Geomorphological processes in channel heads initiated by groundwater outflows (The Parsęta catchment, north-western Poland)

Małgorzata Mazurek

doi:10.2478/v10117-011-0025-x

Abstract

Geomorphological processes in channel heads initiated by groundwater outflows (The Parsęta catchment, north-western Poland) Channel initiation is caused by a combination of various hydrogeomorphic processes. In the humid temperate zone of the Polish Plain, in areas with permeable deposits, seepage erosion is the primary mechanism of stream channel initiation. In the 24 channel heads selected in the southern part of the Parsęta catchment (NW Poland), the zones of occurrence of the following processes were identified: (1) seepage erosion; (2) falls, dry ravel events and slides; (3) creep, solifluction, surface runoff and erosion; (4) channel processes; and (5) landforms created under the impact of plants and animals. The co-occurrence of various morphogenetic processes produces variations in the accumulation conditions, and as a result, a diversity of deposits. Channel heads morphology shows the effect of the topography of the zero-discharge catchment, the type and magnitude of groundwater outflows, the variability of the geological structure, and the possibility of material being removed from the alcoves.

Highlights

The channel head is a significant element of the headwater system (Hack & Goodlett 1960, Gomi et al 2002, Benda et al 2005); it is a place where concentrated water flow and sediment transport start, and where bedforms evolve between distinctly developed channel banks (Dietrich & Dunne 1993)
Channel heads morphology shows the effect of the topography of the zero-discharge catchment, the type and magnitude of groundwater outflows, the variability of the geological structure, and the possibility of material being removed from the alcoves
The alcove’s morphology shows the effect of the topography of the zero-discharge catchment, the type and magnitude of groundwater outflows, the variability of the geological structure, and the possibility of material being removed from the alcoves

Summary

Introduction

The channel head is a significant element of the headwater system (Hack & Goodlett 1960, Gomi et al 2002, Benda et al 2005); it is a place where concentrated water flow and sediment transport start, and where bedforms evolve between distinctly developed channel banks (Dietrich & Dunne 1993). In the 1980s, groundwater outflows became an object of independent research because they were considered to be a morphology forming factor that initiated seepage erosion and spring sapping (Dunne 1980, LaFleur (ed.) 1984, Higgins & Coates (eds.) 1990). In the lowland area of central Europe with its high sediment infiltration capacity, the excess of rain- or melt-water usually infiltrates into the soil and nourishes the groundwater, which is drained by outflows. In such areas, groundwater seepage erosion can be the primary mechanism that controls channel initiation (De Vries 1976, 1994) and the development of a valley head (Ahnert 1998)

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