Orientador: Marcílio Vieira Martins Filho / Banca: Zigomar Menezes de Souza / Banca: Renato Farias do Valle Junior / Banca: João Antonio Galbiatti / Banca: Jose Marques Junior / Resumo: O escoamento superficial da água provoca o transporte dos nutrientes do solo, quando este encontra-se com a superfície desprotegida de cobertura. O presente trabalho teve como objetivo avaliar as possíveis relações entre posições do relevo, erosão em entressulcos e seus reflexos nas perdas de solo, matéria orgânica e nutrientes em área cultivada com a cultura de cana-de-açúcar submetida à colheita mecanizada. Parcelas experimentais foram submetidas à ação de uma chuva simulada com intensidade de 60 mm h-1, durante 65 minutos. Foram feitas análises do sedimento erodido para determinar perdas de solo, matéria orgânica e nutrientes. Houve maiores perdas de solo, matéria orgânica e nutrientes no sedimento das parcelas com 0% e 25% de cobertura por palha de cana-de-açúcar. Em média, as perdas no sedimento erodido foram significativamente reduzidas nas parcelas com 75% e 100% de cobertura por resíduos de palha de cana-de-açúcar. Na perda de água, observou-se que houve diferenças estatísticas das médias dos níveis de cobertura 0% e 25% em relação aos demais (50%, 75% e 100%) em todas as posições da vertente. No topo, a diferença do maior valor (168.600 L ha-1) para o menor valor (120.300 L ha-1) foi de 48.300 L ha-1. Os resultados permitem concluir que acima de 50% da cobertura com palhada, na área estudada, reduz a perda de solo e matéria orgânica, e a concentração de nutrientes no sedimento erodido / Abstract: The water superficial drainage provokes the transport of soil nutrients especially in unprotected surfaces. The present work had as objective to evaluates the possible relationship between positions in a relief and soil losses induced by erosion in an area cultivated with the sugarcane under mechanized harvest. The studied plots were submitted to simulate rain events with intensity of 60 mm h-1, for 65 minutes. The analyses of eroded sediments in terms of volume, soil losses, organic matter and nutrients were conducted. There were larger sediment losses at plots with 0% and 25% of sugarcane crop residues cover. On average, the losses in the eroded sediment were significantly reduced in the portions with 75% and 100% surface residues covering. In terms of water loss it was also observed significant differences between 0% and 25% to the others (50%, 75% and 100%) in all positions in the slope. In the top the difference of the largest value 168,600 L ha-1 for the smallest value 120,300 L ha-1 it was of 48,300 L ha-1. The results points that 50% of crop residues covering would reduce soil losses, including organic matter and nutrients / Doutor

Forest roads and stream crossings have the potential to be sources of sediment from forest operations. Recent litigation has renewed interest in furthering research related to forest road Best Management Practices (BMPs). Three legacy (100 year old) forest road stream crossings were monitored for suspended sediment for nine months before and six months after upgrading three unimproved ford crossings with one bridge, one culvert, and one improved ford. During construction, rainfall simulation was utilized to estimate the sediment contribution of each crossing with minimal BMPs (BMP-), BMPs equal to state recommendations (BMP), and BMPs beyond state recommendations (BMP+). Construction costs were recorded to quantify the change in cost with a change in BMP level. Three levels of rainfall simulation were used on each BMP treatment for each crossing resulting in 27 rainfall simulations. Water samples collected by an automatic sampler downstream of the crossings were analyzed for suspended sediment. Pre - and post- construction time periods were compared to assess how the improved crossings altered total suspended sediment concentrations downstream of the crossings. The number of stream crossings constructed per year in Virginia was also estimated using satellite imagery on 400 harvest tracts. Site visits were conducted on 240 harvest tracts where data were collected on the presence of crossings, the types of crossings, and the level of BMP implementation. Rainfall simulation experiments showed decreased sediment with increased BMP level and daily total suspended sediment concentrations measured over 15 months showed a decrease in mean daily sediment concentration after construction of the bridge and culvert crossings. There was no decrease in sediment concentration for the ford crossing. Statewide crossing construction and BMP implementation rates were estimated. Approximately 67% of the audited stream crossings were characterized as having BMPs that were equal to or beyond state recommendations. Increased BMPs and upgrading of stream crossings resulted in decreased total suspended sediment. However, increased BMP implementation also increased stream crossing construction costs. Effectiveness of increased levels of BMPs and the pre and post construction analysis suggests the improvement of a legacy stream crossing may reduce total suspended sediment concentrations. / Ph. D.

A serrapilheira é compreendida como a camada acima do solo formada a partir de materiais que caem da vegetação, funcionando como um mecanismo de interceptação da chuva. Apesar do processo de interceptação ser significativo em áreas de florestas, geralmente esse processo é subestimado ou mesmo negligenciado em modelos hidrológicos, justificado pela dificuldade na obtenção desses dados. Este projeto propôs o desenvolvimento de um equipamento que permite realizar medidas em campo da interceptação da serrapilheira em área de cerrado sensu stricto. Com o equipamento desenvolvido, LID (Litter Interception Device), são realizadas medidas do volume de água retido na serrapilheira e do volume que passa pela serrapilheira, atingindo o solo. O LID foi testado e calibrado em laboratório utilizando chuva simulada de três diferentes intensidades sobre o equipamento, contendo três quantidades diferentes de serrapilheira, 2,97, 1,45 e 0,60 kg.m-2. As amostras de serrapilheira utilizadas nos testes foram retiradas de uma área experimental de mata nativa de cerrado sensu stricto, localizada no município de Itirapina, Estado de São Paulo. As intensidades utilizadas foram definidas a partir de uma curva Intensidade-Duração-Frequência (IDF) gerada para a área experimental. Além do bom funcionamento do LID, os testes serviram para determinar os parâmetros Cmax e Cmin (capacidade máxima e capacidade mínima de armazenamento, respectivamente) da serrapilheira do cerrado sensu stricto. Os resultados mostraram que com o LID são realizadas medições da taxa de retenção de água na serrapilheira (mm.min-1), bem como de sua evaporação (mm.min-1) com precisão. Os testes para calibração do pluviógrafo revelaram que as medidas eram sempre subestimadas, necessitando utilizar uma curva de calibração (R2 = 0,99) para corrigir os registros da intensidade que passa para o pluviógrafo. Os valores encontrados para os parâmetros Cmax (1,0 a 3,07 mm) e Cmin (0,78 a 2,27 mm) corroboram com os encontrados por outros autores para a serrapilheira de diferentes florestas. Verificou-se que a variável quantidade de serrapilheira (kg) influencia mais nesses valores, do que a intensidade da chuva (mm.h-1). Conclui-se com os resultados que o LID pode ser utilizado em estudos que pretendam analisar o papel da serrapilheira em processos hidrológicos, sejam estes para a determinação da interceptação da chuva em campo, ou mesmo na determinação de parâmetros em laboratório. / Forest litter is the layer above the ground of the forest formed by materials that fall from the vegetation itself. The vegetation materials are through various stages of decomposition, functioning as a mechanism of rainfall interception. Although the interception process is significant in forested areas, this process is usually underestimated or even neglected in hydrological models due to the difficulties on obtaining these data. We proposed the development of a device that allows the field measurements of the forest litter interception in a cerrado sensu stricto area. The Litter Interception Device (LID), was tested and calibrated in the laboratory. We used simulated rainfall with three different intensities to test the device and also three different amounts of litter, 0.100, 0.230 and 0.470 kg. The litter samples used in the tests were taken from an experimental area of cerrado sensu stricto located in Itirapina, State of São Paulo, Brazil. The intensities of simulated rainfall were obtained from an Intensity-Duration-Frequency (IDF) curve made for the experimental area. Besides the LID functioning tests, the device was tested to determine the parameters Cmax and Cmin (maximum capacity and minimum storage capacity, respectively) of the cerrado sensu stricto forest litter. The results showed that the LID allows measurements of the volume of water retained in the forest litter (mm.min-1) as well as its evaporation (mm.min-1). The pluviometer calibration tests revealed that the measurements were always underestimated, requiring a calibration curve (R2 = 0.99) to correct the volume records that flow to the tipping bucket pluviometer. The values found for Cmax (1.0 - 3.07 mm) and Cmin (0.78 - 2.27 mm) are according with those found by other authors for different kinds of forest litters. It was verified that the variation in the amount of forest litter (kg) influenced more in these values, than the rainfall intensity (mm.min-1) . We concluded that the LID can be used in studies that intend to analyze the role of the forest litter in hydrological processes, whether they area for the determination of the interception of rain in the field or even and in laboratory studies to determine interception parameters of forest litter.

Policy makers, water managers, farmers and many other sectors of the society in southern Africa are confronting increasingly complex decisions as a result of the marked day-to-day, intra-seasonal and inter-annual variability of climate. Hence, forecasts of hydro-climatic variables with lead times of days to seasons ahead are becoming increasingly important to them in making more informed risk-based management decisions. With improved representations of atmospheric processes and advances in computer technology, a major improvement has been made by institutions such as the South African Weather Service, the University of Pretoria and the University of Cape Town in forecasting southern Africa’s weather at short lead times and its various climatic statistics for longer time ranges. In spite of these improvements, the operational utility of weather and climate forecasts, especially in agricultural and water management decision making, is still limited. This is so mainly because of a lack of reliability in their accuracy and the fact that they are not suited directly to the requirements of agrohydrological models with respect to their spatial and temporal scales and formats. As a result, the need has arisen to develop a GIS based framework in which the “translation” of weather and climate forecasts into more tangible agrohydrological forecasts such as streamflows, reservoir levels or crop yields is facilitated for enhanced economic, environmental and societal decision making over southern Africa in general, and in selected catchments in particular. This study focuses on the development of such a framework. As a precursor to describing and evaluating this framework, however, one important objective was to review the potential impacts of climate variability on water resources and agriculture, as well as assessing current approaches to managing climate variability and minimising risks from a hydrological perspective. With the aim of understanding the broad range of forecasting systems, the review was extended to the current state of hydro-climatic forecasting techniques and their potential applications in order to reduce vulnerability in the management of water resources and agricultural systems. This was followed by a brief review of some challenges and approaches to maximising benefits from these hydro-climatic forecasts. A GIS based framework has been developed to serve as an aid to process all the computations required to translate near real time rainfall fields estimated by remotely sensed tools, as well as daily rainfall forecasts with a range of lead times provided by Numerical Weather Prediction (NWP) models into daily quantitative values which are suitable for application with hydrological or crop models. Another major component of the framework was the development of two methodologies, viz. the Historical Sequence Method and the Ensemble Re-ordering Based Method for the translation of a triplet of categorical monthly and seasonal rainfall forecasts (i.e. Above, Near and Below Normal) into daily quantitative values, as such a triplet of probabilities cannot be applied in its original published form into hydrological/crop models which operate on a daily time step. The outputs of various near real time observations, of weather and climate models, as well as of downscaling methodologies were evaluated against observations in the Mgeni catchment in KwaZulu-Natal, South Africa, both in terms of rainfall characteristics as well as of streamflows simulated with the daily time step ACRU model. A comparative study of rainfall derived from daily reporting raingauges, ground based radars, satellites and merged fields indicated that the raingauge and merged rainfall fields displayed relatively realistic results and they may be used to simulate the “now state” of a catchment at the beginning of a forecast period. The performance of three NWP models, viz. the C-CAM, UM and NCEP-MRF, were found to vary from one event to another. However, the C-CAM model showed a general tendency of under-estimation whereas the UM and NCEP-MRF models suffered from significant over-estimation of the summer rainfall over the Mgeni catchment. Ensembles of simulated streamflows with the ACRU model using ensembles of rainfalls derived from both the Historical Sequence Method and the Ensemble Re-ordering Based Method showed reasonably good results for most of the selected months and seasons for which they were tested, which indicates that the two methods of transforming categorical seasonal forecasts into ensembles of daily quantitative rainfall values are useful for various agrohydrological applications in South Africa and possibly elsewhere. The use of the Ensemble Re-ordering Based Method was also found to be quite effective in generating the transitional probabilities of rain days and dry days as well as the persistence of dry and wet spells within forecast cycles, all of which are important in the evaluation and forecasting of streamflows and crop yields, as well as droughts and floods. Finally, future areas of research which could facilitate the practical implementation of the framework were identified. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

A serrapilheira é compreendida como a camada acima do solo formada a partir de materiais que caem da vegetação, funcionando como um mecanismo de interceptação da chuva. Apesar do processo de interceptação ser significativo em áreas de florestas, geralmente esse processo é subestimado ou mesmo negligenciado em modelos hidrológicos, justificado pela dificuldade na obtenção desses dados. Este projeto propôs o desenvolvimento de um equipamento que permite realizar medidas em campo da interceptação da serrapilheira em área de cerrado sensu stricto. Com o equipamento desenvolvido, LID (Litter Interception Device), são realizadas medidas do volume de água retido na serrapilheira e do volume que passa pela serrapilheira, atingindo o solo. O LID foi testado e calibrado em laboratório utilizando chuva simulada de três diferentes intensidades sobre o equipamento, contendo três quantidades diferentes de serrapilheira, 2,97, 1,45 e 0,60 kg.m-2. As amostras de serrapilheira utilizadas nos testes foram retiradas de uma área experimental de mata nativa de cerrado sensu stricto, localizada no município de Itirapina, Estado de São Paulo. As intensidades utilizadas foram definidas a partir de uma curva Intensidade-Duração-Frequência (IDF) gerada para a área experimental. Além do bom funcionamento do LID, os testes serviram para determinar os parâmetros Cmax e Cmin (capacidade máxima e capacidade mínima de armazenamento, respectivamente) da serrapilheira do cerrado sensu stricto. Os resultados mostraram que com o LID são realizadas medições da taxa de retenção de água na serrapilheira (mm.min-1), bem como de sua evaporação (mm.min-1) com precisão. Os testes para calibração do pluviógrafo revelaram que as medidas eram sempre subestimadas, necessitando utilizar uma curva de calibração (R2 = 0,99) para corrigir os registros da intensidade que passa para o pluviógrafo. Os valores encontrados para os parâmetros Cmax (1,0 a 3,07 mm) e Cmin (0,78 a 2,27 mm) corroboram com os encontrados por outros autores para a serrapilheira de diferentes florestas. Verificou-se que a variável quantidade de serrapilheira (kg) influencia mais nesses valores, do que a intensidade da chuva (mm.h-1). Conclui-se com os resultados que o LID pode ser utilizado em estudos que pretendam analisar o papel da serrapilheira em processos hidrológicos, sejam estes para a determinação da interceptação da chuva em campo, ou mesmo na determinação de parâmetros em laboratório. / Forest litter is the layer above the ground of the forest formed by materials that fall from the vegetation itself. The vegetation materials are through various stages of decomposition, functioning as a mechanism of rainfall interception. Although the interception process is significant in forested areas, this process is usually underestimated or even neglected in hydrological models due to the difficulties on obtaining these data. We proposed the development of a device that allows the field measurements of the forest litter interception in a cerrado sensu stricto area. The Litter Interception Device (LID), was tested and calibrated in the laboratory. We used simulated rainfall with three different intensities to test the device and also three different amounts of litter, 0.100, 0.230 and 0.470 kg. The litter samples used in the tests were taken from an experimental area of cerrado sensu stricto located in Itirapina, State of São Paulo, Brazil. The intensities of simulated rainfall were obtained from an Intensity-Duration-Frequency (IDF) curve made for the experimental area. Besides the LID functioning tests, the device was tested to determine the parameters Cmax and Cmin (maximum capacity and minimum storage capacity, respectively) of the cerrado sensu stricto forest litter. The results showed that the LID allows measurements of the volume of water retained in the forest litter (mm.min-1) as well as its evaporation (mm.min-1). The pluviometer calibration tests revealed that the measurements were always underestimated, requiring a calibration curve (R2 = 0.99) to correct the volume records that flow to the tipping bucket pluviometer. The values found for Cmax (1.0 - 3.07 mm) and Cmin (0.78 - 2.27 mm) are according with those found by other authors for different kinds of forest litters. It was verified that the variation in the amount of forest litter (kg) influenced more in these values, than the rainfall intensity (mm.min-1) . We concluded that the LID can be used in studies that intend to analyze the role of the forest litter in hydrological processes, whether they area for the determination of the interception of rain in the field or even and in laboratory studies to determine interception parameters of forest litter.

The Lockheed Fire burned 31 km2 (7,660 acres) of the Scotts Creek watershed in August 2009. 4.5 km2 (1,100 acres) of California Polytechnic State University’s educational and research facility at Swanton Pacific Ranch. The burned region presented an opportunity for studying the hydrologic response of burned soils in the Santa Cruz Mountains where there is insufficient post-fire studies regarding fire-effects on watershed processes such as infiltration and near-surface runoff. Soil infiltration and soil water repellency were evaluated with rainfall simulations, Mini-disk Infiltrometer (MDI) and water drop penetration time tests (WDPT) at sites represented by variations in burn severity, soils, and vegetation types throughout the Scotts Creek watershed each year for 5 years following the burn. Mixed-effects modeling was utilized on the 3 datasets to evaluate if changes could be detected in infiltration rates and water repellency following the fire. Rainfall simulations and WDPT tests showed that the fire did not have a statistically-significant impact on infiltration rates or soil water repellency, whereas the MDI tests detected a statistically-significant impact on post-fire infiltration. While the MDI results showed that fire had a significant impact on the hydrologic response over time, questions arose regarding challenges associated with sampling suggesting the method may not be pursued on steep slopes with high surface rock fragments or in the presence of large soil macropores. It is recognized that additional understanding would be gained from having multiple replications at each site every year and tests could be conducted on a subwatershed scale to account for the naturally occurring variability of larger watersheds.

Efforts to control surface runoff and erosion from forest roads at stream crossings are critical for the protection of aquatic ecosystems in forests. In this research, annual and event-based sediment delivery rates were estimated for reopened legacy roads at forest stream crossings in the Virginia Piedmont physiographic region, USA. Sediment delivery rates were compared among stream crossing approaches with diverse intensities of best management practice (BMP) implementations for surface cover and water control. Model predictions from the Water Erosion Prediction Project (WEPP) were compared to field observations of surface runoff and sediment delivery to evaluate model performance. Annual sediment delivery rates from reopened (bare) legacy road approaches to stream crossings were 7.5 times higher than those of completely graveled approaches. Sediment delivery rates ranged from 34 to 287 Mg ha⁻¹ year⁻¹ for the bare approaches and from 10 to 16 Mg ha⁻¹ year⁻¹ for the graveled approaches. Event-based surface runoff and associated total suspended solids (TSS) concentrations were compared among a succession of gravel surfacing treatments that represented increasing intensities of BMP implementations on reopened approaches. The three treatments were No Gravel (10-19% cover), Low Gravel (34-60% cover), and High Gravel (50-99% cover). Median TSS concentration of surface runoff for the No Gravel treatment (2.84 g L⁻¹) was greater than Low Gravel (1.10 g L⁻¹) and High Gravel (0.82 g L⁻¹) by factors of 2.6 and 3.5, respectively. WEPP predictions of event-based sediment yield show clear differences among the different road surface treatments, but prediction intervals were wide, reflecting substantial prediction uncertainty. These findings show that reopened legacy roads and associated stream crossing approaches can deliver significant quantities of sediment if roads are not adequately closed or maintained and that corrective best management practices (BMPs), such as gravel and appropriate spacing of water control structures, can reduce sediment delivery to streams. Watershed management decisions that hinge upon WEPP predictions of sediment yield from forest roads must necessarily take into account a wide range of potential erosion rates for specific management scenarios. / Ph. D.

Manure contains nutrients for crop growth; however, overapplication, with time, can result in excess nutrients in soil, which can subsequently be lost in surface runoff. <p>The general purpose of this research is to study the effect of liquid hog manure, applied as an agricultural fertilizer, on water chemistry of surface runoff from rainfall simulation tests. Specifically the research focuses on runoff water chemistry comparisons between lands receiving hog manure at different rates, via different injection methods, and upon different slope positions. <p>To examine these objectives, soil nutrient supply rates (P, NH4-N, and NO3-N) of the 0 5 cm depth of soil adjacent to rainfall simulation positions, and runoff water chemistry (TP, OP, NH4-N, NO3-N, DOC, Cl- and coliforms) during rainfall simulation tests were collected before and after manure addition. <p> Generally, manure application did increase soil NH4-N and NO3-N supply rates, and runoff NH4-N concentration. Soil P supply rate and runoff TP concentration were not affected by the manure addition; however, runoff OP concentration at one site (Perdue) increased significantly due to manure addition. The manure treatments applied in this study did not cause any significant increases in fecal or total coliform in runoff from rainfall simulation tests conducted 7 8 months after manure application. None of the water quality parameters exceeded the Guidelines for Canadian Drinking Water Quality. <p> Manure injection method (regular versus low soil surface disturbance) had consistent effects on runoff chemistry, but application rate did not. The regular disturbance method had significantly higher concentrations of water quality parameters than the low disturbance method. <p> The position of the test on the slope did not result in any consistent trends in runoff chemistry, whether before or after manure addition. Foot slope positions had higher soil NH4-N supply rates than upper slope positions, both before and after manure addition. Soil NH4-N, NO3-N, and P supply rates between landscape positions were not likely influenced by manure addition. <p> Regression tests between soil nutrient supply rates and runoff chemistry indicate that soil NH4-N supply rates are a good index to predict runoff NH4-N concentration, but soil P did not predict runoff P.

Manure contains nutrients for crop growth; however, overapplication, with time, can result in excess nutrients in soil, which can subsequently be lost in surface runoff. <p>The general purpose of this research is to study the effect of liquid hog manure, applied as an agricultural fertilizer, on water chemistry of surface runoff from rainfall simulation tests. Specifically the research focuses on runoff water chemistry comparisons between lands receiving hog manure at different rates, via different injection methods, and upon different slope positions. <p>To examine these objectives, soil nutrient supply rates (P, NH4-N, and NO3-N) of the 0 5 cm depth of soil adjacent to rainfall simulation positions, and runoff water chemistry (TP, OP, NH4-N, NO3-N, DOC, Cl- and coliforms) during rainfall simulation tests were collected before and after manure addition. <p> Generally, manure application did increase soil NH4-N and NO3-N supply rates, and runoff NH4-N concentration. Soil P supply rate and runoff TP concentration were not affected by the manure addition; however, runoff OP concentration at one site (Perdue) increased significantly due to manure addition. The manure treatments applied in this study did not cause any significant increases in fecal or total coliform in runoff from rainfall simulation tests conducted 7 8 months after manure application. None of the water quality parameters exceeded the Guidelines for Canadian Drinking Water Quality. <p> Manure injection method (regular versus low soil surface disturbance) had consistent effects on runoff chemistry, but application rate did not. The regular disturbance method had significantly higher concentrations of water quality parameters than the low disturbance method. <p> The position of the test on the slope did not result in any consistent trends in runoff chemistry, whether before or after manure addition. Foot slope positions had higher soil NH4-N supply rates than upper slope positions, both before and after manure addition. Soil NH4-N, NO3-N, and P supply rates between landscape positions were not likely influenced by manure addition. <p> Regression tests between soil nutrient supply rates and runoff chemistry indicate that soil NH4-N supply rates are a good index to predict runoff NH4-N concentration, but soil P did not predict runoff P.

Characterizing the uncertainty in rainfall using stochastic models has been a challenging area of research in the field of operational hydrology for about half a century. Simulated sequences drawn from such models find use in a variety of hydrological applications. Traditionally, parametric models are used for simulating rainfall. But the parametric models are not parsimonious and have uncertainties associated with identification of model form, normalizing transformation, and parameter estimation. None of the models in vogue have gained universal acceptability among practising engineers. This may either be due to lack of confidence in the existing models, or the inability to adopt models proposed in literature because of their complexity or both. In the present study, a new nonparametric Matched Block Bootstrap (MABB) model is proposed for stochastic simulation of rainfall at daily time scale. It is based on conditional matching of blocks formed from the historical rainfall data using a set of predictors (conditioning variables) proposed for matching the blocks. The efficiency of the developed model is demonstrated through application to rainfall data from India, Australia, and USA. The performance of MABB is compared with two non-parametric rainfall simulation models, k-NN and ROG-RAG, for a site in Melbourne, Australia. The results showed that MABB model is a feasible alternative to ROG-RAG and k-NN models for simulating daily rainfall sequences for hydrologic applications. Further it is found that MABB and ROG-RAG models outperform k-NN model. The proposed MABB model preserved the summary statistics of rainfall and fraction of wet days at daily, monthly, seasonal and annual scales. It could also provide reasonable performance in simulating spell statistics. The MABB is parsimonious and requires less computational effort than ROG-RAG model. It reproduces probability density function (marginal distribution) fairly well due to its data driven nature. Results obtained for sites in India and U.S.A. show that the model is robust and promising.