OPAQUE -

Operationelle Abfluss- und Hochwasservorhersage in Quellgebieten   operational discharge and flooding predictions in head catchments

Overview

Working package 1

Early warning about critical atmospheric situations and critical catchment conditions

This work package deals with three main topics:

1. Development of an early warning system for weather conditions favorable of extreme precipitation by means of climatological downscaling.
2. Estimation of soil moisture.
3. Extend, condition and thickness of snow cover for the assimilation into the hydrologic model.

Early warning system

Current weather forecasts shall be refined for flood forecasting by means of statistical models. These models are calibrated using observations of atmospheric conditions (reanalyses), on the one hand, and local weather records (representing the catchment) on the other. The models are adapted to flood-relevant weather conditions. Both deterministic as well as probabilistic weather forecasts shall be considered. The first to identify particularly critical atmospheric circulation types, the latter to obtain an early warning system based on probabilities. The deterministic forecasts are derived from the global forecast model, GME, of the DWD, and probabilistic forecasts from the ensemble prediction system, EPS, of the ECMWF. Of these models, we seek to use those fields that optimally combine predictability and hydrologic relevance, such as pressure and moisture fields.

The statistical models, which are based on weather types and on regression, respectively, have been successfully applied in climate impact research for the provision of precipitation scenarios. For OPAQUE, they will be adapted to the special needs of weather forecasts.

The use of numerical and empirical models thus combines the predictive power of dynamics with the accuracy of long observational records. It is expected to provide a prototype early warning system of heavy rainfall in the range of approximately 3 - 5 days, and thus exceeds the accuracy and reliability of conventional weather forecasts.

Soil moisture

For soil moisture, a suitable observation net for the spatial distribution of soil moisture was set-up with innovative spatial TDR technology measurements, with geo-radar as well as microwave information taken from airplane and satellite. A further goal is the determination of a filter function, which allows a reliable esti- mation of soil moisture in the models LARSIM and NASIM on basis of the observed moisture.

Snow cover

With respect to snow cover a network of ground stations for the measurement of snow thickness and snow moisture is to be developed. Pressure sensors, so-called snow pillows as well as snow moisture measurement cables are used. The data from the distributed, ground-based snow measuring net are geo-statistically combined with procedure for the satellite-based estimation of the spatial expansion of the snow cover, developed in the context of In-Ferno project. Additionally a spatially distributed snow model is used for the description of the energy balance and the temperature and water regime of the snow cover.