A utilização de imagens SAR para modelação de cheias Sandra Heleno, CERENA, Técnico, ULisboa

Transcrição

1 A utilização de imagens SAR para modelação de cheias Sandra Heleno, CERENA, Técnico, ULisboa 1979 Tagus Floods, Portugal Project RIVERSAR:

2 A utilização de imagens SAR para modelação de cheias Sandra Heleno, CERENA, Técnico, ULisboa RIVERSAR s Team : Sandra Heleno (PI) Ana Paula Falcão Alexandre Gonçalves Magda Matias Rita Pestana Rui Ferreira António Trigo-Teixeira Rodrigo Oliveira Amélia Araújo Ricardo Canelas Margarida Silveira Francisco Seixas Ana Fonseca Dora Roque Nuno Afonso The project was funded by Fundação para a Ciência e a Tecnologia. The SAR images were provided by the European Space Agency. Teresa Álvares Emília Van Zeller

3 floods account for 40% of all natural hazards worldwide social and economic impacts of floods are high: in the last decade of the 20th century, floods alone were responsible for the loss of about human lives and affected more than 1.4 billion people Near real-time monitoring of floods calls for automated mapping of water extent, using remote sensed images prediction of flood extents can be done using hydraulic flood models, but these must be calibrated using data from past floods Northern England, 2015 Northeastern India, 2015

4 floods account for 40% of all natural hazards worldwide social and economic impacts of floods are high: in the last decade of the 20th century, floods alone were responsible for the loss of about human lives and affected more than 1.4 billion people Near real-time monitoring of floods calls for automated mapping of water extent, using remote sensed images prediction of flood extents can be done using hydraulic flood models, but these must be calibrated using data from past floods RIVERSAR: improvement of these methods using SAR imagery sensed over the Tagus River Northern England, 2015 Northeastern India, 2015

5 Synthetic Aperture Radar systems: Active systems (day and night) Synthetic aperture antenna Able to see trough clouds darker areas means low backscatter (e.g. water surface) Entroncamento Golegã Why SAR imagery? Tagus, ERS2, Nov 7, 1997 Santarém

6 the Tagus is the river that originates the largest inundation areas in Portugal; its food frequency is high (floods every 2.5 years in average); floods may have a high social and economical impact: agricultural and urban areas on the floodplain Entroncamento Golegã Why the Tagus river? Tagus, ERS2, Nov 7, 1997 Santarém From 1992 to 2012, 23 SAR images of Tagus floods were sensed by ESA s ERS2 and ENVISAT satellites (spatial resolutions of 12.5m and 75m) In the same period, only two Landsat optical images were available (without cloud cover)

7 07/11/ /11/2006 Building a database of flood extension maps Semi-automated separation between water and land regions 05/01/ /02/2001 (Seixas et al., Proc. of International Geoscience and Remote Sensing Symposium) (Roque et al., Photogr. Eng. and Remote Sensing)

8 Combining topography and bathymetry datasets for hydrodynamic simulations To simulate the floods we need to have a digital terrain model (Falcão et al., ASCE's Journal of Surveying Engineering)

9 and impose boundary conditions: flow upstream in Tramagal and Zêzere and water level downstream in Ómnias (hydrometric stations). hydrodynamic simulations: STAV2D and TUFLOW (Canelas et al., Proc. 3rd IAHR Europe Congress ; Araújo et al., Journal of Coastal Research) We also simulated the dykes present in the floodplain, which constrain the water flow. The floods of November 1997, January of 2001, and November of 2006 were simulated using two separate hydrodynamic models to compute flow velocities and water levels on a 70-km stretch of Tagus river: a in-house 2D finite-volume model (STAV2D) and the 2D finite difference commercial model TUFLOW

10 Model Calibration Different land cover surfaces offer different resistances to the flow of water over them (urbanized areas, forest, vineyards, agricultural land). Roughness coefficient values (corresponding to land cover classes of the Tagus floodplain) were calibrated by comparing the simulated flood extent area with the delimitation of the floods on SAR images, to produce 100-m resolution roughness coefficient maps. (Pestana et al., European Space Agency Special publication)

11 roughness coefficient map Final inundation maps (including Tagus largest known flood) All results and products of the project were made available to the Portuguese environmental agency, one of the partners of RIVERSAR

12 RIVERSAR s Team : Sandra Heleno (PI), Ana Paula Falcão, Alexandre Gonçalves, Magda Matias, Rita Pestana, Rui Ferreira, António Trigo- Teixeira, Rodrigo Oliveira, Amélia Araújo, Ricardo Canelas, Margarida Silveira, Francisco Seixas The project was funded by Fundação para a Ciência e a Tecnologia Ana Fonseca, Dora Roque, Nuno Afonso. The SAR images were provided by the European Space Agency. Teresa Alvares, Emília Van Zeller Roque, D., Afonso, N., Fonseca, A. M. & Heleno, S.: OBIA Flood Delimitation Assisted by Threshold Determination with Principal Component Analysis. Photogrammetric Engineering & Remote Sensing (2014). Falcão, A. P., Matias, M., Pestana, R., Gonçalves, A. B. & Heleno, S.: A methodology to combine topography and bathymetry datasets for hydrodynamic simulations, the case of Tagus River. ASCE's Journal of Surveying Engineering (2016). Araújo, MAVC, Pestana, R, Matias, M, Roque, D, Trigo-Teixeira, A & Heleno, S.: Using simplified remote sensing bathymetry and SAR imagery in the validation of a hydraulic model for the Tagus River floodplain. Journal of Coastal Research (2016). Seixas, F., Silveira, M. & Heleno, S.: Segmentation of SAR images using Textons. Proceedings of IEEE International Geoscience and Remote Sensing Symposium (2014). Canelas, R.B., Heleno, S., Pestana, R. & Ferreira, R.M.L.: Flood mapping at river Tagus. A methodology based on mathematical modelling and SAR imaging. Proceedings of 3rd IAHR Europe Congress (2014). Pestana, R., Matias, M., Canelas, R., Araújo, A., Roque, D., Van Zeller, E., Trigo-Teixeira, A., Ferreira, R., Oliveira, R. & Heleno, S.: Calibration of 2D Hydraulic Inundation Models in the Floodplain Region of the Lower Tagus River. European Space Agency Special Publication SP-722 (2013).

13 RIVERSAR s Team : Sandra Heleno (PI), Ana Paula Falcão, Alexandre Gonçalves, Magda Matias, Rita Pestana, Rui Ferreira, António Trigo- Teixeira, Rodrigo Oliveira, Amélia Araújo, Ricardo Canelas, Margarida Silveira, Francisco Seixas The project was funded by Fundação para a Ciência e a Tecnologia Ana Fonseca, Dora Roque, Nuno Afonso. The SAR images were provided by the European Space Agency. Teresa Alvares, Emília Van Zeller Roque, D., Afonso, N., Fonseca, A. M. & Heleno, S.: OBIA Flood Delimitation Assisted by Threshold Determination with Principal Component Analysis. Photogrammetric Engineering & Remote Sensing (2014). Falcão, A. P., Matias, M., Pestana, R., Gonçalves, A. B. & Heleno, S.: A methodology to combine topography and bathymetry datasets for hydrodynamic simulations, the case of Tagus River. ASCE's Journal of Surveying Engineering (2016). Araújo, MAVC, Pestana, R, Matias, M, Roque, D, Trigo-Teixeira, A & Heleno, S.: Using simplified remote sensing bathymetry and SAR imagery in the validation of a hydraulic model for the Tagus River floodplain. Journal of Coastal Research (2016). Seixas, F., Silveira, M. & Heleno, S.: Segmentation of SAR images using Textons. Proceedings of IEEE International Geoscience and Remote Sensing Symposium (2014). Canelas, R.B., Heleno, S., Pestana, R. & Ferreira, R.M.L.: Flood mapping at river Tagus. A methodology based on mathematical modelling and SAR imaging. Proceedings of 3rd IAHR Europe Congress (2014). Pestana, R., Matias, M., Canelas, R., Araújo, A., Roque, D., Van Zeller, E., Trigo-Teixeira, A., Ferreira, R., Oliveira, R. & Heleno, S.: Calibration of 2D Hydraulic Inundation Models in the Floodplain Region of the Lower Tagus River. European Space Agency Special Publication SP-722 (2013).