Morphology and controlling factors of landslide cirque gullies: a case study from the Sprogu gravas nature monument (SE Latvia)

Abstract

Human-induced changes of landscape and the vegetation cover have been recognized in the majority of studies focusing on gully formation as one of the most important factors triggering the development of gullies throughout the world. However, detailed studies of singular erosion landforms in south-eastern Latvia, particularly those that are located on steep slopes of river banks modified by mass movement processes and presently found under forest, indicate that these gullies are not a geomorphic features resulting entirely from human agricultural activities. Such short, bottleneck-shaped gullies (Crosta, di Prisco, 1998), described in Latvia as landslide cirque or spring cirque gullies (Venska, 1982), can be found in deep river valleys and subglacial tunnel valleys in Latvia, but few studies have reported on their morphological characteristics and their origin. This study investigates these landslide cirque gullies initiated via mass movement processes in the local case-study area of the river Daugava Valley in south-eastern Latvia. The objectives are (1) to determine the spatial distribution of these gullies, (2) to measure their morphological and topographical characteristics and (3) to interpret the factors that led to their development.