Effects of Kilickaya Dam on concentration and load values of water quality constituents in Kelkit Stream in Turkey

This paper evaluates the effects of Kilickaya Dam on Kelkit Stream water quality constituents. For this purpose, the analyses are based on data from Fatli water quality monitoring station located downstream of Kilickaya Dam. Kruskall–Wallis and Barlett's statistics to test median and variance homogeneity, respectively, were used for statistical analyses of water quality constituents (TDS, Na+, K+, Ca2++Mg2+, Cl− and SO42−). In addition, to compare concentration and load mean values of each water quality constituent from pre-Kilickaya Dam period with those of the post-Kilickaya Dam periods, z-test was used. There was a slight decrease in mean concentration and load values of all water quality constituents except load values of Na+ (11.1% increased) and Cl− (4.5% increased) which has occurred during the post-Kilickaya Dam period compared to the pre-Kilickaya Dam period. The percent decreases in mean concentration values of TDS, Na+, K+, Ca2++Mg2+, Cl− and SO42− were 12.6, 9.4, 16.5, 15.3, 10.3 and 21.5, respectively. Similarly the percent decreases in mean load values were calculated as 3.6, 7.8, 8.0 and 2.8 for TDS, K+, Ca2++Mg2+ and SO42−, respectively. The reason for these decreases in concentration and load values is probably due to reservoir where the water has a long hydraulic residence time (as an average of 264 days) and the exposure to chemicals by aquatic organisms or populations that ingest the water. In addition to this, within the reservoir system, dissolved salt concentrations may be diluted by runoff from winter snowmelt and spring rainfalls. The Kruskall–Wallis and z-test results show that concentration values of the pre-Kilickaya Dam period for each water quality constituent (except Na+ for mean value) were significantly different from those of the post-Kilickaya Dam period. Considering Kruskall–Wallis and z-test, load mean values of the pre-Kilickaya Dam period for each water quality constituent were not significantly different from those of the post-Kilickaya Dam period (except Na+ for median homogeneity) but Barlett's test results showed that load values of the pre-Kilickaya Dam period for each water quality constituent were significantly different from those of the post-Kilickaya Dam period in terms of variance homogeneity. Therefore, it can be concluded that Kelkit Stream water quality characteristics were highly affected by Kilickaya Dam.