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Increasing urbanization is often accompanied by problematic changes in watershed hydrology. Decreasing surface permeability can lead to increased overland flow volumes, which may spread surficial contaminants and increase the strain on municipal stormwater infrastructure. This study examines a mixed-use property in the Proctor Creek watershed in Atlanta, Georgia, to better understand how land-management practices influence soil overland flow potential. Field saturated hydraulic conductivity (Kfs) measurements were collected from soils 1) subjected to compaction, 2) in urban agricultural use, and 3) under common lawn maintenance. Mean values were 9.1E-7 cm/s, 2.2E-4 cm/s, and 9.0E-6 cm/s respectively. Measurements were collected in-situ with the use of the Aardvark constant-head permeameter. Statistical analyses indicated a substantial difference in Kfs based on land-management practices and that urban farming can increase soil Kfs and limit overland flow. Additional analysis revealed no significant difference in grain-size distributions suggesting land-management practices controlled Kfs, not soil texture.

The objective of this study was to investigate the spatial relationship between the most likely distribution of saturated hydraulic conductivity (K-s) and the observed pressure head (P) distribution within a hillslope. The cross-correlation analysis method was used to investigate the effects of the variance of lnK(s), spatial structure anisotropy of lnK(s), and vertical infiltration flux (q) on P at some selected locations within the hillslope. The cross-correlation analysis shows that, in the unsaturated region with a uniform flux boundary, the dominant correlation between P and Ks is negative and mainly occurs around the observation location of P. A relatively high P value is located in a relatively low Ks zone, while a relatively low P value is located in a relatively high Ks zone. Generally speaking, P is positively correlated with q/Ks at the same location in the unsaturated region. In the saturated region, the spatial distribution of K-s can significantly affect the position and shape of the phreatic surface. We therefore conclude that heterogeneity can cause some parts of the hillslope to be sensitive to external hydraulic stimuli (e.g., rainfall and reservoir level change), and other parts of the hillslope to be insensitive. This is crucial to explaining why slopes with similar geometries would show different responses to the same hydraulic stimuli, which is significant to hillslope stability analysis. (C) 2016 Hohai University. Production and hosting by Elsevier B.V.

Rain fall-runoff response in temperate humid headwater catchments is mainly controlled by hydrolo gical processes at the hillslope scale. Applied tracer experiments with fluore scent dye and salt tracers are well known tools in groundwater studies at the large scale and vadose zone studies at the plot scale, where they provide a means to characterise subsurface flow. We extend this approach to the hillslope scale to investigate saturated and unsaturated flow path s concertedly at a forested hill slope in the Austrian Alps. Dye staining experiments at the plot scale revealed that crack s and soil pipe s function as preferential flow path s in the fine-textured soils of the study area, and these preferenti al flow structures were active in fast subsurface transport of tracers at the hillslope scale. Breakthrough curves obtained under steady flow conditions could be fitted well to a one-dimensional convection-dispersion model. Under natural rain fall a positive correlation of tracer concentrations to the transient flows was observed. The results of this study demon strate qualitative and quantitative effects of preferential flow feature s on subsurface stormflow in a temperate humid headwater catchment. It turn s out that / at the hill slope scale, the interaction s of structures and processes are intrinsically complex, which implies that attempts to model such a hillslope satisfactorily require detailed investigation s of effective structures and parameters at the scale of interest.

No description available.

No description available.

Climate change is expected to lead to more intense and severe rainfall events in the future, significantly increasing the risk of urban flooding. This change, characterized by spatial and temporal shifts in precipitation patterns, presents a challenge to the capacity of existing urban drainage systems, which may lead to higher runoff volumes than they were initially designed to handle. Relying solely on enlarging stormwater infrastructure to tackle this issue could be expensive and may transfer the flooding risk downstream, rather than effectively resolving it. Furthermore, climate change may also lead to prolonged dry spells, potentially resulting in soil compaction and diminished soil infiltration rates. Given these considerations, it is essential to ensure urban drainage systems are both adaptable and space-efficient, with an enhanced capacity to manage the heightened rainfall caused by climate change.   As awareness of the hydrological and environmental impacts of urbanization on catchments grows, there has been a paradigm shift toward adopting green infrastructure solutions. These approaches diverge from traditional 'end-of-pipe' strategies, emphasizing more holistic and sustainable methods. The overall aim of this thesis is to investigate the implications of climatic conditions and geographic location on the retention and detention capacity of three types of infiltration-based facilities: a biofilter cell, a green roof, and a grass swale. A rainfall-runoff model of a biofilter cell and a green roof, combined with swale irrigation experiments, was used to evaluate the capacity of these facilities to reduce runoff volumes and attenuate peak flows. The analysis was conducted in four urban areas representing oceanic (Cfc), humid continental (Dfb), and subarctic (Dfc) climatic zones. The assessment also includes the effect of temporal and spatial variation of saturated hydraulic conductivities (ksat). Swale irrigation experiments were conducted to evaluate the effect of outflow controls on swale retention and detention capacities, under high soil moisture conditions.   Results for biofilter cells and green roofs showed that retention capacities were influenced by the combined effect of antecedent wetness, the extent of winter periods, and the frequency and intensity of rainfall events. Conversely, green roofs were found to have a higher sensitivity to initial soil conditions and antecedent dry weather periods, which was observed through a spread distribution of runoff volume reductions. Grass swales exhibited a large spatial distribution of hydraulic conductivity (ksat) values, with lower values at the swale bottom and higher values at the slope on the right side. Results from a full-scale infiltration test showed that overall, grass swale infiltration capacities are representative of the measured ksat values at the swale bottom. Finally, the presence of outflow controls was observed to enhance the retention and detention capacities of grass swales, even under high levels of soil moisture content. This increase in swale hydrological functionality was influenced by swale outflow controls, leading to greater utilization of the grass swale surface area. Differences between swales with outflow controls and those without were noted due to the effect of the additional storage capacity provided by an outlet control weir. Conversely, it was shown that swales without outflow controls experienced limited retention under high soil moisture content, restricted by the finite capacity of surface depression storage.

This study focused on determining the groundwater flow paths in the crystalline subsurface rocks of the Bulawayo metropolitan, Zimbabwe, through analysing the discontinuities of the electrical properties of the ground, as well as in the magnetic field of the underlying rocks. Further, borehole water quality was analysed by measuring and mapping several chemical parameters, specifically TDS, salinity and the electrical conductivity. The electrical and magnetic anomalies were measured at two field sites within the Bulawayo province, the Harry Allen Golf Course and the Barbour Fields dumpsite, while 120 boreholes were sampled for water quality in a large part the province. Two magnetometers were used to measure the magnetic field and the time and location of the measurements, which resulted, after processing in SURFER, into the magnetic field map of these areas. This was used, in conjunction with the geologic map of the Bulawayo province, in order to determine useful locations for the electrical resistivity surveys. These included electrical resistivity tomography and vertical electrical sounding and were performed with an earth resistivity/induced polarization (IP) meter in order to measure the electrical resistivity of the ground. Inverse modelling was used in the RES2DINV software program to produce the topographic image of resistivity. The results for the borehole sampling showed that the maps for the three chemical parameters were very similar, with the western and northern parts of the mapped area displaying higher concentration values. The results of the electrical resistivity surveying showed probable areas of groundwater flow with its relationship to electric conductivity.

A previsão de áreas suscetíveis a escorregamentos translacionais rasos tem como fundamental etapa a investigação dos fatores condicionantes e dos mecanismos de ruptura. Algumas destas propriedades, como os parâmetros físicos e hidrológicos dos solos, são determinantes para a instabilização de encostas que estão sujeitas a eventos pluviométricos intensos. Uma destas propriedades é a condutividade hidráulica saturada, cujo comportamento pode influenciar no desenvolvimento de poro-pressão positiva ou levar à perda de sucção dos solos, ocasionando rupturas. Desta forma, o objetivo principal desta pesquisa foi analisar a distribuição lateral e vertical da condutividade hidráulica saturada (Ksat) dos solos e sua influência nos escorregamentos translacionais rasos na Serra do Mar (SP). Para tanto, foi selecionada uma bacia representativa da Serra do Mar e nela foram escolhidas três cicatrizes acessíveis e com limites bem preservados para a realização dos ensaios in situ. As profundidades onde foram realizados os ensaios foram definidas a partir da caracterização morfológica dos mantos de alteração nas trincheiras abertas no topo, no centro e na lateral das cicatrizes (0.25, 0.50, 1.00, 1.50, 2.00 e 2.50 m). Finamente, foram realizados os ensaios in situ utilizando-se o Permeâmetro de Guelph, utilizando-se duas cargas hidráulicas H para a que fosse possível calcular a Ksat empregando-se as equações de Richards, Laplace e a análise de Elricket al. (1989), embora tenha sido utilizada esta última para a análise da variação dos valores. A partir dos valores de Ksat, das propriedades físicas dos materiais (distribuição granulométrica, micro e macroporosidade, porosidade total. Além disso, foi analisada a tendência de variação entre 10-4 e 10-7 m/s, predominando da Ksat com a profundidade. Foram obtidos 41 valores de Ksat, os quais variaram entre as ordens de grandeza 10-5 e 10-6 m/s (82,5% dos valores), que mostraram a pequena variabilidade da Ksat nos perfis de alteração investigados, se comparada às diferenças observadas nas propriedades dos solos e corroboram com os trabalhos desenvolvidos na Serra do Mar. Quando confrontado com as propriedades físicas dos materiais (por exemplo, granulometria e porosidade total), observou-se, principalmente, a correlação positiva com a fração areia. De forma geral, foi possível identificar uma tendência de aumento da Ksat com a profundidade, assim como a existência de algumas descontinuidades hidráulicas significativas, tanto de redução quanto de aumento brusco da Ksat em uma pequena profundidade. / The prediction of landslides-prone areas has as fundamental step researching controlling factors and failure mechanisms. Some of these properties, such as the physical and hydrological soil properties are crucial to the instability of slopes subject to intense rainfall events. One of these properties is the saturated hydraulic conductivity, whose behavior can influence and lead to the development of positive pore-pressure or the loss of soil suction, causing failures. The main objective of this research was to analyze the lateral and vertical hydraulic conductivity (Ksat) of soils and their influence on shallow landslides in the Serra do Mar (SP). Therefore, we selected a representative basin in the Serra do Mar and there three accessible scars, well preserved, were chosen for in situ measurements. Was also performed the topographical characterization of the scars (slope angle, curvature and orientation and contributing area). The depths where the measurements were performed were defined from the morphological characterization of soil profiles in opened trenches at the top, at the lateral and inside the scars (0.25, 0.50, 1.00, 1.50, 2.00 and 2.50 m). At last, were performed the in situ measurements using the Guelph Permeameter, using two heads H for calculating Ksat using Richards equations, Laplace equations and Elrick et al. (1989) analysis, although the latter has been used to analyze the range of values. From the Ksat values and physical soil properties (e. g. grain size distribution, micro and macroporosity, total porosity) we discussed the role played by them in Ksat values. Moreover was analyzed the trend of Ksat variation with depth. We obtained 41 Ksat values, which varied between 10-4 e 10-7 m/s, mostly among the orders of magnitude 10-5 e 10-6 m/s (82.5% values), that showed the small variability of Ksat in the soil profiles if compared to the observed differences in soil properties, and corroborate with studies developed in the Serra do Mar. When confronted with the physical properties of materials (eg, grain size and total porosity), we observed mainly the positive correlation with the sand content. In general, we observed a tendency of increase of Ksat with depth, as well as the existence of some significant hydraulic discontinuities, both the sudden decrease as the increase in Ksat in a small depth.

O presente trabalho teve por objetivo avaliar o potencial do ensaio de ascensão capilar e de uma técnica de otimização de parâmetros para estimar os parâmetros hidráulicos dos solos. O ensaio de ascensão capilar é de execução simples e rápida e reflete um fenômeno condicionado pelas propriedades hidráulicas do solo. Na representação matemática da ascensão capilar, utilizou-se o modelo de Terzaghi (1943) que considerou tratar-se de uma condição de fluxo governada pela condutividade hidráulica saturada (ks), e o modelo de Lu & Likos (2004b), que utilizaram a equação de Gardner (1958) para representar a função condutividade hidráulica, considerando que o fluxo se dá em meio não saturado. O processo de otimização utilizou a rotina SOLVER componente do programa EXCEL, e foi testado utilizando-se os dados experimentais de Lane & Washburn (1946) e de Zhang & Fredlund (2009). Em seguida, resultados de ascensão capilar de oito amostras de solos típicos do Estado do São Paulo, Brasil, foram modelados com os parâmetros derivados da técnica. Observou-se que tanto o modelo de Terzaghi (1943) quanto o de Lu & Likos (2004b) conseguiram reproduzir os resultados experimentais de ascensão capilar, com melhores resultados associados ao modelo de Lu & Likos (2004b) para a maior parte dos solos analisados. A previsão da condutividade hidráulica saturada, de forma geral, diferiu menos de uma ordem de grandeza dos valores medidos experimentalmente, embora maiores discrepâncias tenham sido notadas para determinados tipos de solos. O parâmetro de Gardner da função condutividade hidráulica resultou em valores da mesma ordem de grandeza dos valores reportados na literatura para solos similares. Os resultados sobre a aplicação do ensaio de ascensão capilar e da técnica de otimização mostraram-se promissores para a determinação de parâmetros hidráulicos dos solos analisados, com a vantagem de ter-se um procedimento simples e rápido para a finalidade descrita. / This study evaluates the potential of capillary rise test and a parameter optimization technique to estimate soil hydraulic parameters. The capillary rise is a simple and expedite test that is conditioned by soil hydraulic properties. In the mathematical representation of the capillary rise we used the model of Terzaghi (1943), who considered that saturated hydraulic conductivity commands the phenomeno and the model of Lu & Likos (2004b) who used the Gardner equation (1958) to represent the hydraulic conductivity function, considering that the flow takes place in a non-saturated condition. The optimization process used the SOLVER routine, component of the EXCEL program, that was firstly tested using experimental data of Lane & Washburn (1946) and Zhang & Fredlund (2009). Then, results of capillary rise of eight samples of typical soils of the State of São Paulo, Brazil, were modeled with the parameters derived from the technique. It was observed that both the Terzaghi (1943) and Lu & Likos (2004b) models were able to reproduce the experimental results of capillarity, although the best results were yielded by the model Lu & Likos (2004b) for most soils. The prediction of saturated hydraulic conductivity, in general, differed less than one order of magnitude of experimentally measured values, although larger discrepancies have been noted for certain types of soils. The resulting Gardner parameter of the hydraulic conductivity function were of the same order of magnitude of the values reported in the literature for similar soils. The results on the application of capillary rise test and optimization technique proved promising for the determination of soil hydraulic parameters analyzed, with the advantage of having a simple and rapid procedure for the purpose described.