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Z. Michalczy, M. Łoś

Its value was 1.80 1/s km² for the basin above the city, 0.91 1/s kn² in the centre of Lublin, and 1.93 1/s km² in Sobianowice, i.e. a little mon than in the upper part of the basin. From the measurements mentioned f shortage of river supplies can be found, and even a decrement at an amount o 0.42 m³/s of flowing waters.

TABLE 1. Mean unitary flows and outflows calculated from five flow masurement series carried out by the Department of Hydrography, Maria Curie-Sdodowska University, and the Municipal Company for Water Supply and Treatmen in Lublin in rainless periods of 1990—1992 (measurements were madę on the days:9.05.1990, 12.07.1990, 19.05.1991, 23.07.1992 and 18.08.1992)

No	River	Measurement locality	Basin area [km^2]	Flow [m3/s]	Unitry outflow ['s km^2]
1	Bystrzyca	Nowiny	480	0.865	1.80
2	Krężniczanka	Krężnica	225	0.330	1.48
3	Bystrzyca	Wrotków	718	0.768
4	Czerniejówka	Głuszczyzna	56	0.089
5	Czerniejówka	Lublin	172	0.023
6	Czechówka	Dąbrowica	29	0.018	0.61
7	Czechówka	Sławinek	67	0.001	0.01
8	Bystrzyca	Tatary	1046	0.875	0.84
9	Ciemięga	Pliszczyn	152	0.263	1.73
10	Bystrzyca	Sobianowice	1265	2.440	1.93

On the basis of hydrometrie materials for 1982-1991 the nagnitude of the outflow from the particular parts of the Bystrzyca river >asin and Lublin differential collecting area was estimated (Table 2). Hylrometric data from the Pliszczyn water-gauge on the Cimięga river, cosing its basin with relatively smali transformation of water conditions, W3re taken as the basis for calculations. The mean outflow from this basin was 3.22 1/s km². In the years 1982-1991 the average area of the Lublin cepression funnel was 178 km². Assuming the mean outflow at 3.22 1/skm², the supply in this funnel was only 0.57 m³/s. This is a decided smal amount to compensate for the exploitation of underground water in tie Lublin region, estimated on average at 1.6 m³/s. The remaining part of;he water exploited from communal and industrial intakes (1.03 m³/s), reaching water-bearing layers, comes from top waters in the city area. Unierground supply from the upper part of the Bystrzyca river basin and its tibutaries may also have a positive influence. Of 1.60 m³ water exploited ai amount of 1.51 m³/s returns as wastewater to the Bystrzyca river, which is discharged within the Lublin differential collecting area, and 3.09 m³/s constitutes non-returnable loss.

In recent years, very advantageous changes in water managenent have taken place in Lublin. Economizing on water and reduced industrial