Erosion processes in Slovene Istria – part 1: Soil erosion

In 2005 and 2006 intensive measurements were made of various erosion-denudation processes in the Dragonja River basin. The measurements included geomorphic processes in the badlands: the rockwall retreat of steep bare flysch slopes, movements of flysch debris along erosion gullies, and geomorphic processes on talus slopes. At the same time, measurements of soil erosion were made in three different land use areas: bare soil in an olive grove, an overgrown meadow, and a forest. The results are presented in two parts. Part One presents the measurements of soil erosion, and Part Two in the next issue of the journal (No. 49-2) will present geomorphic processes in the badlands.The measurements of soil erosion made on one-meter-square closed erosion plots south of the village of Marezige revealed that the greater part of the annual erosion was caused by only a few major erosion events. Between May 2005 and April 2006, interrill erosion amounted to 9,013 g/m2 (90 t/ha) on bare soil in an olive grove with an inclination of 5.5º and an average weekly proportion of specific runoff of 23%, 168 g/m2 (1.68 t/ha) on an overgrown meadow with an inclination of 9.4º and an average weekly proportion of specific runoff of 8%, and 391 g/m2 (3.91 t/ha) in a forest with an inclination of 7.8º and 415 g/m2 (4.15 t/ha) in a forest with an inclination of 21.4º with an average weekly proportion of specific runoff of 6% regardless of the inclination. The amount of precipitation during the reference year was slightly below the long-term average

Erosion processes in Slovene Istria – part 2: Badlands

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/m2 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.Monitoring on talus slopes of the badlands revealed their dual character because erosion here alternates with accumulation

Probability modelling of landslide hazard

In this journal, the authors (Zorn, Komac 2004) previously described the use of two deterministic methods for establishing the possibility of landsliding. This time, they take a step forward and using the example of the flysch Goriška Brda hills present the probability modelling of landslide hazard. In probability methods, the intensity and distribution of the processes are established by comparing indirectly determined landscape elements and the actual situation, while in deterministic methods, subjective decisions have an impact on the result. We have elaborated a probability map for landslides with a fixed return period using the Dempster-Shafer method on the basis of the data on 800 landslides that occurred with intensive precipitation in the fall of 1998

Soil erosion on agricultural land in Slovenia – measurements of rill erosion in the Besnica valley

The article describes soil erosion in Slovenia. There is little concrete data on soil erosion due to the lack of awareness of this process and the fragmentation of farmland. Long-term measurements of soil erosion have only been done at one location; elsewhere, there have only been short observations and calculations and modeling on the basis of empirical equations. To increase our knowledge of this phenomenon, we took measurements of soil erosion on a field in the Besnica Valley northwest of Kranj.With the decrease of agricultural land use in Slovenia due to natural, social, and economic factors, the amount of material lost to erosion has decreased in the last few decades.For protection from erosion, various preventive methods such as terracing, mulching, and contour plowing are employed. The awareness that protection against erosion is a demanding and long-term task is gradually increasing, but nothing can replace the soil that has been lost due to erosion

Thickness and geodetic mass balance changes for the Triglav Glacier (southeastern Alps) from 1952 to 2016

Various geodetic and lidar measurements performed on the Triglav Glacier (Julian Alps, Slovenia) make it possible to study not only the extent of the glacier but also changes in its thickness and volume. These measurements also make it possible to calculate the geodetic mass balance of the glacier. Thickness and volume changes were calculated using glacier area measurements from 1952, 1975, and 1992, and annually between 1999 and 2016. The mean thickness decreased from 39.2m in 1952 to 2.45m in 2012. The maximum thickness decreased from 48.3 m in 1952 to 5.2 m in 2007. The mean specific mass balance was calculated for the area of 1 hectare that the glacier covered in 2016. From 1952 to 2016, the annual specific mass balance was −0.45m w.e.a−1