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Automated soil moisture systems are commonly used in precision agriculture and environmental monitoring. 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 under lab and field conditions. The laboratory tests aimed at evaluating the response speed, best supply voltage, temperature dependency, calibration, and applicability for controlled infiltration column tests (one meter high). Laboratory tests indicated that the sensor is temperature and voltage-sensitive. The use of 5.5 V as supply voltage for the sensors drastically reduced the correlation between output and degree of soil saturation, thus we suggest the use of 3.3V. Soil temperature had a negligible impact on the sensor output: 0.27% of soil saturation degree per degree Celsius. For field implementation, a low-cost monitoring station was built using Arduino as a microcontroller and tested during three months. The sensors could represent daily and seasonal oscillation in soil moisture resulting from solar heating and precipitation. 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's response in dry soil. The monitored wetting front was compared to the one estimated by Hydrus model and had a high correlation. The low-cost sensor performance was later 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 promote soil moisture measurements with high accuracy at a high acquisition cost. On the other hand, low-cost sensors, such as the SKU:SEN0193, provide data with medium accuracy at a very low acquisition cost, enabling spatial monitoring through multiple-point measurements. Thus, the use of the SKU:SEN0193 sensor is suggested in projects with budget limitations with short duration where there is a medium requirement accuracy or when the spatial variability of soil water content is considerable. Despite the physical fragility of the hardware used (sensors and monitoring station) and the lower accuracy when compared to other commercial sensors, this work demonstrates through the case study of the SKU:SEN0193 sensor the possibility of using low-cost technologies for monitoring environmental variables.

The Brazilian Cerrado ecoregion, or wooded Cerrado, is considered one of the biodiversity hotspots. Despite the region’s importance in terms of supplying the water, food, and energy demand, there have not been enough ground-based studies. Furthermore, the lack of validation due to scale incompatibility and the great site-specific heterogeneity transpires in difficulty in the validation process.The eddy covariance method has the potential to directly measure water vapor or trace gases on an in situ scale. Their measurement directly reflects the surrounding study site; thus, each time interval has a corresponding footprint. So, each study site's heterogeneity can affect the target vegetation's representativeness.Here, we aimed to assess how two approaches for integrating remote sensing products and in-situ data affected representativeness in the wooded Cerrado. We used the Enhanced Vegetation Index (EVI) in both approaches, which are described as follows: (i) a fixed-fetch approach of the surrounding area considering a radius of 2 km and (ii) a lagrangian footprint approach that varied by a 30-minute time interval. We assessed their performance based on their hourly and seasonal association with canopy conductance, which was carried out using in-situ data.Compared to the fixed-fetch technique, the EVI footprint-integrated approach has a smaller range between the lower and upper quantiles, which is indicative of better targeting of the vegetation. Furthermore, we discovered that the integrated footprint technique produced a stronger association between EVI and canopy conductance than the fixed-fetch approach throughout most seasons and examined hours. The difference is most pronounced in the winter season, reaching a gain in the correlation of almost 100%, and for the autumn and spring with consistent gains of about 30%. Our findings highlight that integrating remote sensing products with footprint analysis can significantly improve the analysis's representativeness when targeting a specific land use or land cover, hence improving understanding of complex and heterogeneous areas.

This paper evaluates the calibration effectiveness for estimating monthly average flow using the SWAT model in a watershed located at Espirito Santo state in Brazil. Six methodologies were tested, ...

Considering the economic and environmental damages caused by soil loss, it is clear the necessity of information about the effect that vegetation has on soil loss rate. The present paper uses the R...

PurposeThe most common methodology to estimate erosivity is using rainfall data obtained from rain monitoring stations. However, the quality of this estimation may be compromised due to low density, operational problems and maintenance cost of rainfall monitoring stations, common problem encountered in developing countries such as Brazil. The objective of this study was to evaluate the applicability of pluviometric data obtained by TRMM satellite images for the spatiotemporal characterization of erosivity in the state of Espírito Santo (Brazil).Design/methodology/approachFor this, rainfall data and annual and monthly erosivities of 71 rainfall stations were statistically compared with those from TRMM images.FindingsFor this, rainfall data and annual and monthly erosivities of 71 rainfall stations were statistically compared with those from TRMM images. The estimate proved that TRMM is efficient since the NSE values were higher than 0.70 and the coefficient of determination was higher than 0.77 for monthly and annual erosivities, but in most months and yearly, erosivity was overestimated.Practical implicationsThe use of satellite images to estimate rainfall allowed the spatial representation over time (months) of the oscillating degree of erosivity in the state of Espírito Santo (Brazil). The spatialization may provide an identification of areas and periods in which are essential for the implementation of land use management in order to minimize environmental problems related to soil loss.Originality/valueThe technique applied may be an alternative to overcome common problems on rainfall monitoring station, such as low density, low data reliability, high manutention and maintenance cost and operational problems.

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 comp...

Brazil is seen as a potential world breadbasket in which an increase of around 40% in its current production is expected by the year 2050 to attend food demand imposed by world population growth. The disorderly intensification of agriculture results in erosion, losses and exhaustion of soil nutrients, abandonment of the area, and opening of new agricultural ones. The authors were motivated by the questioning of how significant the changes at surface runoff and soil loss over time are. Thus, this work aimed to investigate the temporal component (10 years) in the surface runoff and soil loss of a typical soil found in the Cerrado biome (Brazilian Savanah), an area that shelters a large part of the national agricultural production. The study area is located in Itirapina municipality, central region of the State of São Paulo, Brazil (22º10'S, 47º52'W, elevation of 790m). The region's mean annual rainfall is about 1486 mm and humid subtropical climate, with hot summers and dry winters. The soil type found is the Orthic Quartzarenic Neosol (RQo), which occupies approximately 15% of the Cerrado biome superficial area. Surface runoff and sediment yield are monitored in rectangular experimental plots (5 meters wide, 20 meters long, and 9% slope). Monitoring takes place in six plots kept under bare soil (three plots constructed in 2011, called P1, and another three plots constructed in 2020, called P2). Runoff flows downhill and is automatically registered through large tipping buckets and then stored in large boxes (360 liters). Runoff samples are collected after each precipitation event to identify the amount of sediment in the liquid sample. To study the pedological characteristics, soil samples were collected at different depths (15, 30, 60, and 90 centimeters) of the experimental plots in 2013 and 2022 and sent to laboratory analyses such as granulometric, porosity, density, and hydraulic conductivity. It was observed that P1 has a runoff volume 10.3% greater than P2 under the same dimensions and slope. Runoff usually starts first and lasts longer at P1 than P2. P1 soil exposure to precipitation and solar radiation over 10 years modified the superficial pedological characteristics, causing: clogging of the pores, loss of superficial soil layer, particle breakdown, and deposition near the outlet plot. Currently, the sediment carried at P1 is rich in soil particles of larger dimensions while P2 has high clay contents. The differences in the hydrological responses of the experimental plots were confirmed through laboratory analyses demonstrating that P1 has lower clay, organic matter, and porosity contents in the plot surface layers compared to P2. Most runoff and soil loss monitoring are limited to campaigns covering isolated events up to 1 year, but records over a long time as given above are scarce, especially in tropical and subtropical areas, demonstrating its relevance to the soil research community.

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.

Made available in DSpace on 2022-04-29T08:41:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Similar to most countries, the Brazilian water resources management considers topographically delineated catchment as a territorial unit for policy implementation. Yet, previous studies have shown that catchments are not hydrologically isolated, and topographic limits often neglect the groundwater boundaries. Thus, studies on effective catchment areas are promising for shedding light on inter-catchment groundwater flow. Here, we investigated the deviation between the topographic and effective areas across Brazil. We applied the effective catchment area index (ECI) to 733 Brazilian catchments and identified the most influencing attributes on the ECI by using principal component and random forest analyses (PCA and RFA, respectively). Further analysis was carried out by contrasting the ECI values against the expected range of the Budyko curve, considering both topographic and effective catchment areas (classic and adjusted framework, respectively). We noted that nearly 32% of the Brazilian catchments presented more than 30% of difference between the effective area and its topographic boundaries. In general, the more arid biomes in Brazil—the Cerrado and Caatinga—are prone to have smaller effective areas while larger effective areas were mostly found in the Atlantic Forest biome, a humid tropical region with a higher mean elevation. Our findings indicate that the aridity index was the main driving factor and negatively correlated with ECI followed by mean slope, precipitation seasonality, and mean elevation. We highlight the potential of adopting a pooling of catchments based on their interconnectivity to minimize management costs while maximizing synergies and lessening trade-offs between ecosystem functioning and water transfer processes. Our results contribute to a better country-wide understanding of hydrological connectivity among catchments and highlight the need to consider the effective catchment area to overcome water-food-energy security challenges on multiple scales. Department of Hydraulics and Sanitation São Carlos School of Engineering University of São Paulo, SP Department of Civil and Environmental Engineering Bauru Engineering College São Paulo State University – UNESP, SP Faculty of Engineering Architecture and Urbanism and Geography Federal University of Mato Grosso do Sul, MS Department of Civil and Environmental Engineering Bauru Engineering College São Paulo State University – UNESP, SP CAPES: 001 FAPESP: 2015/03806-1 FAPESP: 2019/24292-7 FAPESP: 2021/14016-2 CNPq: 309752/2020-5 CNPq: 441289/2017-7

The interception process is an important redistributor of water fluxes, which can considerably affect terrestrial evaporation. Not only the canopy intercepts water, but also from the forest floor significant amounts of water vapor return to the atmosphere. Remaining forests are important areas to evaluate the possible effects of climate change on the water partitioning process. Despite the hydrologic and ecosystem services offered by Cerrado forests, the interception process, as well as climate change threats on the evaporative flux of such forests, are still unknown. This study attempts to anticipate the possible impacts on the forest floor interception process in Cerrado stricto sensu considering future scenarios of climate change. To accomplish this, we used data of field monitoring from June 2017 to February 2020 in an undisturbed Cerrado s.s. forest in São Paulo State, Brazil. We calibrated and validated an improved version of the Rutter interception model (Rutter et al., 1971), which includes interception from the forest floor. Projected climate change scenarios were obtained from the National Institute for Space Research (INPE, Brazil) from 2006 to 2099 with 5km spatial resolution generated by Eta-HadGEM2-ES regional climate model under representative concentration pathway (RCP) 4.5. The results indicate increased rainfall and decreased potential evaporation in the decade 2041-2060. By the Rutter model, the total interception increased for this period (2041-2060) associated with decreased forest floor evaporation. During the first (2006-2020) and the last (2081-2099) decades, the predictions suggest an increase of 2.4% on the average annual percentage of forest floor evaporation, also an increase of minimum annual interception percentages (from 17.1% to 18.7%). Thus, our results demonstrate the relevance of forest floor to the interception process and suggest that it can be even more relevant in the future due to the climate changes.

A degradação do solo e água são listados como os principais problemas ambientais no mundo. Para alcançar um uso eficiente dos recursos naturais, é necessário um completo entendimento do ciclo hidrológico mediante as alterações de cobertura do solo. Para isso, faz-se necessário obter informações em diferentes escalas espaciais e temporais, sendo imprescindível o monitoramento in situ. Este trabalho teve como objetivo principal conceber, dimensionar e calibrar básculas para o monitoramento contínuo do escoamento superficial em parcelas experimentais sob quatro condições de usos do solo comuns na região Sudeste do Brasil (Cerrado stricto sensu, pastagem, cana-de-açúcar e solo exposto). Os equipamentos foram dimensionados por meio do método racional e possuem as seguintes resoluções volumétricas: 11,63mL (cerrado), 64,16mL (cana-de-açúcar), 139,86mL (pastagem) e 660,95mL (solo exposto). Cada equipamento foi submetido a testes em laboratório (calibração dinâmica) sob dez intensidades de escoamento, distribuídas uniformemente até uma vazão correspondente a uma chuva com período de retorno superior a 100 anos. Cada vazão foi registrada ao longo de seis intervalos de tempos de amostragens (1, 2, 5, 10, 20 e 30 minutos) em regime de cinco replicatas. Os equipamentos foram testados em laboratório sob altas intensidades de escoamento e tiveram desempenho satisfatório. Após realização dos testes dinâmicos, foram verificados ajustes a partir de quatro diferentes curvas de calibração, utilizando equações dos tipos: linear, potencial, inverso da vazão e quadrática. Dentre as alternativas, a regressão linear foi a que apresentou melhor correlação (R² acima de 0,99) com os dados medidos. Com o uso dessa curva para calibração, o erro residual encontrado foi estimado em -1,35%, 0,04%, 3,18% e 3,73%, para as básculas a serem instaladas na parcela de cerrado, cana-de-açúcar, pastagem e solo exposto, respectivamente. Uma vez constatada a ocorrência de erros sistemáticos, foi investigado como as diferentes variáveis (intervalo de análise, velocidade de basculada, vazão de entrada e dimensão da cavidade da báscula) influenciam no erro de medição do equipamento. Apenas a variável dimensão da cavidade possui correlação positiva significativamente estatística, enquanto as demais influenciam de forma não linear e não significativa. Futuramente, por meio do uso desse equipamento em parcelas experimentais, será possível identificar o comportamento de escoamento superficial em ambiente não antropizado (Cerrado stricto sensu) e em condições de modificação do uso do solo (cana-de-açúcar, pastagem e solo exposto). A caracterização de como as atividades antrópicas influenciam no ciclo hidrológico permitirá a proposição de técnicas mitigadoras dos impactos resultantes dessas atividades, promovendo a perpetuação das atividades econômicas em consórcio com a manutenção da qualidade e quantidade dos recursos hídricos. Por fim, a metodologia empregada nesse trabalho poderá ser facilmente reproduzida, tanto para a calibração quanto para a construção de equipamentos aplicados a outras condições de escoamento superficial. Soil and water degradation are listed as major environmental problems in the world. Achieving efficient use of natural resources requires a complete understanding of the water cycle through changes in land cover. Thus, information at different spatial and temporal scales, as well as in situ monitoring, are necessary. Our main goal was to design, size and calibrate tipping buckets for continuous runoff monitoring in experimental plots under four common land use conditions in Southeastern of Brazil (Cerrado stricto sensu, pasture, sugar cane and bare soil). The equipment was designed using the rational method and has the following volumetric resolutions: 11.63mL (Cerrado), 64.16mL (sugarcane), 139.86mL (pasture) and 660.95mL (bare soil). Each equipment was subjected to laboratory tests (dynamic calibration) under ten flow intensities, evenly distributed until a maximum flow corresponding to a rainfall with a return period greater than 100 years. Each flow rate was recorded over six sampling times (1, 2, 5, 10, 20 and 30 minutes) under five replicates. The equipment was tested in lab under high flow intensities and performed satisfactorily. After performing the dynamic tests, adjustments were verified using four different calibration curves: linear, potential, flow inverse and quadratic. Among the alternatives, the linear regression had the best correlation (above 99%) with the monitored data. Using these curves for calibration, the residual errors were -1,35%, 0,04%, 3,18%, and 3,73% for the tipping buckets to be installed in the Cerrado, sugarcane, pasture, and bare soil, respectively. Once the occurrence of systematic errors was verified, it was investigated how the different variables (sampling time, tipping speed, inlet flow rate and size of the weighing cavity) influenced the measurement error. Only the \'cavity size\' variable has a statistically significant positive correlation, while the others influenced nonlinearly and non-significantly. In the future, by using this equipment in experimental plots, it will be possible to identify runoff behavior in non-anthropized environment (Cerrado stricto sensu) and under conditions of land use modification (sugar cane, pasture and exposed soil). The characterization of how anthropic activities influence the hydrological cycle will allow the proposition of techniques that mitigate the impacts resulting from these activities, promoting the perpetuation of consortium economic activities with the maintenance of the quality and quantity of water resources. Finally, the methodology employed in this work can be easily reproduced for calibration and construction tipping buckets applied to other runoff conditions.

The uncertainties present in hydrological models have made them difficult and often impossible to apply. This work evaluated the sensitivity of input parameters in the SWAT model used for the modeling of average monthly flow-discharge in the Jucu River Basin, located in the southeast portion of the state of Espírito Santo, Brazil. Sensitivity analysis was performed using the SWAT-CUP program, which uses the SUFI-2 algorithm. Four sensitivity analysis tests differing by the length of hydrological series, number of iteration and fluviometric station locations resulted in different sensitivity levels of input parameters used in the model. In this way, the present study emphasizes the need for a greater detailing of methodological processes used in the sensitivity analysis, so that different hierarchies of parameters can be obtained through the same tool. Resumo As incertezas presentes em modelos hidrológicos têm dificultado e muitas vezes inviabilizado sua aplicação. Este trabalho tem como objetivo a avaliação da sensibilidade dos parâmetros de entrada no modelo SWAT para a modelagem de vazões médias mensais na bacia do rio Jucu, localizado na porção sudeste do estado do Espírito Santo (Brasil). A análise de sensibilidade foi realizada por meio do programa SWAT-CUP ao qual faz uso do algoritmo SUFI-2. Quatro testes que se diferenciavam pelo tamanho da série hidrológica, escolha da estação de monitoramento de vazões e número de variações dos valores dos parâmetros durante a análise de sensibilidade resultaram em diferentes níveis de sensibilidade para os parâmetros de entrada do modelo SWAT. Desta forma, o presente estudo enfatiza a necessidade de maior detalhamento dos processos metodológicos empregados na análise de sensibilidade, tendo em vista que diferentes hierarquias de parâmetros podem ser obtidas por meio da mesma ferramenta.

Purpose – The purpose of this paper is to propose a set of lifecycle-based indicators to describe material eco-efficiency of buildings normalized per unit of gross floor area (GFA), and at verifying feasibility of their calculation for building materials and components, based upon four case studies. The paper also examines the effects that discrepancies between two carbon footprint accounting methods (embodied CO2 (ECO2) vs embodied CO2e) have on communication of environmental performance of selected materials. Design/methodology/approach – The lifecycle assessments (LCAs) were performed through LCA support platform SimaPro 7.3. Data for materials/components production cycle modeling were collected from primary and secondary data from national literature or adapted from Ecoinvent database. Embodied energy, ECO2, blue water footprint (bWF), non-renewable content and volatile organic compound emissions (VOCe) indicators were calculated from lifecycle inventory (LCI) outputs, while embodied CO2e was calculated using CML 2001 v.2.01 impact assessment method. Findings – Obtained results suggest that a core database comprised of 12 materials and components – cement, ceramic blocks, steel rebar, sawn timber planks, PVC tubes, plywood, PVC conduits, roof steel structure, roundwood, ceramic tiles, hydrated lime and adhesive mortar – provides a very reasonable description of a building's embodied energy (99.63 percent), embodied CO2e (97.50 percent), bWF (96.26 percent), non-renewable content (97.53 percent) and VOCe (95.38 percent) profiles. Except for bWF of cement and concrete, substantial reductions in the metrics’ values captured environmental advantages of partially substituting ground granulated blast furnace slag (ggbs) for clinker Portland. Originality/value – The disclosure of embodied energy and carbon, as well as of other environmental performance data at whole-building level (per unit of GFA) pointed out in this paper, allows comparability and helps to establish performance goals and benchmarks and to guide policy decisions. Following a coordinated methodological outline, future works are expected to evolve to gradually constitute a LCI database that enables the use of the proposed metrics and of LCA as decision-making tools in the building sector.