The goal of our group was to analyze the change in Indonesia, more particularly Banda Aceh, suffered from the Tsunami that hit December 26th, 2004. Our results show the extent of the destruction that the Tsunami left Indonesia on a global scale. We have analyzed images taken in December 2004, prior to the Tsunami hitting, February 2005 and in June 2009. With each of these images it is easy to identify the devastation, the rebuilding and relocation of people after the Tsunami. Images taken in RGB color (Red, Green, Blue; what is seen by the human eye) shows the destruction and rebuilding at a quick glance. One can look at the coastlines and see how they have changed, along with loss of a significant amount of lush vegetation.
Images shown in the Infrared give the opportunity to see beyond what the human eye cannot see. Images in the infrared show moisture content in the soil as well as healthy vegetation. This allowed for our group to take an even closer look at the trauma, and provided more evidence as to where exactly the destruction of the tsunami tore through Indonesia.
Using nightlight data, we were able to show the tsunami's destruction of heavily populated areas of the island. This allows us to identify how fast the people of the area were able to rebuild the damaged infrastructure, and places they found most favorable for the relocation of their towns.
Through the SRTM elevation map of Banda Aceh, we were able to see the areas of low elevation which were affected the most by water damage from the Tsunami. This gave us the opportunity to the areas affected most by water damage.
Through the use of these devices it has allowed us to witness the extent of destruction caused by the 2004 Tsunami and understand where and when rebuilding took place and where the relocation of people took place.
Thursday, December 2, 2010
Introduction
On December 26, 2004, a massive earthquake with a magnitude measured at around 9.2 occurred beneath the Indian Ocean. It occurred off the West Coast of Sumatra, Indonesia. This undersea earthquake caused a tsunami impacting all the coasts that are along the Indian Ocean. The earthquake was caused by the subduction of plates, which set off several tsunamis along the coasts of landmasses surrounding the Ocean. Waves 30m high devastated the coasts of 14 different countries, killing over 230,000 people. The 2004 tsunami is known as one of the most deadly natural disasters ever recorded.
Banda Aceh was arguably the hardest hit area. Projected damage costs were targeted at $4.4 Billion and “the loss of a generation." 700,000 people were homeless and farmers, fisherman, and small businesses were completely destroyed leaving people with no source of income and thus, the inability to rebuild. What has been since deemed the biggest story of the disaster is not the economic damage to the country, but the destruction of citizens’ lives and their inability to recover with no plan on how or where to start. Almost every source of agriculture within 3 miles of the ocean was destroyed due to flooding, livestock were killed, and everything poisoned. Even today, six years after the tsunami, some of the land is still infertile. Estimates say that $675million in environmental damage was incurred to the Banda Aceh region alone. The highest most expensive portion of the damage at $1.4billion were to housing and shelter within the region including the destruction of small businesses.
Essentially, our project looks along the northern coastal city Banda Aceh, Indonesia. We will be using a variety of satellite images from before, immediately after, and five years after the tsunami hit. Our images will portray the dramatic changes to the city and coastline after the disaster.
Banda Aceh was arguably the hardest hit area. Projected damage costs were targeted at $4.4 Billion and “the loss of a generation." 700,000 people were homeless and farmers, fisherman, and small businesses were completely destroyed leaving people with no source of income and thus, the inability to rebuild. What has been since deemed the biggest story of the disaster is not the economic damage to the country, but the destruction of citizens’ lives and their inability to recover with no plan on how or where to start. Almost every source of agriculture within 3 miles of the ocean was destroyed due to flooding, livestock were killed, and everything poisoned. Even today, six years after the tsunami, some of the land is still infertile. Estimates say that $675million in environmental damage was incurred to the Banda Aceh region alone. The highest most expensive portion of the damage at $1.4billion were to housing and shelter within the region including the destruction of small businesses.
Essentially, our project looks along the northern coastal city Banda Aceh, Indonesia. We will be using a variety of satellite images from before, immediately after, and five years after the tsunami hit. Our images will portray the dramatic changes to the city and coastline after the disaster.
Methods
The study area will include the Northwestern tip of Banda Aceh,Indonesia, located on the Island of Sumatra. This city is infamous for the devastating hit it took after the 2004 Tsunami.The data for our project has been collected from many sources.
The night light images of Indonesia were taken from the National Geophysical Data Center (NGDC). To do this, we downloaded the night light image of the world of each year and loaded this onto ENVI and subset the country of Indonesia. When our region was subset, we density sliced the image to show concentration of light in color. Represented in our project are night light images of Indonesia from the years 2003 to 2009. These images were downloaded separately and then organized in an efficient way to compare the changes in night light over this seven year period. Using ENVI, we compared night light from 2004 to 2005. This was done by computing a difference map by combining the 2004 and 2005 images and comparing the similarities and differences in where light was coming from.
To compare geographical and geophysical changes from before and after the Tsunami we downloaded Landsat images of Banda Aceh from data discover tool, Glovis. These were all extracted from the USGS Earth Resources and Observation Center website. To compare these changes from this region, we downloaded a before picture taken in May,2004. Our after picture we downloaded was taken in February 2005, and our present picture was taken in January 2009. After unzipping each image twice, we loaded the three images into ENVI. We then used the algorithm to replace the bad values of the pictures, which were diagonal black lines running through each image. When our pictures were clear we changed from from the RGB view to the Infrared view and compared the before, after, and present effects that the 2004 Tsunami had on Banda Aceh, Indonesia. When this was done, we were able to see clearly the differences in vegetation and land destruction after the Tsunami.
To retrieve our elevation data, we brought up the Global Land Cover Facility homepage. We then entered the Earth Data Science Interface and downloaded the portion of Indonesia from the world map. After unzipping the image and loading it onto ENVI we had elevation data for Banda Aceh for the year 2000.
The night light images of Indonesia were taken from the National Geophysical Data Center (NGDC). To do this, we downloaded the night light image of the world of each year and loaded this onto ENVI and subset the country of Indonesia. When our region was subset, we density sliced the image to show concentration of light in color. Represented in our project are night light images of Indonesia from the years 2003 to 2009. These images were downloaded separately and then organized in an efficient way to compare the changes in night light over this seven year period. Using ENVI, we compared night light from 2004 to 2005. This was done by computing a difference map by combining the 2004 and 2005 images and comparing the similarities and differences in where light was coming from.
To compare geographical and geophysical changes from before and after the Tsunami we downloaded Landsat images of Banda Aceh from data discover tool, Glovis. These were all extracted from the USGS Earth Resources and Observation Center website. To compare these changes from this region, we downloaded a before picture taken in May,2004. Our after picture we downloaded was taken in February 2005, and our present picture was taken in January 2009. After unzipping each image twice, we loaded the three images into ENVI. We then used the algorithm to replace the bad values of the pictures, which were diagonal black lines running through each image. When our pictures were clear we changed from from the RGB view to the Infrared view and compared the before, after, and present effects that the 2004 Tsunami had on Banda Aceh, Indonesia. When this was done, we were able to see clearly the differences in vegetation and land destruction after the Tsunami.
To retrieve our elevation data, we brought up the Global Land Cover Facility homepage. We then entered the Earth Data Science Interface and downloaded the portion of Indonesia from the world map. After unzipping the image and loading it onto ENVI we had elevation data for Banda Aceh for the year 2000.
RGB Images
2004 RGB2005 RGB
2009 RGB
In order to witness the destruction of the tsunami in 2004, we collected images before the tsunami hit, images a couple of months after the tsunami, and images from present day. These images were collected from a LANDSAT satellite which we downloaded for free off the internet. With these images, we used a program software ENVI, to manipulate the data, by first putting it into RGB color, which gives it color equivalent to what the human eye sees. In these images alone, one can see destruction very clearly.
The 2004 images, taken prior to the tsunami, shows Banda Aceh of Indonesia, very green and full of healthy vegetation. When placed side by side with the image taken in 2005 after the tsunami, it is very evident the amount of destruction Banda Aceh suffered. The three areas, in which we focused our study and gathered evidence from include, Banda Aceh, Lhonga, and Pulau Peunasu. Looking at the 2005 image the land is brown and barren, and this shows where the brunt of the devastation took place. The tsunami wiped out healthy vegetation and destroyed agricultural and residential land, leaving it in ruins. The coastline is another strong indicator of the power of this tsunami having been completely wiped out. It clearly doesn't have the same linear structure compared to the 2004 image. The image taken in 2009 is used to show how much the area has recovered since tsunami. The return of green, healthy vegetation shows that the ecosystem is recovering well, and appears very similar to the image taken prior to the disaster. It also shows the rebuilding and relocation of the people. There is a lot movement away from the coastline and relocation in places in higher elevation.
Infrared Images
2004 IR
2005 IR
2009 IR
In order to get an even better view and understanding of the destruction in Indonesia, we must see past what the human eye can see, in a quite literal sense. In ENVI, we chose to look at the infrared bands. To be more precise, in the RGB scale, instead of looking at the red, green and blue bands, we placed one visible band, (band 3) in the red, band 5 in the green and band 4 in the blue, both of which are infrared.
Once this image was loaded, we produced our infrared images which would more clearly show the destruction and shows us what we cannot see with the human eye. When looking at the images in Infrared, the heat of the earth's surface is captured. When comparing the 2004 image to the 2005 image, the evidence of the tsunami's path is very clear, devastating the coast of Banda Aceh and flowing through the lowlands into Lhonga. The blue areas in the 2005 image show the destruction, for these are cool places that aren't giving off heat; it is land left in ruin. These areas are highlighted along the coastlines especially in Banda Aceh and Lhonga, where one can witness the removal of entire towns. When looking North, at the island of Pulau Peunasu the blue is highlighted deep into the land and shows the path the tsunami took on it's south shore.
The 2009 image captures how Banda Aceh has recovered from the Tsunami. At a quick glance one can see how the vegetation has returned and the reconstruction of the coastline has retained its linear form. Take a close look and there is evidence of new rebuilding and relocation of people. It looks like there are more areas devoted to agriculture closer to the coasts, while cities and towns seem to have been rebuilt at higher elevations and further from the coast.
Density Slice of Damaged Land After Tsunami
Based on our map, excluding the Ocean, the red portion of Sumatra, Indonesia was completely destroyed and inundated by the 2004 Tsunami. This includes infrastructure. The only things still standing in this area were palm trees. The green portion of our map marks the area where all agriculture had been destroyed and poisoned by water damage. The blue portion still shows areas of some damage, but to a lesser extent that the area closer to the coast experienced. However, this blue area was where many survivors from the more coastal area relocated after the earthquake and tsunami destroyed their original homes.
2003-2009 Nighlight Series
In order to view a different aspect of the destruction caused by the 2004 Tsunami, we analyzed nightlight images taken annually from years 2003 to 2009. The color coded nightlight images we created, using data downloaded from the Defense Meteorological Satellite Program’s website, show a general trend of increased lighting as the years move forward. An interesting occurrence took place in 2005, the year immediately following the great 2004 tsunami. The 2005 image displays dark areas that were once lit, as well as areas that continued to increase in luminosity despite the tsunami event. The dimming of light that occurred along the west side of the island is due to the tsunami event. Since the tsunami hit the northwest side of the island, central and eastern Sumatra were not affected, and the nightlight concentration continued to increase each year.
Nightlight Difference Before and After the Tsunami
To get a closer look at the tsunami’s effect on nightlight, we performed a change detection analysis, and created a difference map to easily see changes in lighting from before and after the tsunami. The map shows the light that was present in 2004 but went dim after the tsunami, as well as the new light that came about the year after the tsunami hit. The northwestern edge of the island displays blue (Nightlight Present in 2004 But Not 2005), while the northeastern edge displays red (Nightlight Present in 2005 But Not 2004). This reveals the relocation of the inhabitants from the west to the east, away from the destruction caused by the tsunami.
Discussion
Other Studies: Other studies have shown that the use of satellite imagery can help make a quick damage assessment. In 2004 it took over a week for the U.S. government to provide and support or aid, due largely to the fact that there was a lack of information regarding the damage. Our study along with others, prove that with remote sensing and satellite imagery, we can make quick early assessments of natural disasters on a global scale. With such knowledge accessible early, countries will be able to make a damage assessment and receive support in a timely fashion.
Limitations: For our project, one of the limitations we ran into was the inability to find extremely high resolution data. This prevented us from finding specific small-scale locations within the area and the inability to analyze data on the infrastructure that was damaged. For example, we could not zoom-in close enough on a community to analyze the buildings, streets, and agriculture destroyed.
Also, if we had access to property values in the Banda Aceh region, we could accurately estimate the costs of damages that incurred. Unfortunately for us, Zillow only works for buildings in the United States. If we could locate some of the in-country migratory statistics, we could break down where people have moved since the disaster and where citizens are restarting their lives.
Future Research: For future research in this realm, with grants or the ability to spend significant amounts of money, we could do a break down on the specific communities and how damaged they were by the tsunami. With more recent, expensive, high resolution data, we could analyze these specific areas and compare and contrast them and determine which locations were most significantly damaged and how they are rebuilding since the disaster. Personal interviews would also help tremendously in discover more of the emotional trauma that the Tsunami caused, and not just the physical trauma.
Limitations: For our project, one of the limitations we ran into was the inability to find extremely high resolution data. This prevented us from finding specific small-scale locations within the area and the inability to analyze data on the infrastructure that was damaged. For example, we could not zoom-in close enough on a community to analyze the buildings, streets, and agriculture destroyed.
Also, if we had access to property values in the Banda Aceh region, we could accurately estimate the costs of damages that incurred. Unfortunately for us, Zillow only works for buildings in the United States. If we could locate some of the in-country migratory statistics, we could break down where people have moved since the disaster and where citizens are restarting their lives.
Future Research: For future research in this realm, with grants or the ability to spend significant amounts of money, we could do a break down on the specific communities and how damaged they were by the tsunami. With more recent, expensive, high resolution data, we could analyze these specific areas and compare and contrast them and determine which locations were most significantly damaged and how they are rebuilding since the disaster. Personal interviews would also help tremendously in discover more of the emotional trauma that the Tsunami caused, and not just the physical trauma.
References
References
Borrero, Jose C. "Science Magazine: Sign In | Science/AAAS." Science. Web. 30 Nov. 2010. .
Brown, Paul. Tsunami cost Aceh a generation and $4.4bn. London: UK Guardian, January 2005. http://www.guardian.co.uk/world/2005/jan/22/tsunami2004.internationalaidanddevelopment
Chen, P., L. K. Kwoh, and S. C. Liew. Tsunami Damage Assessment Using High Resolution Satellite Imagery: A Case Study of Aceh, Indonesia. Tsunami Damage Assessment Using High Resolution Satellite Imagery: A Case Study of Aceh, Indonesia. Centre for Remote Imaging, Sensing and Processing, National University of Singapore, Lower Kent Ridge Road, Singapore 119260., 2005. Web. .
Miura, H., S. Inoue, and A. C. Wijeyewickrema. EVALUATION OF TSUNAMI DAMAGE IN THE EASTERN PART OF SRI LANKA DUE TO THE 2004 SUMATRA EARTHQUAKE USING REMOTE SENSING TECHNIQUE. Web.
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