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Monitoring and Case Study Data
The key role of the participants in WP6 is
a responsibility in execution of the Theme 6, which is aimed
at bringing innovations and skills in geophysical investigation
techniques and at collation of data from flood events.
A) Monitoring Programme (Geophysical Investigation
Techniques)
The monitoring of embankment conditions in
situ, through test application and selection of optimal geophysical
methods will be performed. The need of bringing this idea
for monitoring of long protective structures such as dams,
dikes, levees and embankments is an inference for using appropriate
geophysical methods. The advantage for being very effective
in practical applications is based on the fact, that they
are non-destructive, relatively fast and inexpensive. The
assessment of their performance in form of case study is a
focus of the work. Determining structural conditions and homogeneity
of material conditions will basically serve as link for investigation
in breach formation processes, for application of subsequent
geotechnical methods and for giving predictions in flood risk
assessment and associated uncertainties.
Geophysical methods applicable for to this project will generally
involve:
- Geoelectric methods - estimation of
places with seepages, evaluation of homogeneity and clayishness)
- Ground Penetration Radar (GPR) - evaluation of homogeneity
and structural conditions
- Micro-seismic methods - data derived for estimation
of material properties
- Gravimetry - evaluation of homogeneity and structural
conditions
The monitoring of the in situ embankment conditions
is executed as a field tests at two testing sections of anti-flood
dams in the Odra river basin of North Moravia (Czech Republic).
Anti-flood dams at both sites have been heavily damaged during
catastrophic flood in 1997. This relates to the sites Jilesovice
and Spluchov. General testing geophysical measurement consists
of 3 scheduled stages:
- the 1-st stage has been performed in April 2003 at increased
water discharge and at increased moisture of dam material
after snow melting
- the 2-nd stage has been performed
in September 2003 at low water level after the extremely dry
summer
- the 3-rd stage shall become measured at occasional
flood level, not later than in Spring 2004 nevertheless, after
summer snow melting (probably in April 2004).
The monitoring is executed together with collation of case study
data relating to breach formation and extreme flood events
for model validation and analysis of breach formation and
breach location. The target of testing measurements is confirmation
of the results’ reliability related to successive geophysical
methods at varying climatic conditions and an attempt at follow
up (long-term monitoring) of changes in geo-mechanical properties
of the dams at repeated impacts of high water level.
B) Case study for breach parameters
The main focus will be exerted on data collation
and their analysis from historical dike breaches from Hungarian
and Czech cases from the last two centuries. In particular
these data will be provided for analysis under Theme 2 (Breach
Formation) and Theme 5 (Combined Risk Assessment and Uncertainty).
Data relating to breach formation and catastrophic flooding
will be stored in a special database for further evaluation
and processing. Best appropriate parameters from breach events
were estimated with regard to their availability. These data
will contribute to the analysis of formation mechanisms and
assessment of breach location factors.
Only by means of comprehensive study is it possible to assess
the complexity of flood event occurrence.
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