Quality of the water for irrigation in the Irrigated Perimeter Cachoeira II in the municipality of Serra Talhada/PE

Abstract

Aiming to characterize the waters used for irrigation in Cachoeira II Irrigation Perimeter, as well as to evaluate the variation of the water quality along the year, water samples were collected from the main irrigation water sources (Cachoeira river, Pajeú river and wells), at each three months during one year.
Physical and chemical analyses (electric conductivity, pH, cations and anions) were carried out and the results, analyzed by descriptive statistics. The waters showed sodium-chlorine predominance, independently of the salinity level, places and sources of origin. The waters used for irrigation showed  high risk of salinization and sodification, due to the high levels of sodium and chloride. pH values were within the normal limits (6.5 to 8.4), however, the waters from wells presented Cl^- concentrations higher than 3 mmolc L^-1, with average values of 19.53 mmolc L^-1. The highest average values of RAS were observed in the third sampling time, at the end of the dry season, in all analyzed water sources. The waters from wells presented high CE values at all sampling times, representing a risk for many crops of economic value.