Tuesday, February 18, 2014

Some Pearls of Wisdom About The Pearl River Delta

Weng, Q. "A Remote Sensing-GIS Evaluation of Urban Expansion and Its Impact on Surface         Temperature in the Zhujiang Delta, China." International Journal of Remote Sensing 22.10 (2001): 1999-2014. Web.

China is by far the least likely to pop up in your head when it comes to progression in environmental protection and conservation. It did not get that notion just from its smog filled skies in densely populated cities. China's then rapidly elevating population in the Zhujiang, or Pearl River, Delta caught the attention of Weng. The area of choice was to evaluate the swelling population growth of the Pearl River delta over the past two decades and estimate the impacts of rapid urbanization in this area.

Weng concluded that the primary reason for the increased population is the fact that this delta in particular was rich in agricultural soil due to its subtropical climates and seasonal monsoons. (The Pearl River Delta has always been a hot spot for agricultural production and its silk production can be traced back as far as the Ming Dynasty and ancient China). In short, this area was a boom for economical growth.

To investigate, Wang used remote sensing and GIS to:

  • detect urban growth
  • assessing the impact on the surface of the region
Weng then categorized the land using Erdas Imagine computer software and Landsat images, Weng constructed a map that enhanced the area by identifying several key elements:
  • urban or built-up land
  • barren land
  • cropland
  • horticultural farms
  • dike-pond land
  • forests
  • water
This way, when overlapped with boundaries, streets, and buildings using GIS, there could be a clear relationship between geographical objects and urban development.

It was inferred that urban development usually gives rise to changes in the Earth's surface. Think about it, if you remove vegetation from the land, the more solar radiation will hit the ground, thus raising the surface temperature. Weng evaluated the effects of urbanization by using TM thermal data and observing that areas with higher development tended to have a higher intake of radiation.

Comparing the 1987 to 1997 data, it was clear that there was a reasonably high increase in urbanization in the Pearl River Delta such as the build-up of land and horticulture farms. Weng discovered that the mean surface temperature had risen by 13.01 C and that there was a direct correlation between urban development and degradation of the land.

What does this all mean? Rapid development of an area that was once rich in agricultural land has now faded away into dust due to rapid development. The lack of vegetation can increase the mean surface temperature and most likely kill off any valuable microorganisms used to keep the soil healthy and fertile. 

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