High resolution remote sensing of surface water

Transcription

1 High resolution remote sensing of surface water GEOBIA for multi-temporal & multi-spectral data sets Eric Masson University Lille 1 Sciences and Technologies eric.masson@univ-lille1.fr

2 Presentation overview This presentation focusses on two cases of water remote sensing for SUstainable WAter(shed) Management The methodologyused is based on GEOBIA(GEographical Object Based Image Analysis) using ecognition software First case: (Morocco) 1 unsustainable touristic water uses 2surface water monitoring with a Spot5data set Second case: (French Polynesia) 3 a reticulated lagoon full of phosphates 4 Atoll water monitoring with a Worldview2 data set 5 remote sensing of surface water and SUWAMA

3 Fisrt case: Tahaddart watershed (Morocco) CNES 2009 Distribution Spot Image S.A.

4 1 Unsustainable touristic water uses (1/2) Touristic seasonnal pressure in Tangier region Landscape features in advertising for Tangier region from 1023 touristic images Lagoons and cascades Swimming pool Beach Recreative grass Sea Data: Délégation de Tanger, Ministère du tourisme, Maroc Luxurious bushes Trees Palm trees Data: national and international touristic flyers, websites and leisure projects images Funtains

5 1 Unsustainable touristic water uses (2/2) Perception of Tangier environment: - touristic advertising is exhibited in luxurious wet and green environment - there is no reference to water scarcity or water access problemsin resorts projects Consequences: - tourists are looking for landscapes and facilities without any idea of water balance consequences (over consuption, pollution ) - potential recreational water uses promote a huge tourisitic resort development on the Tahaddart shoreline to cope the growing touristic demand - major local impacts on hydro-ecosystems during the construction phase (many years) - long term impacts on water quality and quantity by supplying touristic sector water needs - future water conflicts in a semi-arid are under climate change

6 Tahaddart shoreline and touristic developement upon coastal aquifers Backside view of june 2009 Photo credits: Masson E. 2009

7 Tahaddart shoreline and touristic developement upon coastal aquifers Same project (frontside view) after 2 years (june 2011) Photo credits: Masson E. 2011

8 2. Surface water monitoring with a Spot5 data set (2/4) Surface water monitoring is a solution to provide a good indicator of water scarcity for a «SUWAMA»in the tahaddart. The 9 april dam has been chosen for its strategic influence in Tangier region water supply SPOT 5 sensor properties Multispectral: XS, 4 bands (G, R, Nir, Swir), 10 m native to 2.5m (Pansharpening) Panchromatic: PAN, 2 bands (backward & foreward view) 5m native to 2.5m (backward/foreward combination) SPOT 5 multitemporal dataset used 1 archive dataset (June 2008) in dry year conditions (below average rainfall) 2 acquisitions programing dataset (April & September 2009) in wet year conditions (above average rainfall) 12 bands multitemporal dataset for surface water monitoring Native 10m XS sensor data No Pan data regarding to research project objectives

9 2. Surface water monitoring with a Spot5 data set (2/4) The 5 april Dam reservoir in april 2009 (wet year condition) -total surface of 1,451 ha - water supply for Tangier city -a sustainable solution to Tangier aquifer s over consuption CNES Distribution Spot Image S.A.

10 2. Surface water monitoring with a Spot5 data set (3/4) Surface water evolution from june 2008 to september 2009 Key map: - April 2009 (imagery) - September 2009 (red line) -June 2008 (white line) CNES Distribution Spot Image S.A.

11 2. Surface water monitoring with a Spot5 data set (4/4) GEOBIA classification ruleset used for water surface extraction Results Date Surface (ha) Surface water variation Water availability period 19 JUNE Dry year (early summer) 9 APRIL Reference wet year (spring) 24 SEPTEMBER Wet year (late summer)

12 Second case: (French Polynesia) Mataiva Atoll is the most western island of the Tuamotu archipelago (French Polynesia) N Area of interest 2 km

13 3 a reticulated lagoon full of phosphates Description of Mataiva Lagoon - Maximum depth of 35meters (mean 8m) with a tide range of +/-55cm - The lagoon is poorly connected to the sea despite its 9 hoas people living on the atoll including 4 tourist pensions - Main economic activity is coprah culture - Alga production of phosphates at high rate - One of the last native forest of the touamotus Impacts : - Low human impact except coconut plantation - High water turbidity due to phosphate and shallow water environnement - Low biodiversity compare to other Tuamotu atolls (lot of dead coral) - But high economical value regarding to phosphate potential exploitation - Phosphate extraction would lead to a higher turbidity with strong impact on lagoon habitats and biodiversity

14 4 Atoll water monitoring with a Worldview2 data set (1/4) Worldview2 data and sensors parameters MS data wavelength Coastal: nm Blue: nm Green: nm Yellow: nm Red: nm Red edge: nm Nir 1: nm Nir 2: nm

15 4 Atoll water monitoring with a Worldview2 data set (2/4) NDWI NDVI Panchromatic band R: Nir 1; G : Red; B: Green R: Nir2; G: Red edge; B: Yellow R: Red; G: Green; B: Blue

16 4 surface water monitoring with a Worldview2 data set (3/4) Classification ruleset building using: image segmentation, object information and GEOBIA algorithms

17 4 surface water monitoring with a Worldview2 data set (4/4) Results: Each water classe (i.e. ocean, reef pond, lagoon pools and lagoon shallow waters) is exported to ArcGIS (shapefiles) including all object attributes A fisrt step in Mataiva water monitoring has been done but many water quality indicators can be calculated using GEOBIA and Worldview2 imagery The next steps are coral mapping and bathymetry classification combining field survey (64 depth points) and GEOBIA methodology All the ruleset can be applied to other atoll by simple paste and copy pending minor ajustement and field validation

18 5 remote sensing of surface water and SUWAMA (1/2) GEOBIAalgorithms and ecognition 8are very efficient tools for surface water monitoring Multitemporal, multispectral, multirelosution and multisensor(i.e. optical, radar, lidar) dataset can be combined to build robust image classification rulesets VHR data (i.e. Worldview 2) improves water surface monitoring of very small water body ressources Satellite image archives (i.e. SPOT5) allows retrospective monitoring (30 years) of water bodies at high to very high spatial resolution New satellite constellation (i.e. Rapide Eye) providing daily dataset will helps water ressource managers to monitore hydro-ecosystem flash disruptions

19 5 remote sensing of surface water and SUWAMA (2/2) SUWAMA strongly requires a monitoring of: hydro-ecosystem functions, goods and services landcover and landuses coupled with socio-economic data BUT SUWAMA also requires: a broader knowledge intregation of the very complex sociohydro-ecosystems called watersheds SUWAMAwill surely benefit from VHR remote sensing and geobia methodology to: update GIS data to perform a spatially distributed monitoring of watersheds or watermass units initiate a better collaboration between classical remote sensing analysts and field scientists comming from a wide range of scientific backgrounds

20 Thank you for your attention