Rural agriculture in Mlondozi, as for South Africa, is has a low productivity, which is the result of poor knowledge, information, beliefs and land tenure which limits the acquiring of loans for inputs. A LandCare Project was conducted for four years. Training was in the form of farmer managed research demonstrations which included the taught Conservation agriculture farming system which they compared to the Traditional farming system. Eighteen farmers initially joined the program and their soils were monitored for four years. At the end of the project undisturbed soil samples were taken from their fields where maize was cultivated following no-till (NT) farming system, and the conventional tillage system (CT). The soils from the two farming systems were compared using a laboratory rainfall simulator for run-off, erosion and infiltration. Each storm event in the rainfall simulator lasted for a period of 110 minutes (50 rotations). There were two statistical analyses done on the results. The first was a t-test was applied to the data to test for differences between the two systems, with a sample size of 72, at 18 sights with 4 replicates, except for carbon which was 36 analyses for the 18 sights. There was a significantly higher soil loss for NT soils for storm 1, compared to the CT soil, and a non significant difference for run-off for storms 1 and 2. Infiltration was significantly lower for the NT soil for the first storm, and not significantly higher for the NT soil for the second storm. The CT soils had a significantly higher infiltration rate for the first 16 rotations. After 68 minutes (rotation 34) the NT soils infiltration rate was higher. For simulated storm 2 the CT soils had a slightly higher infiltration rate up to 32 minutes (16 rotations) where after NT soils had a higher infiltration rate. Between 48 and 80 minutes (rotations 24 and 40) the NT soils had a significantly higher infiltration rate. From the results it can be concluded that the NT soils maintained the aggregate stability far longer than the CT soils. The initial and final infiltration rates were compared for the NT and CT soils for the simulated storms 1 and 2. The CT soils’ initial and final infiltration rate was similar, while the NT soils had a higher initial and final infiltration rate for the second storm, due to the soils settling with the first storm. The results question current literature that states that sealing of soils is a permanent feature. The carbon content of the NT soils was not significantly higher than the CT soils, which corresponded with the results. / Dissertation MInst (Agrar)--University of Pretoria, 2014 / gm2015 / Plant Production and Soil Science / MInst (Agrar) / Unrestricted

Orientador: Archimedes Perez Filho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-22T04:45:44Z (GMT). No. of bitstreams: 1 Quaresma_CristianoCapellani_D.pdf: 11456086 bytes, checksum: ac3b2ad24ae2edbaa1dd18ac224886b6 (MD5) Previous issue date: 2012 / Resumo: Com base na Teoria do Equilíbrio Dinâmico e na abordagem sistêmica, formulou-se a hipótese de que a gênese e a aceleração de processos erosivos, identificados atualmente na bacia do Rio Santo Anastácio-SP/Brasil, resultam de rompimento do equilíbrio dinâmico, com conseqüente reativação da rede de drenagem. Tratam-se, portanto, de exemplos de processos e formas antropogeomorfológicos, tendo em vista que foram desencadeados pelo uso e ocupação das terras, que desrespeitaram fragilidades e dinâmicas naturais, bem como por alterações no nível de base local pela construção da Usina Hidrelétrica de Porto Primavera. Assim, adotou-se método comparativo dos anos de 1962 e 2010 com base em 85 amostras circulares de 10km2, distribuídas a fim de abarcarem o maior número de canais de primeira ordem, bem como de diferentes elementos físicos. Na seqüência, para o ano de 1962, traçaram-se as redes de drenagem, a fim de comparar índices (Densidade de drenagem e Densidade hidrográfica), e elaborou-se mapa de uso e ocupação das terras, com base em fotointerpretação por estereoscopia de 332 fotografias aéreas e, para fins comparativos, o mesmo procedimento foi realizado para o ano de 2010, utilizando-se de 24 cenas - ALOS/ PRISM e AVNIR2. Os resultados foram confrontados com mapas pedológico, geológico e geomorfológico da área de estudo, os quais foram digitalizados e vetorizados. Além disso, a obtenção de dados de precipitações pluviométricas permitiu melhor entendimento dos padrões de precipitação da área, e trabalhos de campo possibilitaram o reconhecimento da área e a reambulação dos mapas produzidos. Os resultados permitiram verificar que a rede de drenagem encontra-se em estado de desequilíbrio, pelo menos, desde a década de 60. Este estado manifesta-se pela retomada erosiva acelerada da rede de drenagem, em busca do restabelecimento de perfis de equilíbrio, mais ajustados em relação ao aumento brusco de entrada de matéria e de energia, ocasionado, sobretudo pelo desmatamento nas primeiras décadas de ocupação / Abstract: Based on the Theory of Dynamic Equilibrium and systemic approach, formulated the hypothesis that the origin and acceleration of erosion, currently identified in the River Basin Santo Anastácio-SP/Brazil, result from disruption of the dynamic balance, with subsequent reactivation of the drainage network, examples of geomorphological processes and forms with anthropogenic genesis, considering that were triggered by the use and occupation of land, that disrespected weaknesses and natural dynamics, as well as changes in local base level for the construction of the Porto Primavera Hydroelectric Plant. Thus, the years 1962 and 2010 were compared, based on 85 samples with circular 10km2, distributed with the goal of straddling the largest number of first-order channels, and different physical elements. Subsequently, for the year 1962 were traced drainage networks to compare indexes Drainage density and Density hydrographic, and the map has been prepared for use and occupation of land, based on photointerpretation of 332 stereoscopic aerial photographs and, for comparative purposes, the same procedure was performed for the year 2010, using 24 scenes - ALOS / PRISM and AVNIR2. The results were compared with pedological, geological and geomorphological maps, which were scanned and vectorized. Furthermore, data from rainfall allowed better understanding of the patterns of precipitation in the area, and field work enabled the recognition of the area, and the correction of maps produced. Results showed that the drainage system is in a state of imbalance, at least since the 60s. This condition is manifested by erosions' reactivation of the drainage network, seeking the restoration of equilibrium profiles, more consistent with the new entry conditions of matter and energy, caused mainly by deforestation in the early decades of occupation / Doutorado / Análise Ambiental e Dinâmica Territorial / Doutor em Geografia

La question du changement de la couverture terrestre est devenue importante dans le monde entier au cours des dernières années, non seulement pour les chercheurs, mais aussi pour les planificateurs urbains et les écologistes qui préconisent l'utilisation durable des terres dans l'avenir. En Europe méditerranéenne, les caractéristiques de couverture du sol ont considérablement changé depuis la Seconde Guerre mondiale en raison des activités humaines intensives, de la croissance de la population, et de l'étalement urbain et touristique. La plupart des études antérieures sur les changements de l’occupation du sol dans la région méditerranéenne se sont centrées sur un problème particulier et / ou ont décrit un type spécifique de changement de la couverture terrestre. Peu de recherches ont pris en compte les transformations de plusieurs catégories d’occupation du sol en même temps. De même, rares sont les travaux qui considèrent plusieurs variables dans le changement de l’occupation du sol au cours du temps, au-delà des traditionnels effets de l’altitude et de la pente. Nous souhaitons ici intégrer la variété des catégories et des composantes d’évolution. En outre, si certaines études à propos de la modélisation des mutations de la couverture terrestre se concentrent sur les variables d’influence, peu se penchent sur l’influence de la période historique et des échelles de temps différentes sur la prédiction. Ainsi, dans cette thèse, les changements de l’occupation du sol ont été prédits en utilisant différentes échelles de temps pour évaluer les impacts de la période historique dans la prédiction de la carte de la couverture terrestre d'ici 2025. Enfin, si l’étendue spatiale varie dans les différentes recherches, il semble utile de s’interroger sur les effets de la taille du terrain d’étude et de la résolution des cellules prises en compte, dans la prédiction. Les transformations de l’occupation du sol ont un impact significatif sur la dégradation des terres, y compris l'érosion des sols. / The European Mediterranean coastal area has experienced widespread land cover change since 1950 because of rapid urban growth and expansion of tourism. Urban sprawl and other land cover changes occurred due to post-war economic conditions, population migration, and increased tourism. Land cover change has occurred through the interaction of environmental and socio-economic factors, including population growth, urban sprawl, industrial development, and environmental policies. In addition, rapid expansion of tourism during the last six decades has caused significant socioeconomic changes driving land cover change in Euro-Mediterranean areas. Mediterranean countries from Spain to Greece experienced strong urban growth from the 1970’s onwards, and a moderate growth rate is projected to continue into the future. Land cover change can result in environmental changes such as water pollution and soil degradation. Several previous studies have shown that Mediterranean vineyards are particularly vulnerable to soil erosion because of high rainfall intensity and the fact that vineyards are commonly located on steeper slopes and the soil is kept bare during most of the cultivation period (November to April) when precipitation is at its highest. The main objective of this thesis is to predict long-term soil erosion evolution in a Mediterranean context of rapid urban growth and land use change at the catchment scale. In order to achieve this, the following specific aims have been formulated: (i) to analyze the spatial dynamics of land cover change from 1950 to 2008; (ii) to compare the impact of historical time periods on land cover prediction using different time scales; (iii) to test the impacts of spatial extent and cell size on LUCC modeling; and (iv) to predict the impact of land cover change on soil erosion for 2025.

The subject of the Master´s thesis is to design comprehensive flood control measures in the catchment Lhotecký stream in the built up areas of Nová Lhota village, who for several years struggling with the problem of water entering into the urban area during heavy rainfall. On the basis of this Master´s thesis, was created study of resolving the issue of flooding in the village, to a lesser extent, soil erosion and not least improve the ecological stability of the landscape around. For the analysis of the current situation was used digital maps in the GIS and subsequent application of the calculated values to the model DesQ. Through the standard formulas for dimensioning was created for a comprehensive protection of the village. This proposal will in the future serve as a basis for comprehensive land consolidation.

L’érosion des sols constitue une menace majeure pour la durabilité de la production agricole. Cette étude vise à développer une méthode originale de traçage des sédiments au sein de deux bassins versants agricoles aux caractéristiques contrastées. Différents marqueurs ont été utilisés pour tracer l’origine lithologique des particules (concentrations élémentaires, rapports ⁸⁷Sr/⁸⁶Sr), déterminer de quel compartiment des sols (surface ou profondeur) elles proviennent (¹³⁷Cs) et étudier leur dynamique temporelle (⁷Be, ²¹⁰Pb_xs). Sur le bassin du Louroux (24 km², France), caractéristique des plaines agricoles du Nord-Ouest de l’Europe, les résultats ont montré un transfert accru de particules très fines (<2µm) via le réseau de drainage. Lors de l’étude de trois crues successives, les sédiments accumulés dans le chenal ont d’abord été transportés, avant l’exportation de particules directement érodées de la surface des sols. L’utilisation de modèles de mélange a montré que les particules érodées à la surface des sols contribuent majoritairement aux sédiments de l’étang situé à l’exutoire. D’autre part, les deux zones lithologiques discriminées par le rapport ⁸⁷Sr/⁸⁶Sr contribuent équitablement aux particules qui se déposent dans l’étang. Les fortes variations observées depuis les années 1950 peuvent être interprétées comme le résultat de l’aménagement du bassin. Ces résultats ont montré le potentiel de l’isotopie du strontium (⁸⁷Sr/⁸⁶Sr) pour le traçage lithologique des sources de particules. La méthode a dès lors été transposée au site de Guaporé (2000 km², Brésil), un bassin agricole au climat plus érosif, à la topographie plus accentuée et aux lithologies plus contrastées. En combinant les rapports ⁸⁷Sr/⁸⁶Sr et les éléments les plus discriminants des cinq types de sols dans les modèles de mélange, les résultats montrent une contribution très majoritaire des types de sol localisés en aval du bassin. Celle-ci reflète une sensibilité croissante des sols à l’érosion selon un transect amont-aval, avec un système d’agriculture intensive appliquant des techniques de conservation des sols à l’amont et de plus petites exploitations familiales qui pratiquent un labour traditionnel en aval. Le couplage de ces traceurs améliore la compréhension de la dynamique des particules à l’échelle du bassin versant et fournit des données spatio-temporelles essentielles pour mettre en place des mesures de lutte contre l’érosion des sols. À terme, ces données pourraient être utilisées pour valider des modèles d’érosion et de transfert particulaire. / Soil erosion is recognized as one of the main processes of land degradation in agricultural environments. This study develops an original fingerprinting method to examine sediment source contributions in two contrasted agricultural catchments. Several properties were used to trace sediment lithological sources (⁸⁷Sr/⁸⁶Sr ratios, elemental concentrations), soil surface and subsurface sources (¹³⁷Cs) and to quantify their temporal dynamics (⁷Be, ²¹⁰Pb_xs).In the Louroux catchment (24 km², France), representative of drained areas of Northwestern Europe, results showed the dominant contribution of very fine particles (<2 µm) transiting through the tile drainage system to suspended sediment. Sediment accumulated in the river channel was mainly exported during the two first floods investigated in 2013 whereas the next event was characterized by the transport of sediment eroded from the cultivated soil surface. Mixing models were used, and results indicated that surface sources contributed the majority of sediment deposited in the pond, at the outlet of the catchment. The two lithological sources, discriminated using ⁸⁷Sr/⁸⁶Sr ratios, contributed in similar proportions to downstream pond sediment. In contrast, significant variations were observed since the 1950s. These changes may be related to the progressive implementation of land consolidation schemes within the catchment. Results obtained in the Louroux catchment revealed the potential of ⁸⁷Sr/⁸⁶Sr ratios to trace sediment lithological sources. The methodology was then applied to the larger and steeper Guaporé catchment (2000 km², Brazil), exposed to a more erosive climate and characterized by contrasted laterite soils. ⁸⁷Sr/⁸⁶Sr ratios and elements that discriminated the five soil types found in the catchment were incorporated in mixing models. Results showed that the major part of sediment was supplied by soils located in lower catchment parts. This result suggests the higher sensitivity of land cultivated with conventional farming practices (downstream contribution), compared to areas cultivated under conservation agriculture (upstream contribution). Coupling several tracers (⁸⁷Sr/⁸⁶Sr ratios, elemental concentrations and radionuclides) was shown to improve the understanding of sediment sources and dynamics at the catchment scale and to provide crucial information to guide the implementation of management measures to limit soil erosion. This fingerprinting approach produced an original dataset that may be used to calibrate and validate models simulating erosion and sediment transfers.

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.

A study of soil erosion in the United States, especially in Texas, which brings attention to the causes of soil erosion under the existing system of farm management. The material gathered and compiled and arranged under certail main heading. Two chapters deal with present and immediate causes of erosions and their results. One full chapter takes up the history of the conservation movement and attempts to show how slow Texans have been in comparison with some of the other states of the United States. The study calls for further research, teaching of better land-use, raising awareness of soil erosion causes and conditions.

Auf der Grundlage von Szenarien zu künftigen Starkregenereignissen wurde mit dem Modell Erosion-3D die Entwicklung der Bodenerosion durch Wasser berechnet. Eine Analyse der projizierten Starkregenereignisse zeigt, dass durch den Klimawandel die Häufigkeit der sommerlichen Starkregenereignisse abnimmt und die Starkregenintensität zunimmt. Landnutzung und unterschiedliche Bodenbearbeitungsverfahren haben allerdings einen bedeutend größeren Einfluss auf das Ausmaß der Bodenerosion als die künftig zu erwartenden Starkregenereignisse.

In mehrjährigen Stoppelbearbeitungsversuchen mit Grubbern, Scheiben- und Kreiseleggen sollten Einsatzhinweise zur Verringerung der Bodenerosion bei pflugloser Bodenbearbeitung für verschiedene Maschinentypen entwickelt werden. Dazu wurde vor allem die Bodenbedeckung mit Mulchmaterial als wichtiger Indikator für den Schutzgrad beobachtet. Zusätzlich wurden Daten zur Stroheinarbeitung in den Boden sowie zur Ausprägung der Bodenoberflächen und Bearbeitungssohlen ermittelt und der Zugleistungsbedarf für die Geräte gemessen. Im Ergebnis konnte der Bodenbedeckungsgrad nur wenig durch Veränderung der Einsatzbedingungen der Stoppelbearbeitungsmaschinen beeinflusst werden. In erosionsgefährdeten Gebieten kommt daher dem Zwischenfruchtanbau und Bodenbearbeitungsverfahren, die einen hohen Bodenbedeckungsgrad gewährleisten (Streifenbodenbearbeitung, Direktsaat), eine entscheidende Rolle zu. Der Bericht enthält die vollständigen Ergebnisse der Untersuchung.

MSCAGR (Soil Science) / Department of Soil Science / Accelerated soil erosion is a serious agricultural problem in South Africa limiting soil productivity and little it’s known about its effect on soil quality. This study aimed to provide a less laborious, less time consuming and inexpensive protocol of estimating the effects of accelerated erosion on the soil quality. An assessment was undertaken in sites showing threat of accelerated erosion using various direct physical soil quality indicators. Four sites with different soil types were identified at initial survey. In each of the sites, two areas were selected. These areas were then classified as Not Visibly Eroded (NVE) and Visibly Eroded (VE). Each measurement in all site was done in those area classified respectively. The most stable structure and consistency were observed in NVE areas. Medium and large stones were observed in VE areas in all soil types studied. The VE soils were lighter in colour compared to soil colour in NVE. Aggregate stability and moisture content were significantly higher for the NVE and VE areas. Difference in values of water stable aggregates between NVE and VE was clear which showed that stability of aggregates is important in determining soil susceptible to erosion. Bulk density values were slightly different for the two areas. However, there was no significant difference between the bulk density of NVE and VE. Differences between soil texture for NVE and VE areas are only apparent for the sand, clay and silt particles with no changes in textural class. For all soil types investigated, silt was vulnerable to accelerated erosion with respect to soil texture. The research has provided baseline protocol for using physical soil quality indicators to find out effects of accelerated erosion. Soil functionality is critical in the restoration process of soil quality, and the methods used here could be effectively applied in a broad range assessment of erosion impact. / NRF