Influence of Prolonged Drought on Groundwater Quality: Irrigated Perimeter of Lower Acaraú – State of Ceará– Northeast of Brazil

This study had with objective to evaluate the influence of climatic seasonality and dry season prolonged on parameters of the groundwater quality of irrigated perimeter of lower Acaraú - Ceará, for the years 2010, 2011, 2015 and 2016. Hydrochemical analyzes of the attributes of HCO3-, Ca2+, Cl-, Mg2+, K+, pH, EC, SAR and Na+ in the periods of june (2011; 2015; 2016) and november (2010; 2015; 2016) were performed in six ponds for comparison with previous study. In 2016 it was held on reading the water level of the ponds to identifythe water table variation. The cluster analysis was applied by software SPSS 16.0, where the means of the groups were compared by the T test with 5% significance and presented in boxplot. The Piper Diagram was used in the classification and evaluation of waters. The methodology of the Salinity Laboratory of the United States was used in the evaluation of irrigation water quality with the use of Qualigraf software. The groundwater dynamics indicated that the prolonged drought reduced the water the level of the water table. There was the formation of two groups. Group 1 did not indicatethe reduction of rainfall in the years 2012 to 2016, showing similarity with the attributes of the year 2011 to 2015 and 2016. The elevation of salinity indicator variables in group 2 was obtained due to their location. The classes of irrigation water ranged from C1S1 to C3S2.