Recent land subsidence caused by the rapid urban development in the Hanoi region (Vietnam) using ALOS InSAR data
Since the 1990s the land subsidence due to the rapid urbanization has been considered a severely destructive hazard in the center of Hanoi City. Although previous studies and measurements have quantified the subsiding deformation in Hanoi center, no data exist for the newly established districts in...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-03-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | http://www.nat-hazards-earth-syst-sci.net/14/657/2014/nhess-14-657-2014.pdf |
| Summary: | Since the 1990s the land subsidence due to the rapid urbanization has been
considered a severely destructive hazard in the center of Hanoi City.
Although previous studies and measurements have quantified the subsiding
deformation in Hanoi center, no data exist for the newly established
districts in the south and the west, where construction development has been
most significant and where groundwater pumping has been very intensive over
the last decade. With a multi-temporal InSAR approach, we quantify the
spatial distribution of the land subsidence in the entire Hanoi urban region
using ALOS images over the 2007–2011 period. The map of the mean subsidence
velocity reveals that the northern bank of the Red River appears stable,
whereas some areas in southern bank are subsiding with a mean vertical rate
up to 68.0 mm yr<sup>−1</sup>, especially within the three new urban districts of
Hoang Mai, Ha Dong – Thanh Xuan and Hoai Duc – Tu Liem. We interpret the
spatial distribution of the surface deformation as the combination of the
nature of the unsaturated layer, the lowering of groundwater in the aquifers
due to pumping withdrawal capacity, the increase of built-up surfaces and the
type of building foundation. The piezometric level in <i>Q</i><sub>p</sub> aquifer
lowers particularly after 2008, whereas the groundwater level in
<i>Q</i><sub>h</sub> aquifer remains steady, even if it loses its seasonal
fluctuation in urban areas and drawdowns in neighboring water production
plants. The time evolution deduced from the InSAR time series is consistent
with previous leveling data and shows that the lowering rate of the surface
slightly decreases till 2008. The analysis of groundwater levels in
instrumented wells shows a correlation between the behavior of groundwater
with the urban development and the acceleration of groundwater withdrawal.
Also, the time variations suggest that the deformation became non-stationary,
with upward and downward transient displacements related to the charge and
discharge of the aquifers. |
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| ISSN: | 1561-8633 1684-9981 |