Published Article / To assess and predict runoff and soil loss on different tillage methods coupled with alternative cropping systems in the central highland vertisols of Ethiopia, a study was carried out at Ginchi, Agricultural Research Sub-Center during 1996. The experiment was conducted on runoff plots of 4 meter wide by 22 meter long, on surface slopes that range between 0.1% and 2.3%. The data collected was analyzed using regression models and an empirical formula developed by the Soil Conservation Service of America (SCS, 1964; 1972), known as curve number (CN). Both the regression model and the SCS simulated the mean daily runoff reasonably well with R2 93% and 83%, respectively. The overall results obtained explain that the improved tillage practice, BBF could drain the excess surface water safely.

No description available.

Thesis (M.S. - Soils, Water and Engineering)--University of Arizona, 1982. / Bibliography: leaves 81-83.

Orientador: Antonio Cesar Germano Martins / Banca: Roberto Wagner Lourenço / Banca: Darllan Collins da Cunha e Silva / Resumo: A perda de solos em bacias hidrográficas pode causar prejuízos ambientais e comprometer os usos múltiplos potenciais desta bacia. Ações como desmatamento, atividades agrícolas, entre outras, expõem o solo aos agentes naturais (precipitação, vento) e estes desprendem e carreiam o solo para as porções mais baixas na bacia, promovendo o assoreamento dos corpos d'água. Estudos sobre o tema são importantes para auxiliar na gestão, manejo e entendimento destes ambientes e mitigação do fenômeno. Neste sentido, este trabalho tem como objetivo estimar a perda de solo na sub-bacia do Pirajibu-Mirim. Para isto, foram utilizadas ferramentas de análise de imagens e de dados da bacia para calcular a Equação Universal da Perda de Solos (EUPS) definida por Wischmeier & Smith (1978). A sub-bacia está inserida no município de Sorocaba-SP e tem uma área de aproximadamente 54 km². Para compor a equação, todas as variáveis foram levantadas separadamente para então calcular a EUPS em ambiente SIG para os anos de 2000 a 2016. Os resultados indicaram que os anos de 2003 e 2012 apresentaram os maiores valores de perdas de solo acima de 200 ton/ha.ano e em 2013 os menores valores de perdas de solo acima de 200 ton/ha.ano. Outra informação importante foi que no período estudado, aproximadamente 50% da área tem perdas de solo abaixo de 15 ton/ha.ano, indicando boa preservação do solo. / Abstract: The loss of soil in watershed can cause environmental damage and compromise the multiple potential uses of this watershed. Action as deforestation, agricultural activities, among others, expose the soil to natural agents (precipitation, wind) that causes the release of these soils to lower portion of watershed, promoting silting of the water bodies. Studies about the theme are important to improve the management and understanding of these environments and phenomenon mitigation of silting. Therefore, this work had as aim the estimation of soil loss in sub basin Pirajibu-Mirim. For this, tools of image and data analysis were used to estimate the Universal Soil Loss Equation (USLE) defined by Wischmeier & Smith (1978). The sub basin is inserted in Sorocaba city, São Paulo state and has an area 54km². To compose the equation, the variables were obtained separately and then the USLE was calculated from 2000 to 2016. The results indicated that the years 2003 and 2012 demonstrated the highest values of soil loss above 200 ton/ha.a and 2013 the lowest value of soil loss above 200 ton/ha.a. Other important information is that in studied period, almost 50% of the area had soil lower than 15 ton/ha.a, indicating satisfactory soil preservation. / Mestre

Digital satellite remote sensing and Geographic Information Systems (GIS) have been used effectively to determine the Universal Soil Loss Equation (USLE) output for a number of North Texas watersheds. This method involves determining the values of each of the USLE factors and using these factors as information layers within the GIS.

Soil erosion was assessed at Camp Williams National Guard Base by creating an erosion risk classification map and comparing the erosion impact of disturbance regimes on different hillslopes. Soil erosion does not appear to be a problem for most of Camp Williams. The Revised Universal Soil Loss Equation was applied using GIS to create a soil erosion risk map for the entire Camp Williams facility. The map indicated where problem areas occurred and showed relative erosion risk, but its lack of quantitative accuracy should be noted. Areas of concern included landscapes with little or no protective vegetation such as roads, abandoned agricultural fields, and sensitive riparian areas where gullies tend to form and expand. The Water Erosion Prediction Project model was used to evaluate the erosion impacts of various disturbances on five study hillslopes. The model did not appear to function well on the Camp Williams study hillslopes because the distribution of infiltration rates could not be satisfactorily represented. However, hydraulic conductivity measurements collected for this task were useful in providing insight into some of the physical processes of erosion. The hydraulic conductivity measurements showed some of the impacts of military activities, grazing, and wildfire on soil properties. Erosion bridges were also used on the five study hillslopes in an attempt to measure soil Joss and deposition. However, the bridges Jacked the capability of measuring the low rates of erosion during the time period set for this experiment. The bridges showed potential for measuring erosion in rills, gullies, highly disturbed areas, or in longer duration experiments.

The following conclusions may be drawn from this investigation: (1) The photometer is an accurate and dependable device for measuring light absorption by turbid soil and water solutions when the soil particles are of nearly constant size. The tests made with the soil that had passed through a 100-mess sieve proved this fact, also, the tests made with the composite soil gave vary accurate results. (2) the composite runoff soil samples from the three slopes must have contained particles of approximately the same size. This is shown by the accuracy of the results obtained with this soil. / Master of Science

Fifteen field plots were installed on a "Mountain Top Removal" type of surface mine near Beckley, West Virginia to evaluate the the predictability of the Universal Soil Loss Equation for a selected eastern surface mine spoil. Comparison of predicted and measured soil losses indicated significant error. For slopes greater than 20% the equation overpredicted for all predictions. Predictions for erosion losses greater than three tons/acre were significantly more accurate than those for losses less than 3 tons/acre. Comparison of soil characteristics of unmined and reclaimed areas indicated the reclaimed areas had significantly greater amounts of clay and silt present, and had greater bulk density. The reclaimed areas also had significantly lower infiltration rates, organic matter, very-fine sand and total sand. The erodibility factor, K, was also greater for the reclaimed area than for the unmined area. / Master of Science

Master of Science / Department 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.

Orientador: Carlos de Almeida Nóbrega / Banca: Luiz Roberto Cottas / Banca: Henry Lesjak Martos / Resumo: A expansão territorial do agronegócio e da área urbana na Alta Bacia Hidrográfica do Rio Jacaré Pepira impacta a preservação de seus recursos naturais. A erosão se destaca como um processo do meio físico que possui uma relação estreita com o uso do solo. Para estudo da vulnerabilidade à erosão realizou-se uma análise segmentada dos fatores naturais e antrópicos, apoiando-se no modelo matemático da Equação Universal de Perda de Solo (EUPS). O meio físico foi compartimentado nas sub-bacias que estão parcial ou totalmente inseridas na Área de Proteção Ambiental (APA) de Corumbataí. As sub-bacias foram consideradas como unidades de análise, com a medição de parâmetros morfométricos. Para estudo dos fatores antrópicos, realizou-se levantamentos de campo para caracterização do uso e manejo do solo praticado nas principais explorações agropecuárias com a identificação de feições erosivas lineares. As informações de ocupação do solo foram extraídas da classificação automática de imagens de satélite dos anos de 1988 (TM/Landsat) e 2004 (CBERS) com controle de campo. O trabalho apresentou como resultado o zoneamento da área quanto à susceptibilidade natural, vulnerabilidade e adequação ao uso do solo. As informações integradas em um banco de dados em SIG/SPRING permitem fornecer instrumentos para trabalhos de gerenciamento ambiental. / Abstract: Territorial expansion of agrobusiness and urban areas in the Jacaré Pepira River watershed impact its natural resources. Erosion stands out as a physical environment process that has a close relationship with land use. The study of erosion vulnerability was accomplished on a natural and human factors segmented analysis, based on Universal Soil Loss Equation (USLE) model. Physical environmental was shared on the sub-basin belong to APA de Corumbataí (Corumbataí Environmental Protection Area). Sub-basins were considered as units of analysis, witch the morfometric parameters measurements. Field work was used on human factor study, aiming the management characterization for main crops, including the identify of areas affected by gullies. Data about land use were obtained by automatic classification of 1988 (TM/Landsat) and 2004 (CBERS) satellite images with field control. Zoning of the area was accomplished based on natural erosion potential (PNE), erosion vulnerability and wishing land use. Data input to a GIS/SPRING database can provide tools for environmental management. / Mestre