Erosion processes in Slovene Istria – part 2: Badlands

Abstract

Talus slopes form below bare flysch walls, for example, in the Mrtvec badlands along the Dragonja River (photograph: Matija Zorn). Pod golimi fli{nimi stenami nastajajo meli{~a, kot na primer na erozijskem ari{~u Mrtvec ob Dragonji (fotografija: Matija Zorn). ABSTRACT: This article is a continuation of the article on soil erosion in submediterranean Slovene Istria from the first issue of the 2009 (49-1) journal. In this article we present geomorphic processes in the badlands of the same area (Dragonja River basin, SW Slovenia): sediment production from steep bare (Eocene) flysch slopes (rockwall retreat), movements of flysch debris along erosion gullies, and geomorphic processes on talus slopes. Sediment production of flysch rocks was determined by measurements on erosion plots and totals around 80 kg/m 2 per year on average, which means that steep bare flysch rockwalls retreat at a speed of 35 to 50 mm per year. The badlands not only contain flysch walls but also slopes already eroded by erosion rills and gullies. A dam in one of the erosion gullies with the catchment area of 0.1 ha captured 20 tons of debris in fourteen months. MATIJA ZORNMonitoring on talus slopes of the badlands revealed their dual character because erosion here alternates with accumulation.

The Importance of Measuring Erosion Processes on the Example of Slovenia

“…The primary peak is connected with the alternation of temperatures above and below freezing during the daytime in the colder part of the year. The secondary and tertiary peaks are connected with heavier precipitation in the spring and summer (for more details see Zorn, 2009b). …”

“…Measurements of erosion processes in badlands were taken in flysch areas in southwestern Slovenia (Zorn, 2008(Zorn, , 2009b, not far from measurements of soil erosion, and in a dolomite area in central Slovenia in the Polhov Gradec Hills (Komac, 2003). Measurements included (1) sediment production from steep bare slopes (rockwall retreat) and (2) movements of debris along erosion gullies.…”

Loss of natural heritage from the geomorphological perspective – Do geomorphic processes shape or destroy the natural heritage?

“…Geomorphic processes constantly reshape them, the cliffs retreat for few centimetres per year (Zorn 2009). Due to constant abrasion they preserve their shape by parallel rockwall retreat (Savigear 1952).…”

Erosion processes in Slovene Istria – part 1: Soil erosion

“…45-1) presented a detailed study of erosion processes in Slovenia with an emphasis on soil erosion on agricultural land (Komac and Zorn 2005). The article showed (see also Hrvatin, Perko and Petek, 2006) that there is a major lack of measuring erosion processes in Slovenia, which was one of the reasons for undertaking detailed studies of erosion processes (including soil erosion) in the following years in Slovene Istria (Zorn 2007a;2007b;2008a;Zorn and Petan 2007;. In 2005 and 2006 we measured soil erosion and surface runoff on a weekly basis in the flysch Dragonja River basin in three different land use areas: on bare soil in an olive grove, an overgrown meadow, and forest.…”

“…49-2, of the journal; Zorn 2009). We also measured chemical denudation monthly in the Dragonja River basin (Zorn 2007a;2008a).…”