In this monthly feature, we span the globe to examine Our Changing Landscape with time series of medium resolution RapidEye satellite imagery. The RapidEye archive dates back to late 2008 and already contains more than 8 billion square kilometers of data. Last month we found ourselves in a shadowy valley in Lebanon looking at the construction of a dam, and in March we travel east with a look at a rapidly-growing Chinese city, Shiyan, for this Our Changing Landscape.
The RapidEye Constellation
RapidEye is a constellation of five 5-meter medium resolution satellites each offering five spectral bands of information. The RapidEye constellation offers daily revisits to every location on the planet with a huge footprint that is 77-km wide. The data is priced competitively with a starting cost of $1.28 per square kilometer for all five spectral bands – academics do receive discounts. RapidEye adds a fifth band, the red edge, to the ‘traditional’ multispectral set of blue, green, red and near-infrared (NIR). The additional spectral data in the red edge band allows users to extract more useful land ‘information’ than can be from traditional 4-band imagery sources. When RapidEye imagery is ordered as a Level 3A Orthorectified product, images from multiple dates are extremely well registered, making it the ideal data source for Our Changing Landscape.
The Growth of Shiyan, China
Click on the image above to see an animation of 5-meter natural color RapidEye imagery collected over Shiyan, China on November 23, 2009, June 24, 2011, October 9, 2013 and May 5, 2016. In these images, you can see many changes from 2009 to 2016, including new roads, highways, structures and clusters of buildings. These images definitely confirm the rapid growth of the Shiyan metro area as well as the mountain top clearing alluded to in this article. (Images Courtesy: Planet @ 2017)
As all of you are aware of, China is a rapidly growing country, particularly in its eastern half; and Shiyan is a good example of this, averaging 3 to 4% annual growth over the past few decades. Actually, Shiyan is considered a prefecture-level city, meaning it is between a county and a state if you want to put it in American terminology – perhaps akin to a metropolitan statistical area (MSA) but with a unified regional government. While population figures can be hard to verify in China, according to a 2010 census, about 3.3 million people lived in Shiyan with some 768,000 in its urban center.
Shiyan is located in the northwestern portion of Hubei province, about 650 miles (or 1,050 kilometers) west of Shanghai and the East China Sea. The prefecture covers 459 square miles (1,190 square kilometers), with the city proper covering 78 square miles (203 square kilometers). The prefecture is situated in a valley that is surrounded by the Qinling, Wudang and Daba Mountains with the Han River running through from west to east. The mountains that surround Shiyan are considered some of the holiest locations to the Taoist faith.
With 3% plus annual growth rates in recent history, it is not surprising to hear that multiple development projects are planned and/or underway for the prefecture. For example, there is a 245 mile (395 kilometer) high-speed train planned to connect Shiyan with Wuhan. The prefecture is also the site of one of China’s most ambitious growth projects (as well as one of the most widely critiqued for its environmental impacts) whereby they are literally flattening mountains to expand habitable lands. And finally, it appears that the city center of Shiyan is under renovation (or planned to be) in many locations though this article is a bit hard to follow. So now it is time to turn to the 5-meter RapidEye archive to see how the city has changed since 2009!
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