Zróżnicowanie warunków odpływu podziemnego w dolinach rzecznych jako element oceny zagrożenia jakości wód (na przykładzie doliny rzeki Tocznej)

Abstract

DIVERSIFICATION OF UNDERGROUND WATER RUN-OFF CONDITIONS IN RIVER VALLEYS AS AN ELEMENT OF WATER QUALITY RISK ASSESSMENT: TOCZNA VALLEY CASE STUDY (EASTERN POLAND) Summary River valleys of erosional–accumulation origin are significant, capacious hydrogeological structures, with stable underground water feeding from uplands water-bearing horizons. This kind of hydrogeological conditions result in constant increase of discharge, measured downstream along the channel. In the areas of glaciogenic relief lowlands, in polygenic river valleys some of the valleys sections are adopted melt -out depressions. The non-alluvial poorly permeable deposits filling up those forms, as well as disturbance in escarpments zones of uplands, linked with glacial genesis of valley section, may significantly disturb the drainge in polygenic river valleys underground water feeding. This phenomenon can be recognised via observing downstream discontinuity of channel discharge rate. Thus, it can serve as an element of genetic analysis of river valleys from glacial-relief lowlands. Toczna river valley is described as an example of this phenomenon.