Geomorphometric attributes of channel heads initiated by seepage erosion in a postglacial zone (NW Poland)

TitleGeomorphometric attributes of channel heads initiated by seepage erosion in a postglacial zone (NW Poland)
Publication TypeBook Chapter
Year of Publication2015
AuthorsMazurek, Małgorzata
Secondary AuthorsJasiewicz, Jaroslaw, Zbigniew Zwoliński, Helena Mitasova, and Tomislav Hengl
Book TitleGeomorphometry for Geosciences
Pagination251 - 254
PublisherBogucki Wydawnictwo Naukowe, Adam Mickiewicz University in Poznań - Institute of Geoecology and Geoinformation
CityPoznań, Poland
ISBN Number978-83-7986-059-3
Abstract

Channel initiation, which is a key factor in the evolution of landforms, is caused by a combination of various hydrogeomorphic processes. This study supplies quantitative data about the size of channel heads driven mostly by groundwater seepage in lowland areas. The chief aims of the present paper is to examine the geometry and morphometry of channel heads in NW Poland and identify the nature of the erosional effect of groundwater outflows. Detailed topographic studies were conducted in selected 24 channel heads (in the form of headwater alcoves) judged to be representative in hydrogeomorphological terms in the southern part of the Parsęta catchment (NW Poland). Morphometric surveying of headwater zones made it possible to identify morphological effects of groundwater seepage erosion in a postglacial landscape.

Headwater alcoves of various forms are often distinctive features of the postglacial relief of the Parsęta catchment. Those predominating in the study area are compact landforms, semi- circular and narrowing, or paraboloidal, elongated in outline, as evidenced by the low values of the indices of form Cf and circularity Ck as well as the elongation index Cw. A small proportion of headwater alcoves located in scarps are complex, composed of several alcoves combined by a common outflow. The elongation is primarily due to backward erosion along the long axis of an alcove, but in favourable morphological conditions it may have been predetermined by the shape of the initial forms. The scarps closing alcove heads can reach heights of more than ten metres. The transition of alcove slopes into a flat bottom takes place via a clearly marked segment of a concave slope. The diversity of channel head morphology is related to the areal extent of the contributing area, structural or lithological variability which locally increases hydraulic conductivity, and the character and discharge of groundwater outflows.

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