172
D. Wrzesi´ nski
strong human impact on the water cycle. It is observed, among others, in the Vistula
River between gauges Goczałkowice and Nowy Bieru´ n, in rivers of the Silesian
Foothills, in the Skawa River, and in the Odra River catchment in its tributaries –
the Bystrzyca River with the Piława River, and the ´
Sl˛ eza River. In most rivers, the
low-water phase has a relatively stable or stable date of occurrence, usually falling
for the autumn, autumn–winter, and winter periods. A stable low-season period is
characteristic of many rivers in the Dunajec River catchment and the tributaries of
the Odra – the Kaczawa River and the Bystrzyca River with the Strzegomka River in
the Sudety Mountains. Relatively unstable minima occur in individual rivers in the
Sudety Mountains and the San River catchment in the summer-autumn period. In the
annual cycle, the sequence of hydrological periods is represented by low low-water
(or normal period) → average high-water → normal period (or low low-water) →
low high-water → average low-water. Sometimes the high-water period in spring is
prolonged and connected with the high-water period in summer (the San River).
Type 5 – the pluvial-nival regime. This regime is represented by rivers whose
average flow of the summer month is higher or almost equal to the average flow of the
spring month, and in both cases, the flow is generally 130–180% of the average annual
flow. Such regularity in the Sudety Mountains is exhibited by the Nysa Kłodzka River,
and in the Carpathian Mountains by the upper Vistula River, the Soła and Uszwica
rivers, and rivers in the Dunajec catchment. At the country level these rivers are
distinguished by the highest flows, which on average are about 500 mm, and in the
case of mountain streams are higher than 1000 mm, or even 1500 mm (the Potok
Ko´ scieliski River, the Białka River at gauge Łysa Polana). That flow consists mainly
of surface flow, while the share of the groundwater supply is usually lower than
40%. As a rule, rivers with that regime are also distinguished by high variability
of daily flows (Cv > 1.5). The date of flooding in these rivers is relatively stable
and stable. Such a feature of the flow regime is characteristic of rivers in the Nysa
Kłodzka, Soła and Dunajec catchments, in which the stable date of monthly maxima
falls in the spring or the spring–summer period. In turn, strongly stable maxima are
recorded only in the Białka and Potok Ko´ scieliski rivers (May–July). In most rivers,
the minimum monthly flows have a relatively stable date of occurrence, usually
falling in the autumn, autumn and winter periods, and in the Tatra Mountains rivers
in the winter period. Many rivers in the Dunajec River catchment are characterized
by the stable low-water period. The most stable date of the appearance of monthly
minima is characteristic only of the Tatra Mountains streams: the Białka and Potok
Ko´ scieliski. In the sequence of hydrological periods, the regime of these rivers is
characterized by the occurrence of the average (low) low-water → normal period →
long, high high-water in spring–summer → normal period → average low-water.
9.3 Changes of Flow Regime Patterns
Contemporary climate changes and the human impact on water relations make the
features of the river flow regime change. Studies on the regularity of their variability
in the multi-year period (1951–2010) and the hydrological cycle allow identifying
D. Wrzesi´ nski
strong human impact on the water cycle. It is observed, among others, in the Vistula
River between gauges Goczałkowice and Nowy Bieru´ n, in rivers of the Silesian
Foothills, in the Skawa River, and in the Odra River catchment in its tributaries –
the Bystrzyca River with the Piława River, and the ´
Sl˛ eza River. In most rivers, the
low-water phase has a relatively stable or stable date of occurrence, usually falling
for the autumn, autumn–winter, and winter periods. A stable low-season period is
characteristic of many rivers in the Dunajec River catchment and the tributaries of
the Odra – the Kaczawa River and the Bystrzyca River with the Strzegomka River in
the Sudety Mountains. Relatively unstable minima occur in individual rivers in the
Sudety Mountains and the San River catchment in the summer-autumn period. In the
annual cycle, the sequence of hydrological periods is represented by low low-water
(or normal period) → average high-water → normal period (or low low-water) →
low high-water → average low-water. Sometimes the high-water period in spring is
prolonged and connected with the high-water period in summer (the San River).
Type 5 – the pluvial-nival regime. This regime is represented by rivers whose
average flow of the summer month is higher or almost equal to the average flow of the
spring month, and in both cases, the flow is generally 130–180% of the average annual
flow. Such regularity in the Sudety Mountains is exhibited by the Nysa Kłodzka River,
and in the Carpathian Mountains by the upper Vistula River, the Soła and Uszwica
rivers, and rivers in the Dunajec catchment. At the country level these rivers are
distinguished by the highest flows, which on average are about 500 mm, and in the
case of mountain streams are higher than 1000 mm, or even 1500 mm (the Potok
Ko´ scieliski River, the Białka River at gauge Łysa Polana). That flow consists mainly
of surface flow, while the share of the groundwater supply is usually lower than
40%. As a rule, rivers with that regime are also distinguished by high variability
of daily flows (Cv > 1.5). The date of flooding in these rivers is relatively stable
and stable. Such a feature of the flow regime is characteristic of rivers in the Nysa
Kłodzka, Soła and Dunajec catchments, in which the stable date of monthly maxima
falls in the spring or the spring–summer period. In turn, strongly stable maxima are
recorded only in the Białka and Potok Ko´ scieliski rivers (May–July). In most rivers,
the minimum monthly flows have a relatively stable date of occurrence, usually
falling in the autumn, autumn and winter periods, and in the Tatra Mountains rivers
in the winter period. Many rivers in the Dunajec River catchment are characterized
by the stable low-water period. The most stable date of the appearance of monthly
minima is characteristic only of the Tatra Mountains streams: the Białka and Potok
Ko´ scieliski. In the sequence of hydrological periods, the regime of these rivers is
characterized by the occurrence of the average (low) low-water → normal period →
long, high high-water in spring–summer → normal period → average low-water.
9.3 Changes of Flow Regime Patterns
Contemporary climate changes and the human impact on water relations make the
features of the river flow regime change. Studies on the regularity of their variability
in the multi-year period (1951–2010) and the hydrological cycle allow identifying