三峡水库与太湖蒸发特征及其影响因素的对比研究

Comparative analysis of evaporation and influencing factors between Three Gorges Reservoir and Taihu Lake

摘要

【目的】峡谷型水库与湖泊或湖泊型水库具有显著不同的形态特征，但在蒸发研究中常简单移植来自湖泊蒸发的认识和估算方法，可能存在显著偏差。旨在对比典型峡谷型水库(三峡水库)与湖泊(太湖)蒸发特征及影响因素的差异，从能量平衡与水汽传输角度揭示其原因，为提升对峡谷型水库蒸发规律的认识和估算精度提供支撑。【方法】基于2014—2021年三峡水库巴东漂浮蒸发站和2014—2018年太湖平台山通量站的长期观测数据，从水体储热变化与水气传输特征角度出发，通过二者月蒸发量变化、储热变幅、蒸发扩散系数与气象因子之间的关系，对比分析两类水体的蒸发差异及其影响因素。【结果】研究表明：三峡水库巴东段月蒸发量呈现独特的8月和12月双峰特征，而太湖表现为8月单峰且仅滞后1个月；三峡水库巴东段储热变幅(-12.1~14.4 mm/d)显著高于太湖(-0.97~0.97 mm/d),深水储热效应导致二者蒸发与水温季节变化差异明显；三峡水库蒸发扩散系数与水平风速的相关性较弱，未表现出显著依赖关系，在水汽温差为正的情况下保持稳定，而在水汽温差为负的逆温期增强，相比之下太湖蒸发的扩散系数受水平风速显著影响，且随水汽温差的增大而增强。【结论】三峡水库等峡谷型水库的蒸发特征及其能量和动力驱动与湖泊(太湖)具有显著差异，水体传热对能量平衡的影响与峡谷地形导致的河谷风环流可能是其主要原因，在峡谷型水库蒸发的观测和估算等研究中不能直接采用湖泊蒸发的方法，需要构建专门针对峡谷型水库的方法。

Abstract

[Objective] Canyon-shaped reservoirs exhibit significantly different morphological characteristics compared to lakes or lake-type reservoirs. However, in evaporation studies, knowledge and estimation method derived from lake evaporation are often directly applied, which may lead to substantial biases. By comparing the evaporation characteristics and influencing factors between a typical canyon-shaped reservoir(Three Gorges Reservoir) and a lake(Taihu Lake), the differences are revealed from the perspectives of energy balance and water vapor transport, providing support for improving the understanding and estimation accuracy of evaporation in canyon-shaped reservoirs. [Methods] Based on long-term observational data from the floating evaporation station at Badong in the Three Gorges Reservoir(2014—2021) and the Taihu Lake Platform Mountain station(2014—2018), the energy balance equation was employed to analyze the heat storage changes and water vapor transport characteristics of the two water bodies. The monthly evaporation, heat storage variations, and the relationships between the evaporation diffusion coefficient, horizontal wind speed, and water-air temperature difference were compared to uncover the driving mechanisms of evaporation in the two systems. [Results] The study revealed that:(1) The monthly evaporation of the Three Gorges Reservoir exhibits a unique bimodal pattern with peaks in August and December, with the December peak lagging five months behind the net radiation peak, while Taihu Lake shows a single peak in August with only a one-month lag.(2) The heat storage variation in the Three Gorges Reservoir(-12.1 to 14.4 mm/d) was significantly greater than that in Taihu Lake(-0.97 to 0.97 mm/d), with deep-water heat storage effects leading to distinct seasonal variations in evaporation and water temperature between the two.(3) The evaporation diffusion coefficient in the Three Gorges Reservoir shows weak correlation with horizontal wind speed and no significant dependency, remaining stable under positive water-air temperature differences but increasing during inversion periods. In contrast, Taihu Lake's vapor transfer coefficient was influenced by wind speed and increased with the water-air temperature difference. [Conclusion] The evaporation characteristics of canyon-shaped reservoirs like the Three Gorges Reservoir and their energy and dynamic drivers differ significantly from those of lakes(e.g., Taihu Lake). The impact of water heat transfer on energy balance and valley wind circulation induced by topographic effects are likely the primary causes. Therefore, lake-based evaporation method should not be directly applied to canyon-shaped reservoirs. Instead, specialized approaches tailored to canyon-shaped reservoirs must be developed for evaporation observation and estimation.

关键词

三峡水库 / 峡谷型水库 / 湖泊 / 太湖 / 水汽传输 / 水体储热 / 影响因素 / 蒸发特征

Key words

Three Gorges Reservoir / canyon-shaped reservoir / lake / Taihu Lake / vapor transport / water heat storage / influencing factors / evaporation characteristics

基金资助

国家自然科学基金项目(52130906)

流域水循环模拟与调控国家重点实验室课题(SKL2024YJTS06)

中国水利水电科学研究院五大人才计划项目(ID0199A062021)