70
A. Choi´ nski and R. Skowron
the case of spatial distribution of tarns, their considerably lower densities of occurrence are observed south of the range of the last glaciation. This evidence suggests
their high susceptibility to decline, depending on their age.
5.4 Water Resources of Dam Reservoirs
No favourable conditions for the construction of water reservoirs occur in Poland,
particularly those with considerable surface areas. This results from small water
resources in rivers, considerable variability of outflow, and unfavourable natural
conditions for their construction. The largest reservoirs in terms of surface area as
well as volume are approximate to natural lakes. The reservoir in Solina on the San
River is the largest in terms of water resources. It accumulates 0.47 km
3 of waters,
which constitutes approximately half of the water resources of Mamry, the lake
with the richest water resources in Poland. In terms of surface area, the reservoir on
the Vistula River above the barrage in Włocławek is the largest. Its surface area of
70.4 km
2 is comparable with that of Lake Łebsko, occupying the third position in
this aspect in Poland.
Wi´ sniewski [10] listed dam reservoirs (more than 1 million m
3 ) and determined
their number for 101 (Table 5.3). Only 11 among them have resources exceeding
100 million m
3 . It is worth emphasising that 26 natural lakes are identified to have
water resources exceeding 100 million m
3 .
The location of dam reservoirs in Poland is presented in Fig. 5.3. Notice the very
evident concentration of reservoirs in mountain and sub-mountain regions, in the
Pomeranian Lake District, and on the Małopolska Upland. In the Masurian Lake
District and the belt of lowlands, dam reservoirs occur sporadically. Rivers the best
developed in terms of the number of reservoirs include Bóbr, Radunia, Nysa Łu˙ zycka,
Nysa Kłodzka, Rega, Brda, and Soła.
It is worth emphasising that human activity in Poland in reference to the construction of large dam reservoirs dates back 170 years. The oldest reservoir with a volume
of more than 1 million m
3 is Mylof on the Brda River, launched in 1848. Several
reservoirs in the Sudetic region and the Pomerania come from the first quarter of
the twentieth century. The construction of more than half of the reservoirs (with a
volume of more than 1 million m
3 ) dates back to the period after World War 2.
The total volume of dam reservoirs (more than 1 million m
3 ) is approximately
3.5 km
3 . This constitutes approximately 18% of water resources of Polish lakes and
approximately 6% of the volume of waters outflowing annually from the territory of
Poland. Their total surface area is approximately 500 km
2 , i.e. around 18% of the
area of lakes in Poland.
Due to the inconsiderable economic importance of artificial reservoirs with small
surface areas, they are not included in any comparisons. Obtaining an answer to the
question, however, is equivalent to the determination to what degree man managed
to increase the system of stagnant surface waters in comparison with what nature
created. The analysis of the above issue was performed for the zone south of the
A. Choi´ nski and R. Skowron
the case of spatial distribution of tarns, their considerably lower densities of occurrence are observed south of the range of the last glaciation. This evidence suggests
their high susceptibility to decline, depending on their age.
5.4 Water Resources of Dam Reservoirs
No favourable conditions for the construction of water reservoirs occur in Poland,
particularly those with considerable surface areas. This results from small water
resources in rivers, considerable variability of outflow, and unfavourable natural
conditions for their construction. The largest reservoirs in terms of surface area as
well as volume are approximate to natural lakes. The reservoir in Solina on the San
River is the largest in terms of water resources. It accumulates 0.47 km
3 of waters,
which constitutes approximately half of the water resources of Mamry, the lake
with the richest water resources in Poland. In terms of surface area, the reservoir on
the Vistula River above the barrage in Włocławek is the largest. Its surface area of
70.4 km
2 is comparable with that of Lake Łebsko, occupying the third position in
this aspect in Poland.
Wi´ sniewski [10] listed dam reservoirs (more than 1 million m
3 ) and determined
their number for 101 (Table 5.3). Only 11 among them have resources exceeding
100 million m
3 . It is worth emphasising that 26 natural lakes are identified to have
water resources exceeding 100 million m
3 .
The location of dam reservoirs in Poland is presented in Fig. 5.3. Notice the very
evident concentration of reservoirs in mountain and sub-mountain regions, in the
Pomeranian Lake District, and on the Małopolska Upland. In the Masurian Lake
District and the belt of lowlands, dam reservoirs occur sporadically. Rivers the best
developed in terms of the number of reservoirs include Bóbr, Radunia, Nysa Łu˙ zycka,
Nysa Kłodzka, Rega, Brda, and Soła.
It is worth emphasising that human activity in Poland in reference to the construction of large dam reservoirs dates back 170 years. The oldest reservoir with a volume
of more than 1 million m
3 is Mylof on the Brda River, launched in 1848. Several
reservoirs in the Sudetic region and the Pomerania come from the first quarter of
the twentieth century. The construction of more than half of the reservoirs (with a
volume of more than 1 million m
3 ) dates back to the period after World War 2.
The total volume of dam reservoirs (more than 1 million m
3 ) is approximately
3.5 km
3 . This constitutes approximately 18% of water resources of Polish lakes and
approximately 6% of the volume of waters outflowing annually from the territory of
Poland. Their total surface area is approximately 500 km
2 , i.e. around 18% of the
area of lakes in Poland.
Due to the inconsiderable economic importance of artificial reservoirs with small
surface areas, they are not included in any comparisons. Obtaining an answer to the
question, however, is equivalent to the determination to what degree man managed
to increase the system of stagnant surface waters in comparison with what nature
created. The analysis of the above issue was performed for the zone south of the