Investigation of the temporal and spatial variations of water quality in the Karun basin

In this paper‏ ‏temporal and spatial trend of water quality‏ ‏in the Karun basin were examined ‎from upstream to downstream. To assess the trend of change, 16 stations with a statistical ‎period of 37 years (1353-1390) were selected. Station scattering was considered to cover the ‎whole basin. In order to analyze the trend, the MK test was performed and according to this ‎test, the discharge has decreased throughout the basin, except for the southeastern part of the ‎basin. Changes in z statistics for the quality parameters were higher at Ahwaz and Shushtar ‎stations located below the basin and at a significant level of 1%. After analysis of the ‎concentration of anions and cations along with the type and facies of water, it was ‎determined that Ahwaz, Gotvand and Shushtar stations have chlorine, Sodic facies and other ‎stations with Bicarbonate and Calcic type. The quality of drinking water in the stations has ‎decreased from the upstream to the outlet of the Karun basin and the worst quality is related ‎to stations in Ahwaz, Gotvand and Shushtar, which are within acceptable limits. In the ‎Investigation of agricultural water quality, also determined Ahwaz, Gotvand and Shushtar are ‎located in the C3S1 and other stations in the C2S1. The results show that the water quality of ‎the Karun basin has decreased from the upstream‏ ‏to downstream.‎