Science Service System

Summary of Proposal HYD2498

TitleOn the detection of small-scale water level and water extent change using TerraSAR-X staring spotlight mode
Investigator Braun, Alexander - Queens University, Geological Sciences and Geological Engineering
Team Members
Associate Professor Braun, Alexander - Queen s University, Geological Sciences and Geological Engineering
Associate Professor Fotopoulos, Georgia - Queen s University, Geological Sciences and Geological Engineering
Professor Hutchinson, Jean - Queen s University, Geological Sciences and Geological Engineering
Postdoctoral Fellow Dabboor, Mohammed - Environment Canada, Science and Technology Branch
Professor Rabus, Bernhard - Simon Fraser Univsersity, Applied Sciences, School of Engineering
SummaryVarious engineering and scientific applications require precise knowledge of water levels and water extent and their spatio-temporal variations. The following satellite remote sensing techniques can contribute to the monitoring of changes in water level and extent, i) satellite altimetry, ii) Synthetic Aperture Radar (SAR), and iii) optical and hyperspectral imaging. All of the aforementioned observational techniques have limitations. In particular, satellite altimetry is hampered by the spatial resolution across tracks. Achieving high accuracy water level measurements from SAR observations is difficult under most circumstances. Optical remote sensing cannot provide water level information and is furthermore affected by time of day/night as well as clouds. Fortunately, these limitations can be mitigated through the combined use of multiple sensors and techniques. In fact, at present this is the only viable option for achieving water level/extent monitoring exclusively from space borne platforms. This project proposes a feasibility study to monitor i) water levels and ii) water extent for small scale inland water bodies. The targeted scale of the water bodies ranges from 10s to 1000s of meters and is thus far below the scales which previous attempts have addressed. The motivation for this project originates in the fact that small water bodies are rarely monitored, but could develop significant hazards to local infrastructure. Examples of a such hazards include the building of dams by beavers in small creeks and streams or at the outlet of lakes and ponds. Beaver dams have the potential to raise the water levels at the meter scale which often translates into increasing water extent by 100s to 10000s of squaremeters. Local infrastructure including roads, pipelines, and railway tracks are all prone to undermining by flood water or runoff. The monitoring of water levels is therefore mandatory for large portions of the road and railway network. Railway networks are more relevant as they do not provide detours when flooded. We selected areas which have seen beaver activity and related flooding/undermining nearby railways. Our approach requests the use of the staring spotlight mode of TerraSAR-X at selected target sites in Quebec and British Columbia, Canada. As there is no multi-polarization with this product, we will use the backscatter as a parameter to classify land cover and water surfaces. In addition, we will employ the backscatter signature of radar and laser altimetry over the same areas. High-resolution optical imagery will assist in the validation and support the classification. For selected sites, we will further attempt to merge altimetric time series of water level with Spotlight mode InSAR/PInSAR. While this technique has been proven for large scale water bodies, e.g. Everglades in Florida and the Amazon Basin, our study will attempt to retrieve water level time series for much smaller areas. This component of the project is the most challenging and maybe not even achievable, but the return would be tremendous. The remote sensing products derived will be used in an integrated approach to develop a hazard assessment strategy and eventually a hazard rating for the target sites. This will incorporate additional parameters such as terrain slope, geology, infrastructure resistance, drainage paths, water volume, and land cover. Ultimately, the project results can benefit hazard monitoring from space in order to slowly replace costly and dangerous monitoring via aircraft and helicopter as presently conducted. The project team has experience in SAR, altimetry and environmental hazard assessment.

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