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Summary of Proposal HYD0733

TitleFlood Mapping of Emajõgi River in Alam-Pedja Nature Reserve, Estonia
Investigator Voormansik, Kaupo - University of Tartu, Space Technologies Workgroup
Team Member
Dr Reinart, Anu - Tartu Observatory, Department of Remote Sensing
Praks, Jaan - Aalto University,
SummaryThe Objectives
The main objective of the project is to investigate the temporal development of Emajõe River floods in Alam-Pedja Nature Reserve, Estonia. It is very interesting because currently only in situ data based articles have been published. The secondary objectives are evaluating the TerraSAR-X data by comparing the remote sensing data against in situ measurements and digital elevation models. After the research this spring the feasibility of a commercial service for tourism companies is also studies.

The Method
Processing TerraSAR-X satellite imagery and comparing it against in situ measurements of water level in Emajõe River. The software that is planned to be used for the research is the following: NEST - Next ESA SAR Toolbox from Array Systems Computing Inc and MapInfo from Pitney Bowes Business Insight.

Data Requirements
It is requested to use TERRASAR-X stripmap mode imagery with 3-5 m spatial resolution. 30x50 km shots on every second day could allow investigating the temporal development of the flooded area. It is foreseen the flood would last about 2 weeks in total with the maximum between 15th March and 15th April this year.

The outputs of the project would be articles in peer reviewed and popular science magazines.

The Funding
The salaries of team members are covered by the University of Tartu and Tartu Observatory. For satellite imagery costs preferential rates are requested.
Final ReportThe outcome of the project is following: 1. A scientific article for peer-reviewed magazine was produced. The work is titled "Flood Mapping with TerraSAR-X in Forested Regions in Estonia", the manuscript is forwarded to "Remote Sensing of Environment" editors. 2. A popular science article “Kõnekad satelliidipildid: suurvesi kevadel 2010” for Estonian magazine "Eesti Loodus" was composed and will be published in the March 2011. 3. An oral presentation was made in international conference “Space Downstream Services 2010”. The title of the presentation was “Flood Mapping Based on SAR Imagery in Estonia”. 4. A poster presentation “The Applicability of TerraSAR-X for Flood Mapping in Forest” was made for the 4th TerraSAR-X Science Team Meeting. The initial goal of the initial proposal to map the temporal development of the flood in Alam-Pedja Nature Reserve was achieved. 3 flood maps (5-6th April, 15th April and 27-28th April 2010) were produced. Even more importantly the applicability of X-band SAR was proven for flood mapping in temperate forest. The main article (nr 1 in the upper list) actually focuses more the methodology and assessment how well X-band SAR images suit for flood detection and mapping in temperate forest. In order to assess that a comparison with ALOS PALSAR images was carried out, because L-band SAR is already proven tool for forest flood mapping. It is known that flooded forest creates enhanced backscatter on SAR image, but the canopy penetration of microwaves goes worse with shorter wavelength. The question to answer was whether the X-band SAR could penetrate the temperate forest canopy deep enough to reach the water under the trees for enhanced backscatter on the SAR image. The results show best flooded vs non-flooded forest backscatter separability in deciduous forest (mainly birch trees) during leaf-off season. The flooded vs non-flooded forest backscatter histograms are a bit more overlapping in coniferous (mainly pine groves) and mixed forest (mainly birch together with spruce), but the separability still remains acceptable.

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