Evaluating the chemicals to reduce evaporation in laboratory levels on water quality (a case study of semi-arid mountainous areas)

Evaporation is one of the main reasons for water loss and pressure on water resources. Efforts to reduce its amount under different conditions, along with providing practical solutions and investigating the impact of these methods on water quality, are important. In this regard, the research area was selected as a part of the Cham  Angir watershed in Khorramabad city, Lorestan province, Iran. The present study was conducted with the aim of evaluating the chemical effects of evaporation reduction on water quality using fatty alcohols (a mixture of hexadecanol and octadecanol) in class A evaporation pans. The study was conducted as a time series for 10 hours per day for 2 months, from 2021/8/23 to 2021/10/22. In addition, changes in water quality parameters including pH, electrical conductivity (EC), and dissolved oxygen concentration were monitored daily at a depth of 10 cm during the aforementioned statistical period. The measured evaporation values were analyzed using the SPSS software. The variance ratio of this test, at the 5% level, showed a significant difference in terms of changes in evaporation rate and temperature. The results showed that the cumulative evaporation in the two-month period was 537 mm in the control pan and 398 mm in the pan with the monolayer composition, which reduces the evaporation rate by about 27%. One-way ANOVA with Tukey-Duncan test was used to analyze the data obtained from water quality parameters sampling at a 5% probability level. The mean results of the selected quality parameters including pH, electrical conductivity, and dissolved oxygen were analyzed in two tanks, the control tank and the tank with a monolayer composition of hexadecanol and octadecanol. The results showed a 4.6% decrease in pH, a 4% decrease in electrical conductivity, and a 5% decrease in dissolved oxygen in the tank with the aforementioned composition monolayer compared to the control tank.