Effects of hydraulics structures on dissolved oxygen concentration: A case study from the stream Harsit, Eastern Black Sea Basin, Turkey

Abstract

A sufficient supply of dissolved oxygen (DO) is vital for all higher aquatic life. The problems associated with low concentrations of DO in rivers have been recognized for over a century. The impacts of low DO concentrations or, at the extreme, anaerobic conditions in a normally well oxygenated river system, are an unbalanced ecosystem with fish mortality, odors and other aesthetic nuisances. The primary aim of this study is to determine the spatial and temporal variation of four physicochemical variables including DO concentration, water temperature (T), pH and electrical conductivity (EC) in the stream Harsit, Eastern Black Sea Basin, Turkey. For this reason, a study was fortnightly conducted during the four seasons between March 2009 and February 2010 in five monitoring stations. The obtained data are evaluated according to Turkish Water Pollution Control Regulation (TWPCR), and also it is focused on the effects of hydraulics structures, namely Torul CFRD & HEPP, Kurtun CFRD & HEPP, and Dogankent HEPP, and the sandgravel mining activities on the studied variables. It was concluded that the stream Harsit has high-quality water according to the TWPCR in terms of DO, T and pH. Torul Dam generated a decrease with 13.18 % in the concentration value, and the minimum DO value with 9.23 mg/L was determined in the station after Torul CFRD and HEPP. However, Kurtun Dam increased the DO as 23.22 %, and the maximum DO value with 11.38 mg/L was obtained in the station after Kurtun CFRD & HEPP. Any negative effect from sand-gravel mining activities between the last two stations on the monitored variables was not observed.