Hydrogeomorphic Impacts of Floods in a First-Order Catchment: Integrated Approach Based on Dendrogeomorphic Palaeostage Indicators, 2D Hydraulic Modelling and Sedimentological Parameters

Abstract

Floods represent frequent hazards in both low- and first-order catchments; however, to date, the investigation of peak flow discharges in the latter catchments has been omitted due to the absence of gauging stations. The quantification of flood parameters in a first-order catchment (1.8 km2) was realised in the moderate relief of NE Czechia, where the last flash flood event in 2014 caused considerable damage to the infrastructure. We used an integrated approach that included the dendrogeomorphic reconstruction of past flood activity, hydraulic modelling of the 2014 flash flood parameters using a two-dimensional IBER model, and evaluation of the channel stability using sedimentological parameters. Based on 115 flood scars, we identified 13 flood events during the period of 1955 to 2018, with the strongest signals recorded in 2014, 2009 and 1977. The modelled peak flow discharge of the last 2014 flood was equal to 4.5 m3·s−1 (RMSE = 0.32 m) using 26 scars as palaeostage indicators. The excess critical unit stream power was observed at only 24.2% of the reaches, representing predominantly bedrock and fine sediments. Despite local damage during the last flood, our results suggest relatively stable geomorphic conditions and gradual development of stream channels under discharges similar to that in 2014.

Bank erosion and erosion processes from dendrogeomorphology in southern U.S. prairie streams

“…This is because scour is a flow process associated with sediment detachment from combined shear and turbulence‐induced pressure variations (Roy et al, 2019) that is persistent from year to year in straight channels. This scour yields lower erosion estimates in general compared with meandering channels as shown in this study (Figure 6a) similar to Tichavský et al (2020) where lower peak discharge values derived from dendrochronology were on average lower for straight channels. In contrast, the high erosion estimates and the low correlation among horizontal distance and root exposure times for meanders from all streams studied implicate a different erosional process (Figure 5a–c).…”

Recent gully erosion intensity in an agricultural landscape underlain by fluvioglacial sediments (NE Czechia)

“…The area has a typical temperate climate with a mean annual precipitation of 870 mm (Mikulovice station, 1963(Mikulovice station, -2021. The most intense rainfall is typical for the spring and summer months, which often leads to flash floods in this area (Tichavský et al, 2020).…”