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| Titel |
Soil buffer limits flash flood response to extraordinary rainfall in a Dutch lowland catchment |
| VerfasserIn |
Claudia Brauer, Ryan Teuling, Aart Overeem, Ype van der Velde, Pieter Hazenberg, Piet Warmerdam, Remko Uijlenhoet |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250052497
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| Zusammenfassung |
| On 26Â August 2010 the eastern part of The Netherlands and the bordering part of Germany
were struck by a series of very heavy rainfall events lasting for more than a day. Over an area
of 740Â km2 more than 120Â mm of rainfall was observed in 24Â hours. This extreme event
resulted in local flooding of city centres, highways and agricultural fields, and considerable
financial loss.
We report on the unprecedented flash flood triggered by this exceptionally heavy rainfall
event in the 6.5Â km2 Hupsel Brook catchment, which has been the experimental watershed
employed by Wageningen University since the 1960s. This study aims to improve our
understanding of the dynamics of such lowland flash floods.
We present a detailed hydrometeorological analysis of this extreme event, focusing on its
synoptic meteorological characteristics, its space-time rainfall dynamics as observed with
rain gauges, weather radar and a microwave link, as well as the measured soil moisture,
groundwater and discharge response of the catchment.
At the Hupsel Brook catchment 159.5Â mm of rainfall was observed in 24Â h,
corresponding to an estimated return period in the order of 6000Â years. As a result, discharge
at the catchment outlet increased from 4.4 s-1 to nearly 5Â m3 s-1 (i.e. a specific discharge of
0.77Â m3 s-1Â km-2, or 2.8Â mm h-1). Within 7Â hours discharge rose from 50 to
4.5Â m3 s-1.
The catchment response can be divided into four phases: (1) soil moisture reservoir
filling, (2) groundwater response, (3) surface depression filling and surface runoff and (4)
backwater feedback. The first 35Â mm of rainfall were stored in the soil without a significant
increase in discharge. Relatively dry initial conditions (in comparison to those for
past discharge extremes) prevented an even faster and more vigorous hydrological
response. |
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