Caracterização da qualidade da água superficial na bacia Capiá-AL, para fins de irrigação.

Abstract

The purpose of this study was to evaluate the quality of the surface water and its seasonal variation in Capia-AL hydrological basin, as well as to check out effect of these waters on the soil characteristics. Two samplings were made, each one with 107 samples, in two distinct periods- one in March of 1989 ( dry period ) and the second in June of 1990 ( rainy season period). The chemical analys is of the water collected during dry period showed that 94-40% of the studied waters have too high salinity levels, 52-34 % has high sodium concentration, 2-80 % has average salinity and 25-23 % show low to medium sodium concentration-In the second sampling, waters with very high salinity showed a reduction to 93-46% and waters with low to medium concentration of sodium increased to 27-10 %. In both periods, analysis of boron showed that 2-80% of the waters have phytotoxic problems. As for chloride and sodium, phytotoxic levels were found in 94-40 and 95.33 % samples, respectively, in the first collection, and in the second sampling, these ions showed serious problems in 85.98 and 86-93 % of the waters, respectively. Among the soil samples analysed, 61,11 % had CEs values lower than 1-5 mmhos/ cm- A significant linear correlation between sodium adsorption ratio of saturation extract and the exchangeable sodium percentage was found.