Abstract
Abstract. Study of heavy rain events and their spatial distribution are of great importance. Such events cause local flooding, accelerate soil erosion and cause damage on property. Data for this study were derived by Sokol and Bližňák (2009) from radar reflectivity and daily rain gauge measurements for the period of 2002–2008. We selected heavy rain events using spatial and intensity constrains. We studied relationships between heavy rains, altitude and terrain roughness. Heavy rain totals correlate with both altitude and terrain roughness globally over the Czech Republic. The correlation is also significant for extreme heavy rain totals. The correlation of heavy rain intensities with altitude was not proven. The highest rates of average intensities are located in the south-eastern parts of the Czech Republic. The spatial distribution of heavy rain frequencies strongly corresponds to the spatial distribution of heavy rain totals. The highest percentage of heavy rains in total precipitation is located in the north-west of the Czech Republic. The extreme heavy rains occupy higher altitudes.
Highlights
Heavy rains during the warm period of the year (April to September) are usually caused by strong convection of air mass
We use the same basic data as Sokol and Bliznak (2009) – the precipitation data derived from radar reflectivity and daily rain gauge measurements by merging procedure published by Sokol (2003)
We identified clusters composed of non-null pixels. These clusters represent rain events from which we selected the heavy rain events as the ones fulfilling the following conditions: i) average precipitation of the cluster is higher than a chosen threshold Tprec maximum precipitation within the cluster is higher than 15 mm
Summary
Heavy rains during the warm period of the year (April to September) are usually caused by strong convection of air mass. Such rain events cause local flash floods, accelerate soil erosion and cause damage on property. They are hard to be predicted and the knowledge about their spatial distribution (over the Czech Republic) is insufficient. It is well-known that the spatial properties of precipitation correspond to orography. Basist et al (1994) studied relationships between annual precipitation and six topographic
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