UCLA
Remote Sensing
Vegetation Change
Vegetation Change
Vegetation Change
RESULTS
Using VIIRS Imagery from 2012 to 2016
BLACK MARBLE NIGHTLIGHT CHANGE
The two black marble images were taken using the Suomi NPP satellite and show nightlight coverage in real-time of Yemen. As shown in the maps, nightlight coverage is more prominent in districts with large populations. For instance, some of the biggest cities in Yemen-- Sana'a, Aden, Taiz, and Al Hudayah have the largest concentration of nightlight in the images presented, and thus signify human presence/activity.
DJIBOUTI
2012
Black Marble Image of Yemen
2016
Black Marble Image of Yemen
Results
Due to various events caused by the war: human displacement, a cholera outbreak and a famine, the night light in Yemen has significantly reduced from 2012 to 2016. Nightlight is a big indicator of human presence; thus, from this map, one can see the effects the war has on the movement and deaths of the Yemen population based on nightlight loss.
Most nightlight loss is concentrated towards the west of Yemen, most notably in the capital of Sanaa where most of the attacks and bombings have taken place. Large concentrations are also located towards the south of Yemen. This trail of nightlight loss follows the movement pattern of the Houthi rebel party towards Aden, with the aim to target the president Hadi. Areas where there's a large concentration of nightlight loss also are in districts where there's a large population. For instance, the district with the largest population as of 2016 (about 3 million) is an area that receives large nightlight loss throughout its district.
In contrast, there is little to no nightlight increase with the exception of 6/21 districts, those being: Ma'Rib, Hadhramaut, Raymal, a small portion of Sanaa and Al Hudayah, and Shabwah.
NIGHTLIGHT CHANGE WITH BAND ALGEBRA
Observing
Nightlight Loss
Nightlight Gain
Explained
The difference between this map and the one above is that this one offers quantitative data. The map itself shows nightlight gain in darker shades of black. The darker the shade of black, the greater the nightlight loss. In contrast, the lighter the shade, the more nightlight has been gained.
The cursor value option in ENVI allows us to observe the DN (digital number) of any area on the map and tells us how much nightlight was gained or lost from 2012 to 2016. The gallery on the right gives examples of such in various locations.
When looking at the cursor value menu, "image-download (2) tiff" represents Dec. 6, 2012 nightlight data and "image download (3)" represents the 2016 data. The data number under "band algebra" presents the subtracted value between those two datasets and thus presents the nightlight change quantitatively. Such allows us to understand the full extent to which the war had affected the populations in these areas. The larger the number, the more negative the affects on the population were.
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Examining Specific Regions
Sana'a Bombing Attacks
1,915km
nightlight loss
2
Al Hudayah Cholera Outbreak
525 km of nightlight loss
2
Yemen Migration to Djibouti
815 km of nightlight gain
2
The effects of the war are drastic. Those being bombing attacks all over Yemen, most specifically in the city of Yemen, a large Cholera outbreak in Al Hudaydah and large populations migrating into Djibouti. Above are the kilometers squared of areas lossed or gain in certain areas of Yemen.
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