Empirical methods Comparison of estimation evaporation From Free Water Surface (Case Study: Dez Regulatory Dam)

Subject Areas : watere sciences

Mehdi  Najafvand Derikvandi ¹ (Msc Student of Department of Water Engineering, Shoushtar Branch, Islamic Azad University, Shoushtar, Iran)
Hossein  Eslami ² (water engineering department, water science faculty, Islamic azad university, shoushtar branch, shoushtar)

Received: 2017-06-08 Accepted : 2017-06-23 Published : 2016-09-22

Keywords: Evaporation, empirical method, Evaporation pan, Dez adjustment dam, Mayer,

Abstract :

Evaporation is an important factor in the management of water resources and accurate calculation can be effective strategies to mitigate the effects of drought and implemented in order to protect water resources. Due to lack of evaporation stations and lack of adequate data, empirical methods can be used to estimate evaporation from water surface. In this study, evaporation estimated using 10-year data of Dez adjustment dam station and empirical methods of Mayer, Marciano, Shahtin, Hefner, Ivanof, Tichomirof and USBR and the estimated evaporation compared with pan evaporation values. Based on the R2 and RSME statistics, empirical methods were evaluated. The results showed that the relationship Mayer (R2 = 0.886, RMSE = 1.53) than other experimental methods is more accurate. The USBR equation (R2 = 0.91, RMSE = 1.967) lie in next rank and also a significant difference (P> 0.01) is not seen between actual and estimated values in two ways. Tichomirof method due to significant error (RMSE = 8.152) and lower fitted to actual data (R2 = 0.33) is the lack of credibility and Hefner, Marciano, Ivanof and Shahtin with a determination coefficient equal to 0.548, 0.534, 0.639 and 0.664 have modest validity and reliability for estimating the amount of evaporation from water surface.