From Preparation to Response: Coastal Decision Support during the Caribbean Hurricane Season 2010 with RADARSAT-2
Guy Aubé1, Dirk Werle2, Stu Frye3, Nicole Alleyne4, J-F Saulnier1, Guy Séguin1, Mathieu Benoît5, Claire Gosselin5 and Andy Welch6
1 Canadian Space Agencyhttp://www.asc-csa.gc.ca/eng/default.asp, Earth Observation Applications and Utilizations, 6767 route de l’Aéroport, St-Hubert, Québec, Canada, J3Y 8Y9
2 Aerde Environmental Research, Halifax, Nova Scotia, Canada,
3 NASA / Goddard Space Flight Center, Greenbelt, MD, USA,
4 Caribbean Disaster Emergency Management Agency, Bridgetown, Barbados,
5 VIASAT GeoTechnologies, Montreal, Quebec, Canada
6 Dendron Resources Surveys, Ottawa, Ontario, Canada
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Developing Disaster Management Capacity with Earth Observation
The image of hurricanes in the public perception is shaped in large part by the widespread coverage of weather satellites that capture movement, shape and extent of the menacing cloud formations associated with these powerful natural phenomena (Figure 1). Great strides have been made to analyze and predict the behavior of hurricanes. Still, the destructive forces of excessive rain, high wind and pounding waves usually associated with hurricanes can endanger many people and wreak havoc along their path. The hurricane threat demands careful preparation in order to protect the population and safeguard against damage and loss of properties and livelihoods. Disaster and emergency management at local, national and international scales require reliable and up-to-date information, and resources to support mitigation, response and planning activities.
The Group on Earth Observations (GEO) has chosen to address the challenge of hurricane and more generally disaster management in the Caribbean through its regional end-to-end pilots. The Caribbean Satellite Disaster Pilot (CSDP) is a regional project under GEO Task DI-09-02B. It was established in 2009 in close cooperation with the Committee on Earth Observation Satellites (CEOS) and regional institutions such as the Caribbean Disaster and Emergency Management Agency (CDEMA), the Caribbean Institute for Meteorology and Hydrology and the University of the West Indies (UWI). The objectives of the pilot are threefold: (i) to demonstrate the effectiveness of satellite imagery to strengthen regional, national and community level capacity for mitigation, management and coordinated response to natural hazards; (ii) to identify specific satellite-based products that can be used for disaster mitigation and response on a regional level; (iii) to identify capacity building activities that will increase the ability of the region to integrate satellite-based information into disaster management initiatives. The CSDP has established five sub-projects:
• Project 1: Sensor Web Satellite-based Flood Prediction and Warning – Caribbean-wide
• Project 2: Coastal Decision Support with Earth Observation
• Project 3: Urban Risk Mitigation (focus on high resolution issues in urban context)
• Project 4: Multi-hazard Vulnerability Mapping (with risk assessment, flood and landslide focus)
• Project 5: Integration of Satellite Data into Local Operational Flood Warning and Response Systems
Canadian Space Agency (CSA) leads the end-to-end regional demonstrations on behalf of CEOS, and the CSA has been active in a number of CSDP projects, including playing a lead role with Grenada for CSDP No. 2. The CSA is contributing RADARSAT-1 and RADARSAT-2 data products as well as know-how regarding their usefulness for disasters and security management. NASA is contributing additional EO data to complement the supply of Canadian radar data for the benefit of the Caribbean project partners. The common goal is to take a coordinated, timely and needs-based approach to utilize detailed EO data effectively when preparing for, assessing and mitigating local and regional impacts of natural hazards such as hurricanes.The
The CSA is participating in the Caribbean Satellite Disaster Project (CSDP) as a member and leader of the Group on Earth Observation (GEO) Task DI-06-09. This GEO Task demonstrates how Earth Observation can (1) strengthen regional, national and community level capacity for mitigation, management and coordinated response to natural hazards; (2) support disaster mitigation and response efforts on a regional level; and (3) increase through capacity building the ability of disaster and emergency response authorities to integrate satellite-based information into disaster management initiatives.
Under the umbrella of the CSDP, the CSA is committed to foster one of six sub-projects, entitled “Coastal Decision Support with Earth Observation”, also known as “CSDP No. 2”. The goal of CSDP No. 2 is to enhance EO capacity of authorities in British Virgin Islands (BVI), Grenada, Jamaica and St. Lucia that are engaged in coastal disaster management and emergency response. This article outlines on-going activities involving Canadian RADARSAT as well as other EO satellite data acquisitions to-date over selected Caribbean sites, and highlights some image maps and information products that were produced as part of several trials during the 2010 hurricane season. From this trial phase we expect constructive feedback and further improvements, particularly with regard to operational usefulness of detailed EO satellite data.
Coastal Decision Support During the 2010 Hurricane Season in the Caribbean Region
The Atlantic hurricane season officially starts at the beginning of June and concludes at the end of November. Most tropical systems that form in the Atlantic basin will occur during this period. Based on information provided by the National Oceanic and Atmospheric Administration (NOAA) National Hurricane Center in the United States, the Atlantic hurricane season of 2010 was extremely active (Figure 2), comparable to the 1995 Atlantic hurricane season and the 1887 Atlantic hurricane season with the third most named storms (19). The 2010 season also ties with the 1969 and 1887 seasons for the second most hurricanes (12). From the end of August toward the end of September, 2010, there was hardly a single day without at least one tropical cyclone active in the region. Further detail is available at: http://en.wikipedia.org/wiki/2010_Atlantic_hurricane_season (accessed Nov. 14, 2010).
Preparation and Response: Generating detailed RADARSAT-2 Data and Information Products
The CSDP participants initiated CSDP Project No. 2 during a joint CSDP meeting held at Montego Bay, Jamaica, in December 2009. In April 2010, the CSA conducted further on-site consultations in Barbados, the British Virgin Islands, Grenada, Jamaica and Saint Lucia. The goal was to confirm with the disaster and emergency management staff the particular needs and possible delivery of timely image map products during the 2010 hurricane season. Based on stated CSDP goals and the consultation process, we prepared a work plan and a RADARSAT-2 data acquisition strategy for review by CSDP lead authorities and project partners in the Caribbean. The emergency management authorities in the BVI, Grenada, Jamaica and Saint Lucia formally endorsed the plan.
At the beginning of the 2010 hurricane season a series of RADARSAT-2 data acquisitions were acquired at the CSA. The preparations culminated in the successful acquisition of approximately 50 detailed RADARSAT-2 images in ultra-fine mode over selected portions of the four participating island states. We acquired the 3-meter resolution images in July 2010 in both ascending and descending orbital passes for all areas as pre-hurricane reference data sets. They represent a potentially valuable element for ‘change-detection’ exercises involving RADARSAT-2 data acquired during or immediately after the passage of a tropical storm and hurricane system. NASA EO-1 ALI optical satellite imagery was acquired on occasion to complement the radar data. Although the optical data sets are hampered by cloud coverage, they offer complementary information for radar image analysis if they can be acquired under relatively cloud-free conditions.
The trials during the 2010 hurricane season involve an entire chain of activities from (i) initial situational awareness, to (ii) RADARSAT-2 data acquisition planning, (iii) communication, (iv) EO data reception and distribution, (v) image processing and product generation, (vi) draft product relay and transfer to Caribbean operation centers, and (vii) assessment and evaluation of products and procedures. Preparations also included the drafting of product templates and annotations, the selection and utilization of complementary satellite imagery, and consideration of electronic product delivery options for preliminary EO satellite based products to the project partners in the Caribbean.
Situational awareness of hurricanes in the Caribbean relied heavily on information from the National Hurricane Center in the United States and on expert assessments of the Caribbean project partners. Actual RADARSAT-2 data acquisitions were based on an informed “anticipatory” planning process; data acquisition conflicts had to be avoided or resolved, opportunities needed to be explored for matching the pre-season reference data sets, and coordination was required with the RADARSAT Hurricane Watch and Background Mission programs.
For the duration of the hurricane season CSA contracted two Canadian companies, Dendron Resources Surveys and VIASAT GeoTechnologies, to stand-by for rapid RADARSAT image processing and for EO-based information product generation and delivery. Following the successful execution of the acquisition plans and raw data collection, the processed RADARSAT-2 SAR imagery were available within a few hours from the satellite operator, MacDonald Dettwiler and Associated Ltd (MDA), for further image processing, change detection analysis and product generation for selected areas.
Our focus was on any potential hurricane or tropical storm impact on the territories of the four project partners in BVI, Grenada, Jamaica and Saint Lucia. Three of the four countries were affected during the 2010 hurricane season, and the CSA team acquired more than 30 detailed RADARSAT-2 images in total after ‘Earl’ in August, ‘Nicole’ in September, and ‘Tomas’ in October and November of 2010. The following contains a more detailed account of the events and EO related response activities.
Hurricane Earl and its Impact on the British Virgin Islands
On August 29, 2010, Earl strengthened to become the season’s third hurricane. Earl quickly intensified to a Category 4 and became the second major hurricane of the season on August 30 as it approached the Virgin Islands. The islands were battered with tropical storm winds and high gusts. Throughout the region, heavy rains flooded low-lying areas; power and water supply was lost to the entire Territory; and several vessels on Tortola were grounded. The BVI Government estimated that the cost associated with the impact of Earl amounted to $7 million.
CSA relied on RADARSAT-2 imagery collected before the passage of Earl in July 2010, and immediately after on September 2, 2010 to provide assistance for local damage assessments along the coastlines of the islands of Tortola and Anegada. Change detection involving the two data sets indicated minor damage (Figure 3) as well as flooding in low-lying areas. A set of four annotated image maps with partial coverage of the islands of Tortola and Anegada were transferred to the BVI Department of Disaster Management for further review of the RADARSAT-2 image analysis results. Actual communication took place via Internet, but it was hampered by local power failures. Access to all the image map products referred to in this article may be obtained soon at www.ceos.org/disasters/csdp.
Tropical Storm Nicole and its Impact on Jamaica
Nicole attained tropical depression status over the northwestern Caribbean Sea on September 28, 2010. Torrential rains fell along the eastern periphery of the storm system across the western Caribbean, particularly Jamaica, where more than 300,000 residences were left without power during the passage of the storm. There were 13 confirmed fatalities. In Jamaica, schools and some businesses closed on September 29 and 30. Emergency officials issued a flood warning for flood-prone areas. The extensive floods resulted in damage estimated at $235.4 million. CSA obtained RADARSAT-2 Fine mode imagery immediately after the passage of Nicole on October 2, 2010 to provide assistance for regional damage assessment of the east-central portion of Jamaica. Change detection also involved July 22 Fine mode imagery collected during the preparation phase of the project. A color composite product for the Kingston – Spanish Town area is shown in Figures 4 and 5, covering an area of approximately 50 km by 30 km at a spatial resolution of 10 meters. A set of three annotated image maps were transferred to the Jamaican Office for Disaster Preparedness and Emergency Management (OPDEM) for further assessments of the RADARSAT-2 image analysis results.
Hurricane Tomas and its Impact on Saint Lucia
On October 29, Tomas became the twelfth hurricane of the season and crossed the Windward Islands as a Category 1 hurricane, severely affecting Barbados, Saint Lucia and Saint Vincent. Tomas weakened slowly until midnight on November 2. On November 3, Tomas regained strength, and early on November 5 it became a hurricane again as it approached Haiti. On Saint Lucia, there was widespread damage to homes and power lines. Throughout the island, severe flooding and mudslides resulted in at least 14 fatalities. Early assessments indicated that damage would reach US$500 million. Reports also indicated that much of the banana crop, the largest agricultural export product of the island, was destroyed.
By monitoring the early development and track projections of Hurricane Tomas, based on US National Hurricane Center advisories, CSA was able to plan RADARSAT data acquisitions in advance of Tomas approaching the Leeward Islands. The CSA obtained RADARSAT-2 Ultra-fine mode imagery over the island of Saint Lucia just before and immediately after the passage of Hurricane Tomas on October 24 and on October 30, respectively. The RADARSAT change detection products were transferred to the national emergency management authorities in Saint Lucia and offered some guidance to non-governmental organizations as well, e.g. MapAction of Great Britain. The products provided useful information for the northern portion of the island (Figure 6), clearly indicating nature and area extent of local flooding in low-lying areas at a spatial resolution of 3 meters. Optical imagery taken from the International Space Station (ISS) on December 16, 2009 and by the American EO-1 ALI sensor on November 9, 2010, provided useful reference information for the interpretation of the radar imagery. In the absence of detailed digital elevation model (DEM) data, the radar data was of limited utility in mountainous terrain, hence it was not possible to identify areas of landslides and mudslides with any degree of reliability during the trial stage.
Testing the CSDP No 2 Experience for Flood Monitoring in Haiti
The US National Hurricane Center provided early indication that the track of Hurricane Tomas was pointing toward Haiti, threatening the island and its population with strong winds and heavy rainfall on November 5. Within a cooperative framework of the CSDP a number of RADARSAT-2 data acquisitions were planned to assist rainfall prediction modeling. Following the activation of the International Charter for disaster relief assistance, the Canadian Space Agency acquired further RADARSAT-2 imagery on November 6 immediately after the passage of Hurricane Tomas. Using the experience from the CSDP Project No. 2 and the RADARSAT-2 imagery acquired immediately before and after the passage of Hurricane Tomas, an EO based information product detailing extended areas of flooded terrain was prepared and delivered rapidly for use under the International Charter. Details are presented in Figure 7, which not only contains the results of RADARSAT-2 data analysis but also contains a background image of EO-1 ALI Band 7 data acquired under nearly cloud-free condition two weeks after the event on November 13, still showing residual flooding in the Gonaives region of Haiti.
Summary and Outlook
The 2010 Hurricane season in the Caribbean sets the stage for a number of trials with regard to detailed change detection and damage assessment involving multi-temporal RADARSAT-2 Fine and Ultra-fine mode data acquisition before and after the passage of significant hurricane and tropical storm events. Focusing on the four participating island states of the British Virgin Islands, Grenada, Jamaica and Saint Lucia, Table 1 contains a summary of the types and number of EO-based information products and images collected. We concentrated and relied upon radar imagery for product generation and feature identification. While optical images, for example EO-1 ALI appear to be useful and complementary to radar image analysis, there was a significant problem in that cloud coverage frequently obscured areas of interest on the ground. The ready availability of DEM and GIS data layers remains an issue, as both would help to increase accuracy and analysis of the EO data set.
While the technical feasibility of acquiring, processing and relaying EO-based geospatial information products to CSDP project partners in the Caribbean was tested with success during the 2010 hurricane season, there remains important work to be done in order to increase local capacity to utilize the products in an effective and timely manner and to assess their accuracy, content and format in operational settings of disaster and emergency management situations.
In close cooperation with Canadian industry and the Caribbean project partners, the CSDP No. 2 team is planning a series of EO-related information and training sessions in the British Virgin Islands, Jamaica, Saint Lucia, Grenada, and at CDEMA. These sessions address technical, operational and administrative issues and will include a critical review and evaluation of the 2010 hurricane season trial results. Based on the review and evaluation process we will jointly address how Earth observation technology and analysis know-how can make useful contributions to the practice of emergency and disaster management in the Caribbean.