Department Urban Water Management

Due to climate change, extreme precipitation events are becoming more frequent and climate models indicate that they will increase in frequency and intensity in the future. Construction and planning decisions made on the basis of historical precipitation data are not representative of the future, which is why Eawag is researching a solution to this problem under the name Future Rainfall. The aim of the Future Rainfall project is to provide synthetic future rainfall time series in a high spatial and temporal resolution for engineering applications, e.g. for runoff and flood simulations.

The project is divided into three main tasks. These include: (1) the generation of synthetic precipitation time series based on historical data, (2) spatial interpolation, and (3) the integration of future scenarios. To achieve these tasks, we are using a weather generator algorithm to statistically generate synthetic future rainfall time series that are adapted to the local rainfall characteristics.      

1. Generation of synthetic rainfall time series based on historical data

Everything starts with a rainfall model which is calibrated using historical data and optimised in the first project step to reproduce a synthetic rainfall time series at an observed location. In addition to the comparison of observed and historical data, the generator is also validated on runoff models (SWMM) and optimised for their performance.

2. Spatial interpolation

In the second phase of the project, a spatial interpolation model will be integrated that can generate rainfall time series at locations where no rain gauges are available. A resolution of 2km is targeted.

3. Future scenarios

In order to implement information on future events, data from climate models will be used.