Hydrological simulation of extreme flood scenarios for operational flood management at the Middle Elbe river

Operational flood management at the Middle Elbe river requires comprehensive knowledge about the magnitude and characteristics of possible extreme flood events. Since these events are not sufficiently included in available historical records, an extended sample of extreme flood events was generated by hydrological scenario simulation. Present paper emphasises simulations in the German part of the catchment of the Middle Elbe river and introduces the stochastic-conceptual precipitation-runoff model which was developed for this task. After validation of this model and its coupling with the weather forecast model COSMO and hydraulic-numerical models, a set of 25 flood scenarios could be simulated and provided for a planning of flood protection measures. Analysis of simulated scenarios reveal that extreme flood events at the Mulde and Middle Elbe rivers may have a wide spectrum of characteristics and may considerably exceed the magnitude of past flood events (e.g., those of August 2002)

Modelling spring flood in the area of the Upper Volga basin

Integrated river-basin management for the Volga river requires understanding and modelling of the flow process in its macro-scale tributary catchments. At the example of the Kostroma catchment (16 000 km²), a method combining existing hydrologic simulation tools was developed that allows operational modelling even when data are scarce. Emphasis was placed on simulation of three processes: snow cover development using a snow-compaction model, runoff generation using a conceptual approach with parameters for seasonal antecedent moisture conditions, and runoff concentration using a regionalised unit hydrograph approach. Based on this method, specific regional characteristics of the precipitation-runoff process were identified, in particular a distinct threshold behaviour of runoff generation in catchments with clay-rich soils. With a plausible overall parameterisation of involved tools, spring flood events could successfully be simulated. Present paper mainly focuses on the simulation of a 16-year sample of snowmelt events in a meso-scale catchment. An example of regionalised simulation in the scope of the modelling system "Flussgebietsmodell" shows the capabilities of developed method for application in macro-scale tributary catchments of the Upper Volga basin

Determination of strain in moving objects by X-ray diffraction using synchrotron radiation

A novel method for the determination of strain in moving objects is presented. It is based on X-ray diffraction in parallel-beam geometry. This geometry is not affected by errors of the sample position. Thus also moving objects can be investigated. Feasibility tests were made investigating the rotor blades of a turbo pump during rotation

Flood-risk mapping: contributions towards an enhanced assessment of extreme events and associated risks

Currently, a shift from classical flood protection as engineering task towards integrated flood risk management concepts can be observed. In this context, a more consequent consideration of extreme events which exceed the design event of flood protection structures and failure scenarios such as dike breaches have to be investigated. Therefore, this study aims to enhance existing methods for hazard and risk assessment for extreme events and is divided into three parts. In the first part, a regionalization approach for flood peak discharges was further developed and substantiated, especially regarding recurrence intervals of 200 to 10 000 years and a large number of small ungauged catchments. Model comparisons show that more confidence in such flood estimates for ungauged areas and very long recurrence intervals may be given as implied by statistical analysis alone. The hydraulic simulation in the second part is oriented towards hazard mapping and risk analyses covering the whole spectrum of relevant flood events. As the hydrodynamic simulation is directly coupled with a GIS, the results can be easily processed as local inundation depths for spatial risk analyses. For this, a new GIS-based software tool was developed, being presented in the third part, which enables estimations of the direct flood damage to single buildings or areas based on different established stage-damage functions. Furthermore, a new multifactorial approach for damage estimation is presented, aiming at the improvement of damage estimation on local scale by considering factors like building quality, contamination and precautionary measures. The methods and results from this study form the base for comprehensive risk analyses and flood management strategies

Operational flood management under large-scale extreme conditions, using the example of the Middle Elbe

In addition to precautionary or technical flood protection measures, short-term strategies of the operational management, i.e. the initiation and co-ordination of preventive measures during and/or before a flood event are crucially for the reduction of the flood damages. This applies especially for extreme flood events. These events are rare, but may cause a protection measure to be overtopped or even to fail and be destroyed. In such extreme cases, reliable decisions must be made and emergency measures need to be carried out to prevent even larger damages from occurring. <br><br> Based on improved methods for meteorological and hydrological modelling a range of (physically based) extreme flood scenarios can be derived from historical events by modification of air temperature and humidity, shifting of weather fields and recombination of flood relevant event characteristics. By coupling the large scale models with hydraulic and geotechnical models, the whole flood-process-chain can be analysed right down to the local scale. With the developed GIS-based tools for hydraulic modelling <i>FlowGIS</i> and the Dike-Information-System, (IS-dikes) it is possible to quantify the endangering shortly before or even during a flood event, so the decision makers can evaluate possible options for action in operational mode