Olívio José Soccol

Analysis of probable monthly rainfall in the municipality of Lages, SC

In this study, monthly rainfall time-series with 80 years of collected data were analyzed and adjusted using gamma distribution in order to determine the expected monthly rainfall for Lages, in the State of Santa Cararina. The method of adjustment of model was used to estimate α and β parameters of gamma distribution, and Kolmogorov-Smirnovs test assessed the models fitting to the data. Gamma distribution fitted to observed data of all months of the year (p x). The results showed that the monthly mean rainfall, for all months of the year, occurred at probability level of 31.93% with variation coefficient of 3.63%. Considering these results, it is proved that the found mean values should not be used as parameters in agricultural projects. For all months of the year, the difference between monthly mean rainfall and probable rainfall were 64.49 mm (51.3%) and 73.03 mm (58.1%), at probability levels of 75 and 80% respectively.

Avaliação de um hidrociclone de Rietema para remoção de areia da água de irrigação

In this work, objective was to evaluate the capacity of a Rietema kind of hydrocyclone, with 50 mm diameter, to retain suspended sand in irrigation water. The hydrocyclone was operated with pressure differentials that varied from 10 to 60 kPa and discharges between 1,159.90 and 2,603.60 L h-1. The sand concentration in suspension varied from 2.81 to 7.01 g L-1. The best results were obtained for the pressure differentials of 10 and 20 kPa, with cut diameter sizes of 50 mm showing granulometric efficiency of 70%.

Hydrocyclone for pre-filtering of irrigation water

The use of water containing suspended sediments causes serious problems to irrigation systems. Choosing the right filtering system type and capacity is essential to avoid increases in operational and maintenance costs of irrigation resulting from the need for cleaning and frequent component replacing. Pre-filters, such as the hydrocyclone, are important for their significant capability of retaining particles suspended in the water. Data on hydrocyclones performance for pre-filtering of irrigation water can be found in the literature, but research data in Brazil are scarce. Therefore, four Rietema type hydrocyclones (50 mm diameter) were constructed, one with circular-end and the other three presenting rectangular-end feeding tubes. The evaluation of hydrocyclones performance was conducted by using suspensions of fine sand and clay soil particles under varied pressure differentials. The comparison criteria were the discharge and the separation capability, given by total efficiency and reduced total efficiency. The hydrocyclone with circular-end feeding tube presented the highest indexes for the adopted criteria, considering sand and soil suspensions.

Alteração no diâmetro e na perda de carga em tubos de polietileno submetidos a diferentes pressões

Procedeu-se a avaliacao das alteracoes de diâmetro e da perda de carga em tubos de polietileno de baixa densidade, com diâmetros nominais DN12 e DN20, quando submetidos a pressoes de operacao de 50, 100, 150, 200, 250, 300, 350 e 400 kPa. Os diâmetros foram medidos com um paquimetro digital, suas alteracoes por meio de dois dendrometros interligados a um datalogger e as perdas de carga por um transdutor de pressao diferencial. Verificou-se a influencia da pressao de operacao sobre os diâmetros internos e na perda de carga, principalmente para o tubo DN20. Foram ajustadas equacoes correlacionando-se a vazao e a perda de carga, para cada uma das pressoes, alem de outra obtida com todos os pares de valores, para cada modelo de tubo. As equacoes foram comparadas pelo teste t, verificando-se que, ao nivel de 5% de probabilidade, uma unica expressao nao poderia representar a perda de carga para todas as pressoes testadas. Por esta razao, ajustaram-se equacoes para cada um dos diâmetros, em que a perda de carga foi expressa em funcao da vazao e do diâmetro ou da vazao e da pressao.

Generation of intensity duration frequency curves and intensity temporal variability pattern of intense rainfall for Lages/SC

The objective of this work was to analyze the frequency distribution and intensity temporal variability of intense rainfall for Lages/SC from diary pluviograph data. Data on annual series of maximum rainfalls from rain gauges of the CAV-UDESC Weather Station in Lages/SC were used from 2000 to 2009. Gumbel statistic distribution was applied in order to obtain the rainfall height and intensity in the following return periods: 2, 5, 10, 15 and 20 years. Results showed intensity-duration-frequency curves (I-D-F) for those return periods, as well as I-D-F equations: i=2050.Tr0,20.(t+30)-0,89, where i was the intensity, Tr was the rainfall return periods and t was the rainfall duration. For the intensity of temporal variability pattern along of the rainfall duration time, the convective, or advanced pattern was the predominant, with larger precipitate rainfalls in the first half of the duration. The same pattern presented larger occurrences in the spring and summer stations.

Corn performance with late sowing in Planalto Catarinense, Brazil, simulated with CERES-maize model

This work had the objective to investigate the delay effects in the sowing date on corn establishment, cycle duration and yield through the computer simulations using CERES-Maize model, in order to help agrarian producers from the Mountainous Area of Santa Catarina, Brazil to take better decisions on it. The computer simulations showed that: 1)the risks on corn establishment increased due to the delay of sowing during the studied years; 2) in some years, its cycles were drastically affected for the lower temperatures; 3) the cycle durations were longer when confronted with the low temperatures; 4) corn income decreased when the cycles were confronted with the low temperatures, water deficiency and low solar radiation; 5) potential incomes averaged 4944 kg ha-1, and under the natural rain conditions averaged 2490 kg ha-1, during all the months analyzed from October to March; 6) besides January, the exploration of this cultivar was not viable because of the high risk of the crop frustration associated to the same ones, due to the thermal conditions (low temperatures and frost).

Evaluation of hydrocyclone as pre-filter in irrigation system

The objective of this work was to evaluate the efficiency of a hydrocyclone to separate sand in irrigation water. To do this, it an experiment was conducted where the hydrocyclone was operated with pressures and discharge that varied from 10 to 60 kPa and from 1,159.90 L h-1 to 2,603.60 L h-1, respectively. During the tests, the sand concentration in suspension varied from 2.81 g L-1 to 7.01 g L-1. The results showed that the best efficiency was obtained with pressure differentials of 10 and 30 kPa, with cut size (d70) of 50 µm.