Engineering-geological and geomorphological conditions of gully erosion in loess deposits in the Kazimierz Dolny area (Opolska Droga Gully)

The article presents the problem of intense erosion in loess gullies in the locality Kazimierz Dolny. Primary reasons for such a quick development of gullies are: lithogenetic and physical-mechanical characteristics of loess, geomorphological and climatic conditions of the region and also human activity. Gully erosion impedes rural activity and communication in the area and causes considerable damages to local roads. In one of the loess gullies typical for the region, called ,,Opolska Droga” near Kwaskowa Góra, physical and mechanical parameters were examined by field and laboratory tests. The results revealed a clear correlation: shear strength of loess considerably decreases when its natural moisture content increases. What is also important, the structure of loess — loose soil skeleton mostly built of quartz and small amount of cementing clay particles — is prone to erosion. Thus, its adverse susceptibility to influence of water occurs to be primary reason of intensive gully erosion development in the area of Nałęczów Plateau . Additionally, geomorphological and climatic conditions, together with human rural activity (often using gullies as local ways of road transport) result in faster erosion development and, in effect, they lead to disastrous results like those that took place in the region during extreme rainfalls some years ago. Any stabilizing engineering works within loess gullies should be preceded by appropriately designed system for the regulation of run-off in the drainage area