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| Titel |
Predicting the Impacts of Rural Catchment Changes on Runoff Generation and Flooding |
| VerfasserIn |
P. Enda O'Connell, John Ewen, Greg O'Donnell |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040209
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| Zusammenfassung |
| While urbanization is widely associated with changes to the runoff generation and flooding regimes of catchments worldwide, the rural landscape has also undergone major changes. Over the past fifty years, much of the European landscape has been transformed as a result of changes in land use and management. The growth in intensive agriculture and associated farming practices have changed natural hydrological functioning at the field/hillslope scale, and as a consequence, flood generation mechanisms at the catchment scale may have been affected. In the UK, there is evidence that soil compaction/degradation has created local scale flooding problems, but it is not clear how flood generation at larger catchment scales may have been affected. A wide range of interventions associated with farming and land use management (e.g. land drainage etc) complicate the overall picture. Similar problems have been observed ad documented in other European countries, and there is the added concern about how the catchments will respond to the more extreme rainfall regimes expected under climate change. There is also frequent controversy over the impacts of afforestation and deforestation in the uplands on lowland floods, particularly in Asia.
There is a pressing need for modelling tools that can provide predictions of the impacts of anthropogenic interventions, whether urban or rural, on the downstream flooding regimes of catchments. Central to the prediction problem is the scale issue: how do local scale changes to runoff generation propagate to larger catchment scales and create impacts? An integrated programme of multiscale catchment experimentation and modelling is being undertaken in the UK to gain a better understanding of how small scale changes in runoff generation propagate to larger catchment scales, and to support decision-making on flood risk mitigation. New modelling tools have been developed which can be used to assess impacts and guide management interventions. The first of these is an information tracking approach which can track runoff generated at any spatial location within a catchment to a downstream point of impact. Packets of runoff are labelled in time and space, injected into a hydraulic network routing model and subsequently tracked to a downstream location where a flood hydrograph is recorded. Using the information provided by all the tracked packets, the hydrograph can be decomposed in space and time, and maps of source runoff constructed for the hydrograph peak, for example. A further new technique, extending the concept of information tracking, is being developed which uses adjoint modelling to create maps of sensitivity to change that can be used to support decision-making in land management for flood mitigation. Predictions in the form of vulnerability maps can be used to assess where in the catchment landscape mitigating interventions might best be made to mitigate downstream flooding. Examples of the application of these techniques to UK catchments will be given. |
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