Changes in short-term rainfall characteristics in long station series

Changes in frequency and intensity of precipitation belong to important potential impacts of climate change. Moreover, characteristics of short-term rainfalls, especially their intensity and design values, are very important for technical (e.g., sewage system) and hydrological practice. However, the measurement of rainfall intensity and related data processing are fairly complicated.

The rainfall intensity has been regularly measured in the Czech Republic since 1898 with a few manual pluviographs. Automatic rain gauges started to replace them in the late 1990s. Nowadays, a large part of historical pluviographs records has been digitalized. Both the digitalized pluviographs records and the automatic rain gauge measurement provide rainfall series in temporal resolution of 1 minute. Concerning the joined series of these two types of measurement, the relatively long series of rainfall intensity are available. The series longer than 60 years are available for 20 stations of the Czech Hydrometeorological Institute.

In our contribution, we focus on changes in characteristics of short-term rainfalls of varying duration (10–360 min) at a few selected stations with the longest series of measurement. Differences among short-term rainfall datasets gained from different sub-periods of the whole measurement period are analyzed. Besides datasets characteristics (e.g., annual maxima, numbers of rainfalls above a threshold) the return levels estimated from different sub-periods are compared. As the joined manual pluviographs and automatic rain gauge series are considered, a potential inhomogeneity caused by the change of the type of measurement needs to be studied and a possibility to use these series in long-term analyses needs to be discussed.