Mountain Gorilla Protection: A Geomatics Approach
 
"Gorillas in the data base"
 
 
Space Shuttle Radar Images
 
 
 
 
STS-68
SRL-2 (Shuttle Radar Lab 2)
 
Sept. 30-Aug. 11, 1994 Shuttle Radar Lab Mission 2
 
 
Liftoff of STS-68 on Sept. 30, 1994
 
 
The second mission flew in early October. The original plan was to be able to acquire spring and fall data (in the northern hemisphere) with the two flights. In between the two flights, the terrible situation in Rwanda developed. We had planned to have crews in the field for both acquisitions, but this quickly became impossible, and the crews in Rwanda had to escape over the border into Uganda. Hundreds of thousands of refugees flooded into the area, establishing huge camps on the border of the reserve. Our second data take quickly became a tool to monitor the situation, and to measure the amount of impact that the refugee camps were having on the reserve.
 
Mt. Nyiragongo began erupting in August, 1994 and so it was added as a target of observation during the second flight of SIR-C/X-SAR. This doubled the size of the acquisition area. Very fluid lava flows from the earlier 1977 eruption killed over 70 people.

The detailed acquisition area for the second flight.
 
 
 

 

X band panchromatic image

 
 
 L band panchromatic image
 
 
 
 
This is the full image
 
 
Click on this image for a full resolution version.
 
You can download a 3 Mb high resolution image from USGS here
 
 
 
 
 
C-band panchromatic image
 
 
 
 
 
Click on this image for a full resolution version.
 
You can download a 3 Mb high resolution image from USGS here
 

 

C and L band comparison

C band subscene

L band subscene

The L band at bottom has a longer wavelength and is more able to penetrate the thick foliage of the area than the C band at top. This makes it is more useful in forest and vegetation studies, as it is able to penetrate deeper into the vegetation canopy and even interact with the ground surface. The western park boundary on the left is almost invisible in C band, but clearly seen in L band. You can see that there is generally much more differentiation in the L band image than in C band.

 
 
 
Color composite images
 
A unique capability of the SIR-C/X-SAR is the ability to create false color composites by assigning red, green, and blue to the C and L bands and different polarizations.
The following are color composites of the C and L band data.

Click on the image for a full resolution version

In this image red is the L-band (horizontally transmitted, vertically received) polarization; green is the C-band (horizontally transmitted and received) polarization; and blue is the C-band (horizontally transmitted and received) polarization. The area is enlarged, compared with the STS-59 data, to inclue the erupting volcano at cener.

The park area acquired on the second flight

 

Different color table
 
October 1994 SIR-C radar image
 
 
October 4, 1994
SRL-2 DT 58.61
 
 
 
This is a different false-color composite of the Virunga region of Central Africa, showing the Virunga volcano chain along the borders of Rwanda, Zaire and Uganda. The image is processed to highlight the recent lava flows, that are visible as blue and red in the center.
The area that is home to the endangered mountain gorillas is at right-center in pink. More heavily vegetated areas are pink, and less vegetated areas are shades of blue. The highway above the lake is visible. Goma is a blue area near the airport runway.
 
The image was acquired on October 4, 1994, on orbit 58 of the space shuttle Endeavour by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X- SAR). The image was acquired from 1:04:16 AM to 1:04:21 sec AM (just after midnight, local time) on an ascending orbit.
 
The area is centered at about 2.4 degrees south latitude and 30.8 degrees east longitude. The image covers an area 56 kilometers by 70 kilometers (35 miles by 43 miles). The dark area at the bottom of the image is Lake Kivu, which forms the border between Zaire (to the left) and Rwanda (to the right). In the center of the image is the steep cone of Nyiragongo volcano, rising 3,465 meters (11,369 feet) high, with its central crater now occupied by a lava lake. To the right are three volcanoes, Mount Karisimbi, rising 4,500 meters (14,800 feet) high; Mount Sabinyo, rising 3,600 meters (12,000 feet) high; and Mount Muhavura, rising 4,100 meters (13,500 feet) high. To their left is Nyamuragira volcano, which is 3,053 meters (10,017 feet) tall, with radiating lava flows dating from the 1950s to the late 1980s. These active volcanoes constitute a hazard to the towns of Goma, Zaire and the nearby Rwandan refugee camps, located on the shore of Lake Kivu at the bottom right.
 
This radar image highlights subtle differences in the vegetation of the region. The green patch to the center left of the image in the foothills of Karisimbi is a bamboo forest where the mountain gorillas live. The vegetation types in this area are an important factor in the habitat of mountain gorillas. The faint lines below the bamboo forest are the result of agricultural terracing by the people who live in the region. This area used to be part of the park.
For a high resolution (2.4-megabyte) copy of this image, click here
 
Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L- band (24 cm), C-band (6 cm) and X-band (3 cm). The multi- frequency data provide a new way to see and understand the region. The SIR-C/X-SAR data, complemented by aircraft and ground studies, give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v.(DLR), the major partner in science, operations and data processing of X-SAR.
Color table inversion image
 
 
 
 
The same image with different color composition. You can see very clearly the different vegetation zones in the Gorilla park, including the bamboo zone at the bottom that shows up as a light green. The airport in Goma show as a white line \ just above the lake (white) on the right.
 
 
 
 
 
 Analysis
 
As the data from the two missions arrived, we began the analysis. initial maps of the vegetation and land cover were made, and 3-D perspective images were created. (See sections below).
 
 
 
This full resolution image shows the northern edge of lake Kivu and the major city of Goma. The main east/west highway between Congo and Rwanda is clearly visible as a blue line. The airport at Goma, which is the only major airport in the region, is visible as a black line just outside the city. The Rwandan border is on the right side of the image. Evidence of intensive volcanism is seen throughout the image, with numerous volcanic vents showing as small hills. The lighter orange area at the left of the image is a recent lava flow.
 
 
A vegetation map produced by manual interpretation of the satellite images and using aerial photographs and field data. This was the first comprehensive vegetation map ever produced of the entire park region.
 
 
This medium resolution images shows the southern portion of the reserve. The terraced agricultural fields surrounding the reserve are shown in blue, with the terraces clearly visible. The green patch at the bottom of the reserve is the bamboo forest, with the haigania forest showing as a brighter pink above the bamboo. The summit of Mount is gray, evidence of the lack of vegetation in this alpine environment. The volcanic peaks all appear to lean to the right of the image. This is refered to as "lay over" and is caused by the fact that the Shuttle radar (which was to the right of the area) looks down at an angle. Steep slopes will appear to be more vertical towards the sensor, and the slopes on the other side will appear to be less steep. The mountains are actually symmetrical.
 
 
This full resolution image shows the northern portion of the reserve.
 
  
 
 
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For more information contact Scott Madry
 
or the Diane Fossey Gorilla Fund