The impact of snowmelt and heavy rainfall runoff on erosion rates in a gully system, Lublin Upland, Poland

The study examines water runoff and geomorphic processes within a permanent gully located in an agricultural catchment of the Lublin Upland, southeast Poland. The studies were conducted in the period 2003 to 2006, during which time the volume and intensity of precipitation were recorded and water runoff and sediment concentration at the outlet of the main gully were measured. After large surface runoff events that resulted in geomorphic effects, erosion and accumulation forms were examined. The role of snowmelt and heavy rains in the runoff of water and suspended solids from the catchment, as well as their effect on the dynamics of certain processes such as rill erosion, piping and accumulation within the gully all were evaluated. It was observed that the gully developed spatially through piping and headcut processes during snowmelt, while the main gully form became shallower as a result of accumulation processes. Headcut erosion at the gully bottom and transport of the material out of the catchment, predominantly during pluvial runoff events, were much less intensive. It was estimated that the intensity of snowmelt runoff in the years 2003 to 2006 was similar to the multi-annual average, while the intensity of pluvial runoff was significantly lower. An attempt was made to describe the dynamics of gully erosion and the direction of gully system evolution on a medium-term time scale (50 to 100 years). It was found that the roles of snowmelt and heavy rains in such catchments are in opposition. Snowmelt runoff events lead to the spatial development of the gullies and make them shallower, while pluvial runoff events add to the deepening of the gully and result in transporting the material outward. These two processes keep the gully system in relative balance. Copyright (C) 2009 John Wiley & Sons, Ltd.