chloride, in a porous media. After this, the simulations results were compared and validated in a mass transport experiment in a sand box.
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Le, Minh Hoang. "Modélisation multi-échelle et simulation numérique de l’érosion des sols de la parcelle au bassin versant." Thesis, Orléans, 2012. http://www.theses.fr/2012ORLE2059/document.
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L’objectif global de ce travail est d’étudier une modélisation multi échelle et de développer une méthode adaptée pour la simulation numérique du processus d’érosion à l’échelle du bassin versant. Après avoir passé en revue les différents modèles existants, nous dérivons une solution analytique non triviale pour le système couplé modélisant le transport de sédiments par charriage. Ensuite, nous étudions l’hyperbolicité de ce système avec diverses lois de sédimentation proposées dans la littérature. Concernant le schéma numérique, nous présentons le domaine de validité de la méthode de splitting, pour les équations modélisant l’écoulement et celle décrivant l’évolution du fond. Pour la modélisation du transport en suspension à l’échelle de la parcelle, nous présentons un système d’équations couplant les mécanismes d’infiltration, de ruissellement et le transport de plusieurs classes de sédiments. L’implémentation et des tests de validation d’un schéma d’ordre élevé et de volumes finis bien équilibré sont également présentés. Ensuite, nous discutons sur l’application et la calibration du modèle avec des données expérimentales sur dix parcelles au Niger. Dans le but d’aboutir la simulation à l’échelle du bassin versant, nous développons une modélisation multi échelle dans laquelle nous intégrons le taux d’inondation dans les équations d’évolution afin de prendre en compte l’effet à petite échelle de la microtopographie. Au niveau numérique, nous étudions deux schémas bien équilibrés : le schéma de Roe basé sur un chemin conservatif, et le schéma avec reconstruction hydrostatique généralisée. Enfin, nous présentons une première application du modèle avec les données expérimentales du bassin versant de Ganspoel qui nécessite la parallélisation du codeThe overall objective of this thesis is to study a multiscale modelling and to develop a suitable method for the numerical simulation of soil erosion on catchment scale. After reviewing the various existing models, we derive an analytical solution for the non-trivial coupled system modelling the bedload transport. Next, we study the hyperbolicity of the system with different sedimentation laws found in the literature. Relating to the numerical method, we present the validity domain of the time splitting method, consisting in solving separately the Shallow-Water system (modelling the flow routing) during a first time step for a fixed bed and updating afterward the topography on a second step using the Exner equation. On the modelling of transport in suspension at the plot scale, we present a system coupling the mechanisms of infiltration, runoff and transport of several classes of sediment. Numerical implementation and validation tests of a high order wellbalanced finite volume scheme are also presented. Then, we discuss on the model application and calibration using experimental data on ten 1 m2 plots of crusted soil in Niger. In order to achieve the simulation at the catchment scale, we develop a multiscale modelling in which we integrate the inundation ratio in the evolution equations to take into account the small-scale effect of the microtopography. On the numerical method, we study two well-balanced schemes : the first one is the Roe scheme based on a path conservative, and the second one is the scheme using a generalized hydrostatic reconstruction. Finally, we present a first model application with experimental data of the Ganspoel catchment where the parallel computing is also motived
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Bienen, Britta. "Three-dimensional physical and numerical modelling of jack-up structures on sand." University of Western Australia. School of Civil and Resource Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0208.
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Mobile offshore jack-up drilling rigs are not custom-designed for a particular location but rated for typical operating characteristics, like water depths. They may be deployed at a number of different sites during their design life. Under the current guidelines, the jack-up is required to be assessed for its suitability for each new proposed location, assuming environmental loading conditions due to wind, waves and current corresponding to a 50-year return period storm applicable to the site. Traditionally, these assessments have been performed in two dimensions, simplifying the jack-up to a plane frame and the loading conditions to be in-plane with the rig's 'axis of symmetry'. This thesis introduces a computer program, named SOS_3D, for the fluid-structure-soil interaction analysis of jack-up response in three dimensions. Extensive experimental series have been performed to provide evidence for the generalisation of the foundationsoil interaction model to general six degree-of-freedom loading conditions and its applicability to load paths and stress levels relevant to jack-up spudcans. These experiments included (1) 1g single footing tests, (2) centrifuge single footing tests and (3) centrifuge model jack-up tests. The latter tests highlighted differences in response and mode of failure depending on the loading direction of the jack-up and re-iterated the importance of three-dimensional modelling. The numerical program SOS_3D introduced early in this thesis was shown to represent a useful tool for the prediction of jack-up behaviour under general combined loading in three dimensions. It provided reasonably good, conservative predictions of the experimentally measured jack-up behaviour.
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Hoffmann, Markus. "Assessment of leaching loss estimates and gross load of nitrogen from arable land in Sweden /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5497-2.pdf.
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Damacedo, João Marcos Ferreira. "Sistema para avaliação da umidade relativa do solo utilizando a análise de impedância e técnicas de ultrassom." Universidade Tecnológica Federal do Paraná, 2010. http://repositorio.utfpr.edu.br/jspui/handle/1/399.
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Visando a melhoria dos processos agrícolas para produção sustentável de alimentos, o conhecimento do teor de umidade relativa vem a cooperar no processo de irrigação, apontada como uma grande consumidora de água, além de auxiliar em estudos hidrológicos, meteorológicos, geotécnicos, dentre outros. Este trabalho apresenta o desenvolvimento do hardware e firmware de um protótipo para ser utilizado com técnicas de ultrassom e análise de impedância, visando o desenvolvimento de futuros produtos para avaliar o teor de água no solo. Para a análise da impedância foi utilizado um sensor de placas paralelas, separadas 24 mm uma da outra, utilizadas juntamente com o hardware e firmware desenvolvido, para detectar a variação da constante dielétrica do solo com acréscimo de água, através da variação da fase dos sinais de tensão e corrente ao passar pelo sensor inserido no meio. Obteve-se, ao analisar 15 amostras, uma relação logarítmica crescente da variação de fase em função do acréscimo de água no solo. No estudo da caracterização da umidade do solo através do ultrassom, obteve-se resultados preliminares expressivos para as mudanças da amplitude dos sinais ultrassônicos de 40 kHz e 100 kHz no modo transmissão/recepção ao propagar-se no solo com diferentes níveis de umidade.To improve agricultural processes for sustainable food production, knowledge of the moisture is useful to cooperate in the irrigation process, identified as a major consumer of water, besides helping in hydrological studies, meteorological, geotechnical, among others. This paper presents the development of the hardware and firmware of a prototype to be used with ultrasound techniques and impedance analysis for the development of future products to evaluate the water content in soil. For the impedance analysis, it was used a parallel plate sensor, with the plates separated from 24 mm each other, used together with the hardware and firmware developed to detect the variation of dielectric constant with the increase of soil water, by varying the phase of voltage and current signals in the sensor inserted in the medium. The results obtained, when analyzing 15 samples, presented a ratio of logarithmic growing of the phase variation due to increased soil water. In the study of characterization of soil moisture using a transmission/reception ultrasound system, the preliminary results have shown significant changes in the amplitude of ultrasonic waves of 40 kHz and 100 kHz propagating through the soil at different moisture levels.
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Abounia, Omran Behzad. "Application of Data Mining and Big Data Analytics in the Construction Industry." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu148069742849934.
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Benseghier, Zeyd. "Etude numérique de l'érosion d'un matériau granulaire cohésif par un écoulement fluide." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0579.
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L’érosion constitue le principal risque auquel sont soumis les ouvrages hydrauliques en terre. Il est donc crucial de quantifier l’érodabilité des sols et plusieurs essais d’érosion ont été mis au point dans ce but. Cependant, leurs modèles d’interprétation sont assez simplistes et des incohérences peuvent être constatées. Malgré plusieurs études expérimentales sur le sujet, les mécanismes d’érosion à l’échelle des grains restent encore mal compris. Dans cette thèse, la méthode numérique LBM-DEM a été mise en œuvre afin d’analyser l’érosion à l’échelle du grain. La cohésion du sol est prise en compte par une loi de contact adaptée incluant éventuellement un modèle d’endommagement dépendant du temps. Une parallélisation GPU a permis en outre d’améliorer la vitesse de calcul et l’efficacité du code. Après une analyse préalable d’un jet impactant laminaire 2D, la pertinence du critère classique de Shields pour les échantillons sans cohésion a d’abord été confirmée avant qu’une généralisation de ce critère ne soit proposée pour les sols faiblement cohésifs avec un accord très satisfaisant. Enfin, le modèle d’interprétation classique de l’essai JET a été adapté à notre problématique afin d’analyser et discuter de façon critique les paramètres d’érodabilité. Enfin, une configuration mieux contrôlée d’écoulement tangentiel à contrainte de cisaillement constante a été étudié, permettant de suggérer une loi de puissance, et non linéaire, pour décrire l’érosion à l’échelle de l’échantillon. Une étude paramétrique sur la cohésion inter-particulaire et la taille des grains a finalement été menée, afin d’examiner le lien entre les paramètres micro et macroHydraulic earthworks are frequently subjected to erosion-induced failure as reported in the literature. Accordingly, several erosion tests have emerged to quantify soil’s erodibility. However, they are based on simplified interpretation models and may lead to some inconsistencies. Despite several experimental investigations on the subject, there is still a lack of understanding of the erosion mechanisms taking place at the grain level. To this end, the LBM-DEM method is used in the present study to analyze numerically the erosion phenomena at the grain scale, with the addition of a cohesion model, including a time-dependent damage law. The computational speed and the efficiency of the code was significantly improved here using GPUs parallelization techniques. Next, after a preliminary analysis of 2D laminar impinging jet flow, the relevance of the classical Shields criterion for cohesion-less samples was first recovered, followed by a proposed generalization of this criterion for weakly cohesive soils with satisfactory agreement. Lastly, an adaptation of the classical JET interpretation model was proposed to our 2D laminar problematic and the erodibility parameters were subsequently quantified and critically discussed. Finally, a constant shear-driven fluid flow configuration at the upper surface of a sample was alternatively studied. A power law function was found to be best suited than the usual linear relation to account for the erosion law at sample scale. A parametric study on inter-particle cohesion and grain size was next performed to investigate the link between micro and macro parameters
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Brito, Gilmar Gonçalves de. "Modelo de monitoramento de deslizamento de encostas por meio de sensor multiparamétrico." Universidade Católica de Pernambuco, 2013. http://www.unicap.br/tede//tde_busca/arquivo.php?codArquivo=947.
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Fenômenos de deslizamentos de encostas ocorrem em todo o mundo em diversas condições climáticas e de terrenos, custando bilhões de dólares e produzindo milhares de mortes, agravando problemas ambientais, econômicos e políticos. Um
problema sério que se associa à questão dos deslizamentos de encostas é o crescimento populacional e a ocupação desordenada das encostas, caracterizando os deslizamentos como uma questão geopolítica e econômica. Ações para mitigar os problemas decorrentes desses fenômenos de deslizamentos incluem o Monitoramento Ambiental das áreas de maior susceptibilidade e o Manejo da População, quando submetidas a elevado risco de deslizamento. Os processos de
monitoração consistem na coleta de um conjunto de sinais e parâmetros, provenientes do solo das encostas, que possam ser usados para o reconhecimento das dinâmicas dos solos. Combinando os sinais provenientes do solo e parâmetros
que reflitam os fatores climáticos e antrópicos, causadores de desestabilizações e deslizamentos, torna-se possível utilizar estes dados combinados em modelos de avaliação de risco para realizar a Predição de Deslizamentos. No Contexto
Brasileiro, existe uma forte relação entre chuvas intensas e deslizamentos de encostas, devido aos fenômenos de escoamento de águas infiltradas no solo e na erosão decorrente, sendo, portanto, o monitoramento preditivo das primeiras camadas do solo um importante recurso para a detecção das áreas de eminente risco de deslizamento. Diversas abordagens para a monitoração dos solos foram
apresentadas internacionalmente, sendo estas abordagens baseadas em diversas tecnologias, como exemplos podem ser citadas as técnicas de ondas acústicas no solo, detectores de umidade relativa e pluviometria seletiva. Essas abordagens
podem tirar proveito do recente paradigma de Redes Sensores, baseados em dispositivos computacionais móveis de baixo consumo, movidos a baterias, que podem formar redes de trocas de dados baseadas em redes sem fio, permitindo a
conexão de diversos sensores de solo, espalhados ao longo das encostas, formando um sistema de coleta destes dados de sensores em tempo real para posterior processamento e avaliação de riscos. Frente ao exposto, este trabalho propõe um sistema de monitoramento baseado em rede sensores, capaz de estimar o risco eminente de deslizamento. O sistema proposto considerou quatro dimensões do problema de desenvolvimento e prototipação do sistema de monitoramento: (1) Proposição de um Ambiente de Simulação Física, a partir da criação de um ambiente de testes em laboratório utilizando escala reduzida; (2) Reconhecimento tecnológico e refinamento de propostas de sistemas pré-existentes, que tenham a mesma finalidade, já descritos na literatura, sejam eles projetos acadêmicos ou sistemas já comercialmente disponíveis; (3) Desenvolvimento de um Sensor
Inteligente Multiparamétrico; (5) desenvolvimento de uma Rede de Monitoramento para coleta de dados vindos da encosta e processamento local. Este trabalho apresenta, como contribuição técnico-científica principal, um ambiente de simulação e monitoração, sendo este ambiente relevante para estudos das dinâmicas dos deslizamentos, bem como para a prototipação de redes de monitoração para aplicações em ambientes reais, para geração de informação sobre os riscos de deslizamento, uteis para as atividades de contingenciamento dos defeitos de deslizamento por parte da Defesa Civil.Landslides occur around the world, in various conditions of weather and terrain, costing billions of dollars, causing thousands of deaths and worsening environmental, economic and political problems. A serious question associated with landslides is the disordered of human occupation - characterizing a geopolitical and economic issue. Actions to mitigate the problems arising from this phenomenon include environmental monitoring of the areas of greatest susceptibility for managing the higher risk population. The monitoring processes consist of recognizing soil dynamics and climatic factors, responsible for causing destabilization and landslides. In the Brazilian context, there is a strong relationship between heavy rains and landslides, since the phenomenon of runoff water infiltrated the soil and produces erosion. Therefore, a predictive monitoring of the first soil layers is an important feature for detecting areas of imminent risk of slippage. Several approaches for monitoring were presented internationally, they are based on different technologies, such as acoustic waves in the soil; detectors of relative humidity and rainfall selective analysis. All these approaches are anchored in the paradigm of remote sensing and smartsensor networks. Based on that, this paper proposes a model to estimate the imminence of of landslides risk. The proposed model is built on four pillars: (i) proposing a physics simulation environment, from the creation of a laboratory scale test environments, (ii) recognizing the technology and refinement of pre-existing models, (iv) developing of multiparametric smart sensor and (v) developing of a peer-to-peer network of sensors. This study aggregates to the scientific and technical contribution a framework for monitoring, useful for studying of landslides dynamics. Such framework is crucial for prototyping monitoring networks to be used by civil defense.
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Spekken, Mark. "Creating optimized machine working patterns on agricultural fields." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-22092015-112051/.
Full textAbstract:
In the current agricultural context, agricultural machine unproductivity on fields and their impacts on soil along pathways are unavoidable. These machines have direct and indirect costs associated to their work in field, with non-productive time spent in manoeuvres when these are reaching field borders; likewise, there is a double application of product when machines are covering headlands while adding farm inputs. Both issues aggravate under irregular field geometry. Moreover, unproductive time can also appear in operations of loading/offloading the machine\'s reservoir with inputs/harvested-goods, which can increase with an improper use of the reservoir due to the inadequate machine path length. On the other hand, irregular steep surfaces present a problem for establishment of row crops and machine paths towards erosion. Though contouring (i.e., performing field operations perpendicular to slope direction) is a common practice to reduce runoff and increase water infiltration, still elevation contours are never parallel, while machine operations always are. Many of these issues were target for optimization in computer path planning for agricultural machines, where unproductivity was overall minimized and attempts of soil loss reduction by more proper path establishment also yielded results. This thesis gathered these issues in a combined path planning approach making possible to address soil loss and unproductive costs to their proper location. A number of methods was proposed and modified: creating and replicating steerable machine track; finding more optimal references for path coverage on irregular surfaces (curved or straight); quantifying the impacts of soil loss for a given path pattern; identifying spatially the water flow and concentration; defining geometrically different manoeuvre types and calculate its time, space and energy demands; obtain the overlapped area of input application; and quantifying the machine replenishment cost in relation to underuse of its reservoir for following tracks of inadequate length. An algorithm-application was achieved, which is capable of simulating a large number of path coverage scenarios and to display optimized ones based on a user defined criteria. Sugarcane crop, grown in Brazilian conditions, was the main object of study in this thesis because of its high in-field mechanization costs (along with unproductive operational costs), high susceptibility of soil erosion in its planting phase, and for occupying an area of predominant rolling surface. Case studies were subject to this algorithm that provided suitable outputs with minimized impacts. The outputs of the algorithm were comprehensive and showed potential for the methods to be used by agricultural decision makers.No contexto agrícola atual, improdutividade de máquinas agrícolas em campo e seus impactos sobre o solo ao longo de suas vias são inevitáveis. Estas máquinas têm custos diretos e indiretos associados ao seu trabalho no campo, como tempo improdutivo gasto em manobras quando estes atingem os limites do talhão. Também nestes limites, há uma dupla aplicação de insumos agrícolas quando as máquinas estão cobrindo cabeceiras. Ambas as questões se agravam em talhões de geometria irregular. Além disso, o tempo improdutivo também pode aparecer em operações de carga / descarga do reservatório da máquina com insumos / bens colhidos, o que pode aumentar com um uso indevido do reservatório da máquina devido ao comprimento inadequado do percurso em campo. Ainda, superfícies irregulares e íngremes apresentam um problema para o estabelecimento de culturas em fileira e caminhos de máquinas contra declive. Apesar de operações em nível serem uma prática comum para reduzir o escoamento e aumentar a infiltração de água, curvas de nível nunca são paralelas, enquanto operações agrícolas são sempre paralelas. Muitas destas questões foram alvo de otimização computacional para planejamento de percursos de para máquinas agrícolas, onde a ineficiência foi, em geral, minimizada e tentativas de redução da perda de solo estabelecimento de percursos mais adequados também produziu resultados. Esta tese reuniu estas questões em uma abordagem de planejamento de percurso quantificando e direcionando custos de perda de solo e improdutividade de máquinas para sua devida localização. Métodos foram propostos e modificados, como: criar e replicar trajetos transitáveis de máquinas; encontrar referências ideais para a cobertura do trajeto em superfícies irregulares (curvas ou retas); quantificação dos impactos da perda de solo por um determinado padrão de percursos; identificar espacialmente o fluxo da água e sua concentração; definir geometricamente diferentes tipos de manobras e calcular o seu tempo, espaço e energia demandada; obter a área sobreposta de aplicação de insumos; e quantificar custo de reposição da máquina em relação à subutilização de seu reservatório para seguir trajetos de comprimento inadequado. Um aplicativo-algoritmo foi obtido capaz de simular um grande número de cenários de padrões de percurso, e exibindo aqueles que foram otimizados por critérios definidos pelo usuário. A cultura da cana, em condições brasileiras, foi a principal cultura de estudo nesta tese devido ao seu alto custo de mecanização (assim como custos operacionais improdutivos), alta suscetibilidade à erosão do solo na sua fase de plantio, e ocupando predominantemente áreas de superfície irregular. Os estudos de caso foram sujeitos ao algoritmo que obteve resultados coerentes e impactos minimizados. Os resultados do algoritmo mostram potencial para que os métodos avaliados sejam utilizados por tomadores de decisão da área agrícola.
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Gogo-Abite, Ikiensinma. "Effluent Water Quality Improvement Using Silt Fences and Stormwater Harvesting." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5226.
Full textAbstract:
Construction sites are among the most common areas to experience soil erosion and sediment transport due to the mandatory foundation tasks such as excavation and land grubbing. Thus, temporary sediment barriers are installed along the perimeter to prevent sediment transport from the site. Erosion and sediment transport control measures may include, but not limited to, physical and chemical processes such as the use of a silt fence and polyacrylamide product. Runoff from construction sites and other impervious surfaces are routinely discharged into ponds for treatment before being released into a receiving water body. Stormwater harvesting from a pond for irrigation of adjacent lands is promoted as one approach to reducing pond discharge while supplementing valuable potable water used for irrigation. The reduction of pond discharge reduces the mass of pollutants in the discharge. In the dissertation, presented is the investigation of the effectiveness of temporary sediment barriers and then, development of a modeling approach to a stormwater harvesting pond to provide a comprehensive stormwater management pollution reduction assessment tool. The first part of the research presents the investigation of the performance efficiencies of silt fence fabrics in turbidity and sediment concentration removal, and the determination of flow-through-rate on simulated construction sites in real time. Two silt fence fabrics, (1) woven and the other (2) nonwoven were subjected to material index property tests and a series of field-scale tests with different rainfall intensities and events for different embankment slopes on a tilting test-bed. Collected influent and effluent samples were analyzed for sediment concentration and turbidity, and the flow-through-rate for each fabric was evaluated. Test results revealed that the woven and nonwoven silt fence achieved 11 and 56 percent average turbidity reduction efficiency, respectively. Each fabric also achieved 20 and 56 percent average sediment concentration removal efficiency, respectively. Fabric flow-through-rates were functions of the rainfall intensity and embankment slope. The nonwoven fabric exhibited higher flow-through-rates than the woven fabric in both field-scale and laboratory tests. In the second part of the study, a Stormwater Harvesting and Assessment for Reduction of Pollution (SHARP) model was developed to predict operation of wet pond used for stormwater harvesting. The model integrates the interaction of surface water and groundwater in a catchment area. The SHARP model was calibrated and validated with actual pond water elevation data from a stormwater pond at Miramar Lakes, Miramar, Florida. Model evaluation showed adequate prediction of pond water elevation with root mean square error between 0.07 and 0.12 m; mean absolute error was between 0.018 and 0.07 m; and relative index of agreement was between 0.74 and 0.98 for both calibration and validation periods. The SHARP model is capable of assessing harvesting safe-yield and discharge from a pond, including the prediction of the percentage of runoff into a harvesting pond that is not discharged. The combination of silt fence and/or polyacrylamide PAM before stormwater harvesting pond in a treatment train for the reduction of pollutants from construction sites has the potential of significantly exceeding a performance standard of 85 percent reduction typically required by local authorities. In fact, the stringent requirement of equaling pre- and post-development pollutant loading is highly achievable by the treatment train approach. The significant contribution from the integration of the SHARP model to the treatment train is that real-time assessment of pollutant loading reduction by volume can be planned and controlled to achieve target performance standards.Ph.D.
Doctorate
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering
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Martin, Adrien. "Analyse des mesures radiométriques en bande-L au-dessus de l'océan : Campagnes CAROLS." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00850877.
Full textAbstract:
Un regain d'intérêt pour la télédétection de la salinité de surface de l'océan (SSS) par radiométrie en bande-L (21cm) est apparu dans les années 1990 et a conduit au lancement des missions spatiales SMOS (nov. 2009) et Aquarius (juin 2011). Cependant, en raison du faible rapport signal sur bruit, l'inversion de la SSS à partir des mesures radiométriques en bande-L est très difficile. Ce travail porte sur l'étude de la signature radiométrique en bande-L des propriétés de la surface de l'océan (en particulier SSS et rugosité) à partir des mesures du radiomètre aéroporté en bande-L CAROLS, acquises dans le golfe de Gascogne en 2009 et 2010. Une première étude a montré que la SSS déduite des mesures du radiomètre CAROLS était précise à mieux que 0.3 pss dans une zone de forte variabilité spatio-temporelle avec une meilleure précision que les modèles océanographiques côtiers. La seconde étude qui combine les mesures passives (CAROLS) et active (diffusiomètre en bande-C STORM) a mis en évidence l'amélioration des nouveaux modèles de rugosité par rapport aux modèles pré-lancement satellitaires. Par ailleurs, l'étude a montré l'importance de la prise en compte des moyennes et grandes échelles de rugosité (> 20 cm) pour l'interprétation des mesures radiomé- triques loin du nadir.
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Yang, Chie-Cheng, and 楊其錚. "Numerical Simulation for Upland Soil Erosion." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/18398831086760203502.
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Lin, Ping-Hsien, and 林秉賢. "Simulation on Seepage Erosion of Soil Slopes." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/03819990975007646419.
Full textAbstract:
碩士國立中興大學
水土保持學系所
104
Seepage erosion behavior is due to groundwater seepage force. Groundwater seepage force moves slope soil particles, and therefore slope failure occurs potentially. According to previous experimental results, we found soil particles flow out from the slope after groundwater seepage started. Flowing of soil particles caused soil scouring and cavitation occurred at slope toe. The slope soil particles on cavitation location collapsed because of the loss of support. To decrease slope failure problems due to soil seepage erosion, we need to learn more about soil seepage erosion behavior. Simulation of soil seepage erosion behavior is mainly based on sandbox test. Although there are many researches about seepage erosion behavior, the results indicate that sandbox tests are usually affected by the model sizes and experimental situations. We use numerical methods to simulate experimental results and study the mechanism of seepage erosion. In this study, we use PFC2D which is based on the discrete element method to simulate soil seepage erosion behavior. Particle flow is a continuous process, which is an advantage to simulating soil seepage erosion behavior with groundwater seepage force. Our results successfully simulate sandbox tests and show that the process of soil seepage erosion completely. It offers a new method which is easier and cheaper to simulate soil seepage erosion behavior and complete process and results.
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Blau, Jeff Bryant. "Parameter identifiability of an erosion simulation model." 1986. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1986_59_sip1_w.pdf&type=application/pdf.
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Parker, Ronald Dean. "The effect of spatial variability on output from the water erosion prediction project soil erosion computer model." 1991. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1991_192_sip1_w.pdf&type=application/pdf.
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Heiberger, Thilo Stefan. "Simulating the effects of a capillary barrier using the two-dimensional variably saturated flow model SWMS-2D/HYDRUS-2D." Thesis, 1996. http://hdl.handle.net/1957/34246.
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"Computer simulation of shoreline erosion on a fetch-limited prairie reservoir (Lake Diefenbaker, 1967-1980)." Thesis, 1989. http://hdl.handle.net/10388/etd-06222012-080457.
Full textAbstract:
Shoreline erosion resulting from wind-generated waves has been noted
as a problem on coastlines and inland water bodies the world over.
In order to determine if computer simulation techniques are of any use
in estimating erosion rates along the shoreline of existing and future
reservoirs on the Canadian Prairies, hindcasted waves were tracked to
the breaker line on Lake Diefenbaker, Saskatchewan.
This thesis presents a method of using predicted wave power values to
estimate potential rates of erosion. The study found that enough
wave energy is generated on the reservoir to remove all eroded
material from the shoreline, regardless of its source of origin. The
predicted rates of erosion were comparable to those observed. The
study also found that varying water levels are of little help in
retarding the process of erosion on Lake Diefenbaker, because of the
cohesive nature of the shoreline sediments.
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Tang, Tsung-Hui, and 唐宗輝. "Studies of Freeways Soil Anchor Performance and Appropriate Numerical Simulation Computer Programs." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/88316069762710080734.
Full textAbstract:
碩士國立宜蘭大學
土木工程學系碩士班
103
In order to response geology variation in hilly areas and climate changing in Taiwan, the construction of the highways use a lot of anchors to reduce mass excavation and to increase the degree of slope stability, so that highway projects can be carried out safely and smoothly. Therefore, the relevant agents organize and assemble a database for ground anchor system, including head appearance, head component, endoscopic visual inspection and lift-off test. This study documents the anchor database system and the statistical analysis for test data of anchors. Finally, this study employs three most commonly used geotechnical engineering slope stability programs in Taiwan, namely PLAXIS, SLOPE/W and STABL, to discuss the stability of freeway slope and the anchor pre-stressed attenuation. This study explains the application, basic operation, analysis methodology, and calculation procedure for PLAXIS finite element method as well as SLOPE/W and STABL limit equilibrium methods. Finally, utilizing the information obtained through the great number of anchor information and the value distribution of anchor lift-off test, PLAXIS, SLOPE/W and STABL for four highway anchor-slope stability analysis are performed. Through the study of how to analyze the stability principles and pre-stressed attenuation behavior for anchor, it is hoped to understand the relationship between the anchor pre-stress attenuation and the safety factor of study anchor-slope. It is also discussed about which software is more suitable and precisely among the three sets of software. PLAXIS finite element method provides higher safety factor from the analysis result of the four anchor-slopes. SLOPE/W and STABL are both limit equilibrium methods and provide almost the same analysis results. The predicted result obtained from limit equilibrium method is a little more conservative. However, is is suggested that the three computer programs can be used to analyze slope stability and give quite close predicted results.
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Horswell, Michael Wilbur. "Spatial modelling to establish priorities for erosion control in commercial forestry plantations." 2002. http://hdl.handle.net/10413/4514.
Full textAbstract:
Commercial forestry is recognized for both its economic contribution as well as its
environmental impact. Of particular concern, is the soil erosion and sedimentation of
watercourses associated with forestry plantations. Environmental laws regulate many of the
activities of the forestry sector. It is critical that the forestry sector ensure that its
operations are compliant with the legal requirements that govern its use of natural
resources. In pursuing legal compliance it is necessary to ensure that erosion control
strategies are developed so as to ensure the positive effects of any interventions are
optimised. The identification of areas that are particularly at risk to erosion or contribute to
sediment delivery is an essential component in prioritising areas for management
interventions.
Establishing the erosion potential for commercial forestry areas is readily accomplished
through the application of existing models. Process based erosion models generally have
greater data requirements than the empirically derived USLE-based models. Given the
paucity of data available, the latter approach was adopted. Two methods of topographic
sub-factor derivation were investigated, those associated with the RUSLE (Renard, Foster,
Weesies & McCool1991) and the Unit Stream Power method presented by Moore and
Burch (1986). Since no existing methods identifying delivery risk areas existed, a method
was developed based on principles and factors identified in the literature. Additionally,
methods for identifying topographic assets, in terms of sediment attenuation, were
developed. From these models three indices were derived; sediment supply, delivery risk
and sediment attenuation.
Thereafter, the mean Sediment Supply Index was divided by stream length for small
catchments defined within the landscape to derive an index of sediment loading to streams.
This index is used to identify priorities for management intervention across the landscape.
The mean slope and sediment supply is used to develop buffer width recommendations for
the streams draining the catchments, using a method developed by Karssies and Prosser
(2001). Using the three indices in conjunction it is possible to make on-site and off-site
erosion control recommendations as well as identify and exploit any natural features that
can be utilized in erosion control.Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002
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Jones, Matthew Robert. "Incorporating the Canegro sugarcane model into the DSSAT V4 cropping system model framework." Thesis, 2013. http://hdl.handle.net/10413/9387.
Full textAbstract:
Canegro is a leading sugarcane crop simulation model and has been used extensively in agronomic research and management. The model has been under development since the late 1980s at the South African Sugarcane Research Institute (SASRI). The Decision Support System for Agrotechnology Transfer (DSSAT) is a software package containing models for a wide range of field crops, and utilities for processing, storing and analysing model inputs and outputs. Canegro was included as part of version 3.1 of DSSAT in the mid-1990s. The SASRI Canegro model was subsequently developed further, but these changes were never integrated, nor incorporated, into DSSAT. DSSAT has also developed substantially, and as of version 4 adopted a modular Cropping System Model (CSM) structure, providing numerous scientific and practical advantages over previous non-modular versions. The DSSAT-Canegro v.3 model was not modified to use this modular structure.
Following recognition of the advantages offered by DSSAT and its modular CSM, a project was initiated to incorporate the Canegro model into the DSSAT CSM. The project entailed: (i) restructuring and integrating the current Canegro plant growth and development code into the DSSAT v4 CSM modular framework, making use of its generic modules for management, soil, weather and the energy balance; (ii) verification of DSSAT CSM Canegro model results against the current SASRI version of Canegro to ensure that the new model produced similar results to the original model, for a set of simulated situations; and (iii) evaluation of the new DSSAT CSM Canegro model against experimental datasets.
The new DSSAT v4 CSM Canegro model has been verified to behave identically to the SASRI Canegro model when the water balance is not modelled and growth can occur at climatic potential rates. When the water balance is simulated but where the crop is not stressed, near identical output is produced by both models. Under water-stressed conditions, some discrepancies appear between the two models, due to differences in the calculation of reference evaporation, soil surface evaporation and runoff. Validation of the new model against data from 16 experimental crops produced root mean squared errors of 6.62 t ha-1 for stalk dry mass and 3.59 t ha-1 for sucrose mass – very similar to published values for Canegro. This project has yielded a functional, well-documented, maintainable and user-friendly version of the Canegro model, which is available for universal use via the official release of the DSSAT v4.5.Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.