Paper Title
Depth-Related Variations Of Water Temperature And Dissolved Oxygen In The Karkheh Dam Reservoir

Thermal stratification (ThS) is considered one of the most important factors affecting the water quality of the dam reservoirs. Therefore, having full understanding of ThS allows water resources managers to prevent and avoid deterioration of water quality in the reservoirs. In this study, time occurrence, duration, and severity of ThS was investigated by depth-temperature profiles of water column measured in the Karkheh Reservoir, Iran. Moreover, the effects of ThS on depth-dissolved oxygen profiles were investigated. The results showed that ThS usually commences from May and continues till mid-November for 7 months. It can be noted, also, that the highest degree of ThS usually occurs during late summer when the temperature difference between the surface and bottom layers in the reservoir exceeds 17 °C. As a result of external forces such as; the reduced intensity of solar radiation and the increased inflows into the reservoir starting from December, an overturn occurs in the reservoir so that the reservoir has a state of complete mixing during February. Index terms- Thermal stratification, Water resources, Karkheh dam, Water column, Mixing.