Interventions of the State Fire Services in the Wielkopolska region (Poland) triggered by extreme precipitation

Precipitation extremes have been intensifying with the warming of climate on a global scale and in most regions of the world (Sun et al., J. Clim. 2021), because in warmer air more water vapor can be stored. According to the Clausius–Clapeyron law, this sensitivity is 6–7% K−1. Analysis of the 99^th percentile of precipitation for Poland for the two periods of 1989–2018 and 1959–1988 (Pińskwar, Int. J. of Climatology 2022),  indicate an increase in sensitivity (6.06%/°C and 5.26%/°C, respectively), and therefore the potential for more extreme precipitation is growing.

In this research we analyze the number of interventions of the State Fire Services in Wielkopolska Region triggered by extreme precipitation. Data (23887 interventions with longitude and latitude) were collected for the period 2010-2021 by 71 units of the Wielkopolska State Fire Service located in the region. Every intervention was linked to the nearest precipitation station (103 gauge stations data from the Institute of Meteorology and Water Management IMGW-PIB). A value of up to 20 km was considered as a representative distance (17810 interventions). Analyses revealed that the highest number of interventions occurred in 2010 (daily maximum of 530 during 24^th of July 2010 with the highest 24h precipitation of 59.5mm; nearly 3% of all interventions). The three highest daily number of interventions in relation to one station occurred in 2021: 9^th of July (99 interventions, with 24h precipitation of 18.6mm and 48h of 69.5 mm, on this day: 326 interventions in Wielkopolska region) and two during 22^nd of June: 85 interventions by 24h precipitation of 136.9mm (Gruszczyn, near Poznan) and 82 interventions by 24h precipitation of 79.4mm (Poznan; both densely populated and impermeable areas). The distance between stations of Poznan and Gruszczyn is only 15.7km. It illustrates, how local and sometimes not recorded is extreme precipitation. For interventions, when precipitation (24h and 5-day) has been not recorded, we use the radar data from IMGW-PIB. The aim of this study is to examine, how extreme precipitation induced interventions of the units of State Fire Service and also to identify the most vulnerable regions in Wielkopolska.

Acknowledgements: Research has been supported by the National Science Centre of Poland [project number 2018/31/B/HS4/03223].