Showing papers in "Revista Brasileira de Recursos Hídricos in 2006"
13 citations
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11 citations
TL;DR: In this article, the displacement of 1/2 pulse pore volume from the CaCl2 solution at 0.01 M in soil columns under saturation conditions and steady water flow regime was analyzed.
Abstract: Essays on the displacement of miscible liquid in soil columns in the laboratory were applied to hydrodisper- sive characterization of three soil samples with different textural classes: sandy loam, sandy clay loam and sand, from Alluvial soil on the banks of Cajueiro Dam in the Brazilian semi-arid. The essays comprise the displacement of 1/2 pulse pore volume from the CaCl2 solution at 0.01 M in soil columns under saturation conditions and steady water flow regime. The solute transport parameters were obtained by adjusting the analytical solution of the convec- tion-dispersion equation CDE (v, D), and the mobile- immobile solute transport model CDE-MIM (v, D, b and w), to the breakthrough curve points, by using the CXTFIT 2.0 computer program
8 citations
TL;DR: A study of interception loss was carried out in a forested area inside the campus of the Federal University of Minas Gerais (UFMG) from January 1997 to June 1998 as discussed by the authors.
Abstract: A study of interception loss was carried out in a forested area inside the campus of the Federal University of Minas Gerais (UFMG) from January 1997 to June 1998. This area is located in the Córrego Engenho Nogueira watershed, where the UFMG and the Center for Nuclear Technology Development (CDTN) are running a few catchment experiments. Throughfall was measured with ten raingauges placed randomly on a 10x10m grid plot and stemflow was collected from six trees located in this plot. The cumulative rainfall used in this study was 1087mm; the cumulative througfall/rainfall and stemflow/rainfall ratios were, respectively, 0,67 and 0,10. Therefore, the estimated interception loss was 23 ± 8% of the total measured rainfall. Two physically-based models for interception loss – Gash and Rutter models – were described and applied in this study. Using both models provided realistic simulation of interception loss in a tropical forest area as they normally do for temperate forests. However, the cumulative interception loss/rainfall ratios have been underestimated; in fact, as compared with the measured 23% loss, the calculated values have been 20% and 19%, respectively, for the Gash and Rutter models. The main reason is the great differences in the measured and calculated interception loss for days with rainfall greater than 25mm. Key-words: Interception; modeling; experimental basin; forested area
8 citations
TL;DR: In this paper, the authors used data from Mãe-Bá lagoon, located on the southern coast of the state of Espírito Santo, to contribute to increasing knowledge about the influence of natural and anthropic aspects on water quality parameters of coastal lagoons, and the interactions between the different environmental variables, besides characterizing the degree of productivity of these environments.
Abstract: Coastal lagoons take up about 13% of the coasts worldwide. They are shallow, highly productive environments, submitted to continental and marine influences. The multiple uses of their waters and anthropic activities performed in their hydrographic basins have caused major changes in the quality of their water resources. The purpose of using data from Mãe-Bá lagoon, located on the southern coast of the state of Espírito Santo is to contribute to increasing knowledge about the influence of natural and anthropic aspects on water quality parameters of coastal lagoons, and the interactions between the different environmental variables, besides characterizing the degree of productivity of these environments. For this water quality monitoring data from the lagoon, during the period from September 1993 to December 2002, were used for the following parameters: water temperature, real and apparent colors, pH, dissolved oxygen, suspended solids, dissolved solids, turbidity, biochemical oxygen demand, chemical oxygen demand, nitrogenated series, total phosphorous, orthophosphates, soluble iron, total iron, fecal coliforms, total coliforms, chlorophyll a, chlorides, conductivity and salinity. Monitoring data on potential industrial effluents and meteorological variables were also surveyed. Statistical tests were performed using the data, at a 5% level of significance. The results were compared with the limits established by current legislation. Mãe-Bá lagoon presented characteristics common to coastal lagoons in general. Seasonality strongly influenced the temperature of the lagoon water, which did not present thermal stratification and showed a dissolved oxygen profile of the orthograde type, mainly due to the small depths and wind action. The lagoon presents slightly brackish water and lower conductivity values than those of coastal lagoons strongly influenced by the sea. The results of the trophic classifications indicated by the Modified Index of Trophic State and by the methodology for a probability distribution of a trophic state based on total phosphorous concentrations determined eutrophic conditions in the lagoon at points located close to sites where domestic effluents are discharged. Systematic increase of pH through the years, supersaturation of disRBRH – Revista Brasileira de Recursos Hídricos Volume 11 n.1 Jan/Mar 2006, 63-77 77 solved oxygen, high values of total phosphorous, differences between the parameters apparent and real color, raw and filtered COD and growth of phytoplankton density, constituted typically by cyanobacteria, indicate the existence of an eutrophication process in Mãe-Bá lagoon.
7 citations
TL;DR: In this paper, a monitoramento da qualidade de agua for reservatorios do Ceara, localizados no semi-arido do Brazil, and atualmente realizado mensalmente com base em medidas de perfis verticais for alguns parâmetros fisicos and quimicos, and em um ponto amostral (proximo a superficie d´agua) for todos os outros parâmars.
Abstract: O monitoramento da agua e realizado em amostragens temporais e espaciais tanto no que se refere a aspectos quantitativos como qualitativos. Para ser eficiente, a amostragem deve considerar processos fisicos, quimicos e biologicos que afetam os parâmetros de interesse. O monitoramento da qualidade de agua para reservatorios do Ceara, localizados no semiarido do Brasil, e atualmente realizado mensalmente com base em medidas de perfis verticais para alguns parâmetros fisicos
e quimicos, e em um ponto amostral (proximo a superficie d’agua) para todos os outros parâmetros. O objetivo deste artigo e
descrever o processo de mistura em lagos em baixas latitudes e estabelecer criterio para o monitoramento de qualidade de aguas nestas regioes. E demonstrado que a estratificacao e a mistura ocorrem em um ciclo diurno governado por variaveis
climaticas, tais como radiacao solar e vento. Assim, a variabilidade mensal nao e somente devido a variabilidade sazonal,
mas tambem a diferencas no horario da medida realizada. Como um resultado, a estrategia de monitoramento deve levar em
consideracao a variabilidade diurna de tais parâmetros e dos processos de mistura e estratificacao, definindo, por exemplo,
uma hora padrao para a medida, o que pode ser muito caro e operacionalmente impossivel.
7 citations
6 citations
6 citations
TL;DR: In this paper, a new approach to rainfall-runoff global modeling, the DPFT method, is presented, using a rainfallrunoff multi-event sample and an iterative algorithm, the average Unit Hydrograph (Transfer Function) of the watershed and an effective rainfall series, associated with each event, are simultaneously identified.
Abstract: A new approach to rainfall-runoff global modeling, the DPFT method, is presented. Using a rainfallrunoff multi-event sample and an iterative algorithm, the average Unit Hydrograph (Transfer Function) of the watershed and an effective rainfall series, associated with each event, are simultaneously identified. This last particular item is the main advantage of the method, and allows the later calibration of different Loss-Function models, relating the measured observed rainfall, to the effective rainfall, calculated by means of the DPFT method. A study case is presented, referring to the application of the method to Serra Azul watershed (109 km), considered as a representative region in the State of Minas Gerais Brazil. The Transfer Function obtained is compared with other methods and shows robust and stable results. The effective rainfalls obtained are consistent. For each rainfall-runoff event, using the observed rainfall effective rainfall pairs, two simple Loss-Function models are calibrated and compared: the Soil Conservation Service model and the φ-index model. Key-words: Rainfall-runoff model, DPFT method, Unit Hydrograph, Loss-Function, ARMAX Formulation
TL;DR: In this article, the authors developed an economic optimisation method for water supply systems, formed by the water distribution network together with the pumping station, taking into account the varia- tion of project boundary conditions during the time in which it is used.
Abstract: The present study deals with the development of an economic optimisation method for water supply systems, formed by the water distribution network together with the pumping station. The method takes into account the varia- tion of project boundary conditions during the time in which it is used. Flow variations, roughness of pipe walls and energy unitary cost are considered during the period of project exploitation. The method is based on a non-linear mathematical pro- gramming model, in order to obtain the minimum total cost of the pipe network/pumping station, taking into account the operational parameters variation over time. The opti- mum design solution was obtained by the algorithm of the Generalized Reduced Gradients (GRG2). The method was applied to the optimum water supply sys- tem design of the city of Itororo in the state of Bahia, Bra- zil. The design solutions obtained show that all the hydrau- lic restrictions had been taken into account. Despite the robustness of the optimisation model, with the variation of flows, head loss and energy unitary cost over time, the method proved to be practicable
TL;DR: In this article, the authors assessed the quantity and quality of water available in the Sapucaí-Mirim River Basin, SP. Through river basin modeling, application of a of simulation model and implementing scenarios of domestic organic load emission reduction, the water resources system performance, conflict between the multiple water uses and the concentration of DO and BOD parameters in the river water that receives often untreated domestic effluents, they showed that electric power generation is compromised and that water has become scarce in terms of quality, showing that it is urgently necessary to construct new wastewater treatment plants.
Abstract: Competition for water has grown in the same proportion that it is becoming scarce, as a consequence of waste, unequal distribution, increase and variety of consumption and water quality degradation. Due to this situation, the present study assessed the quantity and quality of water available in the Sapucaí-Mirim River Basin, SP. Through river basin modeling, application of a of simulation model and implementing scenarios of domestic organic load emission reduction, the water resources system performance, conflict between the multiple water uses and the concentration of DO and BOD parameters in the river water that receives often untreated domestic effluents are analyzed. Although the quantity of water is enough to cover demand, the study shows that electric power generation is compromised and that water has become scarce in terms of quality, showing that it is urgently necessary to construct new wastewater treatment plants. Key-words: water resources, simulation, water quality.
TL;DR: In this article, the authors evaluate the flows that can be allo- cated to users in the Bois River Basin and its sub-basin, Peixe River Basin, in Goias, in order to provide informa- tion for water resources management instruments.
Abstract: This study evaluates the flows that can be allo- cated to users in the Bois River Basin and its sub-basin, Peixe River Basin, in Goias, in order to provide informa- tion for water resources management instruments estab- lished by Federal Law 9.433/97, emphasizing charging for the use of water resources. The Bois River Basin covers 34,552.04 km 2 , correspond- ing to 10% of the total area of Goias. A large amount of river flow data is available, supplied by twenty stations, with historical series and distribution that allowed the regionalization of the flows at the exit from the basin. The RH 3.0 software was developed by Minas Gerais Rural Foundation - RURALMINAS and Federal University of Vicosa, with the support of the Department of Water Re- sources of the Ministry of the Environment. It was used to estimate the guaranteed flow 95% of the time (Q 95 ) to the outflow from Bois River Basin, obtaining the value of 118.100 l/s. The Goias State Council for Water Resources (CERH- GO), in resolution 09/2005, established Q 95 as reference flow for water use rights under the state domain. The maximum flow that can be allocated corresponds to 70% of Q 95 , or, for the Bois River Basin, 82.670 l/s. To check the feasibility of using this reference flow and the portion allocated, the study performed a survey of the criteria used in eleven Brazilian states. The Peixe River Basin has a drainage area of 287.49 km 2 . In this basin, the complete lack of hydrological data and the impossibility of data transfer because of the small drainage area prevent the calculation of Q 95 and its use as Avaliacao das Vazoes Alocaveis na Bacia Hidrografica do Rio dos Bois e sub-bacia do Rio do Peixe, Estado de Goias 58 reference flow. Such situations are common in most small river basins in Goias. In such cases, according to CERH-GO resolution 09/2005, the smallest flow ever measured, preferably during a drought period using a precision
TL;DR: The main objective of as mentioned in this paper was to analyze the water demand for irrigation and for animal and human supply (urban and rural) in the Paracatu basin from 1970 to 1996.
Abstract: Paracatu river is the tributary with the largest contribution to San Francisco river. Water use conflicts in the Paracatu basin began in the 70’s, as economic activities increased in the basin. The main objective of this paper was to analyze the water demand for irrigation and for animal and human supply (urban and rural) in the Paracatu basin from 1970 to 1996. Estimates of the irrigation and animal supply were performed using data from agricultural censuses. Data from demographic censuses were used for human (urban and rural) supply. The water demand for irrigation and for animal and urban supply grew during the period, while the water demand for rural human supply decreased with time. The rate of growth of water demand in the basin was 0.20 m s year, 0.19 m s year corresponding to irrigation. Key-words: water uses; water resources management; water demand.
TL;DR: In this article, a planar concentration field of the dissolved oxygen near the air-water interface has been quantified in an oscillating-grid tank using the laser induced fluorescence (LIF) technique.
Abstract: Detailed experiments have been conducted to obtain information on the basic principles involved in the mechanism of interfacial gas transfer under liquid-side control. Planar concentration fields of the dissolved oxygen near the air-water interface have been quantified in an oscillating-grid tank using the laser induced fluorescence (LIF) technique. The high data resolution reveals the concentration distribution within the concentration boundary layer which is only a few millimeters thick. The measured concentration fields allow the observation of the surface renewal phenomenon. Vertical profiles of mean concentration and fluctuation intensity were obtained from the concentration fields. These profiles supply relevant information to apply models developed to the interface. Key-words: interfacial gas transfer; laser induced fluorescence; oscillating-grid tank; turbulence.
TL;DR: In this article, the authors evaluated the assured energy of small run-of-river (SHP) plants using the average of the censured plant flows over the system critical period, multiplied by plan productivity (kW/m/s).
Abstract: The Brazilian Energy Regulatory Agency – ANEEL proposed that the so-called assured energy of small hydro plants – SHP should be obtained by computing the 30-year long term average of the mean monthly flows censored by the flow corresponding to the maximum plant capacity. The Water Resources Agency – ANA proposed to use the incremental firm energy of the system as the assured energy. In small run-of-river plants, as is the case of most SHPs, this is the equivalent of using the average of the censured plant flows over the system critical period, multiplied by plan productivity (kW/m/s). The evaluation of both ANEEL’s method and ANA’s method is performed by applying these methods to 14 SHP and comparing the results to the guaranteed energy of the analytical method proposed by Fill (1989) for the reliabilities corresponding to return periods of 120 and 50 years. The values of the assured energy obtained by ANA’s method are consistent with the incremental guaranteed energy maintaining system reliability. However values computed by ANEEL’s method are systematically higher and therefore result in a loss of system reliability. Key-words: SHP, assured energy, reliability.
TL;DR: In this paper, the authors presented a time series analysis of the water quality of the Piracicaba river basin, using stations monitored by CETESB (Companhia de Tecnologia de Saneamento Ambiental), in the period from 1979 to 2001.
Abstract: knowledge of time trends of water quality is important for the environmental diagnosis of hydrographic basins. This allowS the evaluation of qualitative water body responses to increasing anthropogenic interventions over the years. This study aims to characterize the water quality of Piracicaba river basin, using stations monitored by CETESB (Companhia de Tecnologia de Saneamento Ambiental), in the period from 1979 to 2001. The biogeochemical parameters evaluated concerning the time trend and magnitude were: dissolved oxygen (DO), biochemical oxygen demand (BOD), total nitrogen, nitrate, ammonia, total phosphorus, chloride and fecal coliforms. Time trend analysis requeres a specific methodology. since the time series obtained are not normally distributed, the samplingS are performed irregularly. The data may present seasonal periodicities and dependence on the rivers discharges. This methodology is divided into graphical analysis and application of trend tests in which, initially, an exploratory analysis of data is performed, followed by confirmation through statistical tests. The results showed that in general water quality degradation occurs in most of the basins, represented by the positive trends of parameters BOD, nitrogen, nitrate, ammonia, total phosphorus, chloride and fecal coliforms, and the negative trend of the dissolved oxigen parameter. Key-words: Trend Series, Time series, water quality
TL;DR: This work determined hydraulic conductivity and sorptivity as a function of soil matric potential {K(h), S(h)} in two layers of a Fluvent at the ebb tide of Cajueiro Dam, located in Tuparetama, Pernambuco.
Abstract: The availability of water for plants in soils under recession agriculture is a result of dynamic processes involving water fluxes to the rooting zone and the extraction of water by roots. Hydraulic conductivity and sorptivity values are very good indicators of the hydrophysical conditions of soils since they are directly related to the movement of water in soil. We determined hydraulic conductivity and sorptivity as a function of soil matric potential {K(h), S(h)} in two layers of a Fluvent at the ebb tide of Cajueiro Dam, located in Tuparetama, Pernambuco. The measurements of infiltration, using a disk infiltrometer, 80 mm in diameter, were performed at the depths of 20 and 60 cm, by applying water supply potentials of 0, -3, -6, and –12 cm. The hydraulic properties, K(h) and S(h), were obtained using the analytical equation for three-dimensional transitory infiltration for short times and long times. The infiltration curves were adjusted by the equation for short times and long times over variable time intervals, considering the time intervals adjusted to the times of gravitational and geometric stabilization. Key-words: hydraulic conductivity, disk infiltrometer.
TL;DR: In this article, the authors evaluated and recommended the best model or group of models for fitting particle-size distribution curves of riverbed sediments using 30 riverbed sediment samples, 14 different models were tested.
Abstract: Knowledge about particle-size distribution of riverbed sediments is essential to use indirect methods for calculating the total fluvial sediment discharge in a river cross-section, as well as for other hydro-sedimentological studies. In general, the techniques used to determine the particle-size distribution of a sample result in point values, requiring subsequent interpolation to fit the complete particle-size distribution curve and to obtain specific characteristic diameter values. The transformation of discrete points into continuous functions can be performed by mathematical models. Thus, the objective of this paper was to evaluate and recommend the best model or group of models for fitting particle-size distribution curves of riverbed sediments. Using the particle-size distribution results of 30 riverbed sediment samples, 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 Lima & Silva 3P model is best for fitting particle-size distribution curves of riverbed sediments