Rainfall variability in the mountain forest catchments of Černá Opava tributaries in the Jeseníky Mountains

An unprecedented bark beetle outbreak has led to a significant decline in forest cover in Central Europe in the last 10 years, affecting an area estimated at more than 200 000 ha in the Czech Republic. Among the many ecological threats associated with extensive clearings, the potential alteration of hydrological processes is one of the most important. Therefore, after 2022, the precipitation-runoff balance in three catchments in the Jeseníky Mts. area was studied. This study focuses on the rainfall variability within the area, which was measured using 24 rain gauges deployed to cover different altitudes as well as the geographical exposures of the mountain catchments. Precipitation data was evaluated based on seven-day totals within the frost-free period. There was a significant increase in precipitation with altitude (12% increase for every 100 m a.s.l.) but only in less than half (48.7%) of the evaluated periods. No significant trend was demonstrated in the remaining periods, and a negative trend in precipitation with altitude was identified in 8.9% of cases. Additionally, the role of exposure was insignificant, although a tendency towards slightly lower precipitation was found for the eastern exposure at altitudes up to 1 000 m a.s.l., which may be related to the prevailing wind direction. We concluded that even a relatively dense monitoring network is not necessarily sufficient to provide accurate precipitation data in forested catchments, especially in mountain areas. Under such conditions, the use of complex models that also use radar data is recommended.