Faculty of Technology, Lebanese University, Abbey, Lebanon.
Faculty of Engineering, Lebanese University, Hadath, Lebanon.
J Environ Manage. 2019 Jul 1;241:502-513. doi: 10.1016/j.jenvman.2018.07.032. Epub 2018 Jul 21.
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.
开阔水面蒸发受多种气象参数影响，如辐照度、土壤温度、相对湿度、大气压和风速等。然而，在测量数据匮乏的情况下，处理这些问题是一项具有挑战性的任务。为了克服这个问题，作者寻求了一种更简化的方法来估算湖泊蒸发量。该技术仅考虑三个气象变量：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，基于 Magnus 公式的非线性回归模型进行训练和测试，以估算露点。2. 简化的彭曼公式提供了湖泊蒸发率的估算值。为了测试该方法的有效性，该方法应用于黎巴嫩的 Qaraoun 湖。在测试过程中，回归模型表现出很高的准确性，拟合值为 0.99。然后，使用彭曼公式估算蒸发率。遗憾的是，现场没有蒸发测量数据来进行测试程序。相反，使用从湖泊最近地区检索到的每月蒸发平均值来研究和比较结果。估算的速率相当好，相关系数为 0.89，平均绝对百分比误差约为 9.8%。在本研究的最后阶段，进行了敏感性分析，以量化温度和相对湿度变化对蒸发的影响。总的来说，结果足够可靠，可以进一步评估 Qaraoun 水库蒸发损失对水力发电和灌溉部门的经济影响。
