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This study examines the hydrologic performance of conventional and low-impact development (LID) stormwater approaches when implemented as retrofit measures in a highly urbanised catchment (10.23 km2). A hydrologic-hydrodynamic model was proposed to simulate different implementation scenarios. Rainfall data and downstream water level observations between 01/2016 and 02/2019 were used to calibrate and validate (0.77 ≤ NSE ≤ 0.97) the model for the current situation. The simulation of stormwater control, as indicated in the municipal regulation, involving on-site retention tanks at a lot scale, led to peak flow reductions of 5% for a 10-year design storm event. When the number of dwelling owners subjected to comply with the control measures was increased, a peak flow reduction of 18% for the same event was reached. Modelling tools can guide policy and rule-making processes from a catchment management perspective, supporting the evaluation and improvement of strategies adopted in urban stormwater management. [ABSTRACT FROM AUTHOR]

The response time of hydrological components is an important feature for establishing the connections within a hydrological system and for characterizing it. This study proposes a quantitative and qualitative assessment on the response times of river discharge components, especially the baseflow, regarding the impulse provided by precipitation, using time series analyses of time and frequency domains. To this end, a set of complementary methods including correlation and spectral approaches was used, which are: autocorrelation, cross correlation, continuous wavelet transform, and cross wavelet transform. Such framework was applied in multiple and nested basin scales (53, 1,867, and 3,519 km2), located in the Jacaré‐Guaçu River Basin (Southeastern Brazil). Based on a digital filtering technique, it was found the baseflow contributes more than 80% of the annual streamflow, revealing a major role of the aquifer in regulating the river discharge in all three studied basins. In addition, we found baseflow represents a range of 24%–27% of the annual precipitation. The uniform results are mainly due to the similar physical characteristics found in those areas. Overall, our framework indicates a baseflow response time for a precipitation of approximately two years for the smaller basins and three years for the biggest one. Such results can support the water allocation in conjunctive water management, by providing estimates of future surface water availability. Research Impact Statement: A framework to estimate the aquifer time lag between precipitation occurrence and its river contribution; it also supports the present and future water allocation in conjunctive water management. [ABSTRACT FROM AUTHOR]

Research to measure soil erosion rates in the United States from natural rainfall runoff plots began in the early 1900′s. In Brazil, the first experimental study at the plot-scale was conducted in the 1940′s; however, the monitoring process and the creation of new experimental field plots have not continued through the years in either country, and are relatively rare in other parts of the world. To better understand runoff and soil erosion rates in Brazil, we review the plot-scale studies that have been conducted across the country. We also evaluated trends, challenges, and perspectives of plot-scale studies in Brazil. Runoff and soil loss records under natural rainfall were compiled from peer-reviewed journals, books, M.Sc. theses, and Ph.D. dissertations, and we organized a database containing the following information: geographic coordinates, region, rainfall, runoff, soil erosion, length of record (plot-years), land cover, tillage system, slope length, and slope gradient. We found mean values of observed annual soil loss ranging from 0.1 t ha y − 1 (grassland and pasture in the southern region) to as great as 136.0 t ha y − 1 (tilled fallow plots, without plant cover, in the northeastern region). Our findings indicated that the southern and southeastern regions of Brazil have the greatest number of runoff and soil loss monitoring sites and length of records (plot-years), corresponding to 67% and 88% of the totals, respectively. In addition, the number of plot-years of data collected has decreased 86% in the last 15 years. However, the number of published documents has increased 10 times in the same period. Around 50% of the experimental studies have 2 years or less of monitored data. In order to reduce the variability of the observed data, develop models, and support decisions, it is important to increase the monitoring period of the experimental sites. Moreover, efforts should continue to allow field observations in all regions of Brazil where data is scarce, in particular paying special attention to the central-western region, where crop production is the main land-use, and along the largest Brazilian agricultural expansion frontier (northern region). [ABSTRACT FROM AUTHOR]

The Guarani Aquifer System (GAS) is a subsurface reservoir that contains the largest volume of fresh groundwater in South America. Despite the relevance of the GAS, a lack of attention has been paid to land use effects on its recharge. We present the most detailed long-term (2004–2011) results of land-use effects on recharge in an outcrop area of the GAS. Water table fluctuations (WTFs) were measured at 11 monitoring wells, which are distributed between different land uses (i.e. eucalyptus, sugarcane, citrus and grassland). Recharge was estimated using a point-scale method (WTF) for each monitored well. The annual recharge estimates for different land uses are eucalyptus forest (135 mm year-1), sugarcane (248 mm year-1), citrus areas (296 mm year-1) and grassland (401 mm year-1). The results indicate that the evapotranspiration seems to be a key parameter in the assessment of recharge in the study area. [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, we review the erosivity studies conducted in Brazil to verify the quality and representativeness of the results generated and to provide a greater understanding of the rainfall erosivity (R factor) in Brazil. We searched the ISI Web of Science, Scopus, SciELO, and Google Scholar databases and in recent theses and dissertations to obtain the following information: latitude, longitude, city, states, length of record (years), altitude, precipitation, R factor, equations calculated and respective determination coefficient (R2). We found 35 studies in Brazil that used pluviographic rainfall data to calculate the rainfall erosivity. These studies were concentrated in the cities of the south and southeast regions (~60% of all the cities studied in Brazil) with a few studies in other regions, mainly in the north. The annual rainfall erosivity in Brazil ranged from 1672 to 22,452MJmm ha−1 h−1 yr−1. The lowest values were found in the northeast region, and the highest values were found in the north region. The rainfall erosivity tends to increase from east to west, particularly in the northern part of the country. In Brazil, there are 73 regression equations to calculate erosivity. These equations can be useful to map rainfall erosivity for the entire country. To this end, techniques already established in Brazil may be used for the interpolation of rainfall erosivity, such as geostatistics and artificial neural networks. [Copyright &y& Elsevier]

Stochastic methods based on time-series modeling combined with geostatistics can be useful tools to describe the variability of water-table levels in time and space and to account for uncertainty. Monitoring water-level networks can give information about the dynamic of the aquifer domain in both dimensions. Time-series modeling is an elegant way to treat monitoring data without the complexity of physical mechanistic models. Time-series model predictions can be interpolated spatially, with the spatial differences in water-table dynamics determined by the spatial variation in the system properties and the temporal variation driven by the dynamics of the inputs into the system. An integration of stochastic methods is presented, based on time-series modeling and geostatistics as a framework to predict water levels for decision making in groundwater management and land-use planning. The methodology is applied in a case study in a Guarani Aquifer System (GAS) outcrop area located in the southeastern part of Brazil. Communication of results in a clear and understandable form, via simulated scenarios, is discussed as an alternative, when translating scientific knowledge into applications of stochastic hydrogeology in large aquifers with limited monitoring network coverage like the GAS. [ABSTRACT FROM AUTHOR]

Abstract: This work presents a highly efficient numerical scheme for solving immiscible, advection-dominated two-phase flow in heterogeneous porous media. The pressure equation is decoupled from the saturation equation using an IMPES approach, while the advective terms are decoupled from the capillary diffusive terms in the saturation equation through sequential operator splitting. The parabolic and hyperbolic equations are approximated in time by implicit and explicit schemes, respectively. Damped Newton linearization is applied to the implicit non-linear diffusive step. Mixed hybrid finite elements are applied to the global pressure equation and to the regularized capillary diffusion term. For both linear systems arising from the approximation procedure, an AMG preconditioned conjugate gradient solver is used. A finite volume scheme with slope limiter is applied to the advective step. Numerical comparison with standard preconditioners demonstrates the reliability of the proposed AMG-preconditioner. Benchmark examples illustrate the robustness of the method. [Copyright &y& Elsevier]

The traditional approach to characterize extreme rainfall events is based on using past observed data to fit a probability distribution, which is used to associate a certain probability of occurrence to a rainfall magnitude, under a stationary assumption. Observed series, however, may exhibit trends and abrupt changes, resulting from the natural hydro climatic variability and the climate change context, which are not usually considered in the stationary modelling procedure and which may affect the characterization of extreme events. In this paper, it was evaluated the presence of these temporal changes in rainfall series and their impact to estimate design quantiles, using rainfall data of 317 stations, located in São Paulo State, Brazil. The results showed that extreme rainfall events are changing in the state. Low-return period events (up to 10 years) are intensifying. Moderate- and high-return period events, on the other hand, did not present a clear spatial pattern. Trends and abrupt changes may significantly influence the estimation of design quantiles. The presence of the former in rainfall series exhibited more influence on low-return period events, showing, however, no clear relationship with high-return period design quantiles. The presence of the latter seems to influence the characterization process, affecting estimated quantiles of all evaluated return periods. Such findings highlight the need to consider the presence of trends and abrupt changes and their influence on design quantiles for a more reliable characterization. [ABSTRACT FROM AUTHOR]

Four bench-scale solute injection experiments were conducted in a natural undisturbed basaltic fractured core of the Serra Geral Formation (SGF) (Brazil) to assess the performance of the equivalent apertures on conservative solute transport. Fracture aperture is particularly important in controlling solute transport in fractured-rock aquifers. The spatial heterogeneity of fracture apertures complicates solute transport modeling. Scientific researchers and mainly hydrogeology professionals still adopt a single value for the fracture aperture field, i.e., an equivalent aperture. However, there is a lack of information about the most suitable equivalent aperture associated with solute transport phenomena, especially for basaltic fractured aquifers. The objective of this study was to evaluate the performance of three types of equivalent apertures on conservative solute transport in a basaltic aquifer sample. The fracture aperture field was measured using the advanced high-resolution and nondestructive technique, x-ray micro-computed tomography. The performance of the equivalent apertures was evaluated using an analytical solution of the one-dimensional advection-dispersion equation (ADE) compared to observed breakthrough curves. As a result, the arithmetic mean of the measured aperture field was 111.74 ± 54.26 μm. The analytical solution of ADE coupled with mass balance aperture was able to predict breakthrough behavior, especially for low volumetric flow rates. This study demonstrates that the mass balance aperture should be adopted as an equivalent aperture instead of the hydraulic and friction loss equivalent aperture when inertial forces of macroscopic flow are negligible. The findings provide a step forward towards better understanding of groundwater contamination risk in basaltic fractured aquifers. [ABSTRACT FROM AUTHOR]

Engineered capping systems are efficient tools for the safety concept for landfills and contaminated land, consisting of multilayer barriers installed at the top of the deposited waste, even years after its closure. The efficiency of such systems is closely associated with avoiding rainwater infiltration into the waste body, a process that can be assessed and monitored with geophysical methods, such as Electrical Resistivity Tomography (ERT). A surface geomembrane capping of approximately 900 m2 was installed over an abandoned unlined landfill in southeastern Brazil and ERT surveys were adopted to assay the effectiveness of the intervention measure. It was possible to verify significantly more resistive regions below the geomembrane and an increase in conductivity values only at approximately 6 m, at the groundwater level of the area. Thus, the reduction of rainwater input possibly, even in the short term, reduces the moisture content and prevents the formation of leachate sheets in unlined landfills, leading the deposit to be more isolated from the surroundings. Lateral flow affected distances as far as 2.5 m from the capping borders, showing that about 70% of the capped area was effectively isolated from the rainfall infiltration. Therefore, capping contributed to reducing leachate production and can be considered an effective method for mitigating impacts from old unlined landfills. [ABSTRACT FROM AUTHOR]

Automated soil moisture systems are commonly used in precision agriculture. Using low-cost sensors, the spatial extension can be maximized, but the accuracy might be reduced. In this paper, we address the trade-off between cost and accuracy comparing low-cost and commercial soil moisture sensors. The analysis is based on the capacitive sensor SKU:SEN0193 tested under lab and field conditions. In addition to individual calibration, two simplified calibration techniques are proposed: universal calibration, based on all 63 sensors, and a single-point calibration using the sensor response in dry soil. During the second stage of testing, the sensors were coupled to a low-cost monitoring station and installed in the field. The sensors were capable of measuring daily and seasonal oscillations in soil moisture resulting from solar radiation and precipitation. The low-cost sensor performance was compared to commercial sensors based on five variables: (1) cost, (2) accuracy, (3) qualified labor demand, (4) sample volume, and (5) life expectancy. Commercial sensors provide single-point information with high reliability but at a high acquisition cost, while low-cost sensors can be acquired in larger numbers at a lower cost, allowing for more detailed spatial and temporal observations, but with medium accuracy. The use of SKU sensors is then indicated for short-term and limited-budget projects in which high accuracy of the collected data is not required. [ABSTRACT FROM AUTHOR]

A system identification approach can be incorporated in groundwater time series analysis, revealing information concerning the local hydrogeological situation. The aim of this work was to analyse water table fluctuations in an outcrop area of the Guarani Aquifer System (GAS) in Brotas/SP, Brazil, using data from a groundwater monitoring network. The water table dynamic was modelled using continuous time series models that reference the hydrogeological system upon which they operate. The model’s climatological inputs of precipitation and evapotranspiration generate impulse response (IR) functions with parameters that can be related to the physical conditions concerning the hydrological processes involved. The interpretation of the model parameters from two sets of monitoring wells selected at different land-use sites is presented, exemplifying the effect of different water table depths and the distance to the nearest drainage location. Systematic trends of water table depths were also identified from model parameters at specific periods and related to plant development, crop harvest and land-use changes.EDITOR D. KoutsoyiannisASSOCIATE EDITOR L. Ruiz [ABSTRACT FROM PUBLISHER]

The popular approach to select a suitable distribution to characterize extreme rainfall events relies on the assessment of its descriptive performance. This study examines an alternative approach to this task that evaluates, in addition to the descriptive performance of the models, their performance in estimating out-of-sample events (predictive performance). With a numerical experiment and a study case in São Paulo state, Brazil, we evaluated the adequacy of seven probability distributions widely used in hydrological analysis to characterize extreme events in the region and compared the selection process of both popular and altenative frameworks. The results indicate that (1) the popular approach is not capable of selecting distributions with good predictive performance and (2) combining different predictive and descriptive tests can improve the reliability of extreme event prediction. The proposed framework allowed the assessment of model suitability from a regional perspective, identifying the Generalized Extreme Value (GEV) distribution as the most adequate to characterize extreme rainfall events in the region. [ABSTRACT FROM AUTHOR]

• Large tipping bucket flow meters tend to underestimate errors. • Between linear, potential, T vs. 1/Q and quadratic regressions, linear was the best. • After linear calibration, the four sized equipment had errors lower than 1.4% • We studied tipping speed, cavity size and time interval impact on errors. • Among those variables, cavity size is the most important one. Inherent errors in tipping bucket flow meters may limit monitoring data reliability. In this work, we perform the static and dynamic calibration of four large tipping buckets, apply different regression curves and investigate the possible measurement error sources. The volumetric capacity (static calibration) of each piece of equipment was determined. They were tested (dynamic calibration) under ten flow intensities, ranging from low to high rainfall intensities (return period larger than 100 years). For each flow rate, the measurement was recorded during six time intervals (1, 2, 5, 10, 20 and 30 min) and four regression equations - linear, potential, T vs. 1/Q and quadratic - were tested. According to the static calibration, the equipment has a volumetric capacity of 11.63 mL (TB1), 64.16 mL (TB2), 139.86 mL (TB3) and 660.95 mL (TB4). When tested under different flow rates (dynamic calibration), underestimations were identified according to the size of the cavity: TB1 (3.31%), TB2 (5.75%), TB3 (9.33%) and TB4 (13.57%). Among the alternative curves, linear regression showed the best correlation (above 99%) with the monitored data. Using this method, the measurement errors were reduced to −1.35% (TB1), 0.04% (TB2), 3.18% (TB3) and 3.73% (TB4). We investigated how the different variables (tipping speed, cavity volumetric capacity and time interval of data collection) influenced the error. Errors follow a parabolic function of tipping velocity and a linear function of cavity volumetric capacity. The time interval of data collection interfered in the data sampled, however no statistical correlation was found. Among those variables, cavity size is the most important one. Given its low cost we aimed to minimize the inherent error in large tipping buckets flow meters and encourage its application, increasing in-situ collection of hydrological data. [ABSTRACT FROM AUTHOR]

There was an error during production which resulted in the alpha symbol (α) being omitted from the article in some locations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inadequate waste disposal areas (n = 104) in Brazil were assessed for contamination. • Most studies were published in Portuguese, undermining dissemination. • Contamination of groundwater and surface water was observed in most studies (>70%) • Coliforms, biochemical oxygen demand, and lead were frequently above Brazilian legislation. • Most dumpsites have insignificant or low vulnerability to groundwater contamination. This work presents an overview of environmental studies performed in areas affected by dumpsites and non-sanitary landfills in Brazil, focusing on physicochemical analysis of surface water, groundwater, and soils, as well as geophysical surveys. The objective was to identify the main contaminants found in these areas and to assess their environmental impact, guiding possible intervention measures, indicating the priority areas, and showing whether post-closure activities are mandatory. The results should support governmental actions, especially considering the recent approval of Brazil's new sanitation framework. The present review assessed 162 publications, which described 104 different municipal solid waste (MSW) disposal sites. The physicochemical parameters of analyzed surface water, groundwater, and soil samples were above Brazilian legislation levels in 74%, 70%, and 24% of the studies, respectively. The parameters more frequently above permissible levels were coliforms, biochemical oxygen demand, dissolved oxygen, and phosphorus for surface water; lead, coliforms, and iron for groundwater; copper, cadmium, lead, and zinc for soil. The results indicated that Brazilian dumpsites are causing negative impacts in surrounding soils and water resources, posing ecological and public health risks that persist even after the site's closure. Considering that this study provides only a reduced scenario, the dimension of this environmental problem in Brazil is noteworthy. Therefore, it is suggested that not only inadequate disposal is prohibited, but also efficient enforcement methods are adopted and aftercare is appropriately regulated in the country, making it obligatory to establish monitoring plans and implement mitigation techniques to avoid abandoning potentially contaminated areas. [ABSTRACT FROM AUTHOR]

hydrological monitoring is essential for a proper decision-making process and modelling. Efforts have been made in Brazil to carry out field activities at the basin scale, but how complete and comprehensive are those studies? Where are they located? How long have they been carried out? What are the main findings? To answer these questions, an overview of experimental monitoring basins in Brazil is presented, listing their geographical locations, monitored variables, operational status, monitoring periods and main publications. We identified 60 monitored sites, spread across most Brazilian biomes, with an average monitoring period of 12 years. However, some publications from these monitoring studies are not fully accessible to the international community. Field hydrology activities in Brazil contribute to a better understanding of hydrological processes in humid and semi-arid regions and inform us about the impacts of land-use change on water quality and quantity. [ABSTRACT FROM AUTHOR]

Land use and climate change can influence runoff and soil erosion, threatening soil and water conservation in the Cerrado biome in Brazil. The adoption of a process-based model was necessary due to the lack of long-term observed data. Our goals were to calibrate the WEPP (Water Erosion Prediction Project) model for different land uses under subtropical conditions in the Cerrado biome; predict runoff and soil erosion for these different land uses; and simulate runoff and soil erosion considering climate change. We performed the model calibration using a 5-year dataset (2012–2016) of observed runoff and soil loss in four different land uses (wooded Cerrado, tilled fallow without plant cover, pasture, and sugarcane) in experimental plots. Selected soil and management parameters were optimized for each land use during the WEPP model calibration with the existing field data. The simulations were conducted using the calibrated WEPP model components with a 100-year climate dataset created with CLIGEN (weather generator) based on regional climate statistics. We obtained downscaled General Circulation Model (GCM) projections, and runoff and soil loss were predicted with WEPP using future climate scenarios for 2030, 2060, and 2090 considering different Representative Concentration Pathways (RCPs). The WEPP model had an acceptable performance for the subtropical conditions. Land use can influence runoff and soil loss rates in a significant way. Potential climate changes, which indicate the increase of rainfall intensities and depths, may increase the variability and rates of runoff and soil erosion. However, projected climate changes did not significantly affect the runoff and soil erosion for the four analyzed land uses at our location. Finally, the runoff behavior was distinct for each land use, but for soil loss we found similarities between pasture and wooded Cerrado, suggesting that the soil may attain a sustainable level when the land management follows conservation principles. [ABSTRACT FROM AUTHOR]

The Guarani Aquifer System (GAS) is the largest transboundary groundwater reservoir in South America, yet recharge in the GAS outcrop zones is one of the least known hydrological variables. The objective of this study was to assess the suitability of using remote sensing data in the water-budget equation for estimating recharge inter-annual patterns in a representative GAS outcropping area. Data were obtained from remotely sensed estimates of precipitation ( P) and evapotranspiration (ET) using TRMM 3B42 V7 and MOD16, respectively, in the Onça Creek watershed in Brazil over the 2004-2012 period. This is an upland flat watershed (slope steepness <1 %) dominated by sandy soils and representative of the GAS outcrop zones. The remote sensing approach was compared to the water-table fluctuation (WTF) method and another water-budget equation using ground-based measurements. On a monthly basis, the TRMM P estimate showed significant agreement with the ground-based P data ( r = 0.93 and RMSE = 41 mm). Mean(±SD) satellite-based recharge ( R) was 537(±224) mm year. Mean ground-based recharge using the water-budget ( R) and the WTF ( R) methods were 469 mm year and 311(±75) mm year, respectively. Results show that 440 mm year is a mean (between R, R and R) recharge for the study area over the 2004-2012 period. The latter mean recharge estimate is about 29 % of the mean historical P (1,514 mm year). These results are useful for future studies on assessing recharge in the GAS outcrop zones where data are scarce or nonexistent. [ABSTRACT FROM AUTHOR]

Medeiros, Patrick Valverde, Francisco Fernando Noronha Marcuzzo, Cristián Youlton, and Edson Wendland, 2012. Error Autocorrelation and Linear Regression for Temperature-Based Evapotranspiration Estimates Improvement. Journal of the American Water Resources Association (JAWRA) 48(2): 297-305. DOI: 10.1111/j.1752-1688.2011.00614.x Abstract: Estimates of evapotranspiration on a local scale is important information for agricultural and hydrological practices. However, equations to estimate potential evapotranspiration based only on temperature data, which are simple to use, are usually less trustworthy than the Food and Agriculture Organization (FAO)-Penman-Monteith standard method. The present work describes two correction procedures for potential evapotranspiration estimates by temperature, making the results more reliable. Initially, the standard FAO-Penman-Monteith method was evaluated with a complete climatologic data set for the period between 2002 and 2006. Then temperature-based estimates by Camargo and Jensen-Haise methods have been adjusted by error autocorrelation evaluated in biweekly and monthly periods. In a second adjustment, simple linear regression was applied. The adjusted equations have been validated with climatic data available for the Year 2001. Both proposed methodologies showed good agreement with the standard method indicating that the methodology can be used for local potential evapotranspiration estimates. [ABSTRACT FROM AUTHOR]

Even though attenuation processes in the subsurface are known to reduce the impacts of contaminant plumes, their importance is significantly dependent on geological and climatic characteristics, as well as on the leachate quality. The knowledge of attenuation processes linked to different geological formations is therefore fundamental in predicting the impacts of waste disposal areas. Geophysical methods are useful tools for assessing and delineating contaminant plumes, as well as their changes with time, which enables their lower-cost monitoring and association with geological and environmental properties. This paper shows the results of geophysical surveys conducted in the years of 1996, 2005 and 2018 in a waste disposal area located at a Guarani Aquifer recharge zone in Brazil. The objective of this study was to show the evolution of the contamination plume, as well as discuss some possible transport and attenuation processes that the contaminants may undergo in similar areas. Five geophysical sections surveyed within a time span of 20 years were compared, and the information was integrated with physicochemical data from monitoring wells. The results show a horizontal plume spreading, reaching about 200 m from the deposit and about 60 m of depth, 20 years after the ending of disposal activities. The measured resistivities in 2018 are similar to the ones found in 1996 and 2005 in the same surveyed areas, showing that a significant temporal attenuation did not occur. Moreover, samples collected close to anomaly zones and within a distance of 200 m from the deposit presented concentrations of some heavy metals above the screening values according to the Brazilian legislation, showing a metals mobility higher than previously expected, which can be possibly explained by the aquifer's acidic conditions. The estimated plume velocity was about 7 m/yr, a plume deepening was observed until about 50 m and changes in water flow direction and/or diffusion processes made the plume spread to areas previously regarded as upgradient. Therefore, the present paper shows that the rehabilitation of sites neighboring waste disposal sites (less than 200 m from it) did not seem to be feasible through natural attenuation in sandy soils and that the plume spreading is significant in this geological formation. Thus, abandoned disposal areas, constantly considered to be closed after the ending of disposal activities in developing countries, generate plumes which move silently and may reach areas of concern in the future. • Geophysical surveys were conducted within a time span of 20 years. • A plume spreading was noticed, reaching about 200 m from the landfill and 50 m deep. • Upgradient areas were affected, explained by hydraulic conductivity anomalies. • The measured resistivities did not significantly change over time. • Sites neighboring the deposit did not undergo natural attenuation in 20 years' time. [ABSTRACT FROM AUTHOR]