Gilberto Coelho

Qualidade da água do Ribeirão Lavrinha na região Alto Rio Grande - MG, Brasil

Conduziu-se este trabalho, com principal objetivo de estudar o comportamento da qualidade da agua, ao longo do tempo, em uma bacia hidrografica de cabeceira do Rio Grande, MG. A bacia hidrografica apresenta uma area de 687 ha e esta situada na Serra da Mantiqueira. Foram amostrados seis pontos no Ribeirao Lavrinha no periodo de maio de 2006 a janeiro de 2007, totalizando sete amostragens. O mapa de uso atual do solo foi gerado a partir de levantamento em campo com auxilio de GPS. Os parâmetros analisados foram: potencial hidrogenionico (pH), oxigenio dissolvido (OD), condutividade eletrica, salinidade, temperatura, demanda bioquimica de oxigenio (DBO), demanda quimica de oxigenio (DQO), nitrato (NO3-), nitrogenio amoniacal (NH3), fosforo (PO4), turbidez, solidos totais, solidos totais dissolvidos (TDS), coliformes termotolerantes (Escherichia coli), coliformes totais. Para os dados calculou-se o Indice de Qualidade da Agua (IQA), proposto pelo Instituto Mineiro de Gestao das Aguas (IGAM) e fez-se o enquadramento em classes conforme Resolucao 357/05 CONAMA. As condicoes ambientais refletiram-se tanto nos valores do IQA quanto no processo de enquadramento. Constatou-se ainda que o principal fator causador do quadro critico e o NMP de coliformes, o qual se associa com a pecuaria. Em menor escala o OD e a DBO sao tambem fatores limitantes.

Coeficiente de cultura (Kc) do cafeeiro (Coffea arabica L.) no período de outono-inverno na região de Lavras - MG

Water balance is very important for evaluating inflow and outflow water in a soil block explored by a crop. This situation allows to estimate parameters associated to crop water schedule such as evapotranspiration and crop coefficient (kc), which are present as physical and biological indicators, especially when associated to the phenologic cycle. Therefore, the objective of this paper was to monitor water and climatic regime from April to Setember/2004 of an adult coffee crop of the cultivar Catuai pruned four years before, and to estimate crop evapotranspiration (ETc) and Kc, applying the water balance method. The results allowed concluding that the coffee crop presented ETc values between 1.23 and 4.39 mm day-1 and Kc from 0.59 to 1.16. Kc showed a relationship with coffee crop phenology; however, it indicated a decrease of the dormancy period and an anticipation of the coffee fruits formation and vegetative development.

Estimativa do escoamento superficial em uma bacia hidrográfica com base em modelagem dinâmica e distribuída

Knowledge on the surface runoff in watersheds is very important for a good conservation of natural resources. However, surface runoff is a complex and dynamic process, especially in the context of spatial variability. An application of the Geographical Information System (GIS) tools in small grid cells is therefore adequate. This way, it is possible to consider the spatial behavior of variables associated to the origin of surface runoff. This study aimed to program the Hydrological Models SCS-CN (SCS-Curve Number) and CN - MMS (CN - Modified) based on the PC Raster Programming Language and a reduced dataset, in distributed and dynamic approaches, to estimate the direct surface runoff in a watershed of Oxissols, in the county of Nazareno, region of Campos das Vertentes, Minas Gerais State. SCS-CN model was applied structuring a CN-map linked to the soil infiltration capacity in the PCRaster GIS format. For the CN - MMS model, we used other maps: saturated volumetric soil moisture content, initial volumetric soil moisture content and soil depth. For the simulation and evaluation of both models, 18 rainfall events that produced surface runoff in the hydrologic year 2004-2005 were used, and their respective surface runoff depths observed. The model performance was evaluated by sensitivity analyses, based on the mean error and Root Square Error. Based on these accuracy statistics, the calibration of the CN - MMS model was better than in the original SCS-CN model, since the initial soil moisture was taken into account. Nevertheless, the adjustment of the models in the SIG PCRaster allowed the development of an effective and useful computer tool to simulate surface runoff, due to the possibility of establishing computer routines considering the problems elated to the spatial variability of data entries of the model.

Produtividade e potencial hídrico foliar do cafeeiro Catuaí, em função da época de irrigação

This work evaluated the effect of different periods of irrigation (A - between 06/01 and 09/30; B - between 09/01 and 09/30; C (control) - without irrigation), on productivity, grain yield and leaf water potential of the coffee crop cultivar (Coffea arabica L), cv. Catuai - Red (IAC 44). The experiment was carried out in 18 years old coffee crop, with 3.5 m of distance between lines of plants and 0.8 m between plants. The leaf water potential was evaluated between 0600 and 1200 hrs, in the period from May until October for the years 2003 and 2004. The high sensitivity of this physiological indicator to irrigation was identified, and that the irrigation from 06/01 to 09/30 (treatment A) always showed the best leaf water status, as well as the best performance of productivity, with a mean value of 4617 kg ha-1. The results corroborate with the fact that the productivity of the crop maintained a direct relationship with its leaf water status and especially with the leaf water potential, which showed itself to be a physiological indicator with good discriminating powers, and for this reason, suitable to be utilized as a reference in the irrigation management.

Application of the Soil and Water Assessment Tool (SWAT) for Sediment Transport Simulation at a Headwater Watershed in Minas Gerais State, Brazil

Abstract. Hydrological models have been increasingly employed for evaluation of pollution caused by diffuse sources in watersheds. In this study, the Soil and Water Assessment Tool (SWAT) was used to simulate streamflow and suspended sediment concentration (SSC) at the Lavrinha Creek watershed (LCW) outlet, which is situated in the Mantiqueira Range region in Minas Gerais State, Brazil. Temporal series associated with climatic variables, streamflow, and SSC were obtained from existing hydrological monitoring that has been conducted in the LCW since January 2006. Eight months (January 2006 to August 2006) were chosen as the warm-up period for the SWAT model, while two years (September 2006 to August 2008) were considered for model calibration and two years (September 2008 to August 2010) for model validation. A statistical index, Nash-Sutcliffe efficiency (NSE), was employed to evaluate the model performance. Streamflow simulations with SWAT on a daily basis resulted in NSE values of 0.81 and 0.79 for the calibration and validation periods, respectively; when simulating sediment concentration, the model resulted in NSE values of 0.68 and 0.75 for the calibration and validation periods, respectively. The SWAT model was considered adequate to simulate streamflow and SSC at the LCW outlet, thus constituting an important tool for water resources management in the Mantiqueira Range region.

Modelagem da hidrógrafa de cheia em uma bacia hidrográfica da região Alto Rio Grande

Surface runoff is one of the most important hydrological cycle components associated with water erosion, being responsible for sediment transport. Several hydrological models have been developed for a better understanding of this process and for representing the hydrological behavior of the watershed. The objective of this study is to analyze the Nash Conceptual Model for Instantaneous Unit Hydrograph (IUH) generating the flow behavior in the Ribeirao Marcela Watershed, Alto Rio Grande region. The IUH generated by the Nash Conceptual Model presents a good accuracy for the modeling of surface runoff hydrograph in this watershed.

Épocas de irrigação e parcelamento de adubação sobre a produtividade do cafeeiro, em quatro safras

Desenvolveu-se o presente trabalho, objetivando-se avaliar o efeito de diferentes epocas de irrigacao e de parcelamentos de adubacao na produtividade do cafeeiro em quatro safras consecutivas. Realizou-se um experimento em faixas, em que, nas parcelas foram avaliados diferentes parcelamentos de adubacao: parcela 1 recebeu 12 aplicacoes de fertilizantes, de forma manual; parcelas 2, 3 e 4 receberam, respectivamente, 12, 24 e 36 aplicacoes de fertilizantes via agua de irrigacao. Nas faixas (subparcelas) foram avaliadas tres epocas de irrigacao, de 1/6 a 30/9 (subparcela A), de 15/7 a 30/9 (subparcela B), de 1/9 a 30/9 (subparcela C) e um tratamento testemunha sem irrigacao (subparcela D), com 3 repeticoes, em blocos. Os resultados de produtividade total de cafe foram submetidos a analise de variância, e, quando pertinente, ao teste de comparacao de medias, detectando-se efeito significativo do fator epoca de irrigacao e safras, e, a unica interacao significativa foi entre safras e epocas de irrigacao, indicando que a irrigacao nao elimina o comportamento bienal de produtividade do cafeeiro. As melhores medias de produtividade (3852,2 e 3527,1 kg ha-1) resultaram das irrigacoes de 1/6 a 30/9 e de 15/7 a 30/9, respectivamente.

Distribuição espacial de valores prováveis de precipitação pluvial para períodos quinzenais, em Guiné-Bissau

The aim of this study was to estimate the probable values of rainfall in the first and second halves of the months and its spatial distribution in Guinea-Bissau. Distribution functions Log-normal 2 parameters were used to estimate the probable values of rainfall adopting the probability level of 75%. The spatial interpolation (kriging) was applied by semi-variogram modeling demonstrating that the probable rainfall estimates have high spatial variability, except in the month of September, when the behavior is homogeneous for both first and second halves. The lowest probable values of rainfalls under 50 mm occur in June and October throughout the country, supporting the use of supplemental irrigation to avoid compromising the periods of sowing (June) and minimize damage at harvest (October, November) for long cycle crops.

Groundwater recharge estimate at Alto Rio Grande - MG watershed

Springs are outcrops of aquifers surface, and the water cycle in this environment pass through the recharge, generally defined as the amount of water added to the aquifer, which may occur locally from rainwater infiltration. This study uses the Water Table Fluctuation (WTF) method to estimate the direct recharge and a groundwater balance to estimate the deep recharge on unconfined aquifers. The WTF method employs data of the aquifer water levels and its specific yield to estimate the direct recharge. The groundwater balance considers the direct recharge estimated by the WTF method, as the water input in the system and outputs as the base flow and deep recharge. The recharge was estimated at four areas at the watershed of Alto Rio Grande city, Minas Gerais (MG) state, in Brazil. The direct recharge estimate was 121.11; 64.62; 83.99; 152.46 (mm/year) for the L1, L2, M1 and M2 areas. The effect of the presence of forest in the recharge area can prevail over slope of relief, allowing more direct recharge, even in sources with steeper relief. The runoff from the springs in the study period exceeded the direct recharge, indicating a situation in which the saturated zone feeds the vadose zone. The annual flow was above the direct recharge pointing a situation of over exploitation of the aquifer, a non sustainable situation. The specific yield of the aquifers could also have been underestimated.

Impacts of urban solid waste disposal on the quality of surface water in three cities of Minas Gerais - Brazil

The environmental impact of three different urban solid waste facilities (USWF) on the quality of the surface water. The studied areas were the Campo Belo sanitary landfill (Varoes River), the controlled landfill of Santo Antonio do Amparo (Fabiano River), and the closed dump of Eloi Mendes (Mutuca River), which are cities located in southern Minas Gerais state, Brazil were evaluated. At each sampling point water samples were collected at five occasions in the raining season (October - March) and in the dry season (April - June) at three sampling points: (P1) upstream the solid waste facility, (P2) downstream nearby the point of influx from the sewage treatment plant in the sanitary landfill, or at the drainage point from the surface flow of the dump and controlled landfill, and (P3) downstream the solid waste facility. Physicochemical and bacteriological analyses were performed, and the results were analyzed based on descriptive statistics. The data were also compared with reference values from the National Environmental Council (CONAMA) Resolution 357/2005 and were used to calculate the water quality index (WQI). It was not possible to detect a significant effect of the solid waste facility on the water quality indicators. The water conditions were unsatisfactory due to violations of the concentrations of phosphorus, ammonia, fecal coliform, and the biochemical oxygen demand/chemical oxygen demand ratio (BOD/COD), probably related to other uses along the drainage area upstream the solid waste facility. These conditions were more critical in the Mutuca river, where the WQI was classified as bad during the entire period at all sampling points.