This report aims to contribute to a better understanding of land subsidence in the Mekong Delta. There are different drivers affecting the sinking land surface in the region. To what extent is the land sinking? In which locations? Is it occurring quickly or slowly? These are simple questions. Based on existing data it is not difficult to answer these questions.
In contrast, questions concerning why subsidence is happening and what can be done to reduce its impacts, are much more challenging. It is clear that natural and anthropogenic factors are contributing. However, to what extent different drivers are responsible in different locations is still not well understood.
The main contribution of this report is the introduction of new data describing the sinking of land using satellite-based methods. Radar satellites collected a large amount of data with high precision covering the total area of the Mekong Delta. The new data describe vertical movements at 750,000 points in the Mekong Delta, and for each point 180 different time series data are available. This totals more than 135 million values and represents a big step forward compared to previously available data.
The large amount of data allows a more detailed spatial and temporal analysis of land subsidence. Some infrastructure, such as buildings, bridges, and power pylons can be identified and a high temporal resolution (time series from the end of 2014 to early 2019) shows a linear development over the period of 4+ years; for example, urbanized areas sink by 2-4 cm/year and agricultural areas by 0.5 – 1 cm/year. By and large this confirms findings from previous research, though in much more detail and with more conclusive results.
(The document attached has been optimized and is now under 7Mb)