1 Introduction to the “Management of Water Resources in Poland”
7
paid to the rational use of resources and their protection in order to maintain water
quality.
Summing up this part of the volume, it should be pointed out that Poland’s water
resources are small and therefore require proper management.
1.4 Change of Flow in Polish Rivers
Part two of the volume is entitled “Change of Flow in Polish Rivers”. The chapter
“Flow Regime Patterns and their Changes” characterizes the hydrological regime
of the Polish rivers. The article distinguishes and characterizes five types of hydrological regime of rivers in Poland. In the lowland areas, three simple nival regimes
are dominant: poorly, moderately and well-formed, while in the highlands and in the
mountains two complex regimes: nival-pluvial and pluvial-nival can be distinguished.
Their spatial differentiation results from the diversity of environmental conditions
of the basin, which leads to the appearance of various forms of river supply, seasonality of the river flow and its variability. The paper also describes how contemporary
changes in climatic conditions and human impact on water relations affect the characteristics of the river flow regime. Multiannual and seasonal changes in river flows
were found, which are of particular importance in the spring and summer seasons
due to the adopted criteria of the typology of the river regime. Studies confirmed
that the destabilization of the flow regime characterisitcs of many rivers in Poland
may be affected by changing climatic conditions. It is caused by the varied intensity
of macro-scale air circulation types, such as the North Atlantic Oscillation, whose
impact is not strong but noriceable and statistically significant, especially in the
winter season.
The purpose of the chapter entitled “Flow Seasonality in Two Big Polish Rivers
– the Vistula and the Oder” is to determine the seasonality of flows of the two
largest Polish rivers: the Vistula and the Oder. For this purpose, the authors used the
seasonality index (IS), half-life date (PK), half-flow date (TPO) and seasonality factor
(GMO) for 14 hydrological stations located along the Vistula and 11 hydrological
stations located along the Oder in 1951–2016. The highest features of IS are for the
upper part of rivers. Then the seasonality index decreases sharply due to the sum of
flows from river inflows, which are characterized by different outflow conditions. A
clear correlation was found between the concentration date (PK) and the half-flow
date (TPO) for both rivers. Similarity of PK indicators in individual years for the
Vistula and Oder rivers in the analyzed multi-year period occurred in the lower and
middle rivers. In the upper sections, the differences between the rivers are greater, and
over the past 30 years the tendency to an earlier concentration date of the Oder has
been increasing. Changes in the IS flow seasonality index showed high variability and
depended on the catchment size. In contrast to PK, relatively the greatest similarities
between the Vistula and the Oder were recorded for their upper sections. With the
increase in the catchment, the seasonality of the Vistula flows became much higher
7
paid to the rational use of resources and their protection in order to maintain water
quality.
Summing up this part of the volume, it should be pointed out that Poland’s water
resources are small and therefore require proper management.
1.4 Change of Flow in Polish Rivers
Part two of the volume is entitled “Change of Flow in Polish Rivers”. The chapter
“Flow Regime Patterns and their Changes” characterizes the hydrological regime
of the Polish rivers. The article distinguishes and characterizes five types of hydrological regime of rivers in Poland. In the lowland areas, three simple nival regimes
are dominant: poorly, moderately and well-formed, while in the highlands and in the
mountains two complex regimes: nival-pluvial and pluvial-nival can be distinguished.
Their spatial differentiation results from the diversity of environmental conditions
of the basin, which leads to the appearance of various forms of river supply, seasonality of the river flow and its variability. The paper also describes how contemporary
changes in climatic conditions and human impact on water relations affect the characteristics of the river flow regime. Multiannual and seasonal changes in river flows
were found, which are of particular importance in the spring and summer seasons
due to the adopted criteria of the typology of the river regime. Studies confirmed
that the destabilization of the flow regime characterisitcs of many rivers in Poland
may be affected by changing climatic conditions. It is caused by the varied intensity
of macro-scale air circulation types, such as the North Atlantic Oscillation, whose
impact is not strong but noriceable and statistically significant, especially in the
winter season.
The purpose of the chapter entitled “Flow Seasonality in Two Big Polish Rivers
– the Vistula and the Oder” is to determine the seasonality of flows of the two
largest Polish rivers: the Vistula and the Oder. For this purpose, the authors used the
seasonality index (IS), half-life date (PK), half-flow date (TPO) and seasonality factor
(GMO) for 14 hydrological stations located along the Vistula and 11 hydrological
stations located along the Oder in 1951–2016. The highest features of IS are for the
upper part of rivers. Then the seasonality index decreases sharply due to the sum of
flows from river inflows, which are characterized by different outflow conditions. A
clear correlation was found between the concentration date (PK) and the half-flow
date (TPO) for both rivers. Similarity of PK indicators in individual years for the
Vistula and Oder rivers in the analyzed multi-year period occurred in the lower and
middle rivers. In the upper sections, the differences between the rivers are greater, and
over the past 30 years the tendency to an earlier concentration date of the Oder has
been increasing. Changes in the IS flow seasonality index showed high variability and
depended on the catchment size. In contrast to PK, relatively the greatest similarities
between the Vistula and the Oder were recorded for their upper sections. With the
increase in the catchment, the seasonality of the Vistula flows became much higher