Jorge Enoch Furquim Werneck Lima

Valores de tensão na determinação da curva de retenção de água de solos do Cerrado

A curva de retencao de agua do solo e essencial para o estudo das relacoes solo-agua. A escolha do numero e da combinacao de pontos a serem levantados para o seu tracado normalmente e feita de forma arbitraria. O objetivo deste trabalho foi definir o menor numero e a melhor combinacao de pontos de tensao que resultem na descricao da curva de retencao de agua de solos do Cerrado. Utilizaram-se cinco curvas de retencao de diferentes solos como referencia, cada uma com 15 pontos medidos pelo metodo da centrifuga e ajustada ao modelo de Genuchten. A partir desses 15 pontos, 385 curvas foram geradas para cada solo, com seis, sete, oito e nove pontos, a fim de serem comparadas com a curva de referencia. A analise da distribuicao estatistica da soma de quadrados dos erros padronizados, entre as curvas geradas e as respectivas curvas de referencia, permitiu definir um modelo de probabilidade que serviu como instrumento para a escolha das melhores combinacoes de pontos de tensao. A combinacao definida pelos oito valores de tensao de 1, 3, 6, 10, 35, 84, 611 e 1.515 kPa e a recomendada para o levantamento das curvas de retencao de agua de solos do Cerrado.

Comparação de modelos matemáticos para o traçado de curvas granulométricas

A distribuicao granulometrica de particulas solidas e essencial para as areas de material de construcao, mecânica dos solos, fisica dos solos, hidrossedimentologia, entre outras. As tecnicas utilizadas na avaliacao da distribuicao granulometrica de amostras resultam em valores pontuais, dependendo de posterior interpolacao para o tracado da curva granulometrica e a obtencao de diâmetros caracteristicos especificos. A transformacao de valores pontuais em funcoes continuas pode ser realizada por meio de modelos matematicos. Entretanto, ha poucos estudos com a finalidade de determinar o melhor modelo para o ajuste de curvas granulometricas. O objetivo deste trabalho foi testar e comparar 14 diferentes modelos passiveis de utilizacao no tracado da curva granulometrica de particulas solidas com base em quatro pontos medidos. O parâmetro de comparacao entre os modelos foi a soma de quadrado dos erros entre os valores medidos e calculados. Os modelos mais recomendados no tracado da curva granulometrica, a partir de quatro pontos, sao os de Skaggs et al. 3P, Lima & Silva 3P, Weibull 3P e Morgan et al. 3P, todos com tres parâmetros de ajuste.

Proposição de um modelo matemático para a avaliação do desempenho de sistemas de irrigação

Mathematical models have been proposed to represent the applied irrigation water distribution profile, which is fundamental to evaluate the performance of irrigation systems. Even though there have been advances, so far, there is not a universally accepted model as the most adequate to fit water distribution profiles from irrigation systems. The objectives of this work were to propose a model for evaluating the performance of irrigation systems, and to develop an irrigation adjusting factor for calculating the gross water depth that takes into account both water application uniformity and efficiency measures. The fitting parameters of the proposed model were determined by using the routine Solver from the spreadsheet Excel and the water application uniformity and efficiency measures were calculated from mathematical expressions derived for this model. According to data from the evaluation of a center pivot irrigation system, the proposed model is adequate for analyzing irrigation performance and for obtaining the devised irrigation adjusting factor, by gathering the required system performance indicators. It also simplifies the analysis procedures and allows a direct calculation of the water depth demand for irrigation.

Comparação da evapotranspiração real simulada e observada em uma bacia hidrográfica em condições naturais de cerrado

The main objectives of this research were: (i) to simulate actual evapotranspiration in a small watershed under natural conditions of Brazilian Savannah during a year, between 08/04/98 and 08/03/99; (ii) to compare observed and simulated values of actual evapotranspiration, runoff and water depth stored in the soil. Using the water balance equation, the actual evapotranspiration (830.53 mm) was computed. During the year, twenty-one intermediate measurements were made in order to use the water balance method for short time intervals. Simulated and measured values of the actual evapotranspiration and the water flow did not have a good correlation. On the other hand, simulated values of the quantity of water stored in the soil to a one meter depth presented results very similar to the measured ones. During the driest period of the year, in spite of the high values of reference evapotranspiration, the actual evapotranspiration presented small values because of the lack of available water to evapotranspirate.

Evaluation of water quality parameters for monitoring natural, urban, and agricultural areas in the Brazilian Cerrado

Abstract: Introduction : Brazil’s Federal District (FD) has seen steep population growth in recent years, and this has increased demand for high-quality water. Aim :The present work aims to evaluate the quality of surface water from two water bodies in the FD at six sampling points, three of which are in the Sobradinho River (the receiving body of a sewage treatment plant effluent) and three in the Jardim River (located in an agricultural region). Methods : Analyses were carried out every thirty days, for twelve months, covering rainy and dry seasons. Parameters were analyzed such as temperature, pH, dissolved oxygen (DO), conductivity, turbidity, total hardness, main ions, total and fecal coliforms ( E. coli ) in water. Ecotoxicological evaluation was also performed, using the micro-crustacean Ceriodaphnia dubia . Results : Data of physical and chemical determinations showed DO, conductivity, Cl – , NO 3 , SO 42– and Na + to be important in indicating contamination by urban effluents. On the subject of biological parameters –

Seleção de modelos para o traçado de curvas granulométricas de sedimentos em suspensão em rios

The knowledge about particle-size distribution of suspended sediments in river is fundamental for some hydro-sedimentological studies. In general, the techniques used to determine the particle-size distribution of a sample results in pointwise values, demanding a subsequent interpolation to fit the complete particle-size distribution curve and to obtain specific characteristic diameters values. The transformation of discrete points into continuous functions can be made by mathematical models. However, few studies have been developed with the purpose of determining the best model for fitting particle-size distribution curves. The objective of this paper was to select models for fitting particle-size distribution curves of suspended sediments in river water. Using the particle-size distribution, results from 30 samples of suspended sediments of river with 8 to 10 measured points, with 14 different models were tested. The parameter used to compare the models was the sum of the square errors between the measured and calculated values obtained in the adjustment of each model. The results showed that the Haverkamp & Parlange (1986) and Skaggs et al. (2001) models, both with three fitting parameters, are the best for adjusting particle-size distribution curves of river suspended sediment samples.

Overview of the work in Latin America on erosion and sediment dynamics

Recently, hydrosedimentological investigations have gained increasing attention from society due to a broader understanding and appreciation of the socioeconomic and environmental impacts of erosion and sedimentation processes. In Latin America, where much of the produced electricity comes from hydroelectric power plants and where land use changes at a considerable rate, a deeper understanding of sediment-related processes is important. Other driving forces that have boosted hydrosedimentological research in the Latin American continent are the increasing international demand for food, which has led to the expansion of agricultural frontiers; mining activities; the unplanned occupation of erosion-prone urban sites by vulnerable families in large cities; the attempts to further exploit new waterways; the management of sediment in harbors; as well as environmental issues associated with aquatic systems. A clear evidence of the societal—including the governmental sectors—perception of sediment-associated issues and questions can be demonstrated by the new regulation published in 2010 by two Brazilian agencies: National Water Agency (ANA) and National Energy Agency (ANEEL). According to the new regulation, the companies that own hydroelectric power plants are obliged to monitor not only water but also sediment fluxes in reservoirs. This initiative generated a large demand for experts in the area and induced investments in research regarding sediment dynamics in fluvial systems, focusing on the socioeconomic sustainability of anthropogenic interventions. Furthermore, the recent construction of hydroelectric power plants in the Amazon region, which receives a considerable input from the Andes, also demands expert knowledge regarding sediment fluxes and integrated water–sediment management. In regions where water conflicts are already a reality, the number of multipurpose surface reservoirs expands at a high rate, generating complex networks, which strongly intervene in sediment and water flows. Considering that the siltation of strategic water reservoirs lessens water availability, a more thorough understanding of sediment sources and dynamics is of paramount interest for water-scarce regions in the continent. The advance of agricultural frontiers and the construction of dams in the Upper Paraguay River basin are, for instance, generating severe changes in the natural sediment fluxes, which lead to discussions on the long-term impact on the Pantanal Biome. The 150,000-km biome is one of the largest wetland systems on earth. Another Latin American region that raises international concern related to sediment fluxes is the area that drains its waters into the Panama Canal. Due to its economic significance, the constant engineering works for the expansion of the canal and its dredging have been a relevant driving force for advances in terms of erosion and sedimentation studies. The great extent of Latin America—with a broad spectrum of climate, relief, soil, and land use—generates a favorable environment for diversified research initiatives in sedimentology. This is an overview related to sediment erosion, transport, and sedimentation in present Latin America. It clearly encompasses great possibilities for scientific and technological advances in the near future. C. Poleto (*) Hydraulic Research Institute, Federal University of Rio Grande do Sul, Porto Alegre, RS CEP 91501970, Brazil e-mail: cristiano_poleto@hotmail.com

Comparative hydrology: relationships among physical characteristics, hydrological behavior, and results of the SWAT model in different regions of Brazil (Hidrologia comparativa: relações entre características físicas, comportamento hidrológico e ....)

Comparative hydrology studies, either by the similarities or the differences in the obtained data and results, represent an important tool for advancing knowledge of cause-effect relationships between the physical characteristics of the basins and their hydrological behavior. The objective of this study was to present a comparative analysis of measured and simulated characteristics of experimental and representative basins in different regions of Brazil. The SWAT model was used. Four catchments were evaluated: Alto Ipanema, located in the Caatinga biome, with semi-arid climate; Tapacura, in the transition zone between the Caatinga and Atlantic Forest biomes, with hot and humid tropical climate; and Lago Descoberto and Alto Jardim, both in the Cerrado biome and with tropical altitude climate. The catchments were compared with respect to their physical characteristics (climate, soil, altitude, and land use). Using sensitivity analysis, it was found which of the SWAT model parameters best explain the hydrological behavior of the study regions. Considering its characteristics, the parameters values obtained in each catchment after model calibration were analyzed and compared, indicating the possibility of using these values as reference for their regions. The results indicate a clear relationship between the physical characteristics of watersheds, their respective hydrological behavior, and the values of two SWAT model parameters, CN2 and SOL_K. For other parameters, the relationship between the obtained values do not reflected adequately the characteristics of the catchment, indicating a need for improvement in the physical basis of the calibrated model.

Impacts of the Urbanization Process on Water Quality of Brazilian Savanna Rivers: The Case of Preto River in Formosa, Goiás State, Brazil

The release of domestic sewage in water resources is a practical feature of the urbanization process, and this action causes changes that may impair the environmental balance and the water quality for several uses. The aim of this study was to evaluate the influence of urbanization on the surface water quality of the Preto River throughout the town of Formosa, Goiás, Brazil. Samples were collected at five points along the river, spatially distributed from one side to the other of the town of Formosa, from May to October of 2012. Data were subjected to descriptive statistics, as well as variance and cluster analysis. Point P2, the first point after the city, showed the worst water quality indicators, mainly with respect to the total and fecal coliform parameters, as well as nitrate concentrations. These results may be related to the fact that this point is located on the outskirts of the town, an area under urbanization and with problems of sanitation, including absence of sewage collection and treatment. The data observed in this monitoring present a public health concern because the water body is used for bathing, mainly in parts of Feia Lagoon. The excess of nutrients is a strong indicator of water eutrophication and should alert decision-makers to the need for preservation policies.

Dynamic Land Use Change as Challenge for IWRM: A Case Study in Central Brazil

The management of water and land resources in the Distrito Federal (DF), Western Central Brazil is characterized by very dynamic changes of land use/land cover driven by economic development, population growth and climate change. This problem is addressed by the project IWAS-AGUA DF which aims at creating a scientific base for the sustainable management of water and land resources in scope of an IWRM approach for the Distrito Federal. Land use change and climate change are affecting water resources in the Distrito Federal already substantially. Major effects identified during the project phase are (1) decreasing base flow during the dry season, partially caused by the expansion of agriculture and urbanization and (2) sediment generation and siltation of reservoirs mostly caused by urbanization. The general objective of the project is to contribute to an IWRM approach for the Distrito Federal, identifying causes of problems and possible solutions to maintain sustainable water supply for the region. The objective of the selected five case studies was to develop approaches with focus on all river basins of DF (1) to assess effects of land use on water resources in the past and with focus on the Pipiripau river basin (2) to predict the efficiency of measures (environmental services) and (3) to develop approaches for land use planning as part of an IWRM. For the Lago Paranoa basin two further case studies (4) for the identification of sediment sources and (5) to classify urban areas in terms of effects on water resources were carried out.