Abstract
This survey tried to evaluate the results of filed research and library studies by using the meteorological and hydrological data in determining the quality reduction mechanism of the Karoon and Dez rivers.
The results of studies during 1994-95 show the changes of river water quality from north to south in the Khuzestan Province.
The survey shows the correlation between the increase of water intake and wastewater discharge into the river; and. the reduction of river water velocity in the lower section of the river reducing the dissolved oxygen of the Karoon.
These results also show that because of the increasing sedimentation and probably by anaerobic decomposition of organic matter in bed sediments, the taste and odor of the water has increased in many places where water intake has occurred. On the other hand, for this reason, the biodegradable organic load in the water has increased.
Based on these results, the reduction in the volume of water flow during some months in each year; and pouring of municipal and industrial wastewater, and excess water from agriculture fields into the orientation of these rivers, are the most important factors for the reduction in water quality of the Karoon and Dez rivers.