Ground water management and its consequences in Delft, the Netherlands
as observed by Persistent Scatterer Interferometry

Freek J. van Leijen and Ramon F. Hanssen

Infrastructure in Delft, the Netherlands, is threatened by ground
water. Subsidence in combination with ground water level rise has
resulted in severe problems, especially in the historical city center.

Apart from natural causes, artificially induced ground water level
fluctuations and subsidence deteriorate the situation. An industrial
complex in Delft has been withdrawing ground water since
1916. However, due to changes in the production process in 2004 the
use of ground water has become unnecessary. As instant termination of
the extraction process would have a severe impact on the already
sensitive ground water situation, a gradual decrease of the extraction
volume is proposed. However, because of the unique soil decomposition
in the Dutch coastal area (sand, clay, peat), even the effects of a
gradual decrease cannot be predicted very well.

In this contribution Persistent Scatterer Interferometry (PSI) results
of the city of Delft are used to deduct the relation between ground
water fluctuations and subsidence. Since 2000 ground water levels at
155 locations in Delft are measured automatically, providing a unique
opportunity to relate subsidence with the actual ground water
level. Using ERS1/2 as well as Envisat SAR data, the full period
between 1992 to 2007 is analyzed.