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Landform classification is important for representing soil physical properties varying continuously across the landscape and for understanding many hydrological processes in watersheds. Considering it, this study aims to use a geomorphology map (Geomorphons) as an input to a physically based hydrological model (Distributed Hydrology Soil Vegetation Model (DHSVM)) in a mountainous headwater watershed. A sensitivity analysis of five soil parameters was evaluated for streamflow simulation in each Geomorphons feature. As infiltration and saturation excess overland flow are important mechanisms for streamflow generation in complex terrain watersheds, the model’s input soil parameters were most sensitive in the “slope”, “hollow”, and “valley” features. Thus, the simulated streamflow was compared with observed data for calibration and validation. The model performance was satisfactory and equivalent to previous simulations in the same watershed using pedological survey and moisture zone maps. Therefore, the results from this study indicate that a geomorphologically based map is applicable and representative for spatially distributing hydrological parameters in the DHSVM.

Methodologies for estimation of direct surface runoff (DSR) hydrographs have been proposed, especially for the Unit Hydrograph (UH) and Instantaneous Unit Hydrograph (IUH). The widely used IUH developed by Nash (NIUH) has two main parameters: number of reservoirs (n) and storage coefficient (k), which by definition are determined based on observed rainfall-runoff events. In order to overcome the need for hydrological data for application of NIUH, geomorphological approaches (GAs) have been developed to provide the aforementioned parameters for ungauged watersheds, thus allowing for the estimation of DSR hydrographs using only relief information. The aim of this study was to evaluate the performance of 4 GAs (GA1 - Nash, 1960; GA2 - Wu, 1963; GA3 - Rosso, 1984; GA4 - Bhaskar et al., 1997). Moreover, this study sought to investigate the influence of different digital elevation models (DEMs) (TOPO, ASTER, SRTM-30 and SRTM-90) on the determination of geomorphological attributes necessary for the application of the above-mentioned GAs. Twenty rainfall-runoff events observed in a small Brazilian watershed were used to evaluate the performance of NIUH combined with different GAs and DEMs for estimation of DSR hydrographs. In view of the results found in this study, the main conclusions are: i) the GAs exert more influence on the parameters n and k than the DEMs; ii) GA1 and GA2 outperformed GA3 and GA4; and iii) GA2 coupled with the ASTER DEM results in the best estimates of DSR hydrographs.

In recent years, concerns regarding the impacts of deforestation of riparian vegetation on water resources have created social and political tensions in Brazil. This research analyzed simulated hydrologic components of a 6.76 km2 headwater watershed with different widths of riparian vegetation. Lavrinha Watershed (LW) hydrological responses were simulated using the Distributed Hydrology Soil Vegetation Model (DHSVM), which was forced using meteorological data from one station (2005-2010). Land cover scenarios where the percent land cover of Atlantic Forest was increased from the control resulted in changes in hydrologic components in the watershed due to increased evapotranspiration and rainfall interception and reduced runoff and overland flow. The base flow/runoff relationship has increased, suggesting that riparian vegetation plays an important role in groundwater recharge. Modeling of hydrologic components linked to riparian buffer scenarios, such as the process used in this study, can be a useful tool for decision-making strategies regarding watershed management. RESUMO Nos últimos anos, as preocupações quanto aos impactos do desmatamento da vegetação ripária nos recursos hídricos criaram tensões sociais e políticas no Brasil. Esta pesquisa analisou os componentes hidrológicos simulados de uma bacia hidrográfica de cabeceira de 6,76 km2 com diferentes larguras de vegetação ripária. As respostas hidrológicas da Bacia Hidrográfica Lavrinha (BHL) foram simuladas utilizando o Distributed Hydrology Soil Vegetation Model (DHSVM) que foi forçado usando dados meteorológicos de uma estação (2005-2010). Os cenários de cobertura do solo em que o percentual da Mata Atlântica foi aumentado do controle resultaram em mudanças nas componentes hidrológicas na bacia hidrográfica devido ao incremento da evapotranspiração e intercepção da precipitação e redução do escoamento total e escoamento superficial. A relação escoamento base/escoamento total aumentou, sugerindo que a vegetação ripária desempenha um papel importante na recarga de água subterrânea. A modelagem dos componentes hidrológicos, associada aos cenários de larguras ripárias, como o processo utilizado para este estudo, pode ser uma ferramenta útil para as estratégias de tomada de decisão referente à gestão de bacias hidrográficas.

Soil degradation by water erosion has been accelerated by human activities. This process is aggravated in the Andes region due to steep slopes, sparse vegetation cover, and sporadic but high intensity rainfall, which together with a shallow soil depth, increases soil erosion risk. The objective of this study was to analyze the soil erosion risk, associated with A1B climate change scenario over the twenty-first century, for the Mantaro River basin (MRB), Peruvian Andes. The temporal analyses revealed maintenance of current soil erosion risk along the twenty-first century in almost all the MRB, whose current risk is either “very severe” or “extremely severe”. At the sub-basin level, for those located in the center and northern MRB, progressive increases were observed in the average erosion rate by the end of this century, increasing the soil erosion risk. In sub-basins under greater influence of the Andes, this risk was classified as “moderate” and remained this way throughout the century, despite the increase in rainfall erosive potential simulated for these. In annual terms, there was a significant trend of decreasing rainfall erosivity and increasing the concentration of rainfall simulated based on A1B climate change scenario. Because the A1B scenario affects rainfall erosivity mainly during the rainy season, this causes a risk to the environmental sustainability and future agricultural activities.

Information on stream flows is essential for water resources management. The stream flow that is equaled or exceeded 90% of the time (Q90) is one the most used low stream flow indicators in many countries, and its determination is made from the frequency analysis of stream flows considering a historical series. However, stream flow gauging network is generally not spatially sufficient to meet the necessary demands of technicians, thus the most plausible alternative is the use of hydrological regionalization. The objective of this study was to couple the artificial intelligence techniques (AI) K-means, Partitioning Around Medoids (PAM), K-harmonic means (KHM), Fuzzy C-means (FCM) and Genetic K-means (GKA), with measures of low stream flow seasonality, for verification of its potential to delineate hydrologically homogeneous regions for the regionalization of Q90. For the performance analysis of the proposed methodology, location attributes from 108 watersheds situated in southern Brazil, and attributes associated with their seasonality of low stream flows were considered in this study. It was concluded that: (i) AI techniques have the potential to delineate hydrologically homogeneous regions in the context of Q90 in the study region, especially the FCM method based on fuzzy logic, and GKA, based on genetic algorithms; (ii) the attributes related to seasonality of low stream flows added important information that increased the accuracy of the grouping; and (iii) the adjusted mathematical models have excellent performance and can be used to estimate Q90 in locations lacking monitoring.

The aim of this study was to map aboveground carbon stock of arboreal vegetation in the Savanna and Atlantic forest biomes in Minas Gerais State, Brazil, in order to assess the best spatial technique for mapping. The dataset was obtained from 148 forest fragments of these biomes. The best form of mapping was based on statistical criteria and mapping quality. The exponential semivariogram model was selected for conducting the study. The geographical model developed in this study for regression-kriging application was fitted having as input longitude and biome variables, and, globally, has presented good spatial behavior of the carbon stock distributed along the Minas Gerais State. From mapping carbon stock by different techniques, it was found that regression-kriging mapping was the most efficient. In addition, as the semivariograms were fitted for each biome using kriging and co-kriging, it is possible to stand out the flexibility for using regression-kriging, including biome as a categorical variable in the geographical model. Another result was the high correlation found between different forms of mapping, which adds reliability for this study. Thus, it was concluded that the carbon stock distribution in the arboreal vegetation of these two biomes is spatially structured. Ordinary kriging and co-kriging have presented satisfactory results, however, regression-kriging has been more reliable for mapping and estimating carbon stock distribution, in the Minas Gerais State.

The Mantiqueira Range region is one of the most important Brazilian headwater regions, from which a great number of springs flow to form one of the most important watercourses for Sao Paulo, Rio de Janeiro and Minas Gerais States. These natural features make the Mantiqueira Range an important hydrological region for research and development of technologies for management and environmental preservation. Areas in which the predominant land-use is native forest have proved to be strategic for groundwater recharge purposes, and thus, to mitigate drought effects that are being observed recently in Southeastern Brazil. In this context, to identify and map these areas lead to better and more successful decision making regarding soil–water conservation and management. In headwater watersheds, the knowledge about spatial distribution of soil–water transmissivity can be very important to sustainable use and conservation of environmental resources. The aim of this study was to evaluate the application of pattern recognition on landscape classification tools combined with digital soil mapping techniques for mapping soil–water transmissivity in a watershed located at one of the most important Brazilian headwaters, in Southeastern Brazil. The model used solum depth and saturated hydraulic conductivity as soil deterministic elements and topographic indexes. The results showed that the method proposed combining terrain attributes and Geomorphons, which is a mapping tool that allows for the identification of landforms within a landscape through digital elevation model analysis, was very efficient and, therefore, used to predict the soil–water transmissivity for the watershed. Areas with high to moderate soil–water transmissivity values were associated with the steepest slopes, shallow and moderately deep Inceptisols and native forest fragments. Since the relief and solum depth features of Inceptisols did not show optimal conditions for soil water percolation, the results demonstrated that land-use and management factors are crucial for groundwater recharge in the region of the Mantiqueira Range. The results also showed that areas with native forests play a fundamental role in water distribution processes in the soil profile in mountainous catchments in Southeastern Brazil. These results strengthen the importance of soil conservation practices and adequate land-use to sustain this kind of environment in Brazil.

Sediment delivery rate (SDR) is traditionally defined as a fraction of upland gross erosion that is transported through the outlet of a given basin, thus representing an index of the sediment transport efficiency. The objective of this study was to evaluate a model-based approach for SDR determination in the Paraopeba River Basin (PRB), located at the central region of Minas Gerais State, Southeastern Brazil. The empirical model known as RUSLE, which stands for Revised Universal Loss Equation, was used embedded in a geographical information system (GIS) to estimate the soil erosion potential. Based on a monitoring network, considering the period between 1997 and 2008, the sediment transport was determined in five sub-basins of the PRB. The average water erosion for PRB was 2.7 ton ha−1 yr−1, while the sediment transport varied from 0.25 to 1.63 ton ha−1 yr−1. Considering the area and the slope as the independent variables, three empirical models were applied for estimating SDR. The results showed ...

Extreme rainfall can lead to heavy damage and losses, such as landslides, floods and agricultural productivity as well as the loss of human and animal lives. To mitigate these losses, water resources management policies are needed, among other goals, to study and predict the frequency of such events in a given region to minimize their harmful effects. The present study investigated the Generalized Extreme Value (GEV) probability distribution applied to the annual maximum daily precipitation data from rainfall stations in the southeastern Brazil. A total of 1,921 rainfall stations were considered, among which the stations with at least 15 years of uninterrupted observations were selected. Subsequently, the stationarity and adherence were tested. GEV probability distribution parameters were then estimated. The results enabled satisfactory spatial interpolation by ordinary kriging and the generation of maps of the distribution parameters. The semivariogram model with the best fit to the three GEV distribution parameters was the exponential model.

Brazilian Atlantic Forest is recognized by the UNESCO as one of the most important biosphere reserves on the planet but is threatened by extinction. The objective of this study was to analyze the main components of the water balance in an Atlantic Forest (Neotropical Forest) catchment in the Mantiqueira Range, Brazil, which is a Tropical Montane Cloud Forest. The main focuses was to analyze baseflow, evapotranspiration, soil moisture, and canopy rainfall interception to understand the hydrologic dynamics in this specially important montane forest. On average from the two studied hydrological years (2009/2010 and 2010/2011), evapotranspiration (ET), streamflow (SF), and water storage in the catchment at the end of hydrological year corresponded, respectively, to 50%, 34.8% and 15.2% of total gross precipitation (P). On average, baseflow corresponded to 73.5% of SF. The estimated potential groundwater recharge during the wet seasons was 403.8mm (21.7% of P observed in the wet season) and 710.5mm (28.5% of P observed in the wet season), respectively, for 2009/2010 and 2010/2011 hydrological years, showing that the catchment is able to store groundwater to provide the maintenance of the streamflow during early recessions and drought periods. Therefore, the baseflow is important in mountainous catchments in the tropical regions to provide important ecological functions, mainly as freshwater reserve.

MUDANCAS TEMPORAIS EM UMA FLORESTA OMBROFILA ATLÂNTICA EM CURTOS INTERVALOS DE TEMPO A caracterizacao e o monitoramento do Dominio Atlântico brasileiro fornecem importante subsidio para a conservacao de seus remanescentes. Variacoes de curto prazo na composicao e estrutura de florestas sao geralmente perdidas em intervalos maiores entre inventarios e podem melhor elucidar a dinâmica florestal. Este estudo teve como objetivo analisar as mudancas temporais na estrutura, composicao e diversidade da comunidade de arvores em uma floresta Ombrofila em Bocaina de Minas, Minas Gerais, Brasil em dois intervalos curtos. O estudo foi realizado com base em dados de circunferencia a altura do peito (1,3 m) (CAP) de arvores medidas em tres inventarios florestais (2009, 2011 e 2012) em 12 parcelas permanentes de 400 m² distribuidos aleatoriamente na floresta. Os resultados indicam um aumento da densidade de plantas e area basal, principalmente devido a continuas perturbacoes antropicas pontuais observadas na floresta, como a presenca de gado e trilhas. Estes disturbios desencadeiam processos iniciais de sucessao em diversos setores da floresta. O gradiente de altitude resulta em elevada heterogeneidade ambiental, com alta substituicao de especies, e em alta diversidade, a qual permaneceu inalterada nos intervalos considerados.Palavras-chave: biodiversidade, dinâmica florestal, conservacao florestal. ABSTRACT: Characterizing and monitoring the Brazilian Atlantic Domain provide important direction for the conservation of its remnants. Short-term variations in forest composition and structure are usually lost in larger intervals between inventories and could better elucidate forest dynamics. This study aimed to analyze temporal changes in the structure, floristic composition and diversity of a tree community of an Ombrophilous Dense Forest remnant in Bocaina de Minas, Minas Gerais state, Brazil, in two short intervals. The study was conducted based on circumference at breast height (1.3 m) (CBH) data from three forest inventories (2009, 2011, and 2012) in twelve 400 m² permanent plots randomly distributed in the area. The results point out to a forest characterized by the increase in plant density and basal area, mainly due to the continuous local anthropogenic disturbances observed in the area, such as the presence of cattle and trails. These disturbances start early successional processes in various sectors of the forest. The altitudinal gradient leads to great environmental heterogeneity, resulting in a high species turnover, as well as high values of diversity which remained unchanged in the intervals considered.Keywords: biodiversity, forest dynamics, forest conservation.

Here we model and describe the wood volume of Cerrado Sensu Stricto, a highly heterogeneous vegetation type in the Savanna biome, in the state of Minas Gerais, Brazil, integrating forest inventory data with spatial-environmental variables, multivariate regression, and regression kriging. Our study contributes to a better understanding of the factors that affect the spatial distribution of the wood volume of this vegetation type as well as allowing better representation of the spatial heterogeneity of this biome. Wood volume estimates were obtained through regression models using different environmental variables as independent variables. Using the best fitted model, spatial analysis of the residuals was carried out by selecting a semivariogram model for generating an ordinary kriging map, which in turn was used with the fitted regression model in the regression kriging technique. Seasonality of both temperature and precipitation, along with the density of deforestation, explained the variations of wood volume throughout Minas Gerais. The spatial distribution of predicted wood volume of Cerrado Sensu Stricto in Minas Gerais revealed the high variability of this variable (15.32 to 98.38 m3 ha-1) and the decreasing gradient in the southeast-northwest direction.

Heavy rainfall in conjunction with an increase in population and intensification of agricultural activities have resulted in countless problems related to flooding in watersheds. Among the techniques available for direct surface runoff (DSR) modeling and flood risk management are the Unit Hydrograph (UH) and Instantaneous Unit Hydrograph (IUH). This study focuses on the evaluation of predictive capability of two conceptual IUH models (Nash and Clark), considering their original (NIUH and CIUH) and geomorphological approaches (NIUHGEO and CIUHGEO), and their advantages over two traditional synthetics UH models - Triangular (TUH) and Dimensionless (DUH), to estimate DSR hydrographs taking as reference two Brazilian watersheds with contrasting geomorphological and climatic characteristics. The main results and conclusions were: i) there was an impact of the differences in physiographical characteristics between watersheds, especially those parameters associated with soil; the dominant rainfall patterns in each watershed had an influence on flood modeling; and ii) CIUH was the most satisfactory model for both watersheds, followed by NIUH, and both models had substantial superiority over synthetic models traditionally employed; iii) although geomorphological approaches for IUH had performances slightly better than TUH and DUH, they should not be considered as standard tools for flood modeling in these watersheds.

The estimation of soil physical and chemical properties at non-sampled areas is valuable information for land management, sustainability and water yield. This work aimed to model and map soil physical-chemical properties by means of knowledge-based digital soil mapping approach as a study case in two watersheds representative of different physiographical regions in Brazil. Two watersheds with contrasting soil-landscape features were studied regarding the spatial modeling and prediction of physical and chemical properties. Since the method uses only one value of soil property for each soil type, the way of choosing typical values as well the role of land use as a covariate in the prediction were tested. Mean prediction error (MPE) and root mean square prediction error (RMSPE) were used to assess the accuracy of the prediction methods. The knowledge-based digital soil mapping by means of fuzzy logics is an accurate option for spatial prediction of soil properties considering: 1) lesser intense sampling scheme; 2) scarce financial resources for intensive sampling in Brazil; 3) adequacy to properties with non-linearity distribution, such as saturated hydraulic conductivity. Land use seems to influence spatial distribution of soil properties thus, it was applied in the soil modeling and prediction. The way of choosing typical values for each condition varied not only according to the prediction method, but also with the nature of spatial distribution of each soil property.

Models have been used by man for thousands of years to control his environment in a favorable way to better human living conditions. The use of hydrologic models has been a widely effective tool in order to support decision makers dealing with watersheds related to several economic and social activities, like public water supply, energy generation, and water availability for agriculture, among others. The purpose of this review is to briefly discuss some models on soil and water movement on landscapes (RUSLE, WEPP, GeoWEPP, LASH, DHSVM and AnnAGNPS) to provide information about them to help and serve in a proper manner in order to discuss particular problems related to hydrology and soil erosion processes. Models have been changed and evaluated significantly in recent years, highlighting the use of remote sense, GIS and automatic calibration process, allowing them capable of simulating watersheds under a given land-use and climate change effects. However, hydrology models have almost the same physical structure, which is not enough for simulating problems related to the long-term effects of different land-uses. That has been our challenge for next future: to understand entirely the hydrology cycle, having as reference the critical zone, in which the hydrological processes act together from canopy to the bottom of aquifers. RESUMO Modelos têm sido usados pelo homem há milhares de anos para controlar seu ambiente de uma maneira favorável para melhores condições de vida para os humanos. O uso de modelos hidrológicos tem sido uma ferramenta muito eficaz para apoiar os decisores que lidam com as bacias hidrográficas para subsidiar diversas atividades econômicas e sociais, como o abastecimento público de água, geração de energia, e a disponibilidade de água para a agricultura, entre outros. Objetivou-se, nesta revisão, discutir brevemente alguns modelos muito aplicados ao estudo do movimento da água e solos em paisagens (RUSLE, WEPP, GeoWEPP, LASH, DHSVM and AnnAGNPS), para fornecer informações sobre os mesmos, para auxiliar no entendimento adequado de problemas específicos relacionados com os processos de hidrologia e erosão do solo. Modelos têm sido alterados e avaliados de forma significativa nos últimos anos, com destaque para o uso de sensoriamento remoto, GIS e processo de calibração automática, permitindo aos mesmos que sejam capazes de simular bacias hidrográficas nas suas condições atuais de uso do solo e mudanças climáticas. No entanto, os modelos hidrológicos têm quase a mesma estrutura física, o que não é suficiente para simular problemas relacionados com os efeitos a longo prazo de diferentes usos do solo. Esse tem sido um dos principais desafios para o futuro: compreender inteiramente o ciclo hidrológico, tendo como referência a zona crítica, na qual os processos hidrológicos agem em conjunto a partir do dossel até a base dos aquíferos.

RESUMO O objetivo deste estudo foi avaliar a continuidade espacial ao longo do tempo (para 5 idades consecutivas) das características dendrométricas altura dominante média, volume e incremento médio anual em povoamentos clonais de Eucalyptus sp no estado de Minas Geais. A área foi plantada em 2003, perfazendo um total de 1.072,6 hectares. Os dados foram oriundos de um conjunto de 116 parcelas permanentes, onde foi realizado inventário florestal sucessivo entre os anos de 2006 e 2010. Aos semivariogramas experimentais, foram ajustados os modelos esférico, exponencial e gaussiano pelo Método dos Mínimos Quadrados Ponderados, para cada idade, selecionando-se o mais adequado com base no erro médio reduzido e desvio padrão do erro médio reduzido da validação cruzada. O comportamento dos semivariogramas foram comparados entre as respectivas medições com base no plotagem dos mesmos de forma escalonada, permitindo avaliar se a estrutura espacial foi alterada com a idade do plantio. O modelo exponencial apresentou-se como o de melhor ajuste e todas as características apresentaram-se estruturadas espacialmente, com os modelos espaciais sendo semelhantes entre as idades do povoamento e para as características estudadas. Foi possível verificar que o grau de continuidade espacial se manteve ao longo dos anos para as características avaliadas e que o semivariograma escalonado demonstrou que a estrutura espacial das características é semelhante entre as diferentes idades do povoamento. Os resultados evidenciam que a utilização de métodos geoestatísticos para avaliar o crescimento de povoamentos de eucalipto ao longo do tempo, consiste de uma importante ferramenta de planejamento, permitindo um melhor acompanhamento e uma predição mais precisa do volume de madeira da floresta, levando em consideração a estrutura de dependência espacial.

Study region The study was conducted in the Rio Grande do Sul state – Brazil. Study focus Studies about heavy rainfall events are crucial for proper flood management in river basins and for the design of hydraulic infrastructure. In Brazil, the lack of runoff monitoring is evident, therefore, designers commonly use rainfall intensity–duration–frequency (IDF) relationships to derive streamflow-related information. In order to aid the adjustment of IDF relationships, the probabilistic modeling of extreme rainfall is often employed. The objective of this study was to evaluate whether the GEV and Kappa multiparameter probability distributions have more satisfying performance than traditional two-parameter distributions such as Gumbel and Log-Normal in the modeling of extreme rainfall events in southern Brazil. Such distributions were adjusted by the L-moments method and the goodness-of-fit was verified by the Kolmogorov–Smirnov, Chi-Square, Filliben and Anderson–Darling tests. New hydrological insights for the region The Anderson–Darling and Filliben tests were the most restrictive in this study. Based on the Anderson–Darling test, it was found that the Kappa distribution presented the best performance, followed by the GEV. This finding provides evidence that these multiparameter distributions result, for the region of study, in greater accuracy for the generation of intensity–duration–frequency curves and the prediction of peak streamflows and design hydrographs. As a result, this finding can support the design of hydraulic structures and flood management in river basins.

As distribuições de probabilidades de valores extremos desempenham importante papel na modelagem de eventos extremos. Elas têm sido amplamente aplicadas em estudos hidrológicos a fim de predizer, para um nível de confiança, valores esperados num dado tempo de retorno. Várias distribuições têm sido empregadas com diferentes métodos de ajuste. Objetivou-se neste trabalho verificar a aderência das distribuições GEV e Gumbel aos dados de precipitação diária máxima anual de doze estações pluviométricas no Alto Rio Grande, MG. Foram consideradas três sub-regiões com características fisiográficas peculiares, cada uma com quatro estações pluviométricas em seus domínios, Planalto Campos das Vertentes (PCV), Serra da Mantiqueira (SM) e uma sub-região de Transição (TR) entre as duas. Para a estimação dos parâmetros utilizou-se o método dos momentos, máxima verossimilhança e momentos-L. A aderência dos ajustes foi avaliada pelos testes de Filliben e Qui-quadrado (χ2). A metodologia dos momentos-L mostrou-se como a melhor opção, independente da sub-região sendo que se recomenda, para as sub-regiões SM e TR, a distribuição Gumbel, enquanto para o PCV a melhor opção de ajuste é a GEV. Probabilistic models have played an important role for stochastic modeling of the extreme events. They have been widely used in hydrological studies to predict, for a confidence level, expected values in a given return period. Several probabilistic models have been applied based on different adjustment methods which estimate the statistical moments of them. The aim of this study was to verify the adherence of Generalized Extreme Values (GEV) and Gumbel probabilistic models at two frequency of occurrence of heavy rainfall events in the Upper Rio Grande region (UGR), Southern Minas Gerais. UGR region was divided into three sub-regions with similar physiographic features in which four rain-gauging stations were studied: Plateau of Campos das Vertentes (PCV), Mantiqueira Range (SM) and a transition sub-region (TR). For estimating the distribution parameters, the Moment Method, Maximum Likelihood and L-moments were tested. The adherence of probabilistic models was evaluated by both Filiben and Chi-square tests. L-moments method showed to be the best method for all sub-regions and models. In addition, for the SM and TR sub-regions Gumbel model produced better results while for the PCV, GEV model was more appropriate.

The Mantiqueira Range region is one of the most important headwaters in southeastern Brazil. In this context, the relationship between pedology and hydrology has been debated and analyzed in recent years, contributing to the creation of a multidisciplinary science call hydropedology. Therefore, the aim of this study was to evaluate the hydropedological properties of a mountainous Clayey Humic Dystrudept in the Mantiqueira Range region, in the state of Minas Gerais, Brazil, comparing two land-uses, native forest and pasture. The hydraulic conductivity results demonstrated that native forest (MFO) has a strong influence on this parameter, offering conditions for movement of water in the soil that are more adequate in this profile than in pasture. These results were supported by pore size distribution analyses which showed that soil from native forest has a greater amount of macropores than soil from pasture as well as greater connectivity between the macropores. In general, the MFO site had greater S index values than the micro-catchment taken from pasture, offering favorable physical conditions for the formation of preferential flowpaths in the soil profile and, therefore, better conditions for groundwater recharge. Soil erosion and water quality results confirmed the importance of native forest areas in the interaction between interception of the direct impact of intense precipitation on the soil surface, and hydropedological attributes, such as saturated hydraulic conductivity and porosity.

The natural vulnerability characterization provides fundamental support for identification of areas more susceptible from the hydrology point of view, assuring the maintenance of water resource features. In this context, this study aimed to characterize the natural vulnerability of water resources based on long-term streamflows, base flow and aquifers’ susceptibility to contamination, for Formoso River basin, located in southwestern Tocantins. For that, subdivision by level 5 Ottobasins and discharge and precipitation data sets, both available from the “Brazilian National Water Agency”, and the geological map developed by “Tocantins State Bureau of Planning” (SEPLAN) were used. The final natural vulnerability of water resources presented degrees varying from low to very high. Areas with lower vulnerability were observed in the basin headwaters, mainly due to the greatest both long-term (SYqlt) and 90% of the exceedance (SY90%) specific discharges. “High” vulnerability were identified in most of the middle basin course while “Very High” vulnerability in the lower basin course given by lower SYqlt and SY90% and by the occurrence of the alluvial aquifers which present high natural susceptibility to contamination. Key words: Natural resources, hydrology, watershed management.

A gestão de cheias em bacias hidrográficas brasileiras deve ser discutida e priorizada, porém o cenário atual indica lacunas quanto às informações hidrológicas com variabilidade espacial e temporal condizentes. A modelagem probabilística de eventos extremos de precipitação, buscando a extrapolação para uma frequência e duração, pode servir como excelente ferramenta de análise e tomada de decisões. O objetivo principal deste trabalho foi analisar o ajuste de diferentes modelos probabilísticos a séries de precipitação máxima diária anual no Rio Grande do Sul. Séries pluviométricas de 342 estações foram ajustadas às distribuições Log-Normal a 2 e 3 parâmetros e Gumbel e a adequação foi realizada pelos testes de Kolmogorov-Smirnov e Qui-Quadrado. Todas as distribuições de probabilidade consideradas foram adequadas; entretanto, a distribuição Log-Normal a 3 parâmetros apresentou os melhores ajustes segundo os resultados do teste Qui-Quadrado. Os parâmetros das distribuições de probabilidades apresentaram variabilidade ao longo do estado e forte relação com a localização, sugerindo que a regionalização de chuvas intensas pode ser empregada no Rio Grande do Sul como excelente ferramenta de gestão. Flood management in Brazilian watersheds must be discussed and prioritized, however, the current scenario indicates that there are gaps in hydrological information with respect to its spatial and temporal variability. The probabilistic modelling of extreme rainfall events, having as goal to extrapolate values for a given frequency and duration, can be used as an excellent tool for analysis and decision-making. The main objective of this study was to analyse the adjustment of different probabilistic models for series of annual maximum daily rainfall in Rio Grande do Sul. Series of 342 rain gauges were adjusted to 2-parameter Log-Normal, 3-parameter Log-Normal and Gumbel probability distributions and goodness-of-fit tests were based on the Kolmogorov-Smirnov and Chi-Square procedures. It was found that all the distributions presented adequate results, however, 3-parameter Log-Normal distribution had the best performance in accordance with the Chi-Square test. The parameters of probability distribution presented variability over the state and a pronounced relationship with the location of rain gauges. This suggests that regionalization of high-intensity rainfall can be employed in Rio Grande do Sul as an excellent management tool.

Climate change is always occurring. Its impacts on the environment are still uncertain, especially due to the difficulty of simulating the earth’s climate accurately. However, the global circulation climate models have been the only scientific tool to assess such impacts and their results have been well accepted. This study aimed to analyze the possible impacts on rainfall erosive potential throughout the twenty-first century for the A1B climate change scenario, in the Grande River Basin (GRB) headwaters, Southeastern Brazil. The results from Eta-CPTEC/HadCM3 model were taken into account to calculate the climatic erosivity indicators “Modified Fournier Index” (MFI) and “Precipitation Concentration Index” (PCI). Based on three meteorological stations, which are monitoring the weather in GRB headwaters since 2005, every 10 min, a statistical relationship between annual rainfall erosivity (EI30) and the respective MFI was adjusted to infer about EI30 in the future. The results have showed an increase in annual amount of precipitation for most months of the year, except for September and October, throughout the twenty-first century. The greatest impacts on EI30 are associated with the projected increase in precipitation for December and January, which can reach up to 49 %. A significant increase in MFI and PCI was observed over the twenty-first century in relation to the present climate. These results demonstrate a potential increase in rainfall erosive power, which causes special concerns due to predominance of shallow soils, associated with undulated to strongly undulated relief in the studied region.

A avaliacao de modelos hidrologicos e etapa indispensavel na modelagem, porem sua abordagem nao deve se restringir ao uso de coeficientes que comparam dados medidos com os simulados, sobretudo para modelos em que isso nao e possivel, como no caso dos modelos de agua subterrânea. Assim, o objetivo do trabalho foi avaliar o modelo BALSEQ no aspecto qualitativo. Para isso, foi feita a analise de sensibilidade das variaveis de entrada, bem como uma avaliacao da estrutura do modelo, para detalhar o comportamento de cada variavel e suas interacoes com as respostas da modelagem.O modelo apresenta estrutura simples mas bastante coerente, o que permite inserir modificacoes e adapta-lo para diversas condicoes de clima, solo e vegetacao. Os resultados da analise de sensibilidade indicam que O BALSEQ tem sensibilidade diferenciada para cada combinacao de solo e vegetacao modelada, o que enfatiza a importância da analise de sensibilidade uma vez que a calibracao do modelo deve ser feita com as variaveis mais significativas. Nas areas com cobertura florestal as variaveis de maior relevância na estimativa da recarga foram a Interceptacao pela Cobertura Vegetal (ICV) e o coeficiente da cultura (Kc), as quais sao parâmetros usados para representar a evapotranspiracao. Enquanto que, nas areas de pastagem e culturas anuais, o escoamento superficial, representado pelo parâmetro do metodo Curve Number- CN, foi a variavel mais importante. De modo geral, o CN e a variavel de maior impacto no balanco hidrico e portanto deve ser criteriosamente calibrado.

Litter corresponds to the layer of decomposing dead organic matter present on the soil surface. This layer is very important for nutrient cycling and contributes with organic matter accumulation in the soil, besides the carbon stock. The objective herein was to quantify the carbon biomass, both content and stock, and map the litter C-stock in the Cerrado biome, which is formed by Savanna Grassland (SG), Cerrado Stricto Sensu (CE) and Forest Savanna (FS), in Minas Gerais state, southeastern Brazil. The data were collected in 26 fragments in Minas Gerais state, totaling 210 sampling locations. A variographic study was conducted and, for mapping, the ordinary kriging method was used for delimitation of homogeneous zones. It was possible to detect high variability in the carbon biomass, carbon content and C-stock in the Cerrado biome litter in Minas Gerais state. The carbon content presented lower variability, ranging from 40 to 44%, so that it is not responsible for explaining the variability of the litter C-stock. Savanna Grassland and Savanna Forest present, respectively, the lowest and highest C-stocks. C-stock presented a considerable spatial structure dependence, allowing to use the geostatistical procedures for mapping it in the Cerrado biome of the Minas Gerais state. The C-stock kriging map showed good accuracy, allowing to verify that the lowest C-stocks in the litter are found from the center to the northern of the Minas Gerais since the highest air temperatures are also verified in this direction. RESUMO A serrapilheira corresponde à camada de matéria morta em decomposição presente sobre o solo. Esta camada é de grande importância na ciclagem de nutrientes e aporte de matéria orgânica sobre o solo, além de estocar carbono. Objetivou-se quantificar a biomassa, teor e estoque de carbono e espacializar o estoque de C da serrapilheira do Cerrado de Minas Gerais. Os dados foram coletados em 26 fragmentos de Cerrado no Estado de MG, totalizando 335 pontos amostrados em todo estado. Foi realizado o estudo variográfico e, para o mapeamento, utilizou-se a Krigagem, para delimitação de zonas homogêneas. Foi possível detectar alta variabilidade nas características avaliadas, biomassa, teor e estoque de carbono na serrapilheira do Cerrado em Minas Gerais, Brasil. O teor de C foi a característica que apresentou menor variabilidade, com intervalo de 40-44%, de modo que não é um atributo crítico para explicar o estoque de C na serrapilheira. O Campo Cerrado tem o mais baixo estoque de C, e o Cerradão o mais alto. O estoque de C apresenta considerável dependência da estrutura espacial, permitindo o uso de procedimentos geoestatísticos para mapeá-lo no bioma Cerrado do estado de Minas Gerais. O mapa de krigagem de estoque de C mostrou boa precisão e com base nele, foi possível verificar que os estoques de menor teor de carbono na serrapulheira são encontrados do centro para o norte do estado de Minas Gerais, onde tem-se as maiores temperaturas médias anuais.

The scarcity of field data to develop soil maps through a pedological survey is one of the main limitations to using distributed hydrological models, especially in small and medium-sized watersheds. The aim of this study was to compare a distributed hydrological model prediction to a soil map based on a pedological survey and a moisture zone map obtained using the Height Above the Nearest Drainage - HAND model. The Distributed Hydrology Soil Vegetation Model - DHSVM, which is a physically-based and distributed hydrological model, was applied to a mountainous watershed, located in the region of the Mantiqueira Range in the south of Minas Gerais in southeastern Brazil, and was compared to both maps mentioned above, taking the soil map developed by the pedological survey as a reference. Daily weather and streamflow data-sets were used for DHSVM calibration and validation using the two different maps (soil and moisture zone maps) as inputs. In both simulations, the DHSVM performed well, with outputs indicating a good relationship between topographical and hydrological characteristics from the two types of maps. Thus, the moisture zone map obtained by the HAND model can also be successfully used in distributed hydrological modeling, especially for mountainous regions in southeastern Brazil.

Soil moisture temporal variability is an important concept in understanding forest management. The objective of this study was to analyse the effect of planting density on soil profile moisture in a clonal Eucalyptus plantation. Soil moisture was observed every 15 days at 25 points distributed throughout the eucalyptus stand between November 2013 and October 2015 to characterize the moisture according to the following three types of spacings: 3 x 2, 3 x 3, and 3 x 5 m. At each point, the 0 - 10, 10 - 20, 20 - 30, 30 - 40, and 60 - 100 cm layers were evaluated using a Profile Probe PR2 model. Soil moisture showed high spatial variability in the 0 - 10 cm layer, whereas from 30 to 100 cm deep, the moisture tended to become more homogeneous throughout the area. The dry periods presented greater temporal soil moisture stability when compared to the rainy seasons. The 3 x 2 m spacing has greater temporal soil moisture stability when compared to the others, while the 3 x 3 m spacing presented greater temporal variability. RESUMO. A compreensão da variabilidade temporal da umidade do solo é importante para um manejo adequado de culturas florestais. O objetivo neste trabalho foi analisar o efeito causado pela densidade de plantio na umidade no perfil do solo em um povoamento clonal de Eucalyptus. A umidade do solo foi observada em intervalos de 15 dias em 25 pontos distribuídos no povoamento de eucalipto entre novembro de 2013 e outubro de 2015 buscando caracterizar a mesma em função de três espaçamentos: 3 x 2; 3 x 3 e 3 x 5 metros. Em cada ponto foram avaliadas as camadas de 0 - 10, 10 - 20, 20 - 30, 30 - 40 e 60 - 100 cm utilizando uma sonda Profile Probe PR2. A umidade do solo apresentou alta variabilidade espacial na camada de 0 - 10 cm, enquanto que a partir dos 30 cm até 100 cm de profundidade a umidade tendeu a ficar mais homogênea em toda a área. O período seco apresenta maior estabilidade temporal da umidade do solo quando comparado ao período chuvoso. O espaçamento 3 x 2 metros apresenta uma maior estabilidade temporal da umidade do solo quando comparado aos demais, enquanto o espaçamento 3 x 3 metros apresentou uma maior variabilidade temporal.

In Brazil, studies addressing soil carbon (C) stocks under native vegetation are scarce and often limited to land use change comparisons at the plot level, while studies across larger areas are based on legacy data that address multiple land uses, use wet-oxidations methods to determine C concentrations (Cc) and lack proper soil bulk density (ρb) determinations. Together, these factors may result in either underestimations or biased soil C stocks, thereby hampering the development of adequate land use policy. In this study, we aimed to (i) determine the soil C stocks at different depths (0–10, 10–20, 20–40, 40–60 and 60–100 cm) in Cerrado woodland remnants in Minas Gerais (MG), southeastern Brazil, (ii) study the spatial distribution of soil C stocks using regression-kriging (RK), and (iii) provide a description of the soil C stock distribution and its relationship with variables that drive the soil C stock in the MG Cerrado. We designed a large soil inventory, in which soil samples were collected for soil Cc and ρb determination, to compute soil C stocks in the Cerrado biome of MG. Afterwards, we used RK to model the soil C stocks across the MG Cerrado to a depth of 1 m. Our results show that using RK to map C stocks across different soil layers in the MG Cerrado resulted in accurate estimates. The soil C stocks in the MG Cerrado tend to increase in the west-east direction, are positively correlated with altitude and silt + clay content, and are negatively correlated with the mean annual temperature and total annual precipitation. On average, the C stored at the 0–40 cm layer accounted for 56% of the total C stocked in the top 1 m of soil. Approximately 1.03 Pg of C is stored in the MG Cerrado soils at a depth of 1 m. The average soil C stock in the MG Cerrado is approximately 53% larger than the average indicated for the Brazilian Cerrado. Our results highlight the need for more detailed regional scale soil C inventories in the country to refine national C accounting. We believe our study can aid the development of adequate land use policy and could be used as a baseline for land use change studies in the MG Cerrado.

The stream flow regime of four springs located in the Mantiqueira Mountain Range region (MG) was evaluated and correlated to the respective recharge area, relief characteristics, land cover and physical and hydrologic soil characteristics. The streamflow regime was characterized by monitoring of discharges, calculating the surface runoff and specific discharge and by modeling the discharge over the recession period using the Maillet method. As all recharge areas have similar relief the effect of it on the streamflow was not possible to identify. Analysis included determining the effect of drainage area size, soil characteristics and land cover on the indicators of the streamflow regime. Size of the recharge area had a positive influence on the indicators mean discharge and surface runoff volume and on the regulation of the streamflow regime (springs L4 and L1). The spring under the smallest area of influence provided the worst results for the above mentioned indicators (spring L3). The effect of forest cover (natural and planted), associated with soil characteristics, was evidenced by the indicators surface runoff (in depth) and specific yield, both independent of the recharge area size (springs L4 and L2). The interaction of area size, soil characteristics and forest cover (natural and planted) provided the best results for all indicators of streamflow regime in the springs studied in the Mantiqueira Mountain Range (spring L4). O regime do escoamento de quatro nascentes inseridas na região da Serra da Mantiqueira - MG, foi avaliado em associação à área de recarga, ao relevo, à cobertura vegetal e aos atributos físico-hídricos do solo. Para tanto, caracterizou-se o regime de escoamento pelo monitoramento das vazões, pelo cálculo do deflúvio e da vazão específica e pela modelagem da vazão no período de depleção segundo "Maillet". Todas as áreas apresentaram relevos semelhantes, dificultando evidenciar o efeito dos mesmos. Foi evidenciado o efeito do porte da área de drenagem, dos atributos do solo considerados e da cobertura vegetal nos indicadores do regime de escoamento das nascentes. O porte da área de recarga evidenciou sua influência positiva sobre os indicadores vazão média e deflúvio em volume e sobre o grau de regularização do regime de escoamento (nascentes L4 e L1), a nascente sob a menor área de influência apresentou os piores valores para esses indicadores (nascente L3). O efeito da cobertura vegetal do solo na forma de mata (nativa e plantada), associado aos dos atributos do solo, foi evidenciado pelos indicadores deflúvio em lâmina e rendimento específico que independem da área de recarga (nascentes L4 e L2). A interação porte de área, atributos do solo e cobertura vegetal sob mata (nativa e plantada), gerou os melhores valores para todos os indicadores do regime escoamento das nascentes (nascente L4).

Land-use changes affect soil water balance. The Upper Grande River Basin (UGRB) headwaters have undergone intense modifications in land use. This study was conducted to simulate, using the LASH model, the impacts on the hydrological regime in the UGRB with five land-use trends: S1 and S2 – reforestation with eucalyptus covering 20 % and 50 %, respectively, from the current grassland area; S3 – reforestation with eucalyptus covering 100 % of the current grassland area only in the sub-basins where this trend is predominant; S4 and S5 deforestation of 30 % and 70 % of the forest remnants in the Mantiqueira Range region for the cultivation of grasslands, respectively. Results demonstrate that runoff would be reduced due to the land-use changes by 51.65 mm yr−1, 110.29 mm yr−1 and 59.48 mm yr−1 for scenarios S1, S2 and S3, respectively. However, scenarios S4 and S5 could increase streamflow by 57.63 mm year−1 and 156.78 mm year−1, respectively. This indicates that land-use changes might make the basin more prone to flooding and other hazards associated with increased runoff.

O objetivo deste trabalho foi avaliar tendências das temperaturas mínimas e máximas no Estado de Minas Gerais. Foram avaliados dados de 43 municípios, tendo-se considerado as escalas anual e sazonal - janeiro, abril, julho e outubro, que representam os meses centrais de verão, outono, inverno e primavera, respectivamente. Séries históricas de temperaturas mínimas e máximas do ar diárias, com extensão mínima de 30 anos, foram analisadas com base no teste de Mann-Kendall e no uso de regressão linear simples. As tendências foram consideradas significativas somente quando ambas as avaliações foram significativas; neste caso, determinaram-se as taxas de alteração das temperaturas. Houve boa concordância entre os testes de significância para a detecção de tendências nas séries históricas, na maioria dos municípios. Observou-se tendência de elevação das temperaturas mínimas em julho de até 1,5ºC por década, com tendências generalizadas de aumento na maior parte do estado, em outubro e janeiro, e também na escala anual. Exceções foram verificadas especialmente em municípios de maiores altitudes, em que as temperaturas mínimas diminuíram no inverno. Há predominância de municípios com tendência significativa de aumento de temperaturas, independentemente da escala de avaliação. Tendências de aumento nas temperaturas são esperadas mais comumente no sentido sul-norte do Estado de Minas Gerais. The objective of this work was to evaluate the trends in minimum and maximum air temperatures in the state of Minas Gerais, Brazil. Data from 43 municipalities were analyzed, considering annual and seasonal scales - January, April, July, and October, which represent the middle months of summer, autumn, winter, and spring, respectively. Historical series of minimum and maximum daily air temperatures, from at least 30 year, were analyzed by the Mann-Kendall test and linear regressions. Trends were considered significant only if both evaluations were significant; in this case, the rates of temperature shift were determined. There was good agreement between the statistical tests for detecting trends in the historical series, for most municipalities. An increasing temperature trend of up to 1.5ºC per decade was observed for minimum temperatures in July, with generalized increasing trends in the greatest part of the state in January and October, and also in the annual scale. Exceptions were verified mainly in municipalities at higher altitudes, in which minimum air temperatures decreased in winter. There is a predominance of municipalities with significant increasing temperature trend, regardless of the evaluation scale. Increasing temperature trends are expected to be more common in the south to north direction, in the state of Minas Gerais.

A erosividade das chuvas é um dos principais agentes causadores da erosão do solo, no sul de Minas Gerais. Por essa razão, objetivou-se, com este trabalho, aplicar cinco distribuições de probabilidades aos valores de erosividades, mensais e anual, e estimar o tempo de recorrência desses valores, com base na melhor distribuição de probabilidades ajustada para a região de Lavras, MG. A série de precipitações estudada foi de 1961 a 2004 e as distribuições de probabilidades utilizadas foram: Gumbel, Gama, Log-normal 2 e 3 parâmetros e Normal, ajustadas pelo método da Máxima Verossimilhança. Verificou-se que as distribuições Gama e Gumbel produziram o menor número de séries não adequadas, registrando-se apenas uma, para o mês de agosto. As demais distribuições produziram maiores números de séries não adequadas, especialmente, a distribuição Log-normal 2 parâmetros. Sendo assim, recomenda-se, para o cálculo de erosividade, que seja feita uma verificação prévia da melhor distribuição para cada período da série estudada, apesar de os dados apontarem um desempenho considerável da distribuição Gumbel. Rainfall erosivity is a major causative agent of soil erosion in the south region of Minas Gerais state, Brazil. Thus, this study aimed to apply five distributions of probabilities to monthly and annual erosivity and estimate the recurrence time of these values with the best distribution of probability adjusted to the region of Lavras, MG. The precipitation series from 1961 to 2004 was used in the study and the distributions of probabilities were Gumbel, Gamma, Log-normal 2 and 3 parameters and Normal. The distributions Gamma and Gumbel produced the smallest number of non-adequate series, with only one recorded for the month of August. The other distributions produced a larger number of nonadequate series, especially, the Log-normal 2 parameters. Thus, it is recommended that for the calculation of erosivity, a previous assessment of the best distribution for each period of the studied series should be done, despite the data pointing out a considerable performance of the Gumbel distribution.

Maintaining the quality of water resources is of great importance for environmental preservation and the quality of life of consumers, and is one of the greatest challenges facing humanity today. Land-use for agriculture and animal farming significantly changes the biological, physical and chemical characteristics of natural systems. This study comprised monitoring of two subbasins located in the Mantiqueira Range region, from which water samples were collected on a monthly basis between June 2010 and May 2011 for analysis. Each subbasin has a distinct vegetation cover, one being predominantly covered by pastureland and the other being entirely covered by Atlantic Forest. The following water quality indicators were analyzed: turbidity, pH, electrical conductivity, total dissolved solids, dissolved oxygen, temperature, nitrate, phosphate, BOD,COD, total and fecal coliforms, and respective discharge measurement. The results showed that water quality degradation in both environments coincided with the local rainy season and was influenced by transport of organic material to watercourses by direct surface runoff. The high concentrations of fecal coliforms found affected the water quality, particularly in the rainy season, and are associated with agriculture and animal farming, the main economic activities in the region. The Atlantic Forest environment, however, had statistically better water quality over time in relation to the pastureland environment, due to the buffering it provides to direct surface runoff. A manutenção da qualidade dos recursos hídricos é de suma importância para a preservação ambiental e qualidade de vida dos usuários, sendo hoje, um dos grandes desafios da humanidade. O uso do solo pelas atividades agropecuárias altera sensivelmente os processos biológicos, físicos e químicos dos sistemas naturais. Neste estudo, foram monitoradas duas sub-bacias localizadas na Serra da Mantiqueira, onde foram coletadas amostras de água para análise entre junho de 2010 e maio de 2011, com periodicidade mensal. As duas sub-bacias apresentam distintas coberturas vegetais, sendo uma predominantemente sob pastagem e outra inteiramente sob Mata Atlântica. Foram analisados os seguintes indicadores associados à qualidade de água: turbidez, pH, condutividade elétrica, sólidos dissolvidos totais, oxigênio dissolvido, temperatura, nitrato, fosfato, DBO, DQO, coliformes totais e fecais e a vazão dos cursos d'água. Os resultados das análises mostraram que a degradação da qualidade da água em ambos os ambientes monitorados, coincidiu com o período chuvoso na região, influenciada pelo transporte de material orgânico aos cursos d'água, pelo escoamento superficial direto. As elevadas concentrações de coliformes fecais afetaram a qualidade dos cursos d'água, principalmente no período chuvoso e estão associadas à agropecuária, principal atividade econômica exercida na região. No entanto, o ambiente sob Mata Atlântica apresentou, estatisticamente, uma melhor qualidade de água ao longo do tempo em relação ao ambiente sob pastagem, devido à maior proteção que a mesma exerce ao escoamento superficial.

The Lavras Simulation of Hydrology (LASH) hydrological model is classified as a deterministic, semiconceptual, and spatially distributed model. This model was developed to make available a tool for hydrological analysis in watersheds with a limited database, and it has presented good streamflow predictions. The aim of this study was to calibrate and validate the LASH model for hydrological simulation of the following watersheds which make up the headwaters of the Grande River basin (southern Minas Gerais state, Brazil): the Aiuruoca, Grande, Sapucai, and Verde river basins. The LASH model simulated adequately the hydrological regimes of the previously mentioned watersheds, presenting satisfactory performances for all the watersheds, which can be emphasized by the Nash-Sutclifffe coefficient (CNS) values greater than 0.70. The analysis of the main hydrological processes simulated by the LASH model confirmed that the results were consistent with the hydrological characteristics observed on the respe...

The spatial characterization of soil attributes is fundamental for the understanding of forest ecosystems. The objective of this work was to develop a geostatistical study of chemical and physical soil attributes at three depths (D1 - 0-20 cm; D2 - 20-50 cm; D3 - 50-100 cm), in an Experimental Hydrographic Micro-catchment entirely covered by Atlantic Forest, in the Mantiqueira Range region, Minas Gerais. All the considered variables presented spatial dependence structure in the three depths, and the largest degrees of spatial dependence were observed for pH in the three depths, soil cation exchange capacity potential in D3, soil organic matter in D1 and D3 and clay and soil bulk density in D2. The method most used for the adjustments of semi-variogram models was the Maximum Likelihood and the most selected model was the Exponential. Furthermore, the ordinary kriging maps allowed good visualization of the spatial distribution of the variables. A caracterização espacial de atributos do solo é fundamental para o entendimento de ecossistemas florestais. Neste trabalho, objetivoi-se desenvolver um estudo geoestatístico de atributos químicos e físicos do solo em três profundidades (P1 - 0-20 cm; P2 - 20-50 cm; P3 - 50-100 cm), em uma Microbacia Hidrográfica Experimental inteiramente coberta por Mata Atlântica, na região Serra da Mantiqueira, Minas Gerais. Todas as variáveis consideradas apresentaram estrutura de dependência espacial nas três profundidades, sendo que os maiores graus de dependência espacial foram observados para pH nas três profundidades, capacidade de troca de cátions potencial do solo em P3, matéria orgânica do solo em P1 e P3 e argila e densidade do solo em P2. O método mais utilizado para ajuste foi o da Máxima Verossimilhança e o modelo mais selecionado foi o Exponencial. Além disso, os mapas de krigagem permitiram boa visualização da distribuição espacial das variáveis.

The SWAT (Soil and Water Assessment Tool) model was used to simulate stream flow and suspended sediment concentration at the Lavrinha Creek Watershed’s outlet, which is situated in the Mantiqueira Range region (Figure 1). This model requires some maps, such as Digital Elevation Model, land-use map and soil map. Temporal series associated to climatic variables, stream flow and suspended sediment concentration were obtained from an existing hydrological monitoring that has been conducted at or near the LCW’s outlet since January of 2006. Eight months (January 2006 – August 2006) were chosen as warm-up period of the SWAT model, while two years (September 2006 – August 2008) were considered for the model calibration and two years (September 2008 – August 2010) for the model validation. A statistical index known as Nash-Sutcliffe (COE) was employed to evaluate the model performance. Stream flow simulations with SWAT model on a daily basis resulted in COE values of 0.809 and 0.793 for calibration and validation periods, respectively; whereas, when simulating sediment concentration, the model resulted in COE values of 0.683 and 0.745 for calibration and validation periods, respectively. The SWAT model was considered adequate to simulate stream flow and suspended sediment concentration in the LCW, thus constituting in an important tool for water resources management in the Mantiqueira Range region.

RESUMO Este estudo avalia a distribuição espacial do potencial natural e atual do solo à erosão hídrica na Bacia do Rio Sapucaí, sul de Minas Gerais, utilizando a equação universal de perda de solos revisada, através de modelagem cartográfica, para a obtenção da erosão potencial (EP) e da erosão atual (EA). Os resultados indicaram que a EP para a Bacia do Rio Sapucaí variou de "Muito forte", na sua região de cabeceira (Serra da Mantiqueira), a "Fraca", nas áreas com topografia mais suavizada e menor erosividade da chuva. Em relação à EA, mais de 55,17 % da Bacia do Rio Sapucaí apresenta perdas de solo abaixo de 10 t.ha-1.ano-1, significando baixo potencial atual de erosão. A identificação de áreas de risco associadas à erosão acelerada, realizadas neste estudo, fornecem subsídios fundamentais para medidas associadas ao manejo, conservação e planejamento do uso do solo. ABSTRACT This study was carried out with the purpose to assess the natural and current soil erosion for the Sapucaí river basin using the revised universal soil loss equation (RUSLE) through cartographic modeling to obtain the natural soil erosion potential (EP) and the current soil erosion (EA). Results have indicated that the Sapucaí river basin has soils with EP varying from "Very strong", in its headwater region (Mantiqueira Range) to "Weak" potential, in areas with smoothing topography and smaller rainfall erosivity. Regarding EA, more than 55.17 % of the basin area present soil losses smaller than 10 t.ha-1.year-1, meaning low current soil erosion vulnerability. The identification of accelerated soil erosion areas, obtained by this study, can be very useful for supporting soil conservation management and planning.

Climate change impacts need to be considered in water resource planning. This work aims to study of the impacts climate change on Lavrinha headwater watershed, located in the Mantiqueira Range, southeastern Brazil. The impacts from climate change (RCP 8.5 scenario) in the Lavrinha watershed runoff were analyzed based on the "Distributed Hydrology Soil Vegetation Model" (DHSVM), forced with the climate simulated for this future climate change scenario. These simulations, in turn, were generated by the Eta regional climate model coupled to Global Climate Model (GCM) HadGEM2-ES for the 2011-2040, 2041-2070 and 2071-2099 periods. The results of this study showed that the runoff is very sensitive to rising temperatures and reduced precipitation, both projected for the RCP 8.5 scenario. The hydrological simulation projected a reduction in the monthly streamflow between 20 and 77% over the twenty-first century (2011-2099), corresponding to drastic reductions in the runoff behavior and consequently in the water production capacity of the region. RESUMO O impacto das mudanças climáticas precisa ser considerado no planejamento dos recursos hídricos. Este trabalho tem por objetivo o estudo dos impactos das mudanças climáticas na bacia de cabeceira Lavrinha, localizada na Serra da Mantiqueira, Sudeste do Brasil. Os impactos oriundos das mudanças climáticas (cenário RCP 8.5) no escoamento da bacia hidrográfica Lavrinha foram analisados com base no modelo "Distributed Hydrology Soil Vegetation Model" (DHSVM), forçado com as condições climáticas simuladas para este cenário futuro de mudanças climáticas. Estas simulações, por sua vez, foram geradas pelo modelo climático regional Eta acoplado ao Modelo Climático Global (MCG) HadGEM2-ES, nos períodos de 2011-2040, 2041-2070 e 2071-2099. Os resultados deste estudo mostraram que a vazão é bastante sensível ao aumento da temperatura e diminuição da precipitação, ambos projetados para o cenário RCP 8.5. A simulação hidrológica projetou uma redução na vazão mensal entre 20 e 77% ao longo do século XXI (2011 a 2099), correspondendo a reduções drásticas no escoamento e, consequentemente, na capacidade de produção de água da região.

In recent years, a relevant debate has been raised by a question related to if the hydropower plants indeed represent a non-consumptive use of water resources. In this context, this work was developed at the Camargos Hydropower Plant reservoir, Grande river basin, southern Minas Gerais state, aiming to estimate evaporation rates, which allow the characterization of the Water Footprint in this facility, between the years of 2010 and 2014. Evaporation rates were estimated based on Linacre, Penman and Penman-Monteith methods. Regarding the distribution of evaporation throughout the year, all methods showed the same seasonal pattern, consistent with the meteorological elements behavior that influence this physical process. Although an annual average evaporation considered normal for the studied region (1329 mm) and a small reservoir area (64 km2), this hydropower plant has presented low electric energy production as it is an old facility (more than 50 years) and has low installed capacity. Therefore, Camargos Hydropower Plant has presented, by all methods, a high Water Footprint (130 m3.GJ–1 on average) compared to estimates for other hydropower plants in Brazil and worldwide. RESUMO Nos últimos anos, um debate relevante tem ocorrido provocado pelo questionamento se as usinas hidrelétricas são de fato de uso não consuntivo dos recursos hídricos. Neste contexto, foi desenvolvido um estudo no reservatório da usina hidrelétrica de Camargos, rio Grande - Minas Gerais, com o objetivo de estimar as taxas de evaporação e caracterizar a pegada hídrica desta usina para o período de 2010 a 2014. A evaporação foi estimada pelos métodos de Linacre, Penman e Penman-Monteith. Em relação à distribuição da evaporação ao longo do ano, todos os métodos apresentaram o mesmo padrão sazonal, condizente com o comportamento das variáveis meteorológicas que influenciam o processo. Apesar de uma evaporação anual média (1329 mm.ano–1) e da pequena área do reservatório (64 km2), por se tratar de um aproveitamento antigo (mais de 50 anos) e com baixa potência instalada, a geração da usina hidrelétrica de Camargos é pequena, resultando, para todos os métodos avaliados, em uma pegada hídrica elevada (média de 130 m3.GJ–1), comparada as estimativas indicadas na literatura para outras usinas hidrelétricas no Brasil e no mundo.

Hydrological models are tools which describe processes and allow predicting the results of making management decisions, and are an important water resource management tool, especially for small-sized watersheds. This work had as an objective to test different calibration strategies and apply the SWAT model for hydrological simulation of the Mortes River Basin, MG. We evaluated 6 fluviometric stations, with drainage area between 272 and 6070 km² for purposes of water resource management. The evaluation of the model performance was conducted by using Nash-Sutcliffe coefficients (CNS) and percent bias (PBIAS). The results obtained from the statistic indices applied in the analysis of the model performance qualified the SWAT hydrological model as adequate for streamflow simulation in the Mortes River Basin. The adopted strategies attest to the applicability of the model as a management tool for water resources planning for other small-sized watersheds without data, in order to plan for rational water use. RESUMO Os modelos hidrológicos são ferramentas que descrevem processos e permitem antecipar as ocorrências e tomar decisões, dessa forma, apresentam-se como uma importante ferramenta de gestão dos recursos hídricos, principalmente no contexto de bacias hidrográficas de pequeno porte. Assim, objetivou-se com este trabalho abordar diferentes estratégias de calibração e teste do modelo SWAT na simulação hidrológica da bacia hidrográfica do Rio das Mortes, MG. Foram avaliados 6 postos fluviométricos, com área de drenagem entre 272 e 6.070 km², para fins de gestão dos recursos hídricos. A avaliação do desempenho do modelo foi realizada usando os coeficientes de Nash-Sutcliffe (CNS) e percentual de viés (PBIAS). Os resultados obtidos dos índices estatísticos aplicados na análise de desempenho do modelo, qualificam o modelo hidrológico SWAT como adequado na simulação da vazão para a bacia hidrográfica do Rio das Mortes. As estratégias adotadas atestaram a aplicabilidade do modelo como ferramenta de gestão e planejamento dos recursos hídricos para bacias menores e sem dados, possibilitando o uso racional da água na bacia.

This study compared the performance of ordinary kriging (OK) and regression kriging (RK) to predict soil physical-chemical properties in topsoil (0-15 cm). Mean prediction of error and root mean square of prediction error were used to assess the prediction methods. Two watersheds with contrasting soil-landscape features were studied, for which the prediction methods were performed differently. A multiple linear stepwise regression model was performed with RK using digital terrain models (DTMs) and remote sensing images in order to choose the best auxiliary covariates. Different pedogenic factors and land uses control soil property distributions in each watershed, and soil properties often display contrasting scales of variability. Environmental covariables and predictive methods can be useful in one site study, but inappropriate in another one. A better linear correlation was found at Lavrinha Creek Watershed, suggesting a relationship between contemporaneous landforms and soil properties, and RK outperformed OK. In most cases, RK did not outperform OK at the Marcela Creek Watershed due to lack of linear correlation between covariates and soil properties. Since alternatives of simple OK have been sought, other prediction methods should also be tested, considering not only the linear relationships between covariate and soil properties, but also the systematic pattern of soil property distributions over that landscape.

Watershed hydrology is greatly dependent on the analysis of intense rainfall, especially when management and conservation of soil and water, flood management and hydraulic designs are necessary. The intense rainfall modeling should preferably use pluviographic data; however, this type of record is more infrequent than daily rainfall. As a result, methodologies of daily rainfall disaggregation have been commonly adopted to adjust intensity-duration-frequency (IDF) curves. This study had as main objective to evaluate the influence of three sets of disaggregation constants on the estimation of rainfall intensities using IDF curves adjusted from daily rainfall series in the state of Rio Grande do Sul. Based on the substantial variation of the coefficients for the 15 municipalities evaluated in this study, it can be stated that the disaggregation constants exerted influence on the adjustment of the IDF curves. Considering the statistical measure applied in this study, the best adjustment was obtained for the disaggregation constants proposed by CETESB. In order to make it available more realistic results in Rio Grande do Sul State for the decision-making in the scope of water resources, it is advisable to: i) use longer and more recent pluviographic data series for the state; ii) evaluate multiparameter probability distributions; and iii) determine regional disaggregation constants.RESUMO: Quando são necessários o manejo e conservação de solo e água, a gestão de cheias e dimensionamentos hidráulicos, a hidrologia de bacias hidrográficas é enormemente dependente da análise de chuvas intensas. A modelagem de chuvas intensas deve preferencialmente empregar dados pluviográficos; entretanto, este tipo de informação é mais incomum do que dados pluviométricos (chuva diária). Assim, metodologias de desagregaçãode chuva diária têm sido comumente empregadas a fim de ajustar curvas intensidade-duração-frequência (IDF). Este estudo teve como objetivo principal avaliar a influência de três conjuntos de constantes de desagregação na estimativa de intensidades de chuva usando curvas IDF ajustadas a partir de séries de chuva diária no estado do Rio Grande do Sul. A variação substancial dos coeficientes obtidos para os 15 municípios avaliados neste estudo permite afirmar que as constantes de desagregação exerceram influência no ajuste das curvas IDF. Considerando a medida estatística aplicada neste estudo, constatou-se que o melhor ajuste foi obtido para as constantes de desagregação propostas pela CETESB. No intuito de disponibilizar resultados mais realísticos no estado do Rio Grande do Sul para a tomada de decisões, no contexto de recursos hídricos, é plausível: i) usar séries de dados pluviográficos mais longas e recentes para o estado; ii) avaliar distribuições de probabilidades multi-parâmetros ; iii) determinar constantes regionais de desagregação.

Hydrological models have been used in many places of the world in order to support practitioners with respect to watershed management actions. The goal of this research was to apply the Lavras Simulation of Hydrology (LASH model) to a Brazilian tropical watershed dominated by Oxisols, to estimate maximum, minimum and mean stream flows for both current land-use (“scenario 1”) and other regional trend land-use scenarios (“scenario 2”—pasture into eucalyptus; and “scenario 3”—eucalyptus into pasture). This model is a continuous, distributed and semi-conceptual model for simulation of different hydrological components on a daily basis. The model had a good performance with respect to the “scenario 1”, resulting in Nash-Sutcliffe coefficients equal to 0.81, 0.82 and 0.98 for minimum, maximum and mean discharges, respectively. When “scenario 2” was simulated, it was found that minimum, mean and maximum stream flows had their values reduced in average by 7.39 %, 13.84 % and 20.38 %, respectively. On the contrary, it was observed in “scenario 3” an increase in average by 0.23 %, 0.44 % and 1.19 % for minimum, mean and maximum stream flows, respectively. With respect to water yield, scenario 2 resulted in a mean reduction of 119 mm, whereas for scenario 3 the difference was not so pronounced in relation to the current land use. Results obtained in scenario 2 are troublesome since this watershed drains into an important regional Hydroelectric Power Plant Reservoir and this approach needs to be considered by the Minas Gerais State electric energy company for its planning strategies for the future.

The Brazilian Law stipulates that water is a limited natural resource doted of economic value, thus it is necessary to develop mechanisms for its adequate management. Actions that encourage the farmers to apply soil conservation practices with the purpose of increase water yield from springs and to promote improvement of its quality, reducing production of sediment transportation, is being encouraged by governments, even with financial compensation for owners. From these assertions, this study aims to quantify the benefits of the conservation actions of the management units and to characterize a Water Yield Indicator (WYI) to support sustainable actions in the watershed of Alto Rio Grande region, in the state of Minas Gerais (MG). To assess the impact of actions it were identified four scenarios of land use and occupation of the watershed from Marcela stream which is located in Alto Rio Grande Region. After analyzing the results, it can be stated that the scenarios simulation has demonstrated important changes in water yield and that the definition of the Water Yield Index from the junction of the erosion potential with the water storage potential, has proved effective, as it integrate quantity and quality of water. A legislação brasileira estabelece que a água é um recurso natural limitado e dotado de valor econômico; logo, há necessidade de se criar mecanismos para sua adequada gestão. Medidas que estimulam os produtores rurais a adotarem práticas conservacionistas, visando a maior produção de água, melhoria de sua qualidade e redução da produção de sedimentos, vêm sendo estimuladas pelos governos, utilizando para isso até mesmo uma compensação financeira. A partir destas asserções, objetivou-se quantificar os benefícios das ações de conservação nas unidades de gestão e definir um Indicador de Produção de Água (IPA) para a tomada de decisão em uma bacia hidrográfica da região Alto Rio Grande-MG. Para avaliar o impacto das ações, foram definidos 4 cenários de uso e ocupação do solo da bacia hidrográfica do Ribeirão Marcela, localizada na UPGRH-GD1 (Alto Rio Grande). Após a análise dos resultados obtidos, chegou-se à conclusão de que as simulações de diversos cenários demonstraram alterações na produção de água e que a definição do Indicador de Produção de Água, a partir da junção do potencial de erosão com o potencial de armazenamento, demonstrou ser eficaz, pois integrou quantidade e qualidade de água.

The SWAT model (Soil and Water Assessment Tool) was applied for simulating the hydrologic pattern of Paraopeba river basin, in Minas Gerais state, under different land use and occupation scenarios, looking to support basin management actions. The model parameters were calibrated and validated, with respect to the data observed from 1983 to 2005. The basin was assessed at the 'Porto do Mesquita' gauging station and change in land use and occupation was based on the annual growth scenarios proposed in the partial report of Paraopeba basin's master plan. The model was found to be highly sensitive to baseflow, its main calibration variable. Statistical analyses produced a Nash-Sutcliffe coefficient above 0.75, which is considered good and acceptable. The SWAT model provided satisfactory results in simulating hydrologic pattern under different scenarios of land use change, demonstrating that it can be applied for forecasting discharge in the aforesaid basin. The current land use scenario provided a peak discharge simulation of 1250 m³ s-1, while in years 2019 and 2029 peak discharge simulations were 1190 m³ s-1 and 1230 m³ s-1 respectively. The 2019 scenario provided the best results with respect to baseflow increase and peak discharge reduction.

A distribuição espacial da condutividade hidráulica saturada (k0) é essencial para estudos relacionados a erosão do solo e escoamento superficial. Este trabalho objetivou estudar a continuidade espacial do atributo hidrológico do solo k o na Bacia Hidrográfica do Alto Rio Grande, MG, e realizar seu mapeamento por meio de técnicas geoestatísticas, utilizando dados sem e com transformação logarítmica. Os modelos de semivariograma esférico e exponencial foram ajustados ao semivariograma experimental pelo método dos Mínimos Quadrados Ordinários (MQO) e Mínimos Quadrados Ponderados (MQP). Técnicas de validação cruzada e preditiva foram aplicadas para a escolha do melhor modelo. Os resultados indicaram que, ao se trabalhar com o logaritmo dos dados de k o, houve redução de pontos discrepantes e de anisotropia, entretanto os valores mais elevados de grau de dependência espacial foram observados nos dados sem transformação. O ajuste do modelo esférico, por meio do método MQO, foi o que produziu melhor desempenho na modelagem da continuidade espacial de k0. Os mapas gerados a partir dos dados sem e com transformação logarítmica não apresentaram o mesmo comportamento na distribuição espacial dos valores, e o mapa dos dados na forma transformada teve o melhor detalhamento da distribuição espacial. Spatial distribution of the saturated hydraulic conductivity (k0) is essential in the study of soil erosion and surface runoff. The purpose of this study was to investigate the spatial continuity of the soil hydrologic characteristic k0 in the watershed Alto Rio Grande, state of Minas Gerais, and to map k0 based on geostatistical procedures, using data without and with logarithmic transformation. Exponential and spherical semi-variogram models were fitted to the experimental semi-variograms in two approaches: ordinary minimum square (MQO) and weighted minimum square (MQP). Cross validation and predictive validation were both applied to choose the best model. The results showed that the use of log (k0) improved the geostatistical applicability due to a reduction in the number of outliers and anisotropy; however, the spatial dependency degree was highest for k0 data without log-transformation. The spherical model fitted by MQO preformed best in the spatial continuity modeling of k0. The spatial distribution in the basin, indicated by the maps developed from data without and with log transformation was not the same; the map developed on the basis of log-transformed data showed a more detailed spatial distribution.

Conceptual rainfall-runoff models at the watershed scale are useful tools for assisting in managing and planning water resources, making it possible to estimate streamflow and to predict hydrologic impacts due to land-use changes. The objective of this study was to calibrate and to validate the LAvras Simulation of Hydrology (LASH Model) (Beskow, 2009) in a Brazilian Tropical Watershed for daily streamflow. LASH is a continuous, distributed, semi-physically based model for simulation of different hydrologic components on a daily basis. The Shuffled Complex Evolution (SCE-UA) global search method was used with the LASH model in order to optimize model parameters that were found to be the most sensitive or not directly measurable. The LASH model was calibrated over a 2-year period, thereafter, the parameters obtained through the calibration were kept constant for the validation step using a different period of time from that analyzed during the calibration. The Nash–Sutcliffe coefficient (CNS) values found were 0.820 and 0.764 during calibration and validation, respectively, whereas, the CNS (log Q) values equal to 0.821 and 0.770 were obtained for the same periods. The SCE-UA method was found to be an efficient algorithm for searching ‘optimal’ model parameter values. It was possible to conclude that the model has a great potential for being applied in generating the long-term streamflow as well as flow-duration curves. Therefore, the model can reliably be applied under tropical conditions of this medium-sized watershed or other similar watersheds, thus making it useful to plan the sustainable development of similar tropical and subtropical watersheds.

A espacialização de variáveis climáticas, notadamente a precipitação pluvial, necessita de estudos constantes, visando ao aperfeiçoamento de interpoladores e desenvolvimento de mapas sem tendência. Objetivou-se, neste contexto, avaliar o desempenho dos interpoladores krigagem (KG), a partir do melhor modelo de semivariograma, cokrigagem (CA), introduzindo a altitude como variável secundária, modelagem estatística (ME), na qual a precipitação média pode ser estimada a partir de coordenadas geográficas, e inverso do quadrado da distância (IQD), para espacialização da precipitação média mensal, precipitação média do período seco e precipitação média anual, em Minas Gerais; para isto se utilizaram informações de 232 postos pluviométricos para modelagem e de 70 para validação, com base no erro médio absoluto, além de um modelo digital de elevação com resolução de 270 m. Quanto à avaliação dos métodos de interpolação, constatou-se bom desempenho das metodologias abordadas, com erro absoluto médio variando de 12,84 a 19,96%, com destaque para a cokrigagem, que obteve menor erro em 50% das situações analisadas.