Açudagem no nordeste brasileiro e no Ceará: estimativa de evaporação do açude Castanhão em um ano seco

Abstract

Water scarcity in semi-arid regions has always been the subject of questioning and discussion. Water availability is a limiting factor in agricultural production and, in severe situations, even threatens the survival of entire populations. The knowledge of the spatial and temporal distribution of the transfer of water vapor to the atmosphere greatly facilitates the establishment of public policies aimed at the rational use of water. Studies on the loss of water by evaporation in large reservoirs provide better control of the use of the dammed waters. The objective of this study is to estimate the evaporation of the Castanhão dam - Ceará/Brazil, taking Penman's (1948) method of measurement, being one of the classic methods for evaporation studies. By means of primary data, from a floating weather station (DantaSales) on the lake of the Castanhão dam, and secondary data, from a station located in terrestrial environment (PCD - Jaguaribe). For this study it was used statistical methods - Pearson correlation method (r), Coefficient of determination (R²), Normal regression model and Mann-Whitney U test - with the objective of correlating and discussing the estimated variables. Considering the above, it is possible to conclude that the variables with the greatest influence on the water losses by evaporation were Solar Radiation, Maximum Air Temperature and Relative Humidity. In general, evaporation in water is 0,79 points greater than the evaporation measured on land. Taking the average evaporation in the water was found to be 3,99 mm/dia-¹ and on land 3,29 mm/dia-¹, so the average evaporation in water is approximately 17,68% greater than the average of terrestrial evaporation.