Remote Sensing And Gis For Natural Disaster

The world has been experiencing an increase in number of natural hazards over the last decade. Most of it can be attributed to an increase in hydro-meteorological events and the increase in vulnerable population. [1] In the past four decades economic losses due to natural disasters have shown an increase by a factor of eight. [2] Satellite remote sensing is an ideal tool for disaster management as it provides information over large areas at short time intervals. However, remote sensing data cannot be used without a proper tool to handle this large amount of data and to combine it with data from other sources such as maps or measurement stations. Thus Geographic Information Systems are increasingly used in conjunction with remote sensing data for disaster management. This essay gives a review of the use of remote sensing and GIS for the Hurricane Katrina that hit in 2005.

1.Introduction

It is firstly important to define natural disaster and to distinguish it from natural hazards. A potentially damaging natural phenomenon such as earthquakes, when occurs in an uninhabited area is not considered a disaster. But when this natural hazard occurs in a populated area resulting in death or injury to human life, and damage or loss of valuable good such as buildings, communication systems, agricultural land, forest and the natural environment, it is considered a natural disaster. [3] The impacts of these disasters have consistently been increasing over the past decades and so has been the global losses and people affected by these disasters as shown in the table below. [2] Decade 1960-1969 US $ billion Decade 1970-1979 US $ billion Decade 1980-1989 US $ billion Decade 1988-1997 US $ billion Factor Last 10:60s Number of large disasters 16 29 70 48 3 Economic losses 50.4 96.9 153.8 426.7 8.5 Insured losses 6.7 11.3 31 93.5 14

The increase in losses is due to advances in technology and developments in communications and infrastructure. The increase in people affected is also due to world population growth in the past decades.

2.Hurricane Katrina

Hurricane Katrina was the most destructive and costliest natural disaster of the Atlantic hurricane season of 2005. It claimed 1833 lives and a damage of $81 billion. [4] It severely caused destruction on the Gulf coast from Central Florida to Texas with New Orleans, Louisiana being 80% flooded [5]. No matter where and what kind of a disaster it is (flooding, earthquake or hurricane), the Disaster Management Cycle is similar for all. The disaster management consists of two phases before the disaster happens which are prevention and preparedness. Three phases happen after the disaster occurs: disaster relief, rehabilitation and reconstruction. [6] Remote sensing and GIS can be used in all these phases to help mitigate, prevent and monitor. Remote Sensing and GIS Tools used to aid Hurricane Katrina's impacts were mapping and mitigation, online disaster response and monitoring and prediction.

3.Mapping, mitigation, monitoring and prediction

Whenever any area is hit by hurricane it becomes inaccessible and techniques of remote sensing and GIS can be used for mapping and mitigation of the hurricane. Being one of the most powerful catastrophes to hit US, there was a need for timely and accurate observations and forecasts from simulations and visualizations enabling information transfer and coordination between different organization, policy makers and emergency responders. Different organizations such as Hurricane Forecast Team, Tropical Prediction Centre and advisories from the National Hurricane Centre were involved in this. The general procedure was that data from different satellite sensors was obtained and analysed using GIS techniques (e.g. software such as ArcGIS). The remotely sensed data was collected through satellites such as LANDSAT, MSIR, QUICKSAT and MODIS. This data allows the analysis of the affected area. The development of hurricane can be viewed from remotely sensed data but the accuracy of the data depends on the resolution of the satellite. This data is then utilized using GIS for example mapping areas of damage, slope map of the area or digital elevation model. This organization of data is not unique to disaster management, but is used in a variety of applications for example mapping a neighbourhood where all the crimes occurred last year. Systems that support this function are termed as GIS. It can in principle therefore use the data from remote sensing and help in the disaster management cycle. The information available is data that relates to specific point or location, and if this information is geographic it can be referenced by a system of coordinates. A GIS is a system (collection of hardware and software) that can create, manipulate and analyse the geographic data provided by remote sensing. So, in the case of hurricane Katrina, GIS showed which areas were destroyed and needed rebuilding, age of housing and utility line grid map highlighting those lines that need to be restored. [7] Figure 1: pre and post Hurricane Katrina-IKONOS Satellite (after http://www.satimagingcorp.com/svc/hurricane_mitigation.html)

As shown in figure 1, Satellite imagery gave state and government agencies the ability to view the damage from multiple angles. After the hurricane, remote sensing was used to determine the extent of landscape change and monitor progress of recovery. As can be seen in the figure, remote sensing allows larger area to be studied in lesser time compared to terrestrial methods. [8] Though media attention was focussed mainly on New Orleans, in the aftermath of Hurricane Katrina many communities across Louisiana and Mississippi also acquired GIS as part of relief effort. For example Hancock County did not have a GIS program and approached companies to provide area maps for the use of aid agencies, people and other concerned personnel. Using GPS coordinates simple maps were built that helped emergency personnel to navigate better in remote parts as shown in fig 2. [9] Figure 2: Maps to Assist U.S. Public Health Service in Slidell, Louisiana (http://www.directionsmag.com/articles/gis-applications-during-response-to-hurricane-katrina-small-local-governmen/122896)

4.People as sensors

The Hurricane Katrina mitigation was facilitated by external people who were not part of government or any organizations. The 2004 tsunami and hurricane Katrina saw the dawn of on-line disaster response community. This has been possible due to the integration of key geo-spatial technologies (Remote sensing, GIS and GPS) with the internet. The traditional phases of the disaster management cycle were facilitated by government and official agencies, but there was also a significant contribution by the public. The public donated money and also shared and posted information faster than official agencies using social networking, blogs, images and forums .People acted as sensors (that is people collected information and acted as a network between agencies and different organizations) to build rapid response databases of the affected area for various aspects of disaster management using geospatial technologies. The principle is the same: Remotely sensed data provides earth observation information that can be analysed using GIS but the internet enhances and facilitates this information to a much larger audience in a much faster way. [7]

5.Conclusion Hurricane Katrina was one of the most devastating hurricanes in US history, the latest developments in technology especially in geospatial technology (remote sensing, GIS and GPS) helped facilitate the disaster management cycle in a more efficient manner than it would have been possible otherwise.

Works Cited 1. Westen, Cees J.Van. Remote Sensing and GIS for Natural Hazards. Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente. Hengelosestraat 90,7500 AA Enschede, The Netherlands : s.n. 2. Company, Munich Reinsurance. Annual Review of Natural Catastrophes. Munich, Germany : Munich Reinsurance Company, 1998. p. 19. 3. WESTEN, Cees VAN. REMOTE SENSING FOR NATURAL DISASTER MANAGEMENT. International Archives of Photogrammetry and Remote Sensing. 2000, Vols. XXXIII,, Part B7. 4. R.D.Knabb, J.R.Rhome, D.P.Brown. Tropical Cyclone Report Hurricane Katrina. s.l. : National Hurricane Centre, 20 December 2005. 5. D.D.Swenson, B.Marshall. Flash Flood: Hurricane Katrina`s Inundation of New Orleans, August 29, 2005. s.l. : Times-Picayune. 6. Mitigating Natural Disasters: Phenomena, effects and options. United Nations. New York : United Nations Disaster Relief Co-ordinator, 1999. p. 164. 7. On Line Disaster Response Community: People as Sensors of High Magnitude Disasters Using Internet GIS. M.Laituri, K.Kodrich. 8, 2008, Sensors, pp. 3037-3055. 1424-8220. 8. Hurricane, Tornados and Cyclone Hazard Mitigation. Satellite Imaging Corporation. [Online] [Cited: December 2, 2012.] http://www.satimagingcorp.com/svc/hurricane_mitigation.html. 9. K.A.Boyd, J.W.Mills. GIS Applications during Response to Hurricane Katrina: Small, Local Government and State Government Experiences . Directions Magazine. [Online] [Cited: December 2, 2012.] http://www.directionsmag.com/articles/gis-applications-during-response-to-hurricane-katrina-small-local-governmen/122896. 10. Varshini, R.V. REMOTE SENSING AND GIS IN HURRICANE MAPPING AND MITIGATION - CASE STUDY IN NEW ORLEANS LA. Institute of Remote sensing, ANNA UNIVERSITY, CHENNAI. Hyderabad, India : s.n.