Evaluation of the Performance of Different Methods for Estimating Evaporation over a Highland Open Freshwater Lake in Mountainous Area

Xiaoni Meng,Yang Liu,Huizhi Liu,Qun Du,Lujun Xu

doi:10.3390/w12123491

Abstract

Lake evaporation is an important link connecting the water cycle and the surface energy cycle and remains one of the most uncertain terms in the local catchment’s water balance. Quantifying lake evaporation and its variability is crucial to improve water resource management and understand the response of the lake system towards climate change. In this study, we evaluated the performances of nine evaporation methods at different timescales and calibrated them by using the continuous eddy covariance (EC) observation data during 2015–2018 over Erhai Lake, a highland open freshwater lake situated in the Dali valley, China. The nine evaporation methods could be classified into combination methods (Bowen-ratio energy budget, Penman, Priestley–Taylor, DeBruin–Keijman and Brutsaert–Stricker), solar radiation-based methods (Jensen–Haise and Makkink) and Dalton-based method (mass transfer and Ryan–Harleman) based on their parameterization schemes. The Dalton-based Ryan–Harleman method is most suitable for estimating evaporation at daily to weekly scales, while the combination methods and solar radiation-based method had good estimates at monthly timescale. After calibration, the biases of the Jensen–Haise and Ryan–Harleman method were slightly reduced, while the biases of the Makkink and mass transfer methods were reduced substantially. The calibrated Jensen–Haise method with small annual bias (−2.2~2.8%) and simple input variables was applied to estimate the long-term trend of evaporation during 1981–2018. The annual total evaporation showed an insignificant increasing trend of 0.30 mm year−1, mainly caused by the significant rising air temperature. This study showed the performance of evaporation methods over water bodies had large discrepancies on different time scales, which indicated the importance of the choice of evaporation methods and provided instruction for water resource management of this region under climate change.

Highlights

Evaporation is a major water loss term in the water budget of inland water bodies, such as lakes and reservoirs [1]
This study is aimed to evaluate the nine evaporation methods at different timescales on the basis of the comprehensive measurements conducted by an eddy covariance (EC) system over the Erhai Lake and revealed the long-term trend of evaporation
The accuracy of methods varied with timescales resulted from theagreement between its parameterization scheme and the drivers of lake evaporation

Summary

Introduction

Evaporation is a major water loss term in the water budget of inland water bodies, such as lakes and reservoirs [1]. There are lots of alternative methods for estimating the evaporation over water body by using basic meteorological variables since the last century, such as the Bowen ratio energy budget method [18,19], Penman method [20], mass transfer method [21] and so on. These methods have been reviewed in previous studies [22,23,24,25,26], etc., and were often grouped into combination methods, solar radiation-based methods and Dalton-based methods. Nine evaporation methods based on different physical constraints and data requirements were selected for the estimation of open-water evaporation and classified into three categories, including the combination methods, solar radiation-based methods and Dalton-based methods

Objectives

Methods

Results

Conclusion