Open water evaporation is influenced by several meteorological parameters such as: irradiance, soil temperature, relative humidity, atmospheric pressure and wind speed. However, dealing with that matter, in a case of measurements scarcity, is a challenging task. To overcome this problem, the authors sought a less-dimensional method to estimate lake evaporation. This technique takes into account only three weather variables: temperature, relative Humidity and dew point. In fact, the approach is summarized as follows: 1- using Levenberg-Marquardt algorithm, a Nonlinear Regression model based on Magnus formula is trained and tested to estimate the dew point. 2- a simplified Penman formula provides an estimate for the lake evaporation rate. To test the approach effectiveness, the suggested method was applied on Qaraoun Lake – Lebanon. Upon testing, the regression model exhibited high accuracy with a goodness of fit value equal to 0.99. Afterwards, the evaporation rates were estimated using Penman formula. Unfortunately, evaporation measurements are not available on site to carry the testing procedures. Instead, outcomes were investigated and compared with the monthly evaporation average retrieved from the nearest region to the lake. Estimated rates were reasonably good with a correlation coefficient equal to 0.89 and mean absolute percentage error around 9.8%. At the final stage of this study, sensitivity analysis is performed to quantify the impact of temperature and relative humidity change on evaporation. Overall, the achieved results were reliable enough to carry out a further assessment of the economic impact of evaporation losses from Qaraoun reservoir on the hydropower generation and on the irrigation sector.

开放水域蒸发受几个气象参数的影响，例如：辐照度、土壤温度、相对湿度、大气压力和风速。然而，在测量稀缺的情况下处理这个问题是一项具有挑战性的任务。为了克服这个问题，作者寻求一种较少维度的方法来估计湖泊蒸发量。该技术仅考虑三个天气变量：温度、相对湿度和露点。实际上，该方法总结如下： 1-使用Levenberg-Marquardt算法，训练和测试基于Magnus公式的非线性回归模型来估计露点。2- 简化的 Penman 公式提供了湖泊蒸发率的估计值。为了测试方法的有效性，建议的方法应用于黎巴嫩 Qaraoun 湖。经测试，回归模型表现出高精度，拟合优度等于 0.99。之后，使用 Penman 公式估算蒸发速率。不幸的是，现场无法进行蒸发测量以进行测试程序。取而代之的是，对结果进行了调查，并与从离湖泊最近的地区检索到的月蒸发平均值进行了比较。估计率相当不错，相关系数等于 0.89，平均绝对百分比误差约为 9.8%。在本研究的最后阶段，进行敏感性分析以量化温度和相对湿度变化对蒸发的影响。全面的，