RESUMOA 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. Palavras-chave: modelagem espacial, climatologia, interpoladoresSpatial interpolation methods for mapping of rainfall ABSTRACTThe mapping of weather elements, especially rainfall, needs constant studies to improve the performance of interpolators, and to obtain unbiased maps. This work aimed to evaluate the performance of some spatial interpolators for mean monthly rainfall, mean rainfall during the dry season and mean annual rainfall in the Minas Gerais State. For that, the ordinary kriging was evaluated and compared, after the semi-variogram modeling, co-kriging (introducing the altitude above sea level as a secondary variable), statistical modeling in which the mean precipitation can be estimated from geographical coordinates, and inverse square distance. In this study, data sets were evaluated from 232 pluviometric stations, in the Minas Gerais area, to apply each one of the interpolators mentioned and 70 stations to evaluate the performance that was conducted on the basis of absolute mean error. In addition, a digital elevation model, with a resolution of 270 m, was applied. The interpolators have shown good performance, with mean errors varying from 12.84 to 19.96%, the cokriging method presenting a smaller absolute mean error in 50% of the situations evaluated.
The proper design of hydraulic structures depends on estimates of maximum stream flows. The scarce stream flow monitoring in Brazil has led to the use of regionalization methods. The main objective of this study was to develop a tool via regional function to estimate maximum stream flows and their corresponding return periods (RP) with the aid of techniques based on the L-moments method, seeking for adequate hydrologic engineering applications and flood risk management. Annual maximum stream flow historical series were adjusted to traditional 2-parameter probability density functions (PDFs) (Normal, 2-parameter Log-Normal, Gumbel, Gamma) and multiparameter PDFs (GEV and Kappa), based on the L-moments method, which were used in the development of the regional function employing the dimensionless curve method. The regional function's predictive capability was determined by cross-validation for different RPs. It can be concluded that the approach based on L-moments was successfully used to adjust the regional function. In addition, the regional function: i) was improved when using the aforementioned multiparameter PDFs and ii) was framed as optimum for RP of up to 100 years and considered useful for practical engineering projects and flood risk management.Keywords: Flood risk management; Statistical hydrology; GEV; Kappa; Mirim-São Gonçalo transboundary basin. RESUMOO dimensionamento adequado de estruturas hidráulicas é dependente das estimativas de vazões máximas. A escassez no monitoramento hidrológico no Brasil tem levado ao uso de métodos de regionalização. O principal objetivo do presente estudo foi desenvolver uma ferramenta via função regional para a estimativa das vazões máximas e seus respectivos tempos de retorno, com o suporte de técnicas baseadas no método dos momentos-L, com vistas a aplicações adequadas da engenharia hidrológica e da gestão de risco de cheias. As séries de vazão máxima diária anual foram ajustadas às funções densidade de probabilidade tradicionais de 2 parâmetros (Normal, 2-parameter Log-Normal, Gumbel, Gamma) e multiparâmetros (GEV and Kappa), baseando-se no método dos momentos-L, as quais foram utilizadas no desenvolvimento da função regional pelo método da curva adimensional. A capacidade preditiva da função regional foi determinada por validação cruzada para diferentes tempos de retorno. Pode-se concluir que a abordagem baseada nos momentos-L no ajuste da função regional foi satisfatória. Além disso,a função regional: i) foi aperfeiçoada quando as distribuições multiparâmetros acima mencionadas foram usadas e ii) foi classificada como ótima para tempos de retorno de até 100 anos sendo útil a projetos práticos de engenharia e na gestão de cheias.
O mapeamento da precipitação mínima provável associada a um período, local e freqüência de ocorrência, consiste em importante ferramenta para subsídios de práticas agrícolas. O objetivo neste trabalho foi mapear a precipitação provável mínima mensal e quinzenal para o Sul do Estado de Minas Gerais, por meio de técnicas geoestatísticas. O nível de probabilidade considerado foi de 75% e o período analisado foi a estação chuvosa (outubro a março). Os valores de precipitação provável foram estimados pela distribuição de probabilidade Log-Normal, após teste de sua adequação, por Kolmogorov-Smirnov, a partir de séries históricas de dados totais diários de precipitação referentes a 69 estações pluviométricas da região e arredores. Os modelos de semivariograma exponencial e esférico ajustados pela máxima verossimilhança (MV) e por mínimos quadrados ponderados (MQP) foram modelados para a escolha do melhor modelo que representasse o semivariograma experimental. Com base no grau de dependência espacial e pela validação cruzada, o modelo exponencial ajustado por MQP apresentou melhor desempenho. Os mapas de precipitação provável mostraram considerável variabilidade durante a estação chuvosa, com os maiores valores estimados para as regiões das Serras da Mantiqueira e Canastra.
14Brazilian Atlantic Forest is recognized by the UNESCO as one of the most 15 important biosphere reserve on the planet but is threatened by extinction. The objective 16 of this study was to analyze the main components of the water balance in an Atlantic 17 Forest (Neotropical Forest) catchment in Mantiqueira Range, Brazil, which is a Tropical 18 Montane Cloud Forest. The main focuses were to analyze baseflow, evapotranspiration, 19 soil moisture, and canopy rainfall interception to understand the hydrologic dynamics in 20 this specially important montane forest. On average from the two studied hydrological 21 years (2009( /2010( and 2010( /2011, streamflow (SF), and water 22 storage in the catchment in the end of hydrological year corresponded, respectively, to 23 50%, 34.8% and 15.2% of total gross precipitation (P). On average, baseflow 24 2 corresponded to 73.5% of SF. The estimated potential groundwater recharge during the 25 wet seasons was 403.8 mm (21.7% of P observed in the wet season) and 710.5 mm (28.5% 26 of P observed in the wet season), respectively, for 2009/2010 and 2010/2011 hydrological 27 years, showing that the catchment is able to store groundwater to provide the maintenance 28 of the streamflow during recession phase via baseflow as well as during drought periods. 29Therefore, the baseflow is important in mountainous catchments in the tropical regions to 30 provide important ecological functions, mainly as freshwater reserve. 31 32 33 65 of the overland flow generation, since the canopy reduces the impact of rainfall intensity 66 over the ground, allowing greater opportunity for water infiltration. Wiekenkamp et al. 67 (2016) studied the role of the soils in the hydrology of a TMCF site in Germany. They 68 concluded that soils with mature native forest have shown high porosity and pores 69 4 interconnected that can generate preferential flows. These features lead to a higher 70 infiltration capacity as well as greater natural streamflow regulation. 71 Muñoz-Villers et al. (2016) provided an important contribution to understanding 72 the nature of the baseflow in a TMCF in the Central Mountainous region in Mexico. 73 Based on hydrologic isotopic readings, they have proven that the baseflow can sustain the 74 streamflow, even in a complex environment characterized by a steep topography and 75 fractured bedrock. In the study in a TMCF site in Thailand by Hugenschmidt et al. (2014), 76 they verified that the baseflow has presented greater predominance in relation to the 77 overland flow. Caballero et al. (2012) studied a hydrological year in a TMCF in Central 78 America and verified that the baseflow/streamflow ratio was approximately 80%, 79 showing a greater predominance of the baseflow in the streamflow. All these studies 80 demonstrated that the baseflow has been predominant in TMCF sites, especially if the 81 native forests are preserved that can improve the soil's structure and permeability and 82 thus favor soil-water infiltration and groundwater recharge (Ma et al. 2017; Wiekenkamp 8...
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