Introduction

The Elbe has its spring in the Czech mountains (Riesengebirge) in an altitude of 1386.3 maSL and its river mouth near Cuxhaven (Germany) in the North Sea. It has a length of 1094.3 km, from which 727 km (66.4 %) of the whole length are located in Germany and 367 km (33.6 %) in the Czech Republic. The Elbe river basin amounts to 148 268 km² and flows across Germany (97 175 km²; 66.54 %), the Czech Republic (49 933 km²; 33.68 %), Austria (921 km²; 0.62 %) and Poland (239 km²; 0.16 %).

Since the beginning of 2003 the JRC has contacted Germany and the Czech Republic in order to get necessary high resolution data such as observed daily and/or hourly discharge data, river geometric data (e.g. cross sections), data about reservoirs and retention polders as well as large lakes and river bed enlargement information (dyke movement, floodplain enlargement). The data collection process was slowed down because of the scatterered responsibilities of the National and Regional Water Authorities especially in Germany.

Case Studies And Scenario Work

The International river conventions like IKSo/MKoo (oder/odra), IKSE/MKoL (Elbe/Labe) and IKSD/ICPDR/ (Danube), to which the European Commission is a contracting party, are the main structures in handling the transboundary items. The European Commission is represented in the relevant flood expert groups which guarantee the necessary links to specialized services of Member-States and Accession countries in order to complement ongoing work at national level. In addition to the EFAS activities for the Elbe, the JRC is supporting the activities and measures in the framework of the "Flood Action Plan" of the IKSE (International Commission for Protection of the River Elbe). Within the framework of this Elbe Flood Action Plan, the JRC carries out two studies for the German Elbe River basin.

The FIRST STUDY for the Elbe Flood Action Plan consists of an evaluation of the German hydropower reservoirs on the river Saale. This study focuses on the development of methods for the assessment of the steering influence of the Saale Reservoirs (Bleiloch, Hohenwarte) to the flood regime downstream of the reservoirs. The target is the calculation of simulated flood waves and simulated time series of annual flood peak discharges on gauges of Elbe and Saale (Figure 1, 2) as well as on their tributaries influenced and non influenced by the reservoirs. Thus the influence of individual reservoirs can be assessed as well as the possibilities for an optimal reservoir steering with regard to flood protection downstream.

Figure 1: Saale Cascade

Figure 2: Comparison of observed and simulated cumulative discharge
of reservoir Hohenwarte for 1996-1998

The SECoND STUDY consists of an evaluation of the possibilities of using new potential flood retention (Figure 3) to calculate the time delay and the prolongation of the flood wave in the Elbe River to during flood events as well as how the polders eventually contributes to decrease the flood peak in the Elbe. Aim is to work out a decision base for planning and realization of measures to build controlled flood polders. Possible effects arising from upstream measures in the Czech Republic (e.g. results of reservoir study of the Czech Republic) will be included. In addition an assessment of local advantages and disadvantages will be made.

Figure 3: Possible locations for steered polders

In this context the Flood Group of the IKSE has discussed and agreed a large amount of planned scenario combinations within the German river basins (Table 1). These scenario calculations will be linked with the results of the separate Reservoir Study of the Czech Republic. Relating to the planned time schedule the scenario calculations should be finished at the end of 2005.

Table 1: Planned scenarios on German Elbe

Model Calibration And Initial Results

To facilitate the calibration, validation and testing of the LISFLOOD model for the Elbe catchment, first of all the Czech part of the Elbe is evaluated separately from the German part. For the German part the Czech inflow near the border or at the gauge Dresden is used. Initial calibration results for the Elbe are shown in the figures.

Figure 4: First Results of Model Calibration of main Elbe at gauge Bernburg 1996/1998

For the middle and the lower course of the Elbe a dynamic wave approach will be used. For this purpose the German administrations provided the JRC with more than 3000 cross sections.

More information:

• M. Gierk, J. Younis, J. A. Szabó, M. Kalaš, K. Bódis, J. Van der Knijff (2004)
  EFAS - Status of Data Collection for the Elbe River Basin and initial Results of hydrological Model Calibration for the German Elbe on 1 km In: 2^nd EFAS workshop, Book of Abstracts, (Editors: J. Thielen, A. de Roo), European Communities, S.P.I. 04.187 (2004)

• J. Younis, J. A. Szabó, M. Kalaš, M. Gierk, K. Bódis, A. de Roo, J. Thielen, J. van der Knijff (2004)
  Calibration and Validation of the LISFLOOD Model to the Czech Part of Elbe and odra River Basins In: 2^nd EFAS workshop, Book of Abstracts, (Editors: J. Thielen, A. de Roo), European Communities, S.P.I. 04.187 (2004)

Contact person: Meike Gierk (meike.gierk@jrc.ec.europa.eu)

Introduction - Floods

Elbe Case Study

Danube Case Study

Flash Floods

Climate Change

Flood Hazard

Flood Risk

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