University of Twente Student Theses


Using Ensemble Streamflow Predictions for extreme discharge purposes in the river Rhine

Huiskes, I. (2016) Using Ensemble Streamflow Predictions for extreme discharge purposes in the river Rhine.

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Abstract:Flood situations caused by high discharges in rivers have large societal impacts. Such as damaged properties and the potential loss of lives. Therefore flood protection measures are taken, which are based on the outcomes of extreme discharge distributions. The state of the art is in this field lies in the classical way to obtain annual maximum discharges from discharge series, plot them in one graph and fit a distributions through these annual maxima points. Subsequently discharges belonging to a specific return period can be deduced from this so called fitted extreme discharge distribution. In many river basins in the world relatively short observation records are present. With the classical approach this results in a low number of annual maxima and therefore a major uncertainty in the final extreme discharge distribution. Longer synthetic discharges series are required in order to make a more accurate estimation of extreme discharge distributions. This research creates long weather series which will be transformed into river discharges with a hydrological model thereafter. For the creation of this weather series two numerical weather products of the European Centre for Mid-range Weather Forecasts (ECMWF) are used. The first product is called EraClim which is a re-analysis for global weather in the period 1901 – 2010. The initial conditions of EraClim’s deterministic re-analysis are 10 times slightly perturbed to obtain 10 so called weather ensemble members from 109 year long. The second product concerns GLOFAS which is available during the period 2003 – 2015 with every day weather forecasts for 15-days ahead. The initial conditions of GLOFAS are 51 times perturbed which results in 51 weather ensemble members. All weather ensemble members have an equal probability to occur. The objective of this research is as follows: The objective is to investigate to which extent products provided by numerical weather and hydrological models for operational flow forecasting can be used for estimating high discharge events in rivers having relatively short return periods (< 50 year) and how do these estimates compare with the estimates derived from classical methods.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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