Wetland InSAR as a Tool for Monitoring Ocean Tide Propagation through Coastal Wetlands
Abstract
Coastal wetlands are considered among the most valuable ecosystems on earth, yet their existence is presently being threatened by climate change (sea-level rise) and human interference (e.g. infrastructure development). These fragile ecosystems depend on a continuous water and nutrient replenishment by ocean tidal flow. While ocean tides are well known and forecasted, tidal flow movements through coastal wetlands are poorly known due to the fact that vegetation resists the flow and delays both inland and seaward flow at rising and subsiding tide conditions, respectively. Wetland InSAR observations provide a new source of information for detecting tidal flow in coastal wetlands, by supplying high spatial resolution maps of water level changes between two SAR acquisition times. In this study, InSAR observations are evaluated for their sensitivity to detect surface water level changes in response to ocean tide propagation through the coastal Everglades' mangrove forests. We used three datasets, which were acquired by the following SAR satellites: ALOS (L-band, 46 day repeat path), Radarsat-2 (C-band, 24 day repeat path), and TerraSAR (X-band, 11 day repeat path). The ALOS interferograms possessed fringes following the transition between the fresh- and salt-water vegetation. Whereas the Radarsat-2 and TerraSAR-X interferograms revealed well-defined, continuous fringe patterns surrounding prominent tidal channels oriented normal to the coastline. Our results suggest that the different fringe patterns obtained by three sensors most likely reflect spatial resolution differences between the three data types. The high spatial resolution wetland InSAR, particularly TerraSAR-X, observations provide important constraints for detailed coastal wetland flow models. Such models can lead to improved quantitative tools for better forecasting tidal flow propagation through coastal wetlands and better understanding of the hydro-ecology of this delicate ecosystem. Figure 1: (a) Google earth satellite image showing locations of the three interferograms used. The purple frame is the ALOS interferogram, the green is Radarsat-2, and red is TerraSAR-X. (b) ALOS interferogram spanning 2010/08/08-2010/09/23 (c) Radarsat-2 interferogram spanning 2008/09/23-2008/10/17 (d) TerraSAR-X interferogram spanning 2008/09/26-2008/10/18
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.G13B0947M
- Keywords:
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- 1222 GEODESY AND GRAVITY / Ocean monitoring with geodetic techniques;
- 1890 HYDROLOGY / Wetlands;
- 4217 OCEANOGRAPHY: GENERAL / Coastal processes;
- 4560 OCEANOGRAPHY: PHYSICAL / Surface waves and tides