Regional-scale hydrological monitoring of wetlands with Sentinel-1 InSAR observations: Case study of the South Florida Everglades
Regional-scale hydrological monitoring of wetlands with Sentinel-1 InSAR observations: Case study of the South Florida Everglades
复制标题
DOI：
10.1016/j.rse.2020.112051
复制
发表时间：
2020-12
影响因子：
13.5
通讯作者：
H. Liao;S. Wdowinski;Shanshan Li
中科院分区：
文献类型：
--
作者：
H. Liao;S. Wdowinski;Shanshan Li
湿地是一个非常脆弱的生态系统，它为各种动植物物种以及人类提供了重要的服务。由于湿地依赖于水的可获得性，保护这一重要的生态系统需要仔细的水文监测。Sentinel-1任务具有覆盖范围广、高时态观测和开放数据政策的特点，为在区域范围的湿地地区绘制高时空分辨率的水位变化图提供了前所未有的机会。在这项研究中，我们评估哨兵1号InSAR观测对整个南佛罗里达大沼泽地湿地的常规水位变化测量。这项研究利用了三年期间(2016年9月至2019年11月)获得的91张哨兵-1号图像，并生成了常规的12天干涉图和相应的整个大沼泽地30米空间分辨率的水位变化地图。高空间分辨率干涉图检测由自然和人类诱导的水流引起的水文信号，包括潮汐、闸门操作和运河溢流；所有这些都不能通过地面测量检测到。大量的InSAR和陆基测量观测使我们能够量化Sentinel-1 InSAR测量的总体精度，整个湿地地区的精度为3.9亿厘米，但对于大沼泽地内较小的水文单位来说更好。我们的研究表明，单个干涉图的对流层延迟可能非常大，高达30厘米(~10条条纹)。当对所有三年的哨兵1号InSAR观测应用对流层改正时，总体精度水平提高了13%，达到3.4亿厘米。虽然我们的研究集中在大沼泽地，但其在哨兵1号观测对湿地空间水文监测的适宜性方面的意义以及由此得出的精度水平也适用于世界各地其他具有类似植被类型的湿地。
Wetland is a very fragile ecosystem that provides important services to a large variety of flora and fauna species, as well as for humans. As wetland depends on water availability, protecting this important ecosystem requires careful hydrological monitoring. The Sentinel-1 mission, featuring a wide swath coverage, high temporal observations and open data policy, provides unprecedented opportunity for high spatio-temporal resolution water level change mapping over regional-wide wetland areas. In this study, we assess Sentinel-1 InSAR observations for routine water level change measurements over the entire south Florida Everglades wetlands. The study utilizes 91 Sentinel-1 images acquired over a three-year period (Sep 2016 to Nov 2019) and generates routine 12-days Interferograms and correspondingly 30 m spatial resolution water level change maps over the entire Everglades. The high spatial resolution interferograms detect hydrological signals induced by both natural- and human-induced flow, including tides, gate operations, and canal overflow; all these cannot be detected by terrestrial measurements. The large number of both InSAR and ground-based gauge observations allow us to quantify the overall accuracy of the Sentinel-1 InSAR measurements, which is 3.9 cm for the entire wetland area, but better for smaller hydrological units within the Everglades. Our study reveals that the tropospheric delay for individual interferograms can be very large, as much as 30 cm (~10 fringes). When applying tropospheric corrections to all three years of Sentinel-1 InSAR observations, the overall accuracy level improved by 13% to 3.4 cm. Although our study is focused on the Everglades, its implications in term of the suitability of Sentinel-1 observations for space-based hydrological monitoring of wetlands and the derived accuracy level are applicable to other wetlands with similar vegetation types, located all over the world.