Luis César de Aquino Lemos Filho

Spatial analysis of the influence of meteorological elements on the reference evapotranspiration in the State of Minas Gerais, Brazil

In general the methodologies most used and recommended to estimate crop water requirements are based on meteorological data. The aim of this study was to evaluate the effect of some meteorological elements on reference evapotrasnpiration (ET0) estimate in Minas Gerais State, Brazil. The values of ET0 were estimated daily by the Penman-Monteith-FAO method, using daily data over a period of 17 years. The influence of each meteorological element on ET0 values was determined by sensitivity tests and interpolated map analysis for each element under study. The results showed that the reference evapotranspiration is very variable in Minas Gerais, with annual average values between 2.51 to 4.59 mm d-1. The sensitivity analysis showed a high variation effect of meteorological elements in ET0 in Minas Gerais, with high sensitivity to vapor pressure deficit, wind speed and radiation. The radiation was the most important meteorological element, with the highest influence in ET0.

Spatial-temporal analysis of water requirements of coffee crop in Minas Gerais State, Brazil

Scientific investigations about crop water requirements are of fundamental importance to the irrigation process. The main objective of this paper is to analyze and to map water requirements of coffee crop in Minas Gerais State, Brazil. Potential evapotranspiration values (ET0) were estimated by the Penman-Monteith-FAO method, using daily data sets available for 42 National Meteorology Institute (INMET) stations for a period of 17 years. The crop coefficient values (kc) considered were extracted from literature. The results were analyzed by means of geostatistical tools. The theoretical semi-variograms were fitted by the Maximum Likelihood method, considering spherical, exponential and Gaussian models. The maps were created using the ordinary kriging method. In a general way, the results have showed that the coffee crop evapotranspiration (ETc) presents high variability in Minas Gerais State. The largest variations, both spatial and temporal, have been observed in the northern part of the State. January and June, respectively, presented the highest and the smallest water requirements of coffee crop. Based on this, we can conclude that due to the coffee crop evapotranspiration (ETc) data distinction in different regions of Minas Gerais, a good estimate of the ETc values for each locality will bring many benefits to the coffee growers regarding irrigation scheduling.

Chuvas intensas para a Microrregião de Pau dos Ferros-RN (Intense Rainfall for Microregion of Pau dos Ferros-RN)

A precipitacao pluviometrica apresenta importância para os estudos climaticos, pois ocasiona implicacoes, quando ocorrida em excesso (precipitacao intensa). Os dados pluviometricos diarios das precipitacoes maximas anuais para a microrregiao de Pau dos Ferros, formada por dezessete municipios, foram disponibilizados pela EMPARN – (Empresa de Pesquisa Agropecuaria do Rio Grande do Norte) no periodo de 1964 a 2011 (48 anos) com o objetivo de analisar o ajuste dos dados de precipitacao maxima a distribuicao de Gumbel por meio do teste de aderencia de Kolmogorov-Smirnov ao nivel de 5% de probabilidade utilizando o software R Version 2.12.1 e estimar a precipitacao maxima diaria anual para diferentes periodos de retorno (2, 5, 10, 20, 50, 100 e 500 anos) para auxiliar no planejamento de obras hidraulicas. 11 dos 17 municipios apresentaram ajuste dos dados de precipitacao a distribuicao de Gumbel, ou seja, 64,71% das amostras dos dados de precipitacao seguem a distribuicao de Gumbel. Os dados de precipitacao maxima diaria anual apresentaram ajuste ao modelo probabilistico de Gumbel, isso indica a possibilidade de realizar estimativas das chuvas maximas para os periodos de retorno de (2, 5, 10, 20, 50, 100 e 500 anos) que servem de referencia para o planejamento de obras hidraulicas. A B S T R A C T Rainfall has importance for climate studies , because it causes implications when occurring in excess ( heavy precipitation). The daily rainfall data of annual maximum precipitation for the micro region of Pau dos Ferros , comprising seventeen counties , were provided by EMPARN - ( Agricultural Research Company of Rio Grande do Norte ) in the period 1964-2011 (48 years) with the objective analyzing data adjustment of the maximum precipitation Gumbel distribution through the test Kolmogorov- Smirnov at 5 % probability using the software R Version 2.12.1 and estimate the likely annual maximum daily precipitation for different periods return ( 2, 5 , 10 , 20 , 50 , 100 and 500 years) to assist in the planning of hydraulic works . Eleven of the 17 counties showed adjustment of the precipitation data to the Gumbel distribution , in other words 64.71 % of the precipitation data samples following the Gumbel distribution . The maximum daily precipitation data showed annual adjustment to the probabilistic model of Gumbel , this indicates the possibility of estimates of maximum rainfall for return periods ( 2, 5 , 10 , 20 , 50 , 100 and 500 years) that serve as reference for planning waterworks . Keywords: precipitation, extreme events, gumbel.