Aneeqa Syed [Hatfield Consultants] Vancouver GIS Users Group Meeting December 8, 2010

Transcription

1 NEAR-REAL-TIME FLOOD MAPPING AND MONITORING SERVICE Aneeqa Syed [Hatfield Consultants] Vancouver GIS Users Group Meeting December 8, 2010 SLIDE 1

2 MRC Flood Service Project Partners and Client Hatfield Consultants: Project Management and Implementation Canadian Space Agency (CSA): RADARSAT-1 & 2 image provider Mekong River Commission (MRC): Client and end-user SLIDE 2

3 Mekong Basin The Mekong River is the 12 th longest river; Originates in China (Tibet); Run through the border of Lao PDR and Myanmar; Continues south through h Thailand, Cambodia and Viet Nam; and Finally flowing into the South China Sea from the Mekong Delta. SLIDE 3

4 Lower Mekong Basin Mekong River Commission (MRC): Members: 1. Cambodia 2. Viet Nam 3. Lao PDR 4. Thailand Observers: 1. China 2. Myanmar SLIDE 4

5 Hydrological Regime over the Study Area Great Lake Tonle Sap River Phnom Penh Bassac River Mekong River MODIS image of the Lower Mekong Basin (Bands 1-3-4), August 1, 2002, during the rising flood stage. Blue areas in the image indicate flowing water, whereas the dark blue or black areas indicate standing water. (Source: US Government / MODIS Science Team) SLIDE 5

6 Mekong Basin Landscape Settlements Highway Lake Flooded Forest, Crop & Vegetation ti Crop & Vegetation Settlements Tonle Sap River Floodplain 0 Km 5 Km 10 Km 15 Km 20 Km Dry season water level Flood water level Understanding LMB landscape to develop conceptual basis for extracting flooded area from RADARSAT data SLIDE 6

7 Hatfield s Flood Mapping Service to MRC First radar flood mapping service was provided d using RADARSAT-1 in 2000; Continued to provide support till 2006 as MRC s need for their Flood Management and Mitigation Program (FMMP); In 2007, Hatfield provided operational nearreal-time (NRT) flood mapping service using semi-automated system; Following MRC s request, Hatfield continued to provide the service in SLIDE 7

8 Near-Real-Time Flood Mapping Service in 2008 SLIDE 8

9 Hydrological Regime over the Study Area Tonle Sap River Phnom Penh Great Lake Mekong River MODIS image of the Lower Mekong Basin (Bands 7-2-1), September 30, 2002, during the peak flood stage. The image was acquired through ESA channels in a geometrically corrected format over the internet. (Source: US Government / MODIS Science Team) Bassac River SLIDE 9

10 NRT Flood Mapping Project Goals NRT Flood Mapping Service: Based on a semi-automated t system; Enable delivery of near-real time (NRT) radar-based consistent flood mapping products; and Web-based product delivery. SLIDE 10

11 Flood Service Products Every 2-3 days during peak flood, and every 5-7 days during early and recession flood, a set of flood map products provided to MRC; The NRT flood products made available to users of the MRC within 24 hours of acquisition; and Flood extent and flood area change products were produced for: The Lower Mekong Basin Individual Hydrological Stations SLIDE 11

12 NRT Flood Mapping Service Area and Acquisition Calendar June December, 2008 SLIDE 12

13 Flood Mapping Service Chain Final products created within 4 to 5 hours of receiving the images from MDA/RSI SLIDE 13

14 Data Processing Chain Ancillary Information: 1. Dry season baseline image: - over identical geographical areas; and - same radar beam mode and overpass as the new image. 2. Base data layers for masking: - Permanent water bodies - DEM (mountains / hills) -Slopes - Floodplain boundary - Maximum flood boundary - Oceans / Seas SLIDE 14

15 NRT Flood Product Levels Level 1: Radar image (RADARSAT-1 & 2) Level 2: Thematic flood image and vector Level 3: Thematic change image and vector Level 4: Flood maps Level 5: Flood Change maps Note: Level 1, 2 & 3 are Data products; and Level 4 & 5 are Map products. SLIDE 15

16 RADARSAT Image and Flood Map: example SLIDE 16

17 Flood Map and Flood Change Map: example Previous Flood map New Change map New Flood map SLIDE 17

18 Product Delivery Mechanism 1. Final products delivered via FTP site; 2. Incorporated into the Flood Forecasting website; 3. Incorporated into the Mekong from Space website; and 4. Flood maps were incorporated into the 2008 MRC/FMMP Flood Report. SLIDE 18

19 Web Publication of the NRT Flood maps Integrated into MRC s Flood Forecasting website SLIDE 19

20 Web Publication of the NRT Flood maps Published into MRC s Image of the Month website: an example from 2007 SLIDE 20

21 2008 NRT Flood Mapping Service Product Status 36 individual dates between Jun-Dec 2008, Maximum of 84 individual flood maps per date. SLIDE 21

22 Aiming for Faster Dissemination and Better Integration at MRC Hydrological Modeling: Integration of the now-casting and forecasting Emergency Response Systems: Automatic detection of infrastructure at risk , or text message alerting End-user Communication: Awareness raising SLIDE 22

23 Flood Area and Volume Analysis using RADARSAT Imagery SLIDE 23

24 Flood Area and Volume Analysis Objectives: To support MRCS for their work on calibration and validation of hydrological and hydrodynamic models in the Lower Mekong Basin: To estimate the flood inundation area and volume; To create flood extent maps for the current year (2002), and for the extreme flood (2001) and draught (1999) years, as well peak flood between 1999 to 2002; Produce results/maps for using in the calibration and validation of hydrological and hydrodynamic models. SLIDE 24

25 Study Area Great Lake Mekong River Tonle Sap River Phnom Penh Study area Bassac River SLIDE 25

26 Methodology 1. Obtain RSAT archive images from 1999 to 2001 for dry season baseline and peak flood conditions; 2. Acquire new RSAT images for current year (2002) 3. Processing of RADARSAT images to delineate inundation area; 4. Integration of groundtruth information; 5. GIS integration of image derived inundation, topographic and other relevant information; and 6. Reporting: methodology and results. SLIDE 26

27 Project Datasets 1. RADARSAT Data Acquisitions 8 scenes from scenes from 1999 to GIS Basemap Data Topographic map Contour (1m) map Digital Elevation Model (DEM) Hydrological map 3. Field Observations Flooding conditions (at time of image acquisitions) Historical hydrological data SLIDE 27

28 Flood Inundation Information from Radar Data 1. Year 2002 Inundation (current year) Inundation mapping throughout the study area; Open water inundation area for eight (8) imaging dates revealing rising, peak and recession flood. 2. Year 1999 Inundation Dry season baseline information from March 1999; Considered as an AVERAGE flooding condition in the Lower Mekong Basin. 3. Years 1999, 2000 and 2001 (Peak Inundation) Flood extents (at time of image acquisitions) SLIDE 28

29 Flooded Area Identification and Classification from RADARSAT Image Areas of low radar backscatter (black areas), corresponding to open water flooding A. Volume scattering (Medium dark) B. Multiple reflections from water surface and vegetation volume (Bright/Light) C. Reflection from smooth water surface (Dark) D. Backscatter from wavy or rough water surface (Bright/Light) July 10, 2002 SLIDE 29

30 Dry Season Baseline Condition Extracted from RADARSAT Image March 16 & 26, 1999 Great Lake Mekong R. Tonle Sap R. Phnom Penh SLIDE 30

31 Open Water Inundated Areas Extracted from RADARSAT Image July 10, 2002 Great Lake Mekong R. Tonle Sap R. Phnom Penh Km SLIDE 31

32 GIS Base Data: DEM Generation Contour Map as Polyline form Convert to Point form Interpolation of DEM (100mx100m) DEM SLIDE 32

33 Water Level Hydrographs on the Dates of Image Acquisitions Water Levels (m) at Stations 1-3 and 5 on the RADARSAT image acquisition dates water Level (m m) Boeung Thom Sakend Res Chunlen Res Oukhsach 10-Jul Aug g Aug g Sep p Oct Nov Dec Jan-03 Imaging dates (Data source: CTI Engineering International Co. Ltd., TSLV study office, February 2003) SLIDE 33

34 Progression of Inundation at Different Stages of Flood Cycle: Radar Imagery SLIDE 34

35 Progression of Inundation at Different Stages of Flood Cycle: derived extent SLIDE 35

36 Comparison of Peak Flood Conditions between 1999 and 2002 SLIDE 36

37 Flood Depth and Volume Analysis WLOS data to obtain water level data for each image date Flood extent from RADARSAT image Zones and Sub-zones Point elevations (Topographic data) Estimate upper water surface by averaging WL data from stations for each Zone / Sub-zone Clip flood extent by Zone / Sub-zone DEM interpolations (100m grid format) Upper water level data for each Zone / Sub-zone Clip DEM shape file by flood extent for each Zone / Sub-zone Convert DEM-grid to Shape file format Subtract upper water level data by clipped DEM for each Zone / Subzone LEGEND Dataset Data preparation Interpolation Spatial processing Flood depth shape file Volume calculation by multiplying flooded area for each depth with flood depth Flood Volume (Gross) SLIDE 37

38 Flood Depth and Volume Analysis Extracted t Flood Extent t from Radar image DEM Interpolation Flood Extent SLIDE 38

39 Flood Depth and Volume Analysis Estimated t Water Level at the Edge of Floodplain l DTM Upper Water Surface SLIDE 39

40 Estimated Depth of Flooded Areas for Different Imaging g Dates in 2002 SLIDE 40

41 Estimated Depth of Flooded Areas During Peak Flood: 1999 to 2002 SLIDE 41

42 Correlation between Radar Extracted Flooded Area and Estimated Volume Correlation between flood inundation area and volume (FAA study area) Area (ha) 600, , , , , , ,000,000,000 14,000,000,000 12,000,000,000 10,000,000,000 8,000,000,000 6,000,000,000 4,000,000,000 2,000,000,000 - olume (m3) V Imaging dates Volume (m3) Area (ha) SLIDE 42

43 Multi-temporal RADARSAT Imagery and Water Level Hydrograph an example Red: August 30, 2001 (Rising) Green: September 23, 2001 (Peak) Blue: March 16, 1999 (Dry) Y G R C M B SLIDE 43

44 Multi-temporal RADARSAT Imagery possible interpretation Y G R C M B SLIDE 44

45 Contact Person Aneeqa Syed, M.Sc. GIS/Remote Sensing and Training Specialist HATFIELD CONSULTANTS Harbourside Drive. North Vancouver, BC, CANADA V7P 0A3 phone SLIDE 45