Estimation of lowland river cross-section changes for different soils

Abstract

Abstract This paper involves a comparative analysis of cross-sectional changes at selected reaches of a lowland river, flowing through the areas of mineral and organic soils. The comparisons were made at the background of design and execution assumptions from the period 1967–1971. Main processes, responsible for the observed changes of riverbeds in mineral soils (silting, conservation works) and organic soils (subsidence, disappearance of the peat deposit), were identified. In case of organic soils, the decrease of cross-sectional area by approximately from 30 to 60% was estimated in comparison to the original project assumptions, and the subsidence of river banks reached even 0.5 m in relation to the level determined in 1967. In the area of mineral soils, more considerable variability of cross-sectional area was noted along with minor changes of river banks elevation, that resulted most likely from the performed maintenance works.