Морфодинаміка елементів ярково-балкових систем Брюховицького масиву Розточчя (за даними багаторазових спостережень)

Abstract

Recent exogenous processes developing in the gullies and balkas of the Briukhovychi Massif of the Ukrainian (Lviv) Roztochchia are described. The main task was to clarify intensity of these processes by the recent relief forming conditions. Within the studied territory the erosion forms are characterized by large sizes – gullies depth is up to 3 meters, the balkas have depth up to 40 meters. Investigated area is forested. The dynamics of the processes on the slopes and valley bottoms during 6 year period has been analyzed on the base of stationary field observations. To determine the representative study sites the remote sensing and the author’s program which modeled the places of development of erosion-denudation processes has been used. Detail investigations have been carried out by the methods of stems and photoplanes. The stems were set on 0,3–0,7 m depth on different segments of the erosion forms. The slopes and valley bottoms morphology were studied by digital photofixation and indirect geobotanical methods. Defluction processes intensity has been determined according to uncovered tree roots. In the small balkas and gullies the defluction is developed mainly on the slopes. Their development rate amounts 0,016 m/year. Due to the slope processes the steepness of upper slope parts has noticeable increased and the kerbs have appeared. In the medium-sized balkas on the slopes almost everywhere defluction is observed and somewhere – gravitation processes, mainly landslides. In deep balkas linear erosion and accumulation within the valley bottoms dominate, landslides and screes dominate on the slopes lower parts and defluction in the middle parts. Linear erosion develops most intensive in the valley bottoms, in their middle and lower parts. In the middle parts of balkas the erosion intensity was 0,08–0,10 m/year, in the lower – 0,15–0,25 m/year. Accumulation dominates in foots and lower parts of the balkas. The debris cones amount 6 m2, their thickness increased by 0,3 m. It’s necessary to note that during the observation period only three wet years have been observed. The rest years were relatively dry and water runoff was not significant. So, based on non-expendable stationary observations on the recent exogenous processes in the Ukrainian Roztochchia it is ascertained that intensity of their development is still noticeable. These processes continue cutting of the relief surface and mark slight tectonic lifting of the area.