10 Flow Seasonality in Two Big Polish Rivers – The Vistula …
199
Fig. 10.7 Multiannual changes in concentration date (PK) for six selected water gauges of the
Vistula and the Oder. Explanations: a – water gauges ´
Scinawa (PKs) and Jagodniki (PKj); b – water
gauges Poł˛ ecko (PKp) and Warszawa (PKw); c – water gauges Gozdowice (PKg) and Tczew (PKt);
PKsr – mean concentration date; R – correlation coefficient
accompanied by early concentration date in the Oder (Fig. 10.7b and c). Reverse
situations happened as well. A characteristic feature of the fluctuations observed for
these water gauges are two phases of relatively early concentration date (1961–1972
and 1987–1995) in both rivers, preceded with and separated by periods of highly
variable and occasionally relatively late concentration date. In the last 15 years,
flow concentration date varied greatly in both rivers. Moreover, the trend for earlier
concentration date observed for the upper Oder catchment and indicated above, was
not noticed.
Changes and fluctuations of the seasonality index IS at the gauges closing three
the Oder and the Vistula catchments of different sizes demonstrate great variability
(Fig. 10.8). At the gauges closing the upper parts of the basins (Fig. 10.8a), the
fluctuations were comparable (R = 0.72); similarly as the length of the multiannual
199
Fig. 10.7 Multiannual changes in concentration date (PK) for six selected water gauges of the
Vistula and the Oder. Explanations: a – water gauges ´
Scinawa (PKs) and Jagodniki (PKj); b – water
gauges Poł˛ ecko (PKp) and Warszawa (PKw); c – water gauges Gozdowice (PKg) and Tczew (PKt);
PKsr – mean concentration date; R – correlation coefficient
accompanied by early concentration date in the Oder (Fig. 10.7b and c). Reverse
situations happened as well. A characteristic feature of the fluctuations observed for
these water gauges are two phases of relatively early concentration date (1961–1972
and 1987–1995) in both rivers, preceded with and separated by periods of highly
variable and occasionally relatively late concentration date. In the last 15 years,
flow concentration date varied greatly in both rivers. Moreover, the trend for earlier
concentration date observed for the upper Oder catchment and indicated above, was
not noticed.
Changes and fluctuations of the seasonality index IS at the gauges closing three
the Oder and the Vistula catchments of different sizes demonstrate great variability
(Fig. 10.8). At the gauges closing the upper parts of the basins (Fig. 10.8a), the
fluctuations were comparable (R = 0.72); similarly as the length of the multiannual