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Z. Michalczyk, M. Łoś

and melioration of their valleys followed. As a result, the local drainage base and water surface were lowered, as a conseąuence of which rubble movement in the river beds was facilitated.

The third period referring to the second half of the 20th c. is characterized by the very fast demographic and spatial development of Lublin. Ali dammed-up mili ponds have ultimately been liąuidated and regulation and partial embanking of rivers and melioration of their valleys completed. Aconsiderable part of them has been designated for parks, sport facilities, allotments and communication routes. The exploitation of underground water is increasing very rapidly, as is the amount of discharged wastewater and the length of storm sewers and sanitation canals in the city. Due to pumping underground water at an amount of 50-58 million m³/year the table is being lowered over an area of about 200 km². Exploitation of underground water substantially impacts upon the water balance of the Bystrzyca river. Its magnitude has exceeded the Bystrzyca flows in Lublin in recent years. A significant role in the determination of water conditions is played by the Zemborzyce Reservoir feeding underground water and thereby deepening shallow flows in the city area.

Water management in Lublin has led to significant changes in water relations in the city area. At present the rivers do not drain the underground water resources, but there are conditions for river waters to escape underground. Humań activity is a virtual threat to the amount and ąuality of water resources in the Lublin region. There are numerous pollution foci in the area of the city struggling with a big water deficit, the liąuidation of which reąuires great costs. At the beginning of the 70’s, Lublin was in danger of being unable to supply the water needed for consumption from the Bystrzyca river resources. However, limited industrial production and economized water management in the last decade have averted this danger but have not erased it. At the beginning of the 21st c. water problems will become one of the most important barriers to the development of Lublin. In the farther perspective a significant increase in water consumption will be possible by conveying it from outside the Bystrzyca river basin.

REFERENCES

Brunner I., Mierzyński Z., Zawadzki A., 1893, Wyniki badan wody studziennej w mieście Lublinie, Pamiętnik Towarzystwa Lekarskiego Warszawskiego 99, 3, Warszawa, 625-655. Gawarecki H., 1974, O dawnym Lublinie, Wyd. Lubelskie, Lublin.

Gawarecki H., 1975, Rozwój urbanistyczny i architektoniczny miasta w latach 1918-1939, [in:] Dzieje Lublina 2, Wyd. Lubelskie, Lublin, 249-265.

Harasimiuk M., Henkiel A., 1982, Objaśnienia do Szczegółowej Mapy Geologicznej Polski, Lublin. Wyd. Geol., Warszawa.

Jałowiec L., 1979, Dokumentacja hydrogeologiczna zasobów wód podziemnych zlewni Bystrzycy, PG, Warszawa (typescript).