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Meteorological origin of the flood and its hydrological effects 
in the Odra and Vistula rivers 
Zbigniew Dziadziuszko & Wlodzimierz Krzymiski 
Institute of Meteorology and Water Management 
Maritime Branch 
Waszyngtona 42 
81-342 Gdynia 
Abstract 
Meteorological conditions and in particular heavy rains in the Southern part of Poland 
resulted in unusual increase of the water levels in the rivers, mainly in the southern 
catchment areas of Odra and Vistula. Due to the rains, in some cases 50-60 mm/day, 
which occurred in 30.06. - 1.07.97 the retention of the soil has decreased significantly. 
After the rainy period at the beginning of July (5-9.07) the flood practically started. 
The area covered by those rains was app. 12,000 km 2 . The highest precipitation (586 
mm in 5 th - 9 th of July) was observed near Lysa Hora in the catchment area of Odra in 
Czech Republic. The second period of the rains started on 18 th of July and persisted 
until 22 nd of July. They were caused by the low area which was blocked by the high and 
thus practically it become stationary. In some areas of Sudety Mountains the sum of 
precipitation exceeded 200 mm in 15-23.07. The rainy area covered both upper Odra 
and Vistula catchment areas After 24 th of July the third period of rains occurred. Its 
centre was placed over San (tributary of Vistula) in the south-eastern part of Poland. 
Those rains didn’t influence flood event significantly. 
Both natural (direct) and indirect factors caused such extent of the summer flood. The 
rains caused increase of the water levels but from the other hand the breaking of the 
river banks (expected and unexpected) caused entering of the water into flood areas. 
The flood started in the area of the tributaries of Odra and Nysa Klodzka several hours 
after the rain occurrence. In some tributaries of Nysa Klodzka the highest water was 
observed just 2-4 hours after the maximum of precipitation. The flood waves from both 
upper Odra and Opawa overlapped each other in the centre of the valley near Ostrava. 
This phenomenon resulted with unusual water level - 660 cm (flow - 2010 m 3 /s) in 
Bohumin. That wave increased near the mouth of Olza, the maximum water level 
increased by 850 cm in Miedonia then. Such sudden increase of water quantity caused 
most serious damages and disasters within the flooded area. 
The second very long (150-200 km) flood wave was formed after the rains in 17- 
21.07.97. Its height exceeded absolute maximum since 1813 year within the catchment 
area of upper Odra. 
The two waves originated from upper part of the river joint finally in the lower Odra 
area forming high water persisting since 22 nd of July until mid-August. Outflow of the 
wave into Szczecin Lagoon occurred in 30.07. - 6.08.97 as 200 years water flow (3670 
m 3 /s). 
The flood in the catchment area of Wisla was slightly different from that occurred 
within Odra drainage area, however in the upper part of the river some big areas were