THE EFFECT OF THE DISCHARGE OF WASTE WATER FROM THE CITY ON THE PHYSICO-CHEMICAL WATER QUALITY IN THE DAM OF WADI EL ARAB, EASTERN ALGERIA

Abstract

Multivariate statistical techniques such as cluster analysis, principal component analysis, and factor analysis and time series analysis were used to evaluate temporal variations in surface water in the Baber watershed. A total of 21 samples (7 from each city) were collected on which eleven phys-chemical parameters were determined. The salinity of the samples brought from the Eastern part (S1) are found to have high TDS values, while part (S2) to the west display low TDS and in the dam (S3) TDS values are intermediate on average. The water type in S1 is SO4-Na, in S2 it is HCO3-Ca-Mg and SO4-Ca-Mg which is the characteristic facies of mixed water in the dam. In the cluster analysis (R-mode), seven variables were classified into two clusters controlled by SO4 and in Qmode, 21 samples are grouped into 3 groups coinciding with the station S1, S2 and S3. Factor analysis indicates two factors, which explained 87% of the total variance in water quality data set. Two factors, which are salinization and sulfates explaine 73% and 14% of the total variance respectively. Time series analysis showed that Ca, Mg, Na, Cl and SO4 have very similar trend with TDS and K have similar pattern as NO3. It suggests that five components control TDS evolution. K and NO3 represent a negative correlation with TDS, it resulted from the human activity as fertilizer and domestic sewages are thrown to the tributaries of Wadi Arab. This study illustrates the benefit of multivariate statistical techniques for interpreting complex data sets in the analysis of spatial and temporal variations in surface water quality