O presente trabalho consistiu na identificação de uma série de atributos do meio físico com o objetivo de gerar uma carta de susceptibilidade à erosão das bacias hidrográficas dos rios Cubatão e Araraquara em escala 1:50.000, ambas pertencentes à bacia do Rio Pardo. Os atributos do meio físico analisados foram o substrato rochoso, os materiais inconsolidados, declividade e uso e ocupação da área. A carta de susceptibilidade à erosão visa identificar áreas com diferentes graus de vulnerabilidade frente ao processo erosivo, de forma a facilitar o planejamento do uso e ocupação daquela região. Este estudo foi realizado seguindo as bases conceituais e metodológicas da cartografia geotécnica tradicional. Nesta pesquisa, foram utilizados sistemas de informação geográfica, tanto para análise de imagens de satélite para um fim específico, quanto para o tratamento dos dados do meio físico obtidos ao longo das etapas do trabalho. Procurou-se também compreender melhor a propriedade chamada de erodibilidade e identificar quais atributos relacionados com o materiais inconsolidados que mais contribuem para a predisponência do mesmo em ser erodido. / In this present work many environmental attributes were identified, in order to create a soil erosion susceptibility chart (1:50.000 scale) for the Cubatão and Araraquara hydrographic basin, which in turn, are part of the greater Pardo river basin. These attributes were bedrock classification, unconsolidated materials, slope and land use. The soil erosion susceptibility chart was meant to help the land use management of that particular region by identifying areas with different soil erosion vulnerability. This study was leaded following conceptual and methodological bases from the traditional engineering geological mapping approach. Geographical information system (GIS) were applied to analyze satellite images for a specific utilization, as well as for dealing with the environmental data, obtained along all the work stages. It was intended also to provide a better understanding of the property called erodibility and to identify which of the unconsolidated material attributes really contributes to its erosion.

Currently there is no suitable and commonly used device for volumetric quantification of snowmelt erosion in the Czech Republic (CR). The determination of erosion rate in the catchment is a essential prerequisite for the correct design of conservation measures. The thesis tries to offer the possible ways of monitoring the snowmelt erosion, compares individual methods and defines their optimal use. In the first year of the research, a runoff plot was developed to capture sheet erosion. The thesis compares also the methods using mobile devices - erosion bridge method and UAV photogrammetry - as effective instrument for snowmelt erosion monitoring. So far, no attention has been paid to snowmelt erosion in CR. Therefore, the thesis focuses mainly on the analysis of causal factors specific to this type of erosion - the erosion potential of snow cover and the possible soil erodibility changes due to freeze-thaw cycles. The thesis assesses the rate of snowmelt erosion risk in selected climatically different catchments and its changes in recent years. shows the timeliness of the problem. In the end, the thesis presents possibilities for solving the problem. The thesis claims the problem of snowmelt erosion actual and offers its possible solution.

Soil erosion has been recognized as an increasing threat to the environment and humans worldwide as anthropogenic activities have accelerated the soil degradation rate. In Sweden, it is estimated that 15% of the arable land is affected by soil erosion, and studies have shown that fields in the south of Sweden lose a substantial amount of soil under certain weather conditions. However, few studies have investigated current soil erosion rates and sediment yield on a large scale, focusing on Sweden. Therefore, this study aimed to estimate the annual soil erosion for all erodible surfaces in the southern half of Sweden and calculate the sediment load emitted into adjacent seas. I here applied the RUSLE model, which is the most widely used soil erosion model worldwide. The model required secondary data of precipitation, soil properties, LULC, and topography.The findings showed that most erodible surfaces in the study area eroded less than 0.5 t ha-1y-1. However, it varied considerably in both space and time. The catchments on the western part of the study area had, in general, a higher mean value than watersheds on the eastern coast. The total sediment load entering the Baltic Sea was 123500 t y-1, while Skagerrak and Kattegat's load was approximately 20% higher. Higher soil erodibility, rainfall erosivity, and steeper slope gradient in these regions could partly explain the spatial pattern. Large temporal variabilities in rainfall erosivity indicated that soil erosion and sediment transportation mainly occurred during the summer. However, previous research suggests that other erosive processes have a more significant impact on soil erosion than rainfall. Thus, the RUSLE may not predict the full extent of soil erosion occurring in the study area. Nevertheless, since there is no previous large-scale estimate of soil erosion in Sweden, it provides insights into the potential risks and extent of rainfall-induced erosion.

Riparian buffers are promoted for water quality improvement, habitat restoration, and stream bank stabilization. While considerable research has been conducted on the effects of riparian buffers on water quality and aquatic habitat, little is known about the influence of riparian vegetation on stream bank erosion. The overall goal of this research was to evaluate the effects of woody and herbaceous riparian buffers on stream bank erosion. This goal was addressed by measuring the erodibility and critical shear stress of rooted bank soils in situ using a submerged jet test device. Additionally, several soil, vegetation, and stream chemistry factors that could potentially impact the fluvial entrainment of soils were measured. A total of 25 field sites in the Blacksburg, Virginia area were tested. Each field site consisted of a 2nd-4th order stream with a relatively homogeneous vegetated riparian buffer over a 30 m reach. Riparian vegetation ranged from short turfgrass to mature riparian forest. Multiple linear regression analysis was conducted to determine those factors that most influence stream bank erodibility and the relative impact of riparian vegetation. Results of this research indicated woody riparian vegetation reduced the susceptibility of stream bank soils to erosion by fluvial entrainment. Riparian forests had a greater density of larger diameter roots, particularly at the bank toe where the hydraulic stresses are the greatest. These larger roots (diameters > 0.5 mm) provided more resistance to erosion than the very fine roots of herbaceous plants. Due to limitations in the root sampling methodology, these results are primarily applicable to steep banks with little herbaceous vegetation on the bank face, such as those found on the outside of meander bends. In addition to reinforcing the stream banks, riparian vegetation also affected soil moisture and altered the local microclimate. While summer soil desiccation was reduced under deciduous riparian forests, as compared to herbaceous vegetation, winter freeze-thaw cycling was greater. As a result, in silty soils that were susceptible to freeze-thaw cycling, the beneficial effects of root reinforcement by woody vegetation were offset by increased freeze-thaw cycling. Using the study results in an example application, it was shown that converting a predominately herbaceous riparian buffer to a forested buffer could reduce soil erodibility by as much as 39% in soils with low silt contents. Conversely, for a stream composed primarily of silt soils that are prone to freeze-thaw cycling, afforestation could lead to localized increases in soil erodibility of as much as 38%. It should be emphasized that the riparian forests in this study were deciduous; similar results would not be expected under coniferous forests that maintain a dense canopy throughout the year. Additionally, because dense herbaceous vegetation would likely not develop in the outside of meander bends where hydraulic shear stresses are greatest, the reductions in soil erodibility afforded by the herbaceous vegetation would be limited to areas of low shear stress, such as on gently sloping banks along the inside of meander bends. As the first testing of this type, this study provided quantitative information on the effects of vegetation on subaerial processes and stream bank erosion. It also represents the first measurements of the soil erosion parameters, soil erodibility and critical shear stress, for vegetated stream banks. These parameters are crucial for modeling the effects of riparian vegetation for stream restoration design and for water quality simulation modeling. / Ph. D.

Desertification is a serious problem in environments where it occurs, namely in dry lands (arid, semi-arid and dry sub-humid areas). This type of degradation affects about one quarter of the land surface, with implications for environmental, economic, political, social and cultural order. The areas in Brazil susceptible to this process are located in the northeast region which is characterized by low rainfall index, high temperatures, severe water deficit, shallow and rocky soils and xerophytic vegetation. São Raimundo Nonato, which is the object of this study, is located in the semi-arid region of Piaui and is a susceptible area to desertification. This has led to the study of degradation / desertification in this area in order to assess the risk of physical deterioration and effective degradation. The risk of physical deterioration was evaluated using the following indicators: climate, rainfall erosivity, erodibility of soils and slopeness. The effective degradation was assessed by considering the indicators discussed above combined with the NDVI of the years 1987 and 2007. The results indicate that 8.3%, 81% and 10.7% of the area are at risk of a low, moderate and high physical deterioration. The effective degradation, taking into account the NDVI for 1987, indicates that 70% and 30% of the area have respectively moderate and high degradation. For the year 2007, the data indicate that 71% and 29% of the area have respectively moderate and high effective degradation. These data reveal a dynamic ecological equilibrium with a subtle trend of improvement in terms of environmental degradation, that is , in the process of desertification in the studied area, since there is a reduction of the class of high effective degradation. The decline and economic stagnation in the area were found during the analysis of major crops and effective livestock . These data revealed a decline in the planted area, productivity and effective livestock, both in number of heads and / or unit of animals. The decline of these indicators corroborates the statement of improvement of environmental conditions in the studied area. / A desertificação constitui um grave problema nos ambientes em que ocorre, qual seja as Terras Secas (áridas, semiáridas e subúmidas secas). Esse tipo de degradação afeta cerca de 1/4 da superfície terrestre, com implicações de ordem ambiental, econômica, política, social e cultural. No Brasil as áreas suscetíveis a esse processo localizam-se na região Nordeste caracterizada por baixos índices pluviométricos, elevadas temperaturas médias, acentuado déficit hídrico, solos rasos e pedregosos e vegetação xerofítica. O Núcleo de São Raimundo Nonato, objeto deste estudo, localizado no semi-árido piauiense constitui área suscetível à desertificação. Esta constatação conduziu ao estudo da degradação/desertificação desta área com o objetivo de avaliar o risco de degradação física e a degradação efetiva. O risco de degradação física foi avaliado a partir dos seguintes indicadores: índice climático, erosividade das chuvas, erodibilidade dos solos e a declividade. A degradação efetiva foi avaliada considerando os indicadores anteriormente citados combinados ao NDVI dos anos de 1987 e 2007. Os resultados indicam que 8,3%, 81% e 10,7% da área apresentam risco de degradação física baixo, moderado e alto. A degradação efetiva, considerando o NDVI para 1987, indica que 70% e 30% da área apresenta respectivamente degradação moderada e alta. Para o ano de 2007, os dados indicam que 71% e 29% da área apresenta respectivamente degradação efetiva moderada e alta. Esses dados revelam uma situação de equilíbrio ecológico dinâmico com uma sutil tendência de melhoria nas condições de degradação ambiental, ou seja, no processo de desertificação da área de estudo, posto a redução da classe de alta degradação efetiva. O declínio e a estagnação econômica da área foram constatados quando da analise das principais culturas e do efetivo de rebanhos. Esses dados revelaram redução da área plantada, da produtividade e do efetivo dos rebanhos em número de cabeças e de unidades animais. A queda desses indicadores corrobora a afirmativa de melhoria das condições ambientais da área de estudo.

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Functions and services provided by soils play an important role for numerous sustainable development goals involving mainly food supply and environmental health. In many regions of the Earth, water erosion is a major threat to soil functions and is mostly related to land-use change or poor agricultural management. Selecting proper soil management practices requires site-specific indicators such as water erosion, which follow a spatio-temporal variation. The aim of this study was to develop monthly soil erosion risk maps for the data-scarce catchment of Ruiru drinking water reservoir located in Kenya. Therefore, the Revised Universal Soil Loss Equation complemented with the cubist–kriging interpolation method was applied. The erodibility map created with digital soil mapping methods (R2 = 0.63) revealed that 46% of the soils in the catchment have medium to high erodibility. The monthly erosion rates showed two distinct potential peaks of soil loss over the course of the year, which are consistent with the bimodal rainy season experienced in central Kenya. A higher soil loss of 2.24 t/ha was estimated for long rains (March–May) as compared to 1.68 t/ha for short rains (October–December). Bare land and cropland are the major contributors to soil loss. Furthermore, spatial maps reveal that areas around the indigenous forest on the western and southern parts of the catchment have the highest erosion risk. These detected erosion risks give the potential to develop efficient and timely soil management strategies, thus allowing continued multi-functional use of land within the soil–food–water nexus.