Klebber Teodomiro Martins Formiga

Estudo hidromorfológico de bacia hidrográfica urbana em Goiânia/GO

Quantifying the consequences of runoff and degree of infiltration in an urban basin allows the assessment of channel drainage patterns, the occurrence of floods and erosion. The objective of this study was to study the hydromorphology of the urban watershed of the Botafogo Stream, aiming to quantify the physical and morphological parameters that interfere in its hydrological behavior. The methodology used in the study was the use of numerical equations, in addition to the raster and vector data generated in the GIS program, favoring the investigation of the parameters of linearity, area, length and hypsometry of the basin, revealing the behavior of the physiography of the river basin and indicating the morphological indices that interfere in its hydrological activity. Floods in the Botafogo Stream have been frequent due to the altimetric gradient (143 m) of the water body that is born at quota 844 and flows at an altitude of 701 m in relation to the level of the sea, indicating a slight slope that contributes to the rapid concentration of rainwater in the Botafogo Stream and its tributaries. The Botafogo River Basin is poorly drained (0.58 km -1 ) suggesting, therefore, that the occurrence of floods is related to the relief.

NOVO MÉTODO PARA DETERMINAÇÃO DO FATOR DE REDUÇÃO DE ÁREA APLICADO EM CHUVAS DE PROJETO

The main objective of this work was to develop an area reduction factor (ARF) determination method, which is a coefficient applied to average rainfall estimates for projects, given rainfall at a point. After a review about the subject, it was verified the needs of developing regional studies and the existence of some deficiencies on current approaches. In this sense, it was tried to create an appropriate methodology given the spatial variability of extreme rainfall. Therefore, the new suggested method, differently from the observed in others techniques, is primarily based on objective assessment of the ratio between extreme average rainfall calculated above several areas and the extreme point rainfall observed in gauges located in the center of those areas. After structuring it, the proposed method was tested in a pilot implementation with data obtained from a raingauge network in the region of Corrego Botafogo Basin, urban zone of Goiânia, GO. The results were analyzed regarding the dependence of ARF to area, duration and order of magnitude (in reference to the exceedance probability). It was found a strong relation with area, a minor with duration and the need of further studies about the exceedance probability influence. Lastly, the ARF values obtained with results fitting were compared with those indicated from other employed empirical models. From this study, it can be concluded that proposed methodology is appropriated to determine ARF, as its results are compatibles with assumptions established. Keywords: project rainfall, rainfall spatial distribution, area reduction factor.

POTENCIAIS USOS DA ÁGUA VIA REGULARIZAÇÃO DE VAZÕES NO RESERVATÓRIO JOÃO LEITE EM GOIÂNIA, GO

Reservoir operation requires a series of decisions that defines the quantity of water must be allocated over time for each one of the water demands and which volumes should be maintained in order to reach optimum predefined uses. In this context, the aim of the study is to identify potential water demands in the Joao Leite reservoir, situated in Goiânia, GO, via water balance calculations performed by the network flow model AcquaNet. The simulations show how much water is stored in the reservoir over time and whether is possible or not provide the assessment for other purposes besides both the water supply and the maintenance of the environmental flow. In order to establish target reservoir storage volumes, waiting water volumes are calculated for different return periods and it has been determined the surplus water demands for both wet and dry seasons. The results showed that the Joao Leite reservoir cannot attenuate floods, since it cannot guarantee the water demands under waiting water volumes. However, numerical results obtained considering minimum water volume as the constrained condition has shown that the reservoir can operate on 50% to 90% of total volume, in which potential water uses can be allocated besides water supply and environmental flow. Keywords: Reservoir operation, Reservoir water balance, Joao Leite Stream.

Uso de modelo hidrodinâmico para determinação da vazão a partir de medições de nível

The use of hydrodynamic models to determine stream discharges has been grown in recent years due to the problems regarding the use of rating curve method for discharge estimating. This study aims to develop a method for determining discharges in open channels using multiobjective evolutionary algorithms (NSGA-II) and free surface level measurements associated with a hydrodynamic model. Data obtained from experiments on a laboratory experimental channel have been used for model calibration and validation. NSGA-II optimization algorithm presented excellent results and Nash-Sutcliffe coefficients greater than 0.99 have been obtained for both calibration and validation of the hydrodynamic model. Discharges calculated by the hydrodynamic model showed variations of up to 150% for the same level when compared to the discharges estimated by the rating curve, which showed that the use of rating curve for discharge measurements during transient flows results in high errors.