عنوان مقاله [English]
The significantly high rate of evaporation from the surface of water results in a notable reduction in utilizing water reservoirs and farm ponds. Floating physical covers are considered to be one of the most effectual approaches toward reducing the rate of evaporation from the surface of water. In the present study, the following six types of covers were utilized with three repetitions for each type of cover on the surface of the standard Sunken Colorado Evaporation Pan. The covers included: polystyrene, wood parts, synthetic honey wax, Perlite and Leica grains, and threshed straw. The three varying percentages of 60, 70, and 80 were examined for polystyrene, wood, and wax covers. Water depth alterations for both covered and uncovered reservoirs were scrutinized in the period starting from May 23rd, 2018 until August 22nd, 2018 in Semnan University in Semnan city. The economical effectiveness of the plan was estimated for each separate type of coating. The findings of the study indicated that the average amount of reduction in surface evaporation in comparison with the control reservoir relevant to polystyrene covers with 60, 70, and 80% coverage, wood parts with 60, 70 and, 80% coverage, synthetic honey wax with 60, 70, and 80% coverage, and Perlite, Leica, and straw are approximately 43, 54, 65, 10, 19, 26, 9, 18, 25, 36, 22 and 20, respectively. Regarding the economic analysis of the study, surveys were carried out on a farm pond located at a distance of approximately 3.8 km from the site. The findings displayed that bearing in mind the 5-year economic life of the plan, polystyrene and Perlite covers are deemed to be economical. Conclusively, the Internal Rate of Return (IRR) for polystyrene covers with 60, 70, and 80% covering, and Perlite covers is 571, 722, 872, and 32, respectively.