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Dissertationen zum Thema „Soil erosion“
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1
Deneke, Fred. „Soil Erosion Control after Wildfire“. College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2002. http://hdl.handle.net/10150/146945.
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DeGomez, Tom. „Soil Erosion Control after Wildfire“. College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2011. http://hdl.handle.net/10150/239603.
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3
Tenywa, Moses Makooma. „Soil erosion overland flow processes on spatially variable soils /“. The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu148784853136528.
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Smith, Jennifer Lynn. „The use of rolled erosion control products (RECPs) for minimizing soil erosion“. Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available, full text:, 2007. http://wwwlib.umi.com/cr/syr/main.
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Brandsma, Richard Theodorus. „Soil conditioner effects on soil erosion, soil structure and crop performance“. Thesis, University of Wolverhampton, 1997. http://hdl.handle.net/2436/99094.
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6
Want, Kay F. „Factors affecting soil erosion in weathered granite hills at Tai Lam, Hong Kong“. Thesis, View the Table of Contents & Abstract, 2001. http://sunzi.lib.hku.hk/hkuto/record/B30109097.
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7
Sherif, Abuabdalla Saad. „Modelling soil erosion in northwest Libya“. Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415535.
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Alegre, Sergio Prats. „Soil erosion mitigation following forest wildfires“. Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11925.
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Doutoramento em Ciências do Mar e do Ambiente - Planeamento e Gestão AmbientalThis study aims to measure the effectiveness of four post-fire emergency techniques for reducing overland flow and soil erosion on the central-Portugal typical forest. The selection and development of these techniques was based on the review of the scientific background, but specially after checking throughout field rainfall simulation experiments which factors were the key for runoff and soil erosion on the specific case of high repellent soils. The forest residue mulch, a new treatment never tested before, was highly effective in reducing runoff and soil erosion in recently burnt eucalypt forest. The logging slash mulch had no obvious effect, but it was attributed to the small amounts of runoff and sediments that the untreated plots produced due to the extensive needle cast following a low severity fire. The hydromulch, a mixture of water, organic fibres, seeds, nutrients and a surfactant used in cutted slopes rehabilitation was also highly successful and was specially indicated for especially sensible areas. The utilization of polyacrylamides, a chemical agent with good performance in agricultural erosion, was not successful in post-fire runoff and soil erosion control, once that did not alter the most important key factor for soil erosion: the ground cover. The development of a new fibre optic turbidity sensor was a successful development on the soil erosion determination methodology, and its patent is being processed in the mean time.
O presente trabalho centra-se na avaliação da efetividade de quatro técnicas de controlo da escorrência e da erosão após incêndios florestais, adaptadas para o caso de povoamentos florestais no centro norte de Portugal. A seleção e desenvolvimento das técnicas foi efetuada após revisão bibliográfica alargada, mas sobre tudo após a comprovação no campo, efetuando simulações de chuva, de quais os fatores determinantes da erosão nos solos típicos do centro norte do País, caracterizados por serem altamente repelentes ainda antes dos incêndios. O “mulch” com restos de casca de eucalipto triturada foi um tratamento pioneiro nunca antes testado e deu bons resultados no controlo da escorrência e da erosão em eucaliptais ardidos. O “mulch” com restos florestais não triturados (ramos, paus e folhas) aplicados em um pinhal recentemente ardido não pode ser bem testado devido à protecção natural que forneceram as agulhas do pinheiro que caíram das árvores. No entanto, a sua alta taxa de aplicação desaconselham a sua utilização. O “hidromulch”, uma variante do “mulch” composto por água, fibras orgânicas e sementes utilizadona restauração de taludes e pedreiras, também deu resultados altamente efetivos e foi indicado para o tratamento de áreas especialmente sensíveis. Por outro lado, a utilização de poliacrilamidas (PAM), um agente aglutinante com bastante êxito na redução da erosão em terrenos agrícolas e com alto potencial devido ao seu baixo custo, não obteve resultados satisfatórios, uma vez que não alterou o principal fator envolvido na geração da erosão: o coberto do solo. No decorrer destas experiências, foi ainda desenvolvido um sensor óptico de turvação que permite facilitar a determinação da concentração de sedimentos nas amostras de escorrência das parcelas de erosão. Atualmente, foi realizado o pedido de patente de um novo protótipo de sensor de turvação da água mais desenvolvido.
9
Visser, Saskia M. „Modelling nutrient erosion by wind and water in northern Burkina Faso /“. Wageningen : Wageningen University and Research Centre, 2004. http://www.mannlib.cornell.edu/cgi-bin/toc.cgi?5046904.
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10
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.
11
Van, der Poel Petrus W. „Plunge pool erosion in cohesive channels below a free overfall /“. Connect to resource, 1985. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1202403267.
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12
Lucas, Andrew K. „Soil Erosion Analysis of Watersheds in Series“. Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1338479427.
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13
Tao, Hui. „NUMERICAL MODELING OF SOIL INTERNAL EROSION MECHANISM“. University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron153263797212618.
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14
Hoshino, Mitsuo, und 光雄 星野. „Soil erosion and conservation in Western Kenya“. Graduate School of Environmental Studies, Nagoya University, 2006. http://hdl.handle.net/2237/7323.
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15
Dubey, Anant Aishwarya. „Erosion Mitigation via Bio-Mediated Soil Improvement“. Thesis, Curtin University, 2022. http://hdl.handle.net/20.500.11937/89779.
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In the present study, the biocementation potent bacteria were isolated from the soil of the Brahmaputra River basin based on the hypothesis that soils are rich in microbial biodiversity. A novel biopolymer-biocement composite was also proposed. The efficacy of biocementation to mitigate soil erosion was studied via lab-scale simulation of aeolian, riverbank and coastal erosion. This study provides solid evidence for substantial improvement in soil erodibility resistance with biocementation.
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Garcia-Chevesich, Pablo Andres. „Erosion Processes and Control“. Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195844.
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This dissertation represents a unique contribution to the Spanish literature of soil erosion. The author of this document has written and published "Procesos y control de la erosion", a textbook about the engineering of soil erosion processes and the design of the most up-to-date methods and products used for erosion control. The text has been presented in Appendix A.Besides the above, the author of this dissertation is an active committee member at the International Erosion Control Association (IECA), specifically the International Development and the SOIL Fund programs. IECA members are drawn from individuals and erosion control business of different sizes. However, there was a lack of knowledge within IECA members about the formation of post-fire water repellent layers. For instance, Appendix B is represented by an article written by the author of this document, published in Environmental Connection (Volume 2, Issue 3), on July of 2008. The article gives a general description of what post-fire water repellency is, how is it formed, what factors affect it, its consequences on soil erosion, and how to control soil erosion on an efficient way when such a layer has been formed as a consequence of fire.Finally, Appendix C is a research paper in process of submission to the International Journal of Wildland Fire, about the formation of post-fire water repellent layers on Chilean Monterrey pine plantations. Since water repellent layers following wildfires have never been documented on Chilean soils, the need for such a publication is urgent, because Chilean land managers have been ignorant of such phenomenon.
17
Lüthi, Marcel. „A modified hole erosion test (HET-P) to study erosion characteristics of soil“. Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36999.
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Today’s increasing demand for energy and natural resources requires safe and reliable infrastructure. This includes hydraulic earth structures like dikes, levees, or dams. Such structures are susceptible to piping, a fundamental type of internal soil erosion. Piping is one of the principal causes of failures and accidents affecting embankment dams. The Hole Erosion Test (HET) is based on soil piping, and is used to determine the erodibility and critical shear stress of a soil. A soil specimen with a preformed axial hole is subjected to a constant-head pressure flow, and the rate of enlargement of the soil pipe is determined indirectly from flow rate and hydraulic gradient. This study presents a Modified Hole Erosion Test (HET-P) that introduces a conventional Pitot-static tube to measure total energy head and flow velocity of the exiting jet, which is correlated to a mean velocity within the axial hole. A series of Modified Hole Erosion Tests (HET-P) was performed on non-erodible PVC specimens with axial holes of constant, but different diameter, followed by HET-P tests on two types of soil, namely glacial till material of a dam core and natural clay deposits from Ontario river banks. Results confirmed that sidewall hydraulic head measurements to determine hydraulic gradients in the standard HET overestimate the resulting axial wall shear stress by as much as an order of magnitude. Furthermore, velocity measurements increase the confidence in test results as they allow for a more direct estimate of the axial hole diameter at any time during a test. A Pitot-static tube used in the HET-P for velocity and pressure measurement can easily be incorporated, and yields more transparent and reliable results by eliminating or amending some of the limiting assumptions of the standard test. It is an easy, fast, and economical approach that can be applied to soils in both constructed earth structures including dams and embankments, and to natural river banks to determine their susceptibility to internal and surface erosion.
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Bejranonda, Somskaow. „An assessment of the soil erosion impacts on lakeside property values in Ohio: a hedonic pricing method (HPM) application“. Connect to resource, 1996. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=osu1244216361.
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Kirby, Peter C. „The seasonal variation of soil erosion and soil erodibility in southwestern Quebec /“. Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65361.
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Pudasaini, Madhu S., University of Western Sydney, of Science Technology and Environment College und School of Engineering and Industrial Design. „Erosion modelling under different land use management practices“. THESIS_CSTE_EID_Pudasaini_M.xml, 2003. http://handle.uws.edu.au:8081/1959.7/721.
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Soil erosion has been recognised as a global threat against the sustainability of natural ecosystem. The work in this thesis has been undertaken to assist in combating this threat, and addresses the soil erosion issues associated with urban construction activities. The Revised Universal Soil Loss Equation (RUSLE) was employed in this research work and the parameters associated with the model were calibrated. This model was chosen for calibration, as it has been proven to be an easy to use tool yet providing reasonable results. Large scale rainfall simulators developed at UWS were used for rainfall simulation at two sites with diverse soil types: dispersive clayey soils at Penrith and highly permeable sandy soil at Somersby (Both in New South Wales, Australia). It is concluded that RUSLE can be successfully used in single storms for erosion prediction. Calibrated values of RUSLE parameters are useful in predicting soil erosion from the construction sites in NSW. It is also identified that in rolled smooth land condition, clayey soils are more erodible than sandy soil. Specific support practices such as short grass strips, gravel bags and silt fences are identified as very effective erosion control measures in reducing soil erosion from 45% to 85%. These results will be very useful in soil erosion prediction planning and conservation management in NSW.Master of Engineering (Hons)
21
Tengbeh, G. Tamba. „The effect of grass cover on bank erosion“. Thesis, Cranfield University, 1989. http://dspace.lib.cranfield.ac.uk/handle/1826/3620.
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The scour experiments on the bare root-free and root-permeated soils indicated that for each soil, critical tractive force (CTF) linearly increases with both root density and vane shear strength. However, for both soilsq CTF was mainly related to vaneýshear strengthp indicating the potential importance of soil shear strength as an index of scour erodibility of cohesive channel bank materials. The analysis of the relative effects of the grass vegetation parameters on scour resistance confirmed the dominance of vegetation shoots relative to the roots in resisting scour in-non-bending vege- tation. The results showed that it is the initial introduction of vegetation into bare (root-free) bank conditions that produces the greatest increase in scour resistance and that subsequent increases in vegetation density bring about relatively lower increases in scour resistance. However, in all the vegetation densities studied, root- permeated so-ils contributed significantly to scour resistance in low flows especially through low vegetation densities. Compared to root- free soil conditions, sandy clay loam soils permeated with 1.8 g/CM3 of roots increased their scour resistance by more than 400%. Althgouh these results may only be indicative of the low flow depths as would exist in shallow grassed channels commonly used for agricultural run- off drainage, they nevertheless highlight the importance of root density in contributing to the total flow resistance of grassed channel banks. The bank stability analysis indicated that for low channel banks (1.5m high), grass roots can stabilise banks with even vertical slopes against toe and slope vailures. For high (2.25m) and vertical bank conditions, the results indi- cate that the effects of increases in root density may need to be com- plemented by bank shaping in order to achieve stability. The scour and bank stability findings indicate that the three most important charac- teristics for the selection of grass vegetation for bank protection are quick establishmentg the development of a stiff shoot system and a strong root mat.
22
Cumbane, Berta Lúcia. „Aplicação de sistemas de informação geográfica para a determinação do potencial natural de erosão dos solos no Distrito de Sussundenga - Moçambique“. Master's thesis, Universidade de Évora, 2012. http://hdl.handle.net/10174/15772.
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Analisa-se neste trabalho o potencial natural de erosão dos solos no Distrito de Sussundenga, Província de Manica, através da aplicação parcial da Equação Universal de Perdas do Solo (EUPS).
A motivação para este estudo surgiu da necessidade de investigação das zonas com maior susceptibilidade à erosão e disponibilização de informação de forma a minimizar os problemas de degradação ambiental. Esta motivação é acrescida pela necessidade de criação de uma base de dados contendo informação sobre a metodologia a usar na determinação dos factores que se encontram na origem da degradação dos solos de Moçambique. O interesse no Distrito de Sussundenga surge no âmbito da implementação da Convenção das Nações Unidas para o Combate à Desertificação, onde esta área foi uma das indicadas como zona de elevado risco.
O trabalho desenvolvido baseia-se essencialmente na revisão bibliográfica e modelação espacial em ambiente SIG, usando o software ArcGis 10. Os dados usados foram um Modelo Digital do Terreno, a distribuição espacial da precipitação e a caracterização dos solos, a partir dos quais se obteve os factores LS, R e K, respectivamente, do modelo USLE. No ambiente SIG fez-se a multiplicação dos mapas temáticos, resultando num mapa indicando os níveis de potencial natural de erosão do Distrito.
Do estudo feito observou-se que cerca de 50% da área do distrito apresenta valores de Potencial Natural de Erosão (PNE) inferiores a 500 ton/ha, correspondendo à classe de potencial baixo. Por outro lado, 27% da área corresponde à classe de potencial muito elevado. O factor topográfico exerce uma forte influência nestes resultados, uma vez que se verifica uma correlação positiva entre os dois factores, sendo o coeficiente de correlação igual a 99,9%; ABSTRACT: The motivation for this study emerged from the need for research of susceptible areas to erosion and providing information about guidelines to minimize the problems of environmental degradation. This motivation is increased by the need to create a database containing details for the methodology to use in determining factors that cause soil degradation in Mozambique. The interest in the district of Sussundenga comes from implementation of the UN Convention to Combat Desertification, where this area was indicated as an area of high risk.
The work is based mainly on literature review and spatial modeling in a GIS environment, using the software ArcGis 10. The data used were the digital elevation models, the spatial distribution of rainfall and soil characterization, from which the LS, R and K factors were obtained, respectively, of the USLE model. In GIS it was done the multiplication of thematic maps, resulting in a map indicating the levels of susceptibility to erosion at district.
The study showed that about 50% of the district area presents values of Natural Potential of Erosion (NPE) less than 500 ton/ha, corresponding to the class of low potential. On the other hand, 27% of the area corresponds at the class of very high erosion potential. The topographic factor exerts a strong influence on these results, since there is a positive correlation between the two factors, and the correlation coefficient is equal to 99.9%.
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Rickson, Richmal Jane. „The use of geotextiles for soil erosion control“. Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/11325.
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Geotextiles are used by engineers for a variety of applications, such as filtration, separation, slope stabilisation, drainage and soil erosion control. At present, there is little research on geotextiles for erosion control, despite the increase in their use in the field. There are no guidelines for soil conservationists or field/civil engineers to indicate which product will be most effective for any given site. Studies that do exist tend to be qualitative and descriptive, rather than quantitative and scientific. There is also very limited identification and understanding of the salient physical properties of erosion control geotextiles. The present laboratory experiments aim to contribute objective, scientific data. These experiments evaluate the performance of seven different erosion control geotextiles. The products are selected to be representative of the types of erosion control geotextile currently on the market. The products tested are four natural fibred products, including three woven bionets and one biomat. Three synthetic geomats are also tested: two are buried and one is installed on the soil surface. A bare soil plot is used as the control in all the tests. The experiments are designed to simulate erosion processes at the sub-process level. This is achieved by simulating rainsplash and overland flow, both separately, and in combination. Experimental variables used include rainfall intensity (35 mm/hr, 95 mm/hr and 115 mm/hr), overland flow rate (40 ml/sec) and soil type (sandy loam and clay loam). Runoff volume, infiltration volume and soil loss are collected for each experimental run. From the results of these tests, it is possible to indicate how geotextiles modify incoming rainfall and surface hydrology, and therefore affect rates of soil detachment and transport. The results show that erosion control effectiveness is influenced by the physical characteristics of the geotextiles tested, soil type and rainfall intensity. The products tested have insignificant effect on runoff volumes generated, but soil loss varies considerably for the different treatments. Overall, the natural, woven products Rickson, R.J. 2000 Cranfield UNIVERSITY perform most effectively, reducing soil loss significantly when compared with the bare soil control, for all experimental conditions tested. The buried, synthetic products were not as efficient at controlling soil loss: under some experimental conditions soil loss from these treatments was even greater than that observed for the bare soil control. The results are analysed in terms of the salient properties of the geotextiles, which explain their performance. The salient properties identified were: percentage ground cover provided by the geotextile, water holding capacity, Geotextile Induced Roughness, wet weight of geotextile and ability to increase overland flow depth. The limitations of the laboratory-based research are indicated, such as the problems of extrapolation from small test plots up to field scale applications, and the difficulties of controlling the interactions between the geotextiles and the experimental variables. Implications of the research to the erosion control industry are made. For existing and potential end-users of erosion control geotextiles, the decision to specify these products is not only related to technical performance (as quantified in the laboratory studies), but also to the assessment of erosion risk, costs and compliance criteria. For manufacturers, identification of the salient properties of effective erosion control geotextiles helps in the development and design of improved products. Recommendations for future research include study of the variability in geotextile performance as related to external factors such as soil type, rainfall intensity, slope steepness and slope length. Incorporating the effect of erosion control geotextiles into physically based erosion prediction models such as EUROSEM and WEPP has great potential. Identification and quantification of critical values of the salient properties of erosion control geotextiles has considerable scope. The performance of geotextiles at controlling erosion over longer time periods (greater than one storm event) requires further investigation. Finally, research into the synergistic relationships between geotextiles and vegetation also warrants further research.
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Nikkami, Davood. „Optimizing the management of soil erosion using GIS“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0025/NQ43582.pdf.
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Somba, Bunga Elim. „The use of GIS for soil erosion assessment“. Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312295.
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Eltner, Anette. „Photogrammetric techniques for across-scale soil erosion assessment“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-212516.
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Soil erosion is a complex geomorphological process with varying influences of different impacts at different spatio-temporal scales. To date, measurement of soil erosion is predominantly realisable at specific scales, thereby detecting separate processes, e.g. interrill erosion contrary to rill erosion. It is difficult to survey soil surface changes at larger areal coverage such as field scale with high spatial resolution. Either net changes at the system outlet or remaining traces after the erosional event are usually measured. Thus, either quasi-point measurements are extrapolated to the corresponding area without knowing the actual sediment source as well as sediment storage behaviour on the plot or erosion rates are estimated disrupting the area of investigation during the data acquisition impeding multi-temporal assessment. Furthermore, established methods of soil erosion detection and quantification are typically only reliable for large event magnitudes, very labour and time intense, or inflexible.
To better observe soil erosion processes at field scale and under natural conditions, the development of a method is necessary, which identifies and quantifies sediment sources and sinks at the hillslope with high spatial resolution and captures single precipitation events as well as allows for longer observation periods. Therefore, an approach is introduced, which measures soil surface changes for multi-spatio-temporal scales without disturbing the area of interest. Recent advances regarding techniques to capture high resolution topography (HiRT) data led to several promising tools for soil erosion measurement with corresponding advantages but also disadvantages. The necessity exists to evaluate those methods because they have been rarely utilised in soil surface studies.
On the one hand, there is terrestrial laser scanning (TLS), which comprises high error reliability and retrieves 3D information directly. And on the other hand, there is unmanned aerial vehicle (UAV) technology in combination with structure from motion (SfM) algorithms resulting in UAV photogrammetry, which is very flexible in the field and depicts a beneficial perspective. Evaluation of the TLS feasibility reveals that this method implies a systematic error that is distance-related and temporal constant for the investigated device and can be corrected transferring calibration values retrieved from an estimated lookup table. However, TLS still reaches its application limits quickly due to an unfavourable (almost horizontal) scanning view at the soil surface resulting in a fast decrease of point density and increase of noise with increasing distance from the device. UAV photogrammetry allows for a better perspective (birds-eye view) onto the area of interest, but possesses more complex error behaviour, especially in regard to the systematic error of a DEM dome, which depends on the method for 3D reconstruction from 2D images (i.e. options for additional implementation of observations) and on the image network configuration (i.e. parallel-axes and control point configuration). Therefore, a procedure is developed that enables flexible usage of different cameras and software tools without the need of additional information or specific camera orientations and yet avoiding this dome error. Furthermore, the accuracy potential of UAV photogrammetry describing rough soil surfaces is assessed because so far corresponding data is missing.
Both HiRT methods are used for multi-temporal measurement of soil erosion processes resulting in surface changes of low magnitudes, i.e. rill and especially interrill erosion. Thus, a reference with high accuracy and stability is a requirement. A local reference system with sub-cm and at its best 1 mm accuracy is setup and confirmed by control surveys. TLS and UAV photogrammetry data registration with these targets ensures that errors due to referencing are of minimal impact. Analysis of the multi-temporal performance of both HiRT methods affirms TLS to be suitable for the detection of erosion forms of larger magnitudes because of a level of detection (LoD) of 1.5 cm. UAV photogrammetry enables the quantification of even lower magnitude changes (LoD of 1 cm) and a reliable observation of the change of surface roughness, which is important for runoff processes, at field plots due to high spatial resolution (1 cm²). Synergetic data fusion as a subsequent post-processing step is necessary to exploit the advantages of both HiRT methods and potentially further increase the LoD.
The unprecedented high level of information entails the need for automatic geomorphic feature extraction due to the large amount of novel content. Therefore, a method is developed, which allows for accurate rill extraction and rill parameter calculation with high resolution enabling new perspectives onto rill erosion that has not been possible before due to labour and area access limits. Erosion volume and cross sections are calculated for each rill revealing a dominant rill deepening. Furthermore, rill shifting in dependence of the rill orientation towards the dominant wind direction is revealed.
Two field plots are installed at erosion prone positions in the Mediterranean (1,000 m²) and in the European loess belt (600 m²) to ensure the detection of surface changes, permitting the evaluation of the feasibility, potential and limits of TLS and UAV photogrammetry in soil erosion studies. Observations are made regarding sediment connectivity at the hillslope scale. Both HiRT methods enable the identification of local sediment sources and sinks, but still exhibiting some degree of uncertainty due to the comparable high LoD in regard to laminar accumulation and interrill erosion processes. At both field sites wheel tracks and erosion rills increase hydrological and sedimentological connectivity. However, at the Mediterranean field plot especially dis-connectivity is obvious. At the European loess belt case study a triggering event could be captured, which led to high erosion rates due to high soil moisture contents and yet further erosion increase due to rill amplification after rill incision. Estimated soil erosion rates range between 2.6 tha-1 and 121.5 tha-1 for single precipitation events and illustrate a large variability due to very different site specifications, although both case studies are located in fragile landscapes. However, the susceptibility to soil erosion has different primary causes, i.e. torrential precipitation at the Mediterranean site and high soil erodibility at the European loess belt site.
The future capability of the HiRT methods is their potential to be applicable at yet larger scales. Hence, investigations of the importance of gullys for sediment connectivity between hillslopes and channels are possible as well as the possible explanation of different erosion rates observed at hillslope and at catchment scales because local sediment sink and sources can be quantified. In addition, HiRT data can be a great tool for calibrating, validating and enhancing soil erosion models due to the unprecedented level of detail and the flexible multi-spatio-temporal application.
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Karim, Md Zahidul. „Characterizing soil erosion potential using electrical resistivity imaging“. Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32899.
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Master of ScienceDepartment of Civil Engineering
Stacey Tucker-Kulesza
The erosion rate, or erodibility, of soil depends on many soil characteristics including: plasticity, water content, grain size, percent clay, compaction, and shear strength. Many of these characteristics also influence soil in situ bulk electrical resistivity (ER) measurements. The objective of this study was to characterize soil erosion potential by correlating the in situ ER of soil with erodibility measured in the Kansas State University Erosion Function Apparatus (KSU-EFA). ER surveys were conducted at eleven bridge sites. Soil samples were also collected at each site with a drill rig from the surface to three meters using thin-walled Shelby tubes. Five samples were collected at each site, tested in the KSU-EFA, and classified according to the Unified Soil Classification System. Analysis showed that the rapid in situ data obtained from an ER survey can be used to categorize the level of erodibility. As such, ER surveys may be used to characterize the soils at future bridge sites or prioritize existing bridges for additional testing to measure the scour potential. Moreover, ER surveys may be used to determine which existing bridges should be closed or closely monitored for scour potential during a flood event. Analytical models to predict critical shear stress using ER and other soil parameters were constructed.
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Parks, Olivia Waverly. „Effect of water temperature on cohesive soil erosion“. Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/49663.
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In light of increased stream temperatures due to urbanization and climate change, theeffect of water temperature on cohesive soil erosion should be explored. The objectives of this study are to: determine the effect of water temperature on the erosion rates of clay; determine how erosion rates vary with clay mineralogy; and, explore the relationship between zeta potential and erosion rate. Samples of kaolinite- and montmorillonite-sand mixtures, and vermiculite-dominated soil were placed in the wall of a recirculating flume channel using a vertical sample orientation. Erosion rate was measured under a range of shear stresses (0.1-20 Pa) for a period of five minutes per shear stress at water temperatures of 12, 20, and 27�"C. The zeta potential was determined for each clay type at the three testing temperatures and compared to mean erosion rates. The kaolinite erosion rate doubled when the temperature increased from 12 to 20�"C, and erosion of vermiculite samples tripled when the temperature increased from 20 to 27�"C. The montmorillonite samples generally eroded through mechanical failure rather than fluvial erosion, and the limited fluvial erosion of the montmorillonite-sand mixture was not correlated with water temperature. The data suggest correlation between zeta potential and erosion rate; however, due to the small sample size (n=3), statistically significant correlation was not indicated. Research should continue to explore the influence of water temperature on cohesive soil erosion to better understand the influence of clay mineralogy. Due to the high degree of variability in cohesive soil erosion, multiple replications should be used in future work. The vertical sample orientation enabled discrimination between fluvial erosion and mass wasting and is recommended for future studies.
Master of Science
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Chengere, Adera. „Soil erosion and crop productivity : assessment and prediction /“. The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487843314694652.
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Rickson, R. J. „The use of geotextiles for soil erosion control“. Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/11325.
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Geotextiles are used by engineers for a variety of applications, such as filtration,
separation, slope stabilisation, drainage and soil erosion control. At present, there is
little research on geotextiles for erosion control, despite the increase in their use in the
field. There are no guidelines for soil conservationists or field/civil engineers to
indicate which product will be most effective for any given site. Studies that do exist
tend to be qualitative and descriptive, rather than quantitative and scientific. There is
also very limited identification and understanding of the salient physical properties of
erosion control geotextiles.
The present laboratory experiments aim to contribute objective, scientific data. These
experiments evaluate the performance of seven different erosion control geotextiles.
The products are selected to be representative of the types of erosion control
geotextile currently on the market. The products tested are four natural fibred
products, including three woven bionets and one biomat. Three synthetic geomats are
also tested: two are buried and one is installed on the soil surface. A bare soil plot is
used as the control in all the tests. The experiments are designed to simulate erosion
processes at the sub-process level. This is achieved by simulating rainsplash and
overland flow, both separately, and in combination. Experimental variables used
include rainfall intensity (35 mm/hr, 95 mm/hr and 115 mm/hr), overland flow rate
(40 ml/sec) and soil type (sandy loam and clay loam). Runoff volume, infiltration
volume and soil loss are collected for each experimental run. From the results of these
tests, it is possible to indicate how geotextiles modify incoming rainfall and surface
hydrology, and therefore affect rates of soil detachment and transport.
The results show that erosion control effectiveness is influenced by the physical
characteristics of the geotextiles tested, soil type and rainfall intensity. The products
tested have insignificant effect on runoff volumes generated, but soil loss varies
considerably for the different treatments. Overall, the natural, woven products
Rickson, R.J. 2000
Cranfield
UNIVERSITY
perform most effectively, reducing soil loss significantly when compared with the
bare soil control, for all experimental conditions tested. The buried, synthetic products
were not as efficient at controlling soil loss: under some experimental conditions soil
loss from these treatments was even greater than that observed for the bare soil
control.
The results are analysed in terms of the salient properties of the geotextiles, which
explain their performance. The salient properties identified were: percentage ground
cover provided by the geotextile, water holding capacity, Geotextile Induced
Roughness, wet weight of geotextile and ability to increase overland flow depth.
The limitations of the laboratory-based research are indicated, such as the problems of
extrapolation from small test plots up to field scale applications, and the difficulties of
controlling the interactions between the geotextiles and the experimental variables.
Implications of the research to the erosion control industry are made. For existing and
potential end-users of erosion control geotextiles, the decision to specify these
products is not only related to technical performance (as quantified in the laboratory
studies), but also to the assessment of erosion risk, costs and compliance criteria. For
manufacturers, identification of the salient properties of effective erosion control
geotextiles helps in the development and design of improved products.
Recommendations for future research include study of the variability in geotextile
performance as related to external factors such as soil type, rainfall intensity, slope
steepness and slope length. Incorporating the effect of erosion control geotextiles into
physically based erosion prediction models such as EUROSEM and WEPP has great
potential. Identification and quantification of critical values of the salient properties
of erosion control geotextiles has considerable scope. The performance of geotextiles
at controlling erosion over longer time periods (greater than one storm event) requires
further investigation. Finally, research into the synergistic relationships between
geotextiles and vegetation also warrants further research.
31
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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Mutter, Ghazi Maleh. „Water erosion of calcareous soils in South-East England“. Thesis, Imperial College London, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318679.
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Nguyen, Gia Huynh Truong. „Evaluating soil erodibility parameters with mini-JET under various soil moisture conditions“. Kansas State University, 2016. http://hdl.handle.net/2097/34526.
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Master of ScienceDepartment of Biological & Agricultural Engineering
Aleksey Y. Sheshukov
Soil erosion is one of the main reasons for agricultural land degradation in the world. Losses of land because of high soil erosion rates and rapidly expanding population result in significant reduction of cultivated land area per capita, and shortage of food on the global scale. Soil erosion can be a major source of sediment in the aquatic systems leading to reduction of organism population and poor water quality. Many factors affect soil erodibility, such as, soil properties, rainfall, topographic features, land use, and management practices, among others. The impacts of soil moisture content, however, are not well understood and. therefore, the primary goal of this study was to quantify two soil erodibility parameters, the erodibility coefficient and critical shear stress, under different soil moisture conditions using the jet erosion test (JET). The JET test uses the apparatus (called mini-JET) that creates an impinging jet of water into the soil and records the resulting scour depth over time. The scour depth time series are then fitted into a non-linear soil erosion equation, yielding the sought values of erodibility parameters. For this study, more than 40 soil samples were collected from several sites in Kansas, processed, and prepared to conduct JET tests in the lab setting. The effects of tillage and soil moisture content were of interest to this study. The results showed varied effects of soil type and sample soil moisture condition on the scour depth development and parameters sensitivity. The critical shear stress decreased and the erodibility coefficient increased with the increase of initial moisture content for clay loam soil, while critical shear stress did not change for sandy loam soil. The study also revealed higher erosive properties of soil collected from the tilled field compared to the no-till field.
34
Pudasaini, Madhu Sudan. „Erosion modelling under different land use management practices“. View thesis, 2003. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20040401.140345/index.html.
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Mobley, Thomas Jackson Melville Joel G. „Erodibility testing of cohesive soils“. Auburn, Ala, 2009. http://hdl.handle.net/10415/1776.
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Kelsey, Kurt L. „Use of the Revised Universal Soil Loss Equation (Rusle) to predict event soil loss /“. Link to abstract, 2002. http://epapers.uwsp.edu/abstracts/2002/Kelsey.pdf.
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Woodun, Jayashree Khanta. „Surface crusting of soils from the South Downs in relation to soil erosion“. Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270498.
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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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Al-Ali, Abdullah Mubarak Abdulmohsen. „Temperature effects on fine-grained soil erodibility“. Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32514.
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Master of ScienceCivil Engineering
Stacey Tucker
Recent climate changes may affect the stability of our infrastructure in many ways. This study investigated the effects of fine-grained soil temperature on erosion rate. If climate change is shown to affect the erodibility of soils the impacts must be identified to monitor the stability of existing infrastructure, improve design of levees and structures founded in erosive environments, and to prevent sediment loss and stream meanders. Fine-grained soil erosion is complicated by the dynamic linkage of multiple parameters, including physical, biological and geochemical properties. This study held constant all parameters that influence fine-grained soil erodibility while only varying soil temperature in order to study the effects it has on erodibility. This study also confirmed previous findings that water temperature affects soil erodibility. The main objective of this study was to investigate the effects of fine-grained soil temperature on erosion rate. This study also instrumented a turbidity sensor to reliably map soil erosion. Based on this research, the conclusion was made that an increase in soil temperature increases soil erosion rate. The turbidity sensor was a valuable tool for comparing soil erosion. Future studies should investigate the effects soil temperatures below room temperature, the magnitude of temperature increase or decrease, and the effects of cyclic heating and cooling on fine grained soil erodibility.
40
Schmidt, Walter, und Marcus Schindewolf. „Erosion 3D Sachsen“. Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-38172.
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Für die Erstellung von Bewirtschaftungs- und Maßnahmenplänen (FFH, EU-WRRL) ist es erforderlich, den bislang noch sehr hohen Aufwand für die Datenbeschaffung und -generierung im Rahmen der Modellierung mit EROSION 3D zu senken. Erreicht werden soll eine schnellere sowie effizientere Abschätzung von Landnutzungsänderungen, Landschaftseingriffen, des Klimawandels usw. auf Oberflächenabfluss, Bodenabtrag sowie Sedimenteintrag in Gewässer mit EROSION 3D.
Im vorliegenden Projekt ist es gelungen, Parametrisierung und Modellanwendung so zu kombinieren, dass eine Bodenabtragssimulation mit dem Modell EROSION 3D flächendeckend für Sachsen mit vertretbarem Zeitaufwand durchführbar ist.
Der korrigierte und angepasste Geo-Basisdatensatz liefert die Primärinformationen zur Datenbankabfrage der Parametrisierungssoftware DPROC. Durch eine interaktive Flächenauswahl, kombiniert mit einem Flächendatenzuschnitt, können Landnutzungs- und Bearbeitungsszenarien für hydrologische Einzugsgebiete oder Oberflächenwasserkörper schnell parametrisiert werden. Die grundlegend korrigierte und erweiterte Datenbank des DPROC erlaubt die verbesserte Abschätzung erosionsrelevanter Bodenparameter, besonders für die dauerhaft konservierende Bodenbearbeitung und die Direktsaat. Die umfangreiche Dokumentation der Arbeitsschritte und die Transparenz der Datenbank ermöglichen es, jederzeit Aktualisierungen (Geo-Basisdaten) und Erweiterungen (DPROC-Datenbank) vorzunehmen.
Von den Projektergebnissen profitieren vor allem die Anwender des Programms EROSION 3D.
Beim Druck des Dokumentes ist zu beachten, dass die Karten im Format DIN A3 erstellt wurden.
41
Kunta, Karika. „Effects of geographic information : quality on soil erosion prediction /“. [S.l.] : [s.n.], 2009. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18136.
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Newman, James Kenneth. „Soil erosion prediction for shaping conservation policy and practice“. [Ames, Iowa : Iowa State University], 2010. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3403858.
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Le, Roux Jacobus Johannes. „Soil erosion prediction under changing land use on Mauritius“. Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-06122006-105202.
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Pricope, Narcisa. „Modeling Soil Erosion in the Upper Green River, KY“. TopSCHOLAR®, 2006. http://digitalcommons.wku.edu/theses/258.
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Off-site soil erosion has tremendous impacts on the present state of most river systems throughout the United States, contributing sediments to channels mainly as nonpoint pollution resulting from land-use and agricultural practices and leading to sedimentation downstream and downwind, a decrease in the transport capacity of streams, increase in the risk of flooding, filling reservoirs, and eutrophication. A primary focus in examining the problems associated with soil erosion arid ultimately in proposing control measures should be on identifying the sources of the sediment. Therefore, a model that would be able to assess soil erosion needs to start by identifying the sediment sources and delivery paths to channels, link these sediment supply processes to in-channel sediment transport and storage and ultimately to basin sediment yield. This study focuses on the Upper Green River Basin in Kentucky and is concerned with analyzing hillslope erosion rates using The Unit Stream Power Erosion and Deposition soil erosion model (Mitas and Mitasova, 1996) and GIS, and thereby estimating patterns of sediment supply to rivers in order to predict which portions of the channel network are more likely to store large amounts of fine sediments. Results indicate that much of the eroded sediments are redistributed within the hillslope system, but also that a large proportion is delivered to the channel. These predictions have been tested by sampling the fine sediment content of the streambed at key locations along the channel network and comparing the observed patterns to those predicted by the soil erosion model. By linking topographic and soil characteristics with land cover data, it has been concluded that high intensity erosion tends to occur at contact between different vegetation covers, on barren lands and croplands, and 15-25% slopes poorly protected by vegetation. Erosion ""hot spots"" have been identified in the Pitman Creek HUC 05110001-90-130 and 05110001-90-050, both part of the Big Pitman Creek sub-basin, as well as in Mill and Falling Timber Creeks with lower intensity.
45
Greener, Mark. „Incorporating sediment transport competence into existing soil erosion models“. Thesis, University of Leicester, 2001. http://hdl.handle.net/2381/30393.
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Competence in this thesis is defined as a limit to the maximum size of particle that can be detached and transported in rain-impacted interrill overland flow. Although there is evidence to show that there is some form of size selectivity occurring in rain-impacted interrill overland flow (i.e. competence), most modern soil erosion models do not simulate competence as a limit to erosion. Existing competence equations were not developed in the shallow rain-impacted flow that occurs in interrill areas. A new competence equation was developed in the laboratory under rain-impacted flow. The new competence equation was used to form the basis of an algorithm designed to incorporate competence in existing soil erosion models. SMODERP was chosen as a suitable model used to assess the effect of competence on rain-impacted interrill erosion. The code of SMODERP was studied and the variables required by the competence algorithm located. The competence algorithm required an input of erosion per model time step, SMODERP did not provided this and had to be modified to yield erosion per time step. The new versions of SMODERP were tested on plot scale data. The effect of competence was found to be large, reducing erosion by a factor of between 3 and 65 times. Competence had the greatest effect on erosion on lower rainfall intensity events. The competence algorithm assumed that there was no spatial or temporal change in surface texture. This assumption was investigated at the field, plot and laboratory scale. There was found to be some temporal and spatial variation in surface texture but only at the laboratory scale and to a lesser extent at the plot scale. This suggests that at smaller scales there is a spatial and temporal variation in surface texture but this variation does not occur at larger scales where other processes may dominate. This thesis has identified a limit (competence) not simulated in most soil erosion models and provided an approach to including this limit into soil erosion models. The effects of competence was shown to be large but more work is need in this area to more fully assess the effect of incorporating sediment transport competence into existing soil erosion models.
46
Menaa, Merouane. „Performance of surface structures subjected to subsurface soil erosion“. Mémoire, École de technologie supérieure, 2008. http://espace.etsmtl.ca/148/1/MENAA_Merouane.pdf.
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Plusieurs infrastructures geotechniques (ex. chaussees, dalles, fondations) exercent une
pression a travers leurs surfaces de contact avec le sol. Le dimensionnement de ces
structures suppose un contact parfait tout au long de la vie de service de celles-ci. Par
ailleurs, I'erosion des sols sous-jacents est un mecanisme qui pent contribuer au
developpement de cavites souterraines et par consequent a une perte locale de contact entre
la structure et le sol, caracterisee par un vide sous la structure.
La performance des structures telles que les chaussees en beton, les dalles ainsi que les
trottoirs sujettes a I'erosion souterraine est etudiee experimentalement et numeriquement
dans ce memoire. Les experiences ont ete menees dans un caisson en acier rigide contenant
du sable ou I'erosion souterraine a ete cree artificiellement; le tout supportant une plaque en
acier rigide. Les deformations de la surface ainsi que les pressions de contact a I'interface
plaque-sol ont ete mesurees afin de quantifier les effets de I'erosion souterraine sur les
contraintes developpees dans la structure. L'etude numerique a ete conduite en utilisant un
modele elastoplastique a 2 dimensions. Le modele a ete calibre avec les resultats
experimentaux et divers scenarios ont ete envisages. Des parametres tels que le volume du
sol erode, sa localisation ainsi que les chargements appliques sur la dalle de beton ont ete
varies. Les resultats de cette recherche ont montre que lorsque le vide est centre directement
sous la dalle, les contraintes de traction developpees dans celle-ci augmentent avec la taille
du vide provoquant ainsi la rupture de la dalle. II a egalement ete conclu que lorsque le vide
est excentre, le sol au voisinage de celui-ci est susceptible de subir une rupture avant que
des contraintes de traction excessives ne se developpent dans la fibre la plus tendue de la
dalle en beton.
47
Koeninger, Nicole K. „Determining Soil Erosion with Varying Corn Stover Cover Factors“. UKnowledge, 2015. http://uknowledge.uky.edu/bae_etds/27.
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Since the Dust Bowl, conservation agriculture has become a common practice globally. Because of the rising interest in the use of corn biomass as a feedstock for biofuel production, the effects of corn stover removal on soil erosion were explored. It was hypothesized that selective harvesting strategies would impact soil erosion differently across a variety of slopes. Soil erosion boxes were constructed, and a rainfall simulator with an intensity of 30 mm hr-1 for 46 min was used to create runoff from slopes of 1, 5, and 10% and three cover factor treatments (no removal and two simulated corn stover removal strategies). Due to research time constraints, simulated corn roots were constructed to emulate actual corn roots in all experiments. The corn stover harvest strategies change the distribution of cobs, husks, leaves, and stalks in field; these changes were represented as the cover factor treatments. Changing the type of plant material on the soil surface impacted the predicted soil erosion from the Revised Universal Soil Loss Equation (RUSLE). Based on the results from this study, the effect of corn stover cover percentages had a significant impact on the predicted and observed soil loss.
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Oliveira, Paulo Tarso Sanches de. „Water balance and soil erosion in the Brazilian Cerrado“. Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-16012015-170452/.
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Deforestation of the Brazilian savanna (Cerrado) region has caused major changes in hydrological processes. These changes in water balance and soil erosion are still poorly understood, but are important for making land management decisions in this region. Therefore, it is necessary to understand the magnitudes of hydrological processes and soil erosion changes on local, regional and continental scales, and the consequences that are generated. The main objective of the study presented in this doctoral thesis was to better understand the mechanism of hydrological processes and soil erosion in the Cerrado. To achieve that, I worked with different scales (hillslope, watershed and continental) and using data from experimental field, laboratory, and remote sensing. The literature review reveals that the annual rainfall erosivity in Brazil ranges from 1672 to 22,452 MJ mm ha-1 h-1 yr-1. The smallest values are found in the northeastern region, and the largest in the north and the southeastern region. I found that the canopy interception may range from 4 to 20% of gross precipitation and stemflow around 1% of gross precipitation in the cerrado. The average runoff coefficient was less than 1% in the plots under cerrado and that the deforestation has the potential to increase up to 20 fold the runoff coefficient value. The results indicate that the Curve Number method was not suitable to estimate runoff under undisturbed Cerrado, bare soil (hydrologic soil group A), pasture, and millet. Therefore, in these cases the curve number is inappropriate and the runoff is more aptly modeled by the equation Q = CP, where C is the runoff coefficient. The water balance from the remote sensing data across the Brazilian Cerrado indicates that the main source of uncertainty in the estimated runoff arises from errors in the TRMM precipitation data. The water storage change computed as a residual of the water budget equation using remote sensing data (TRMM and MOD16) and measured discharge data shows a significant correlation with terrestrial water storage change obtained from the GRACE data. The results show that the GRACE data may provide a satisfactory representation of water storage change for large areas in the Cerrado. The average annual soil loss in the plots under bare soil and cerrado were 15.25 t ha-1 yr-1 and 0.17 t ha-1 yr-1, respectively. The Universal Soil Loss Equation cover and management factor (C-factor) for the plots under native cerrado vegetation was 0.013. The results showed that the surface runoff, soil erosion and C-factor for the undisturbed Cerrado changes between seasons. The greatest C-factor values were found in the summer and fall. The results found in this doctoral thesis provide benchmark values of the water balance components and soil erosion in the Brazilian Cerrado that will be useful to evaluate past and future land cover and land use changes for this region. In addition, I conclude that the remote sensing data are useful to evaluate the water balance components over Cerrado regions, identify dry periods, and assess changes in water balance due to land cover and land use change.O desmatamento nas regiões de Cerrado tem causado intensas mudanças nos processos hidrológicos. Essas mudanças no balanço hídrico e erosão do solo são ainda pouco entendidas, apesar de fundamentais na tomada de decisão de uso e manejo do solo nesta região. Portanto, torna-se necessário compreender a magnitude das mudanças nos processos hidrológicos e de erosão do solo, em escalas locais, regionais e continentais, e as consequências dessas mudanças. O principal objetivo do estudo apresentado nesta tese de doutorado foi de melhor entender os mecanismos dos processos hidrológicos e de erosão do solo no Cerrado Brasileiro. Para tanto, utilizou-se diferentes escalas de trabalho (vertentes, bacias hidrográficas e continental) e usando dados experimentais in situ, de laboratório e a partir de sensoriamento remoto. O estudo de revisão de literatura indica que a erosividade da chuva no Brasil varia de 1672 to 22,452 MJ mm ha-1 h-1 yr-1. Os menores valores encontram-se na região nordeste e os maiores nas regiões norte e sudeste do Brasil. Verificou-se que os valores de interceptação da chuva variam de 4 a 20% e o escoamento pelo tronco aproximadamente 1% da precipital total no cerrado. O coeficiente de escoamento superficial foi menor que 1% nas parcelas de cerrado e o desmatamento tem o potencial de aumentar em até 20 vezes esse valor. Os resultados indicam que o método Curve Number não foi adequado para estimar o escoamento superficial nas áreas de cerrado, solo exposto (grupo hidrológico do solo A), pastagem e milheto. Portanto, nesses casos o uso do CN é inadequado e o escoamento superficial é melhor estimado a partir da equação Q = CP, onde C é o coeficiente de escoamento superficial. O balanço hídrico a partir de dados de sensoriamento remoto para todo o Cerrado Brasileiro indica que a principal fonte de incerteza na estimativa do escoamento superficial ocorre nos dados de precipitação do TRMM. A variação de água na superfície terrestre calculada como o residual da equação do balanço hídrico usando dados de sensoriamento remoto (TRMM e MOD16) e valores observados de vazão mostram uma correlação significativa com os valores de variação de água na superfície terrestre provenientes dos dados do GRACE. Os dados do GRACE podem representar satisfatoriamente a variação de água na superfície terrestre para extensas regiões do Cerrado. A média anual de perda de solo nas parcelas de solo exposto e cerrado foram de 15.25 t ha-1 yr-1 and 0.17 t ha-1 yr-1, respectivamente. O fator uso e manejo do solo (fator C) da Universal Soil Loss Equation para o cerrado foi de 0.013. Os resultados mostraram que o escoamento superficial, erosão do solo e o fator C na área de cerrado variam de acordo com as estações. Os maiores valores do fator C foram encontrados no verão e outono. Os resultados encontrados nesta tese de doutorado fornecem valores de referência sobre os componentes do balanço hídrico e erosão do solo no Cerrado, que podem ser úteis para avaliar o uso e cobertura do solo atual e futuro. Além disso, conclui-se que os dados de sensoriamento remoto apresentam resultados satisfatórios para avaliar os componentes do balanço hídrico no Cerrado, identificar os períodos de seca e avaliar as alterações no balanço hídrico devido à mudanças de uso e cobertura do solo.
49
Abbott, James T. „Late Quaternary alluviation and soil erosion in Southern Italy /“. Digital version accessible at:, 1997. http://wwwlib.umi.com/cr/utexas/main.
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Prosdocimi, Massimo. „Land degradation in agricultural landscapes-Soil erosion by water“. Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422396.
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Land degradation is a well-known problem throughout the world, due to its possible threat to land resources and strict connection with other global environmental issues such as biodiversity and climate. It is widely accepted that the major causes of land degradation include deforestation, soil erosion, overgrazing, inappropriate irrigation, abandonment and/or lack of maintenance of agricultural terraces, land use and cover change, especially because of urban sprawl and commercial development, soil pollution and quarrying. Among land degradation phenomena, soil erosion is one of the most significant issues that negatively influence the agricultural sector. In particular, soil erosion caused by water is one of the most important concern, especially in the Mediterranean area. Among the agricultural landscapes, vineyards deserve attention, because, not only they represent one of the most important crops in terms of income and employment, but they have also demonstrated to constitute, for the Mediterranean areas, the form of agricultural land use that has been causing the highest soil losses. Terraced vineyards deserve a particular mention too. In fact, they represent an important cultural heritage to preserve and if, if not properly maintained, can lead to local instabilities creating hazards for settlements and cultivations, and for the related economy. Although researchers have already dealt with the topic of soil erosion by water in agriculture, there are still some gaps in literature. The processes involved are complex and the analyses can be carried out at different spatial and temporal scales. Indeed, the lack of standardized procedures of collecting data and the variability of temporal and spatial conditions and measurement techniques for the analysis of soil water erosion processes require further research. To overcome these issues, this thesis aims to propose an integrated approach, by means of innovative remote-sensing technologies, field activities, and quantitative analyses to the investigation of soil erosion processes caused by water in agricultural landscapes. Furthermore, this thesis wants also to suggest a possible soil management technique, namely mulching, as an effective solution to mitigate soil and water losses in the before-mentioned environments. Among the remote-sensing technologies, light detection and ranging (LiDAR) and structure-from-motion (SfM) have been applied in this thesis. These have proven to be effective to obtain high-resolution Digital Elevation Models (DEMs). Experimental plots under simulated rainfalls have also been used to quantify and analyze the soil and water losses caused by water. Typical agricultural landscapes, especially Mediterranean vineyards, have been selected as study areas for this thesis.La degradazione del suolo è un problema conosciuto in tutto il mondo, a causa delle sue ripercussioni negative sulle risorse del territorio e della sua stretta connessione con altre questioni di tipo ambientale diffuse a livello globale quali la biodiversità ed il clima. E' ampiamente risaputo che le principali cause della degradazione del suolo sono la deforestazione, l'erosione del suolo, il pascolo intensivo, l'inadeguata irrigazione, l'abbandono e/o la scarsa manutenzione delle aree agricole terrazzate, il cambio di uso e copertura del suolo, soprattutto a causa dell'espansione urbana e dello sviluppo commerciale, l'inquinamento del suolo e le attività minerarie. Tra i fenomeni di degradazione, l'erosione del suolo rappresenta uno degli aspetti che maggiormente influenzano negativamente il settore agricolo, ed in particolare, l'erosione idrica del suolo è uno di quelli che più colpisce il bacino del Mediterraneo. Tra i diversi tipi di colture, i vigneti sono quelli che meritano più attenzione. Infatti, non solo essi rappresentano una delle coltivazioni più redditizie, ma hanno anche dimostrato di essere caratterizzati, all'interno del bacino del Mediterraneo, dai più alti tassi di erosione del suolo. Anche i vigneti terrazzati meritano una menzione particolare. Essi costituiscono un importante patrimonio culturale da preservare e, se non vengono adeguatamente mantenuti, possono causare instabilità locali mettendo in pericolo la sicurezza dei centri abitati, e la produttività delle colture stesse, con conseguenze negative sulla relativa economia. Nonostante l'erosione idrica del suolo in agricoltura sia già stato oggetto di studio da parte di molti ricercatori, permangono tuttavia delle lacune in letteratura. Infatti, i processi coinvolti sono complessi e le analisi che sono effettuate possono riguardare scale sia temporali che spaziali diverse. Per di più, la mancanza di procedure standardizzate per la raccolta dei dati e la variabilità delle condizioni temporali e spaziali, che influenzano i processi, e delle tecniche di misura utilizzate, fanno sì che ulteriori ricerche debbano essere portate avanti. Per ovviare a queste problematiche, questa tesi ha lo scopo di proporre un approccio integrato basato su tecnologie innovative e a basso costo per il telerilevamento, rilievi di campo, ed analisi quantitative al fine di studiare i processi di erosione idrica che caratterizzano gli ambienti agricoli. Inoltre, questa tesi si propone anche di suggerire una possibile tecnica di gestione del suolo, quale la pacciamatura, come soluzione efficace per attenuare le perdite di suolo ed acqua negli ambienti prima menzionati. Tra le tecnologie per il telerilevamento, il LiDAR (light detection and ranging) e la SfM (structure-from-motion) sono quelle che sono state impiegate in questa tesi. Queste tecnologie hanno dimostrato di essere efficaci al fine di ottenere modelli digitali dell'elevazione (DEM-Digital Elevation Models) ad alta risoluzione. Questa tesi ha visto l'impiego anche di parcelle sperimentali sottoposte a simulazioni di pioggia per quantificare ed analizzare le perdite di suolo ed acqua causate dalle precipitazioni. Le aree di studio per questa tesi sono state selezionate all'interno di tipici ambienti agricoli, specialmente vigneti situati nel bacino del Mediterraneo.