Tsunami Disasters Monitoring in Thailand by using Geo-Informatics Technology Dr. Surachai Ratanasermpong, Ms. Supapis Polngam, Mr. Thanakorn Sanguantrakool, Ms. Surassawadee Phoompanich Geo-Informatics and Space Technology Development Agency (Public Organization) 196 Pahonyothin Road, Chatuchak, Bangkok 10900, Thailand Telephone : (662) 940 -6420-9 Fax : (662) 561-3035, 562-0429, 579-5618 Email:- surachai@gistda.or.th, supapis@gistda.or.th, thanakorn@gistda.or.th ABSTRACT: The December 2004 Tsunami is one of the disasters that are caused by purely natural phenomena, yet can bring damages of enormous scale. It has devastating impacts on 6 provinces in the South of Thailand. In response to this disaster, information gathering and geo - informatics technology have been used in phases of mitigation and recovery. An interpretation of the affected area's imageries can be performed successfully in multi - spatial, multi - temporal and multi - spectral characteristics. The affected and damaged area obtained from the interpretation of high - resolution IKONOS and QuickBird imageries are the main information source. With remote sensing, GIS and GPS technology, coastal shoreline erosion and property damage can be mapped. 1. Introduction On December 26, 2004, the 9.0 magnitude Sumatra Andaman mega thrust earthquake spawned a gigantic seismic waves or Tsumami in the Indian ocean which caused large scale coastal flooding in various countries namely Sri Lanka, India, Indonesia, Bangladesh, Malaysia, Thailand, etc. In Thailand, the area affected by the Tsunami was in six provinces of its southern part, including Ranong, Phang-nga, Phuket, Krabi, Trang and Satun. It was estimated that 5,393 people were killed and 3,062 missing. The Tsunami also caused coastal plain flooding, resulting in damage to buildings, road networks, bridges, bay or inlets, coastline, etc. Moreover, electric supplies and telephone lines were disrupted for a couple of days. Earth observation satellite data play a major role in quickly assessing damages caused by both natural and man - made disasters such as flood, landslide forest fire, earthquake and even tsunami. For tsunami disaster monitoring, satellite data are very useful particularly in developing countries such as Thailand for base mapping, for emergency relief logistics, estimate of settlement and structure vulnerability, and affected area and damage mapping. 2. Satellite data for tsunami studies Satellite data can be utilized in three phases of operation. They are mitigation phase, response phase and recovery phase. Tsunami disaster mitigation involves risk reduction. Satellite data integrated with Geographic Information System can be used as inputs to logistic planning for response scenarios, evacuation routes planning and public education programs. For this study, multi - spatial, multi - temporal and multi - spectral satellite data are required. Data from various satellites representing pre - and post - Tsunami period were applied to assess the damage. The utilized data included : low - resolution imageries from LANDSAT, IRS, SPOT 5 and RADARSAT; and high - resolution imageries from IKONOS and QuickBird (1 - meter and 61 - centimeter resolution respectively) . Normally low - resolution imageries, obtained by MODIS instrument on board TERRA and AQUA satellites, are used to identify regional level phenomena. A comparison of MODIS imageries acquired at different periods relating to the tsunami event is shown in Fig. 1. Active tsunami wave shown as white color along Phang-nga coastline ( middle image) and coastal flooding occurred overwhelmingly and are presented in the Figure 1 as sediment deposits in white - cyan color along the Andaman coastline of Ranong, Phang-nga, Phuket, Krabi, Trang and Satun provinces. High resolution data from IKONOS and QuickBird are suitable for pinpointing location, type and degree of damage and identifying as well. After identifying affected area using these data, a field investigation were carried out. Types of damage can be displayed as a summary below. 2.1 Coastal shoreline erosion Damage caused by tsunami is mostly severe at the shoreline where boats, harbors, road networks, buildings, and utilities were destroyed. Besides, aquatic life, plants, animals and humans in the near shore environment were also devastated. Multi - date satellite data are found to be very useful for monitoring shoreline changes (Fig. 2 - 4) Fig. 2 shows the affected area (red boundary) indicated by IKONOS images of Patong beach, Phuket province. We found that the wave could reach as far as approximately 480 meters from the shoreline. Sand beach and beach erosion at lower part of Patong beach were enlarged and the erosion was displayed as yellow vector in Fig.3. Also, river damage, sand bank damage, large run - off and strong waves resulted in erosion of river and beach bank at Kammala beach, Phuket province (Fig. 4) 2.2 Damage to properties All properties near shoreline including buildings, road networks, brigdes, aqua-cultural farms and ships were completely washed away by the Tsunami wave in many places such as Ban Nam Khem and Ko Phra Thong in Phang-nga province. At Ban Nam Khem buildings, roads and aqua-cultural farms away or damaged by huge sand and woods transported by the wave (Fig. 5) Fig. 6 shows severe Tsunami damage and many ships were dragged 600-900 meters from the coastline at Ban Nam Khem, Phang-nga province. The detail of perspective IKONOS image is essential for obtaining an overview of the landscape and effective in visualizing the affected area. These imageries can help us gain a better understanding of how the waves spread over the coastal plain. Phang-nga coastal plain is a shoreline of submergence, most of coastal area is narrow, flanked by steep slopes. The shoreline's shape is quite irregular with many bays and inlets. Various of tin placer deposits are found on alluvial plains which are originated from alluvium transported from eroded granite mountains and also found in shallow sea. Human settlements are common on those shorelines (Fig. 7). Beach bank erosion, buildings submerged by the wave, and bridges and roads washed away from South Sea Coral and Spa Resort, Phang-nga province shown by IKONOS images in figure 8. Fig. 9 displays an area affected by the Tsunami with yellow boundary along Phang-nga coastal plain derived from IKONOS images with natural color composite and highlighting from Laem Krang Yai to Ban Khao Lak. Some places such as Ban Bang Sak, Bang Muang sub district, Takua Pa district, the wave could reach approximately 550 meters from shoreline at 10 meter elevation above mean sea level as shown in Fig. 10. In fig. 11, the wave reached 2,200 meters in distance from the shoreline at Ban Bang Niang, Takua Pa district, Phang-nga province. 3. GISTDA activities in response to Tsunami disaster Recognizing the significance of the Tsunami disaster and its devastating impact, Geo-informatics and Space Technology Development Agency (Public Organization); GISTDA has acquired and processed satellite data from various sources both optical and microwave sensors with low medium and high resolution imageries. GISTDA had provided up-to-date and ready-to-use data integrated with geographical data immediately after the Tsunami disaster to users. Other relevant information collected from GISTDA's field investigation as well. The Satellite Imagery based Information Center for Tsunami Recovery was established on February 11, 2005 in order to supply satellite images, GIS data and relevant technological support for the recovery effort given to the area affected by the tsunami disaster. In addition, technical consultations on data utilization were provided to requested agencies (http://tsunamirecovery.gistda.or.th) About 44 governmental agencies, private organizations and educational institutes have already received and utilized satellite images as part of recovery missions. 4. Conclusions and Recommendations High and low resolution satellite data along with GIS technology are useful and practical for Tsunami disaster assessing and monitoring. They also offer an excellent opportunity of creating a long - term database for the purpose of risk assessment and relief management. As for coastal shoreline erosion study, the satellite data should be preferably acquired during the low tide period. Under low tide condition, maximum land and low waterline are exposed, land-water boundary are distinctly visible. 5. References
 Figure 1. Comparison of images acquired by MODIS instrument onboard TERRA and AQUA Satellite tsunami event, left image was taken on December 22, 2004 (before the Tsunami), middle and right images of December 26, 2004 at 10 :35 and 13:35 local Thailand time were captured during and after the event respectively.  Figure 2. Pre (24 December 2004) and post (28 December 2004) tsunami event of taken by of Patong beach, Phuket province shown by IKONOS image. Red boundary responses to an affected area.  Figure 3. Two period natural color composite IKONOS images (24 and 28 December 2004). Yellow vector indicates sand beach and beach bank erosion at lower part of Patong beach, Phuket province  Figure 4. Natural color composite IKONOS images taken from 2 periods of time (24 and 28 December 2004). Red boundary shows river and beach bank damage at Kammala beach, Phuket province   Figure 5. Pre (IKONOS data acquired on 11 February 2001) and Post (IKONOS data acquired on 29 December 2004) Tsunami images of Ban Nam Khem, Phang-nga province  Figure 6. Severe tsunami damage at Ban Nam Khem, Phang-nga province. Many ships were dragged 600-700 meters from the coast.  Figure 7. Perspective views of Phang-nga coastal plain generated from IKONOS natural color composite taken on December 29, 2004.Number 1with red arrows point tin placer deposits and number 2 shows scattering inlets along the coast  Figure 8. Pre and Post IKONOS images indicate damage of buildings, brigde and roads damage at South Sea Coral and Spa resort, Phang-nga province  Figure 9. Natural color composite IKONOS images (29 December 2004) overlay with affected area in Phang-nga coastal plain (yellow boundary) covering, Laem Krang Yai, Ban Khuk Khak, Ban Bang Niang, Ban Bang La On and Ban Khao Lak  Figure 10. Natural color composite of QuickBird (2 January 2005) image of Ban Bang Sak where woods were washed away and deposited around 550 meters at elevation of 10 meters above mean sea level  Figure 11. Natural color composite of IKONOS (29 December 2004) of Ban Bang Niang where sediment deposited about 2,200 meters far from the shoreline (yellow boundary).
Page 1 of 1
|