Hydraulic conductivity (K) is a key parameter required for the accurate prediction of contaminant transport in an aquifer. Traditionally, pump tests, slug tests, grain size analysis and, to a lesser extent, tracer tests have been employed to estimate the K of an aquifer. These methods have disadvantages in respect to assessing the K of a contaminated aquifer, for example, pumping tests generate large quantities of potentially contaminated water, slug tests interrogate only a small portion of aquifer to generate K values, and tracer tests are costly to perform. The recirculating well pair (RWP) system, assessed in this study, attempts to minimise these disadvantages while producing accurate estimates of K. The RWP system uses two wells, each screened in two positions; one screen injects water and the other extracts water from the aquifer. One well extracts water from the lower screen and injects it into the aquifer via the upper screen, whereas the second well extracts water from the upper screen and injects it through the lower screen. When these two wells are pumped in tandem a recirculation system is created within the aquifer. No water is lost or gained from the aquifer in this system. Hydraulic conductivity can be estimated from a RWP system by either the multi dipole or the fractional flow methods. The multi dipole method estimates K by measuring steady state hydraulic heads, whereas the fractional flow method uses a tracer test to obtain steady state concentrations at the four screens to estimate K. Both methods utilise a 3D flow model to simulate the aquifer system. Inverse modelling in conjunction with a genetic algorithm simulate the hydraulic head values obtained from the multi dipole experiments or the tracer steady state values obtained from the fractional flow method. Hydraulic ii conductivity estimates are obtained by matching the simulated and observed steady state hydraulic head, or tracer steady state values. An investigation of the accuracy of the two RWP methods, when system parameters are varied, in estimating K values was undertaken. Five multi dipole experiments were undertaken with varying dipole flow rates to assess the effect of altering dipole flow rate on estimates of K. Two experiments were also undertaken to assess the effect of altering the pumping well incidence angle as compared to the regional flow on the accuracy of K estimates. Five fractional flow experiments were conducted, four to assess the effect of changing dipole pumping rates and one to assess the influence of altering the incidence angle of the pumping wells on estimation of K. All experiments were undertaken in an artificial aquifer that allowed control of hydraulic parameters and accurate measurement of aquifer K by independent methods. Experimental results were modelled with the two RWP methods. Results indicate that both the multi dipole and fractional flow methods provide accurate estimates of the K of the artificial aquifer (5 % to 57% greater than the actual K and -14% to 17% of the actual K, respectively). Altering the ratio between the pumping well and regional aquifer flow rates had no effect on the estimated K results in both methods. Although preliminary results were positive, further work needs to be undertaken to determine if changing the orientation of the well pairs affects the estimation of K.

Cracks in reinforced concrete structures can occur as a result of many phenomena such as fresh concrete bleeding, restrained shrinkage, thermal gradients, freeze-thaw cycles, alkali-aggregate reactions, and can also be induced by external loading. Thus, concrete becomes more vulnerable to the processes of deterioration by corrosion of reinforcement. The corrosion rate of cracked reinforced concrete in different exposure conditions has been studied by some researchers. However, it is not clear how the presence of cracks affects the corrosion-determining factors, which control the corrosion pattern at the crack. The objective of this project was to develop an understanding of the effects of cracking on the transport characteristics under wetting and drying cycles. In this project, flexural loading induced natural cracks, and parallel-wall artificial cracks were studied. The infiltration properties of those cracks were evaluated by the tension infiltrometry technique. The saturation conditions around the crack were monitored with the Time Domain Reflectometry (TDR) technique. A numerical simulation was carried out to model the evolution of saturation in the cracked beams; in the model two crack modeling approaches were employed and compared. The infiltration test showed that the presence of both artificial and natural cracks (0.3 mm and 1.0 mm) dramatically increased the permeability of concrete. The value of hydraulic conductivity was increased by up to 5 orders of magnitude at the location of the crack. The evolution of water saturation of the cracked concrete under wetting and drying conditions was analyzed as colour-scaled images and the water saturation contours were compared for different crack openings. For the artificial crack samples, a deviation from the expected “perfectly symmetric” flow regime around a straight crack was observed. This was probably caused by the micro cracks induced during the shim pull-out process or a non-uniform compaction around the shim insertion. For the natural cracks, in the drying phase, smaller cracks seemed to have better water storage. Hence, the water saturation decreased at a slightly slower rate. The crack behaved like an open surface that was exposed to the environment. Application of the same material properties to the open surface and the crack surface did not bring a large error for the water flow simulations. A hysteresis phenomenon has been found during the identification of the Van Genuchten material parameters using an inverse modelling approach, with Ks=5×10-10 m/s, α =4.33×10-4, for the wetting phase, n=1.32 and for the drying phase, n=2.0. The simulation results suggest that for the simple flexural crack, the 1D crack line averaged from the front and back crack lines is capable of representing the crack in the wetting and drying scenario. The crack could be modelled as “free surface” or “equivalent porous medium”.

Artificial drainage networks established throughout peatlands during the peat extraction process often remain active following abandonment, maintaining a water table relatively far from the surface of the peat and hindering the survival and reestablishment of Sphagnum mosses. Since cutover peatlands are characterized by low (negative) soil water pressures, sufficient internal water storage and balanced water fluxes are critical for the physiological function of spontaneously regenerated Sphagnum mosses. The relative importance of water exchanges between spontaneously regenerated Sphagnum moss cushions and their surroundings are addressed through investigation of the sensitivity of moss moisture dynamics to a range of environmental variables. Precipitation waters are poorly retained within the cushions, which indicated that rain event water can only be relied upon by the mosses for a short period of time. An imbalance between water inputs and losses from moss cushions identified that additional (small) sources of water, such as dewfall and distillation, are potentially important for physiological processes under dry conditions, common in disturbed peatland ecosystems. As an initial restoration effort, rewetting of the peatland by blocking drainage ditches consequently reduced the runoff efficiency and caused the site-average water table to rise by 32 cm. Higher water tables and a blocked drainage network created conditions more favourable for Sphagnum survival through increasing the moisture content and soil-water pressures within the remnant peat deposit. The hydrologic connectivity between moss cushions and the remnant peat was strong when conditions were wet and the water table was within 30 cm of the surface of the cutover peat but weakened as conditions became drier, as reflected by weakened upward hydraulic gradients in the unsaturated zone below the moss cushions. Runoff variability increased following rewetting, and displayed a greater dependence upon antecedent conditions (capacity to retain additional water on-site) and event-based precipitation dynamics. Evapotranspiration rates were 25% higher following rewetting (3.6 mm day-1) compared to pre-restoration ET rates of 2.7 mm day-1. Total storage changes were restricted following rewetting, as a factor of the reduced runoff losses limiting water table drawdown, thereby constraining peat compression and preventing undue drying of the unsaturated zone. Changes to the system hydrology following rewetting of the peatland by blocking drainage ditches created conditions more favourable for Sphagnum survival through increasing the moisture content and soil-water pressures within the remnant peat deposit; although restoration efforts should aim to constrain water table fluctuations to within the upper 30 cm.

As the world's population shifts toward living in cities, urbanization and its deleterious effects on the environment are a cause of increasing concern. The hyporheic zone is an important part of stream ecosystems, and here we focus on the effect of urbanization on the hyporheic zone from ten first-to-second-order streams within the Virginia Piedmont. We use sediment hydraulic conductivity and stream geomorphic complexity (vertical undulation of thalweg, channel sinuosity) as metrics of the potential for hyporheic exchange (hyporheic potential). Our results include bivariate plots that relate urbanization (e.g., total percent impervious) with hyporheic potential at several spatial scales. For example, at the watershed level, we observed a decrease in horizontal hydraulic conductivity with urbanization and an increase in vertical hydraulic conductivity, which ultimately results in a negligible trend from conflicting processes. Vertical geomorphic complexity increased with total percent impervious cover. This trend was somewhat unexpected and may be due to erosion of legacy sediment in stream banks. At the reach level, hydraulic conductivity increased and sinuosity decreased as the riparian buffer width increased; these trends are weak and are essentially negligible. The hydraulic conductivity results conform to expected trends and are a product of aforementioned concomitant processes. Our results emphasize the complexity of hydrologic and geomorphic processes occurring in urban stream systems at multiple scales. Overall, the watershed level effects enhancing hyporheic exchange, which is contrary to expectations. Given the importance of hyporheic exchange to stream function, further study is warranted to better understand the effects of urbanization. / Master of Science

Grain size distribution, porosity, and hydraulic conductivity from over 400 unlithified sediment samples were analized. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations commonly used to estimate hydraulic conductivity from grain size analyses. It was found that most of the hydraulic conductivity values estimated from the empirical equations correlated very poorly to the measured hydraulic conductivity values. Modifications of the empirical equations, including changes to special coefficients and statistical off sets, were made to produce modified equations that considerably improve the hydraulic conductivity estimates from grain size data for beach, dune, off shore marine, and wadi sediments. Expected hydraulic conductivity estimation errors were reduced. Correction factors were proposed for wadi sediments, taking mud percentage and the standard deviation (in phi units) into account.

Construction projects involving the installation or repair of subsurface structures or utilities often require dewatering to induce a temporary lowering of the local groundwater elevation to facilitate construction. In the event that a known contaminant plume is present in an adjacent area, this dewatering may inadvertently draw the contaminant into the previously uncontaminated work area. Uretek Holdings, Inc. has developed its Injectable BarrierSM to be installed prior to dewatering exercises to provide a groundwater cut-off by reducing the potential movement of groundwater due to the hydraulic gradient induced by dewatering. A benefit of Injectable BarrierSM as compared to conventional methods of hydraulic control is that excavation is not required prior to its installation and no excess soils are generated through its installation. Injectable BarrierSM is a proprietary process registered with the United States Patent and Trademark Office by Uretek Holdings, Inc. Since methodical in-situ testing of the effectiveness of the Injectable BarrierSM has not been performed to date, it was the focus of this research to test the performance of the barrier under in-situ conditions utilizing a subsurface environment indicative of a West-Central Florida location. A testing plot to perform this research was selected on Hillsborough County property in Tampa, Florida which provided both a relatively shallow groundwater elevation in addition to a clay confining layer at a relatively shallow depth, making this an ideal location for testing the performance of the Injectable BarrierSM. After establishing the native conditions through baseline pump testing and repeating the testing procedure following the installation of the Injectable BarrierSM, a quantification of the reduction in hydraulic conductivity was achieved. Pumping tests were performed on the Injectable BarrierSM at its standard spacing as well as modified versions of the barrier with variation in the lateral spacing to include 6 foot, 4 foot, 3 foot, and 2 foot injection patterns to determine if a modified injection process could improve its performance. The 3 foot lateral spacing corresponding to the standard Injectable BarrierSM process indicated a 20% reduction in the hydraulic conductivity following its installation. By performing a small scale excavation following the completion of all pumping tests, it was discovered that the dispersion of the material in the subsurface appeared insufficient to provide the coverage needed to establish a barrier capable of further reducing the local hydraulic conductivity, especially at the shallowest injection depth of 3 feet below land surface (ft bls). It is concluded that modified amounts of injected material, closer lateral injection spacing, and potentially modified injection temperatures and component ratios could increase the effectiveness of the Injectable BarrierSM.

Urbanisation leads to increases in stormwater runoff, resulting in elevated contaminant (e.g. metal, sediment, and nutrient pollutant) loads, decreased local infiltration and greater peak flow intensities. Heavy metal contaminants of concern, primarily copper (Cu), lead (Pb), and zinc (Zn), originate from a variety of sources including wear-and-tear of vehicle parts, corrosion of alloy roofs, legacy petroleum contamination, and multifarious construction practices. Different technologies have been used to mitigate stormwater runoff, ranging from traditional drainage networks fitted with concrete proprietary devices (e.g. vortex sediment separators and filters) to more environmentally integrated sustainable solutions. Rain gardens, a type of Sustainable Urban Drainage System (SUDS) or Water Sensitive Urban Design (WSUD), are employed to control stormwater peak flows and runoff volumes and simultaneously reduce contaminant loads to neighbouring waterways through biologically-active landscaped design. Despite increases in use of rain gardens as a best management practice (BMP) to treat urban stormwater runoff, there is a dearth of knowledge about their treatment and infiltration performance worldwide. It is believed that incorporating topsoil into rain garden design is likely to improve contaminant removal efficiencies (Davis et al. 2001; ARC 2003; Fletcher et al. 2004; Carpenter and Hallam 2010), but design recommendations are not informed by performance data which is limiting. Performance data is necessary for understanding the long-term responses of bioinfiltrative treatment systems and for modelling efforts aiming to predict their mitigation behaviour (Fletcher et al. 2004). In order to evaluate the influence of substrate composition on stormwater treatment and hydraulic effectiveness in rain gardens, mesocosm-scale (180 L, 0.17 m2) laboratory systems were established. Saturated (constant-head) hydraulic conductivity was determined before and after contaminant (Cu, Zn, Pb and nutrients) removal experiments on three rain garden systems comprising various proportions of organic topsoil. Raw stormwater runoff from a neighbouring Christchurch city catchment was collected, characterised, and applied in the removal efficiency experiments. The system with only topsoil had the lowest saturated hydraulic conductivity (160 mm/hr initial to 164 mm/hr final) and poorest metal (Cu, Zn) removal efficiency (Cu 0.3%, Zn 60.5% and Pb 89.5%) at a ‘standard’ contaminant loading rate (Cu = 5.99 ± 0.73 µg/min, Zn = 57.89 ± 6.06 µg/min, Pb = 13.65 ± 2.80 µg/min). The sand-only system demonstrated good metal removal (Cu 56.4%, Zn 73.5%, and Pb 81.6%) with hydraulic conductivity (up to 805 mm/hr) adequate for practical implementation (i.e. greater than the 13 mm/hr minimum requirement (ARC 2003; MDE 2009; SFPUC 2009)). Overall, total metal amounts in the effluent were <50% of influent loads for all experiments, with the exception of Cu in the topsoil-only system, whose removal was negligible (0.3%). Greater metal removal was observed when effluent pH was elevated (up to pH 7.38). The pH increase (from an initial pH of 6.23 in raw stormwater) was provided by the calcareous sand, whereas the topsoil-only system lacked an alkaline source. Consequently, organic topsoil had poorer contaminant removal due to higher dissolved metal fractions, which are more difficult to immobilise at the lower pH. The relationship between pH and dissolved fraction was highly significant (Pearson’s Correlation, p < 0.0001, df = 74) for Cu, Zn, and Pb. Mesocosm-scale systems were then re-established with a calcareous substrate supplement to quantify the effects of pH augmentation on contaminant removal and hydraulic efficiencies. Mussel shells, a waste product from the shell-fish industry, were employed in two different volumetric proportions. Metal removal efficiency was increased in systems with mussel shells (Cu up to 46.6%, Zn up to 80.2%, Pb up to 88.7%) compared to the topsoil-only system (Cu 27.5%, Zn 55.5%, Pb 81.0%). Larger increases in removal efficiency were seen for Cu and Zn because increases in pH from mussel shell enhanced particulate fractions, which are easier to remove in filtration systems, while Pb is mainly in the particulate form at influent pH (Morrison et al. 1990). Effluent from systems with mussel shells also had higher hardness (hardness up to 101.7 mg/L as CaCO3) compared with 22.4 mg/L as CaCO3 in topsoil-only effluent. Hardness reduces metal ecotoxicity (Hyne et al. 2005). Results of these experiments show that mussel shells are a promising rain garden substrate capable of increasing metal removal efficiency and also decreasing metal ecotoxicity in effluent of bioinfiltration systems. Concurrently, an operational field-scale “rain garden” (42 m3; 60 m2) in Christchurch was monitored for hydraulic throughput and contaminant removal. The field system performed extremely well at mitigating peak flows, detaining water throughout storm events and removing total suspended solids (TSS) (90.6% average removal). However, the system failed to reduce effluent median total metal concentrations (Cu = 15.9 µg/L, Zn = 139.6 µg/L, Pb = 11.7 µg/L) below relevant ANZECC guidelines (Cu = 1.8 µg/L, Zn = 15.0 µg/L, Pb = 5.6 µg/L) highlighting the opportunity to optimise these field designs to improve metal removal.

Master of Science / Department of Civil Engineering / David G. Chandler / Infiltration capacity influences the ability of a soil to absorb and transmit water through macropores and micropores of the soil structure. Infiltration is primarily influenced by the soil type, which is dependent on a number of factors including parent material, climate, biological activity, and topography. Spatial controls of land use, land cover, soil texture, slope position, slope gradient and slope aspect are a few of the variables influencing infiltration capacity within a uniform soil type. The goals of the thesis are to (1) quantify the spatial distribution of soil hydraulic properties at the surface of a hillslope using one measurement method - the automated mini-disk tension infiltrometer - and several analysis methods, (2) determine the dependence of depth on soil hydraulic properties using two measurement methods, and (3) compare the results of the investigation with information from the soil survey and soil investigations. First, automated mini-disk infiltrometers were used to determine soil hydraulic properties at ten sites along a hillslope in Konza Prairie Natural Research Area. Several analysis methods were used to extract hydraulic conductivity and sorptivity values from the infiltration data. Next, large intact soil cores were extracted from three selected sites at the same hillslope and analyzed at six depths using a large disk infiltrometer. Finally, the six segments of the large soil cores were analyzed using the same methods as the field measurements with the mini-disk infiltrometers. The results of the field investigation at the ten sites show a variability of soil hydraulic properties over an assumed homogeneous landscape. The values of hydraulic conductivity and sorptivity are dependent on the method of analysis. An empirically based approach produced more realistic values than a physically based approach. The results of the laboratory investigation of the three extracted soil cores also show a dependence of method of analysis and measurement. In addition, the results show a complex relationship among landscape position, depth, and soil structure. Finally, while soil surveys and soil descriptions can provide detailed information on soil properties, an infiltration investigation at a detailed spatial scale provides quantitative values for soil hydraulic properties.

Rejeitos de mineração com muita freqüência são dispostos na forma de lama. A capacidade de estocagem das lagoas onde são depositados depende de suas dimensões e formas de operação, mas também das características físicas, compressibilidade e condutividade hidráulica da lama. No presente trabalho estudam-se as características de consolidação de uma lama argilosa resultante da mineração de areia, por meio do ensaio de consolidação hidráulica (HCT) e modela-se o enchimento de uma lagoa de disposição desse rejeito, empregando a teoria de grandes deformações e mediante o software CONDES. Realizaram-se ensaios de caracterização e HCT com amostras coletadas das lagoas 2, 11 e vertedouro da Mineração Jundu Ltda. em Descalvado, São Paulo. Estes parâmetros foram necessários para as análises de simulação numérica do processo de enchimento da Lagoa 11. Os resultados dos ensaios HCT mostraram um conjunto consistente de propriedades constitutivas do material, também se verificou a importância de alcançar a condição estável nas leituras da diferença de pressão entre o topo e a base do corpo de prova, assim obter uma menor variabilidade dos resultados. A simulação de enchimento se mostrou consistente, onde se obteve a evolução do processo de consolidação em diferentes etapas do lançamento da lama. Observou-se uma concordância dos resultados obtidos na simulação de enchimento. Segundo as análises observou-se que a altura dos rejeitos após um período de dois anos é da ordem de 1.57 m. / Mining waste is frequently disposed of in the form of mud. The storage capacity of a collection reservoir of mining waste depends on its dimensions and on its operational processes, which are based on the physical characteristics of the mud and its compressibility and hydraulic conductivity. This research focuses on the study of the consolidation characteristics of a clayey mud resultant from the process of sand mining. Such characteristics were studied through Hydraulic Consolidation Tests (HCT) and by modeling the waste reservoir filling process using large deformation theory and the CONDES software. Characterization and hydraulic consolidation tests were performed on samples obtained from Reservoirs 2 and 11 and from the Jundu Mine spillway at Descalvado City in the state of São Paulo, Brazil. The characterization parameters obtained were employed in performing numerical analysis of the filling process of waste reservoir 11. HCT test results show the acceptable set of constitutive properties of the analyzed material. During the testing procedures, variability of test results were minimized by obtaining stabilized pressure difference readings between the top and bottom leads of the specimen. Modeling was conducted for instantaneous and progressive filling and both methods yielded the same results. It was observed a predictable parity between the results obtained from instantaneous and progressive filling simulations. The final height after consolidation was measured at approximately two years for both instantaneous and progressive methods of filling. From the analysis, the two-year level was measured at 1.57 meter.

O presente trabalho foi realizado com o objetivo de quantificar e caracterizar a variabilidade espacial dos parâmetros equação K = Kq=0 exp(bq), determinada pelo método do perfil instantâneo. Nessa equação, Kq=0 é o coeficiente linear da reta lnK versus q ou a condutividade hidráulica (K) para o teor de água no solo (q) igual a zero e b o coeficiente angular. O experimento foi realizado no campus da "Escola Superior de Agricultura Luiz de Queiroz" - ESALQ/USP, localizado no município de Piracicaba (SP), em um Latossolo Vermelho Amarelo, álico, A moderado, textura média, (Typic Hapludox), moderadamente a bem drenado. A parcela experimental tinha um comprimento de 70 m e uma largura de 20 m; na sua linha central ao longo do comprimento foram considerados 50 pontos de observação, distanciados de 1 m entre si e, em cada um deles, instalados 5 tensiômetros eqüidistantes com suas cápsulas porosas localizadas às profundidades de 0,15; 0,30; 0,45; 0,60; 0,75 m. No ponto central de cada circunferência de 0,10 m de raio, na qual foram equidistantemente instalados 5 tensiômetros, foi instalada uma sonda de TDR para medida da umidade nas mesmas cinco profundidades em cada ponto de observação. As medições de umidade e potencial mátrico foram feitas durante 62 dias ou 1.370 horas, escolhendo se para este estudo o período compreendido entre os tempos de redistribuição 78 a 604 horas. Os resultados de umidade no solo (q), potencial mátrico (fm), lnKq=0 e b, foram submetidos à análise estatística exploratória e descritiva para verificação da distribuição e identificação de valores extremos. Também se calculou o número mínimo de subamostras necessárias para estimar o valor médio representativo dos parâmetros avaliados, para um nível de probabilidade de 95%, nos valores de 5, 10, 20 e 30% de coeficiente de variação em torno da média. Para os parâmetros lnKq=0 e b a análise do número de amostras foi também feita pela técnica "bootstrap". Análise da estabilidade temporal foi realizada com os dados de umidade no solo e potencial mátrico. Os resultados indicaram que o padrão de variabilidade dos parâmetros hídricos estudados (q, fm, b e lnKq=0 ) aumentou em profundidade, sendo os maiores coeficientes de variação aqueles apresentados pelo b. A variabilidade da umidade (q) foi baixa e aumentou com o tempo de redistribuição, enquanto que o potencial mátrico (fm), apresentou comportamento oposto, qual seja, variabilidade alta no início da redistribuição diminuindo para média no final da avaliação. Não houve relação entre os parâmetros quanto ao número de amostras necessárias para estimar a média, indicando que a utilização dos métodos para determinação de número de amostras pode gerar valores bem diferentes e que sua aplicação deve ser feita com prudência. Tanto a umidade do solo quanto o potencial mátrico apresentaram estabilidade temporal, o que permitiu identificar quais os locais mais indicados para a realização de amostragens com reduzido esforço e grande precisão. / This work was carried out with the objective of quantifying and characterizing the spatial variability of the K = Kq=0 exp(bq) equation parameters, determined by means of instantaneous profile method. In this equation, b is the slope and Kq=0 the intercept of the linear regression of lnK versus q. The experiment site is located at the Campus "Luiz de Queiroz", University of São Paulo, county of Piracicaba (SP), Brasil (22 o 42’ 30" S e 47 o 38’ 00" W) in a Typic Hapludox. The experimental plot dimensions were: length = 70 m and width = 20 m. In the central line of the length, 50 observation points 1m among themselves were considered each one with i) 5 mercury manometer tensiometers equally spaced in a 0.10 m radius circumference with their porous cups installed at 0.15, 0.30, 0.45, 0.60 and 0.75 m soil depths and ii) one TDR probe in the central point of the above circumference to measure soil-water content at the same five soil depths. Measurements of soil-water content and matric potential were made during 62 days of soil water redistribution, but the study was carried out using the redistribution time range from 78 to 604 hours. Results of soil-water content (q), matric potential (fm), lnKq=0 and b were analyzed by the exploratory and descriptive statistics in order to verify the data distribution and to identify outliers values. The minimum number of samples necessary to estimate the mean value of the assessed parameters was also calculated at a probability level of 5%, for variation coefficient values of 5, 10, 20 and 30%. For the parameters lnKq=0 and b, the analysis of number of sa mples was also made by using the "bootstrap" technique. Time stability analysis was used for soil-water content and matric potential data. The results have indicated that the variability of the studied hydric parameters (q, fm, b and lnKq=0 ) increased with soil depth, being the higher variation coefficients those of the parameters b. The soil water-content (q) variability was low and increased with the soil water redistribution time, whereas the matric potential had an inverse behavior, that is, high variability at the beginning of the soil water redistribution, decreasing to a medium one at the end of evaluation. There was no relation among parameters in terms of number of samples needed to estimate the mean, indicating that the use of methods to determine the number of samples can led to values very differents; hence the appliance of these methods should be done with caution. Both soil-water content and matric potential presented time stability, which permitted to identify the best points for future samplings with less effort and high precision.