17 Water Problems in Urban Areas
415
The above discussion can be summarized as follows:
• High and constantly increasing share of sealed surfaces in cities (average 27.8%)
results in reduced infiltration and increased surface runoff component, especially
after downpours in the summer half-year. The consequence of these processes is
the more and more frequent congestion of the surface and underground drainage
network as well as the occurrence of flash floods. This forms an unexpected threat
to the life and property of residents.
• Much larger scale of threats in large Polish cities is caused by transit rivers,
especially during regional floods with a rainy genesis. The cities affected by
the catastrophic floods in the past include: on the Vistula River—Cracow,
Sandomierz, Warsaw, Tczew, Gda´ nsk and Malbork, and on the Oder River—
Racibórz, K˛ edzierzyn-Ko´ zle, Opole, Wrocław, Słubice, Nowa Sól and Krosno
Odrza´ nskie.
• The threat to cities with floods of a different origin (thaw, jam, frazil, sea storm
and caused by failures of damming facilities on rivers) has a rather local range
and it happens relatively rarely.
• Small permanent and periodic watercourses have significant importance, often
underestimated in urbanized areas. They are sometimes the only receivers of
surface runoff waters, and even municipal and industrial sewage. Meanwhile,
from the point of view of nature and ecology, these streams constitute an important
living space of animal and plant organisms. In recent years, a number of activities
have been carried out in many Polish cities for the revitalization of riverbeds and
valleys of small watercourses.
• Interesting is the fact that within 166 Polish cities there are about 350 lakes and
artificial water reservoirs with an area larger than 1 ha, having mainly recreational
functions, on which 173 bathing areas are located. Objects of this type also exist
in cities on the Baltic coast (67) and on rivers (26).
• Water consumption in Polish cities shows a downward trend from the beginning of
political changes, i.e. after 1989, and currently it is 168 m
3 /person. Another positive phenomenon is the decrease in the volume of municipal sewage discharged
into rivers, and at the same time, a very high degree of water treatment (96% in
2016). In as many as 85% of cities this ratio reached 100%, and only in a few
cities it did not exceed 50%.
• Local authorities of Polish cities show the necessity of modern water management
by undertaking numerous initiatives and actions resulting in the development
and implementation of programs aimed at rational, effective management and
usage of existing resources, including those that appear periodically (e.g. New
Urbanism, Eco-Urbanism, Green Urbanism, Sustainable Urban Drainage System,
Water Sensitive Urban Design, Water Urbanism). A measurable element of these
activities is the fact that environmental programs are dominated by tasks related
to the water environment.
The presented chapter is a very on-point answer to the significant increase in
interest, in recent years, in the water environment of cities in Poland—mainly in
relation to the need to improve the quality of life of their residents and the need to
415
The above discussion can be summarized as follows:
• High and constantly increasing share of sealed surfaces in cities (average 27.8%)
results in reduced infiltration and increased surface runoff component, especially
after downpours in the summer half-year. The consequence of these processes is
the more and more frequent congestion of the surface and underground drainage
network as well as the occurrence of flash floods. This forms an unexpected threat
to the life and property of residents.
• Much larger scale of threats in large Polish cities is caused by transit rivers,
especially during regional floods with a rainy genesis. The cities affected by
the catastrophic floods in the past include: on the Vistula River—Cracow,
Sandomierz, Warsaw, Tczew, Gda´ nsk and Malbork, and on the Oder River—
Racibórz, K˛ edzierzyn-Ko´ zle, Opole, Wrocław, Słubice, Nowa Sól and Krosno
Odrza´ nskie.
• The threat to cities with floods of a different origin (thaw, jam, frazil, sea storm
and caused by failures of damming facilities on rivers) has a rather local range
and it happens relatively rarely.
• Small permanent and periodic watercourses have significant importance, often
underestimated in urbanized areas. They are sometimes the only receivers of
surface runoff waters, and even municipal and industrial sewage. Meanwhile,
from the point of view of nature and ecology, these streams constitute an important
living space of animal and plant organisms. In recent years, a number of activities
have been carried out in many Polish cities for the revitalization of riverbeds and
valleys of small watercourses.
• Interesting is the fact that within 166 Polish cities there are about 350 lakes and
artificial water reservoirs with an area larger than 1 ha, having mainly recreational
functions, on which 173 bathing areas are located. Objects of this type also exist
in cities on the Baltic coast (67) and on rivers (26).
• Water consumption in Polish cities shows a downward trend from the beginning of
political changes, i.e. after 1989, and currently it is 168 m
3 /person. Another positive phenomenon is the decrease in the volume of municipal sewage discharged
into rivers, and at the same time, a very high degree of water treatment (96% in
2016). In as many as 85% of cities this ratio reached 100%, and only in a few
cities it did not exceed 50%.
• Local authorities of Polish cities show the necessity of modern water management
by undertaking numerous initiatives and actions resulting in the development
and implementation of programs aimed at rational, effective management and
usage of existing resources, including those that appear periodically (e.g. New
Urbanism, Eco-Urbanism, Green Urbanism, Sustainable Urban Drainage System,
Water Sensitive Urban Design, Water Urbanism). A measurable element of these
activities is the fact that environmental programs are dominated by tasks related
to the water environment.
The presented chapter is a very on-point answer to the significant increase in
interest, in recent years, in the water environment of cities in Poland—mainly in
relation to the need to improve the quality of life of their residents and the need to