High-resolution precipitation forecasts for hydrological risk assessment

Local extreme flooding according to intense rainfall causes problems in Sweden. These problems may increase further in a future, warmer climate. This project investigate the possibilities of high-resolution precipitation forecasts for hydrological risk assessment. The participants are from Karlstad University, SGI and SMHI and the project is funded by MSB (Swedish Civil Contingencies Agency)

Flooding due to heavy rain is a common problem in Sweden, that is expected to increase with a changing climate. The flooding events are often triggered by large-sale, long-lasting rainfall systems (e.g. fronts).

Some environments, notably urban areas, areas with thin soils and steep terrain, respond quickly to local, high-intensity rainfall (e.g. convective cells). These events can occur very suddenly and be over within hours. Nevertheless, the potential for damage on infrastructure, buildings, power plants, etc., is very high.

An early warning system for high-intensity rainfall, which is updated every hour, would potentially provide an effective decision support for operational forecasting, conceivably reducing the damage to society.

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This project aims to;

(1) build up a nationwide database with high-resolution precipitation observations and different forecasts
(2) develop methodology for post-processing the raw forecasts into tailored probability forecasts
(3) evaluate the forecast accuracy and applicability for hydrological risk assessment
(4) assess the economical consequences of intense rainfall and its forecasting.


Forecasting approach and overall project design
In Figure 2, the envisioned project structure is outlined. The project will be organised in four work packages (WPs), where WP1 will focus on the different precipitation products, their evaluation and integration into primary forecasts.

In WP2, tools for post-processing primary forecasts into e.g. probability forecasts and tailoring them for subsequent modelling will be developed.

In WP3, forecasts will be tested and evaluated in a number of relevant case studies.

WP4 will assess economical consequences in terms of damage functions and develop an economical tool.

Figure 2. Envisioned approach and overall project organisation. The coloured boxes represent work packages 1-4.