基于星载激光雷达的高原堰塞湖水文要素反演与变化特征分析

Monitoring and dynamic analysis of water level of Sarez Lake by remote sensing technology based on ICESat-1/2 laser altimeter system

针对帕米尔高原堰塞湖——萨雷兹湖的安全问题及水文站点资料获取困难,缺乏时段固定、精度统一的准实时湖泊水位信息等问题,本文提出了基于星载激光雷达测高数据(ICESat-1/2)的高原湖泊水位综合反演。开展了近20年(2003—2019年)的水位变化遥感调查和时序重建研究,并采用趋势分析和Mann Kendall(M-K)非参数检验,对近20年萨雷兹湖的水位变化特征进行过程分析,初步揭示了萨雷兹湖水位的近期变化趋势和规律。结果表明:①ICESat-1/2激光测高雷达数据在陆地湖泊水位反演中误差可控制在0.05 m之内,精度高度可信,为无/缺资料地区湖泊水文监测提供良好的数据源;②2003—2019年,萨雷兹湖的水位持续呈现显著上升的趋势,水位上升的速率约为0.15 m/a(p<0.01,双尾);③萨雷兹湖的水位年内波动较大(至少7~8 m)。最高水位出现在9—10月,当前平均水位约为3265 m,最低水位出现在3—5月,当前平均水位约为3259 m。以上研究结果可为萨雷兹湖的综合治理及安全评估提供数据支持和技术参考。

In view of the safety problems of Sarez Lake and the difficulty in obtaining hydrological site data,resulting in lack of timefixed and uniform precision of quasi-real-time lake water level information,this paper proposes a plateau lake water level retrieval method based on space-borne laser altimeter data( ICESat-1/2). Sarez Lake level time series survey is carried out by remote sensing altimetry technology and water level changes in the past 20 years( 2003—2019) are reconstructed. Trend analysis and Mann Kendall( MK) nonparametric test are used to analyze the water level variation characteristics of the Sarez lake in the past 20 years. The recent trends and patterns of the water level in Sarez Lake are revealed. The results show that: ①The error of ICESat-1/2 laser altimetry radar data can be controlled within 0. 05 m in the inversion of land lake water level. So the accuracy is highly credible,which provides favorited/promised data source for lake hydrological monitoring in no,lack data area. ②During 2003—2019,the water level of Sarez lake still shows a significant upward trend,and the rate of water level raise is about 0.15 m/a( p < 0.01,two-tailed).③The water level of Sarez Lake is highly volatile during the year( 7~8 m at least). The highest water level occurs from September to October,the current average water level is about 3265 m;the annual minimum water level appears from March to May,and the current average water level is about 3259 m. The above findings provide data support and technical reference for the comprehensive management and safety assessment of Sarez Lake.