| 摘要: |
| 湖泊藻华问题已成为全球水生态环境领域面临的长期挑战，风力条件变化和引调水工程的水力调度能改变湖体水动力结构，对藻类的生长和聚集过程产生影响，进行该过程的精细化监测和机制分析对于湖泊藻华预报预警和应急处置具有重要意义。本研究基于 Hiamwari-8/AHI 卫星遥感高频监测数据，对比分析了归一化差异植被指数（NDVI）、增强植被指数（EVI）和浮游藻类指数（FAI）3种不同指数对太湖藻华的反演效果，开展了典型风力条件下和水力调度下太湖藻华生消过程的持续监测分析。结果表明，FAI 对藻华区域和非藻华区域的区分更加明显，其阈值提取的藻华面积与基于 MODIS 图像解译的藻华面积的相对误差最低，为-2.27%。当营养盐充足且水温持续保持在蓝藻大量生长增殖的阈值以上时，风力条件是导致太湖藻类迁移聚集的关键因子，风向主要影响藻类的水平迁移，使其进行方向性迁移并逐渐形成大面积藻华区域。风速主要影响藻类的垂向迁移并存在临界阈值，当风速低于约2.5 m/s的临界风速时，藻华面积随风速增加而增加；当风速高于临界风速时，藻华面积随风速增加而降低。水力调度对距离较近的贡湖湾区域具有显著影响，主要通过水动力扰动来影响藻类的垂向迁移，使藻类沿水深方向强烈掺混，导致区域藻华面积下降。此外，持续且更大流量的调水将不断增强水动力扰动，减小区域藻华面积。本研究揭示了典型风力条件及水力调度下太湖藻华分布特征和迁移机理，可为湖泊藻华的精确动态监测预警和科学管控提供重要技术支撑。 |
| 关键词: 太湖，蓝藻水华，高频监测，Hiamwari-8/AHI，水力调度 |
| DOI： |
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| 基金项目:国家重点研发计划项目；国家自然科学基金创新研究群体项目；国家自然科学基金面上项目 |
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| High-frequency spatial and temporal dynamics monitoring of algal blooms in Taihu Lake under typical wind conditions and hydraulic scheduling |
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Hu Mingtao,Chen Cheng,Li Gang,Liu Yang,Yao Siyang,He Mengnan,Chen Qiuwen
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1.Nanjing Hydraulic Reserch Institude;2.Jiangxi academy of water science and engineering
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| Abstract: |
| The algal blooms have become a long-term challenge for global water ecology and environment. Changes in wind conditions and hydraulic scheduling of water diversion projects can change the hydrodynamic structure of the lake, affecting the growth and aggregation process of algae. Fine monitoring and mechanism analysis of this process are important for lake algal bloom forecasting, warning and emergency response. Based on the high frequency remote sensing monitoring data from Hiamwari-8/AHI satellite sensors, this study compared and analyzed the effects of three different indices (NDVI, EVI and FAI) in retrieving the algal bloom in Lake Taihu, and carried out the continuous monitoring of algal blooms in Lake Taihu under typical meteorological conditions and hydraulic operation. The results showed that the FAI distinguished the algal bloom area from the non-algal bloom area better, and the lowest relative error between the algal bloom area by FAI and that based on MODIS image interpretation was -2.27%. When nutrient was sufficient and water temperature was consistently above the threshold of cyanobacterial bloom growth and proliferation, wind condition were the key factors leading to the migration and aggregation of algae in Lake Taihu. Wind direction mainly affected the horizontal migration of algae, causing them to migrate in a directional direction and gradually form large algal bloom areas. Wind speed mainly affected the vertical migration of algae and there was a critical threshold. while the wind speed was lower than the critical wind speed of about 2.5 m/s, the algal bloom area increased with the increase of wind speed, and while the wind speed was higher than the critical wind speed, the algal bloom area decreased with the increase of wind speed. Hydrodynamic dispatch had a significant effect on the closer Gonghu Bay area, mainly through hydrodynamic perturbation to affect the vertical migration of algae, which resulted in strong mixing of algae along the water depth direction, leading to a decrease in the regional algal bloom area. In addition, continuous and higher flow transfers would enhance the hydrodynamic perturbation and reduced the area of the regional bloom. This study revealed the distribution characteristics and migration mechanism of algal blooms in Lake Taihu under typical wind conditions and hydraulic scheduling, which could provide important technical support for the accurate dynamic monitoring, early warning and scientific control of algal blooms in the lake. |
| Key words: Lake Taihu, algal bloom, high frequency monitoring, Hiamwari-8/AHI, hydraulic scheduling |
