Qualidade da água subterrânea para irrigação na bacia hidrográfica do Rio Gurguéia, PI.

Abstract

The knowledge of the qualitative characteristics of water for irrigation can contribute in the making decisions about its use in different crops. The objective of this work was to evaluate the quality of water for irrigation in wells, located in the hydrographic basin of Gurgueia River. Samples of water were collected and analyzed in the rainy and dry season of 2004. The obtained data were interpolated in a geographic information system (GIS). The results were demonstrated by thematic maps. It was allowed verifying that great part of the municipal districts had moderate to severe restrictions about infiltration of water in the soil. There was a slight increase in the levels of Na in relation to the allowed maximum limit, where the higher class presented a variation of 2.0 to 3.4 mmolc L-1 in the dry season. It is not recommended sprinkler irrigation in order to avoid the potential toxicities risk for this season.