糯扎渡水库季节性分层特征及气温变化影响

Seasonal stratification characteristics of Nuozhadu Reservoir and influence of temperature changes

摘要

【目的】热分层是湖库水生态系统的重要特征之一，影响水体的混合、对流、营养物质循环以及溶解氧的垂直分布，因此分析水体分层规律及主要影响因素至关重要。【方法】利用糯扎渡水库连续一年的高频剖面数据，分析了日尺度上的温度剖面、热分层参数和热稳定性的时间变化，探讨了不同分层时期热分层的驱动因素，以及气候变暖对热分层及水生态环境的影响。【结果】糯扎渡水库的水体分层明显，水温与溶解氧(DO)垂向分布具有明显的季节性特征，表层与底层温度差在2.8~12.3℃,DO浓度最小值0.59 mg/L出现在了氧跃层中，温跃层厚度最大值为14.85 m,同一时间相对稳定系数(RWCS)达到最大值359.9。【结论】热分层参数的日变化特征揭示了热分层的形成期、平稳期和减弱期，表层水温是影响热分层的主要因素，而气候变暖可能导致热分层更加稳定，分层时间延长，溶解氧剖面浓度和分布情况发生改变，并引发其他环境问题。研究结果为了解糯扎渡水库水体季节性分层和水化学特征，以及气候变暖的影响提供了科学依据，对水库水质管理和生态环境保护具有重要意义。

Abstract

[Objective] Thermal stratification is an important characteristic of lake and reservoir water ecosystems, affecting mixing, convection, nutrient cycling of water bodies, and the vertical distribution of dissolved oxygen(DO). Therefore, understanding the stratification patterns and their key influencing factors is essential. [Methods] Based on the high-frequency profile data collected over one year from Nuozhadu Reservoir, the temporal variations of temperature profiles, thermal stratification parameters, and thermal stability were analyzed on a daily scale. The driving factors of thermal stratification during different stratification periods were explored, and the impact of climate warming on thermal stratification and the water ecological environment was examined. [Results] The water column of Nuozhadu Reservoir showed clear stratification, with significant seasonal variations in the vertical distribution of water temperature and DO. The temperature difference between the surface and the bottom layers ranged from 2.8 to 12.3 ℃, with a minimum DO concentration of 0.59 mg/L occurring in the oxycline. The maximum thermocline thickness reached 14.85 m, while the relative water column stability(RWCS) peaked at 359.9 during the same period. [Conclusion] The daily variations in thermal stratification parameters reveal the formation, stabilization, and weakening phases of thermal stratification. Surface water temperature is identified as the main factor affecting thermal stratification. Additionally, climate warming may lead to more stable thermal stratification, extending the duration of stratification, changing DO concentration profiles and distributions, and causing other environmental issues. The findings provide scientific evidence for understanding the seasonal stratification and water chemistry characteristics of Nuozhadu Reservoir and the impacts of climate warming. The result are significant for reservoir water quality management and ecological environment protection.

关键词

糯扎渡水库 / 热分层 / 热稳定性 / 溶解氧 / 气候变化

Key words

Nuozhadu Reservoir / thermal stratification / thermal stability / dissolved oxygen / climate change

基金资助

国家自然科学基金(52309107)

云南省重点研发计划项目(202203AA080009)

中国长江三峡集团有限公司项目(201903144)

国家重点研发计划(2023YFC3209401-02)

河北省自然科学基金(E2024402142)