Analysis of urban catchment for flood return period assessment

Casas Cardona, Laura

4. term

Water and Environmental Engineering , Master

2016

53

Danmark har i de seneste årtier oplevet ekstreme regnhændelser med store miljømæssige og sociale konsekvenser. Dette studie undersøger et byopland for at vurdere oversvømmelsers gentagelsesperiode, dvs. hvor ofte en oversvømmelse forventes at indtræffe i gennemsnit. Vi bruger historiske regnserier til at analysere sammenhængen mellem regns gentagelsesperiode og oversvømmelsers gentagelsesperiode. Oplandet har stor terrænvariation med både stejle og flade områder, og vandet strømmer på komplekse måder gennem kloaksystemet og på overfladen. Ud fra de historiske data udvælges 10 ekstreme regnhændelser, som simuleres for at undersøge de tilhørende oversvømmelser. Studiet drøfter også, om historiske regnserier er mere egnede end syntetisk regn (modellavede regnprofiler) til oversvømmelsesmodellering. For hver hændelse beregnes maksimal vanddybde, maksimal udbredelse og maksimal vandvolumen ved oversvømmelse. Disse mål sammenlignes for at vurdere, hvilket der bedst kan bruges til at bestemme oversvømmelsers gentagelsesperiode.

Denmark has experienced extreme rainfall in recent decades, causing significant environmental and social impacts. This study examines an urban catchment to estimate the return period of floods—that is, how often a flood is expected to occur on average. We use historical rainfall records to analyse the link between the return period of rainfall and the return period of flooding. The catchment has highly variable terrain, with both steep and flat areas, and water moves in complex ways through the drainage network and across the surface. From the historical series, 10 extreme rainfall events are selected and simulated to study the resulting floods. The study also discusses whether historical rainfall series are more suitable than synthetic rainfall (model-generated rain patterns) for flood modelling. For each event, we calculate the maximum flood depth, maximum flood extent, and maximum flood volume, and compare these indicators to identify which best assesses the flood return period.

[This abstract was generated with the help of AI]

Urban area ; return period ; flood ; assessment

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Casas Cardona, Laura:

• The Hypertrophic Estuary of Mariager Fjord: Pollution of CoastalWaters (2015)