20
K. Kubiak-Wójcicka
The maximum precipitation is in the summer months (June–August). The July
maximum is greatest, but in some stations (mainly in the north and west of the
country) the maximum happens in August. During this period, precipitation is about
2–3 times greater than in winter periods (over 4 times greater in the Tatra mountains).
The minimum precipitation occurs from January to March [8].
In addition to sums of annual precipitation, average air temperature is an important
factor in the size of water resources. The spatial and temporal variability of thermal
conditions in Poland in the period 1951–2015 was analysed by [9]. The annual
average air temperature ranged from 6.4 °C in north-eastern Poland to 8.9 °C in
western Poland. In meteorological stations on the Baltic Sea and in central Poland,
the annual average air temperature is not lower than 8 °C. In the most elevated
region of the country (the Tatra Mountains, southern Poland), the average annual air
temperature was-0.5 °C at Kasprowy Wierch (1,986 m above sea level).
2.2.2 The Hydrographic Network of Poland
Poland’s hydrographic network comprises rivers, canals, lakes, and man-made reservoirs. There are 4,656 rivers in Poland according to IMGW, including 2,913 watercourses (62.6%) with a catchment area of less than 50 km
2 . Of the total 488 rivers
with a catchment exceeding 200 km
2 , as many as 250 (over 51%) are in the Vistula
basin, 177 (36.3%) are in the Oder, and 61 belong to other catchments. Those 488
rivers total 33,456 km in length. The density of Poland’s river system is about average
for Europe, although it is very spatially diverse, ranging from over 3 km/km
2 in the
Carpathians to 0.2 km/km
2 in sandy areas of northern Poland and karst areas of
eastern Poland [10]. Table 2.1 lists the largest river basins in Poland—those of more
than 10,000 km
2 —with the largest areas being the Vistula basin (194,000 km
2 ) and
the Oder basin (119,000 km
2 ).
Table 2.1 List of the largest rivers in Poland [1]
River
Parent
Basin area (km 2 )
Length (km)
Total
of which in Poland
Total
of which in Poland
Vistula
Baltic Sea
193,960
168,868
1,022
1,022
Oder
Baltic Sea
119,074
106,043
840
726
Narew
Vistula
74,527
53,846
499
443
Warta
Oder
54,520
54,520
795
795
Bug
Narew
38,712
19,239
774
590
Note´ c
Warta
17,302
17,302
391
391
San
Vistula
16,877
14,426
458
457
Wieprz
Vistula
10,497
10,497
349
349
K. Kubiak-Wójcicka
The maximum precipitation is in the summer months (June–August). The July
maximum is greatest, but in some stations (mainly in the north and west of the
country) the maximum happens in August. During this period, precipitation is about
2–3 times greater than in winter periods (over 4 times greater in the Tatra mountains).
The minimum precipitation occurs from January to March [8].
In addition to sums of annual precipitation, average air temperature is an important
factor in the size of water resources. The spatial and temporal variability of thermal
conditions in Poland in the period 1951–2015 was analysed by [9]. The annual
average air temperature ranged from 6.4 °C in north-eastern Poland to 8.9 °C in
western Poland. In meteorological stations on the Baltic Sea and in central Poland,
the annual average air temperature is not lower than 8 °C. In the most elevated
region of the country (the Tatra Mountains, southern Poland), the average annual air
temperature was-0.5 °C at Kasprowy Wierch (1,986 m above sea level).
2.2.2 The Hydrographic Network of Poland
Poland’s hydrographic network comprises rivers, canals, lakes, and man-made reservoirs. There are 4,656 rivers in Poland according to IMGW, including 2,913 watercourses (62.6%) with a catchment area of less than 50 km
2 . Of the total 488 rivers
with a catchment exceeding 200 km
2 , as many as 250 (over 51%) are in the Vistula
basin, 177 (36.3%) are in the Oder, and 61 belong to other catchments. Those 488
rivers total 33,456 km in length. The density of Poland’s river system is about average
for Europe, although it is very spatially diverse, ranging from over 3 km/km
2 in the
Carpathians to 0.2 km/km
2 in sandy areas of northern Poland and karst areas of
eastern Poland [10]. Table 2.1 lists the largest river basins in Poland—those of more
than 10,000 km
2 —with the largest areas being the Vistula basin (194,000 km
2 ) and
the Oder basin (119,000 km
2 ).
Table 2.1 List of the largest rivers in Poland [1]
River
Parent
Basin area (km 2 )
Length (km)
Total
of which in Poland
Total
of which in Poland
Vistula
Baltic Sea
193,960
168,868
1,022
1,022
Oder
Baltic Sea
119,074
106,043
840
726
Narew
Vistula
74,527
53,846
499
443
Warta
Oder
54,520
54,520
795
795
Bug
Narew
38,712
19,239
774
590
Note´ c
Warta
17,302
17,302
391
391
San
Vistula
16,877
14,426
458
457
Wieprz
Vistula
10,497
10,497
349
349