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There have been numerous accounts of rivers retreating so much that land that hasn't been dry in almost 1000 years is again in fact dry.
Torrential rain have also become a lot more frequent where i live, where some locations gets weeks or months worth of rain in 30 minutes. Again, the amount of water may not be different, but the sheer volume and logistics of getting rid of it again may cause temporary flooding.
As for the current flooding in central europe, there were places that got a years worth of rainfall in days, which again causes rivers to transport a lot more water, and when the storm moves downstream it again pours more water down, into the already full river.
This means a few things: Salinity of the sea perpetrates deeper on land. The risk of drinkable water buffers getting depleted grows. The risk for flooding rises.
We show that the past three decades were among the most flood-rich periods in Europe in the past 500 years, and that this period differs from other flood-rich periods in terms of its extent, air temperatures and flood seasonality. We identified nine flood-rich periods and associated regions. Among the periods richest in floods are 1560–1580 (western and central Europe), 1760–1800 (most of Europe), 1840–1870 (western and southern Europe) and 1990–2016 (western and central Europe). In most parts of Europe, previous flood-rich periods occurred during cooler-than-usual phases, but the current flood-rich period has been much warmer. Flood seasonality is also more pronounced in the recent period. For example, during previous flood and interflood periods, 41 per cent and 42 per cent of central European floods occurred in summer, respectively, compared with 55 per cent of floods in the recent period. The exceptional nature of the present-day flood-rich period calls for process-based tools for flood-risk assessment that capture the physical mechanisms involved, and management strategies that can incorporate the recent changes in risk.
TL:DR from a fireman:
My father has always been saying "water will find a way". As progress+civilization expand, there is less and less free/open ground. Roads, parking lots, shopping centers, more roads, train tracks (elevated = blocking water), rivers being covered, fires, etc. Water doesn't care, it wants to go through - it will go through.
In the "good old days" it would rain X amount up on that mountain, and 10% of X amount will find its way towards your town. Now, burn that mountain, then add 50 roads/highways/etc. Now 40% of X amount will find its way towards your town.
By the way your town has 30% less free ground (roads, parking lots, etc.)
Thus, floods. You can (rightfully so) poke 100 holes on the above, because each town/village/mountain/river is different, but the point/spirit remains. "Water will find a way".
EDIT: I am always fascinated to read in the news that the (e.g.) "Old lake" flooded again after 30 years". Guys!!! The name of the location is "Old Lake", which means that for about a couple of million years water has been converging there. The fact that some people built there, doesn't Water/Nature from doing its thing.
Extreme floods in central Europe over the past 500 years: Role of cyclone pathway “Zugstrasse Vb” M. Mudelsee, M. Börngen, G. Tetzlaff, U. Grünewald First published: 02 December 2004