Sunday, 21 December 2014

Sediment Matters (Springer)

Source of picture: <>
New book will be published by Springer - a global publishing company. Book with title Sediment Matters (link) was edited by Peter Heininger and Johannes Cullman. Book presents insights into the complex processes controlling sediment behavior in river basins and into state of the art integrated sediment management concepts.

We participate to chapters:
  • Sediment transport in headwater streams of the Carpathian Flysch belt: its nature and recent effects of human interventions.
  • Aspects of sediment transport in single-thread and anabranching river channels in flysch Carpathians (a case study from the Czech Republic).


New Czech Science Foundation (GACR) Project

Assoc. Prof. RNDr. Jan Hradecký, Ph.D. and RNDr. Václav Škarpich, Ph.D. are members of research team for realization of project - GAČR: 15-02067S (2015-2017) – Optimalization of dendrogeomorphic methods in landslide research. Project will be realized during the years 2015 – 2017. Research will focused to defining optimal spatial position and number of trees for field sampling, determining optimal age/size of trees that most sensitively reflect landslide movements and increasing the efficiency of landslide signal extraction from tree-rings. 
Source of picture:

Thursday, 16 October 2014

A complex approach for evaluation of sediment (un)balance in a steep headwater channel

A new paper was published in Catena, where a dendrogeomorphic approach was combined with ERT sounding and bedload transport simulations to estimate sediment budget during high-magnitude flood in a steep channel. It has been resulted from the cooperation with the dendrogeomorphic section of the Department of physical geography and geoecology, University of Ostrava. The methodology and results of this research were also presented on the Conference of Association of Slovac geomorphologists in Snina in October 2014. 

Sediment (un)balance budget in a high-gradient stream on flysch bedrock: A case study using dendrogeomorphic methods and bedload transport simulation
Detailed quantification of material supply into stream channels is crucial for determining sediment (un)balance budget during flood events. Unfortunately, existing quantification methods require long-term field monitoring; otherwise, there is an insufficient amount of usable data. In this study, we introduce a new approach, based on dendrogeomorphic methods, to determine the volume of material supply generated from flysch high-gradient stream bank failures. This approach was supplemented by 1D sediment transport modelling, using a TOMSED model.
We analysed 138 cross-sections from the roots of predominantly broad-leaved trees, which were exposed in bank failures from different floods. Using the spatial position of the roots and dating the exposure time, we determined the volume of material supply into the channel during the last flood, in 2010. In-channel sediment transport was analysed on 14 cross-sections, and the channel sediment thickness was estimated using the geophysically based ERT (Electrical Resistivity Tomography) method.
The total volume of material loss during the 2010 flood within the study area, according to the TOMSED model, was found to be at least 300 m3. This means that the calculated total volume of sediment supply resulting frombank failures during the flood (63.9 m3 based on dendrogeomorphic methods) was significantly lower than the calculated bedload transport for the entire study area. This finding implies that contemporary sediment sourcescannot adequately cover the transport capacity during high-magnitude flood events, and in general, in-channel erosion processes prevail.

Tuesday, 17 June 2014

Documentary Movie about Ostravice River (All rights reserved Czech Television - Česká televize ČT - Public Broadcast)

 Nedej se - Česko suché, místy mokré
New documentary movie about the Ostravice River and ecology, water management, fluvial geomorphology in this river basin. With Assoc. Prof. RNDr. Jan Hradecký, Ph.D.

from the June 15, 2014 - Czech Television public broadcast

Interview about rivers in Czech Republic (All rights reserved Czech Radio - Český rozhlas ČRo - public broadcast).

Interview with Assoc. Prof. RNDr. Jan Hradecký, Ph.D. about water management and anthropogenic pressure on gravel-bed channels in the Czech Republic.

link to interview
from the May 5, 2014 - Czech Radio public broadcast

Wednesday, 21 May 2014

Satina river after heavy rains (May 16th, 2014; Moravskoslezské Beskydy Mts., Outer Western Carpathians; recorded by Lenart J.)

Conference report: State of Geomorphological Research in 2014 (Czech Republic)

April 23rd – 25th, 2014

We participated on the conference State of Geomorphological Research in 2014. It was realized under the patronage of Czech Association of Geomorphologists by the University of J. E. Purkyně in Ústí nad Labem and the Institute of Rock Structure and Mechanics of the ASCR, v.v.i. It was opened to all geomorphology scientists from the Czech Republic, Slovakia and Poland. Conference included 5 scientific sessions. We presented our conclusions from research through the session Fluvial processes and landforms.
The session included wide range of aspects of current research from Czech Republic, Slovakia and Poland. It comprised of fluvial processes and dynamics, morphological spatial variability and changes over various timescales, and fluvial interactions with other processes such as tectonics or ecological dynamics.

We presented our conclusions about:

Contemporary state and river processes of the Olše River channel (Outer Western Carpathian, Czech Republic)
Authors: Václav Škarpich, Tomáš Galia, Jan Hradecký

In the last decades, intense and temporally variable anthropogenic disturbances in the Czech Carpathians basins continuously adjusted new constrains of rivers. Especially afforestation and bank stabilisation caused reduction of sediment supply. Originally gravel-bed character of rivers with high amount of transportable material was changed. The effect of hungry waters (Kondolf 1997) induced progressive channel transformation. Present-day state of channels shows a tendency towards the acceleration of processes linked with river bed deepening. Focusing on the Olše River in the Czech part of flysch Carpathians, the paper summarizes results of energetic potential aspects of contemporary Carpathian river channels. New internal conditions of channels have been affecting acceleration of erosion processes. The main cause is an adjustment of flow dynamics. The unit stream power values (after Bagnold 1966) increased two or three times between the years from 1960 to 2003. Other characteristics, used for evaluation of factors identifying the energetic potential of channels (as hydraulic radius etc.), show increase of values in the year 2003 compared with the year 1960. Contemporary state of the Olše River channel predicts that future development will lead to progressive incision.

Channel patterns and connectivity in Beskydian headwater channels
Authors: Tomáš Galia, Václav Škarpich and Jan Hradecký

The contribution summarizes investigations in small flysch-based mountain streams of Moravskoslezské Beskydy Mts. Continuity in channel-reach morphologies were assesed in longitduinal stream profiles with respect to intensity of bedload transport and thus, (dis)equilibrium between potential sediment supply and transport capacity during flood events. Parameters of observed channel-reach morphologies were statistically evaluated by PCA analysis to obtain leading predispositing factors. Bedload transport was evaluated by simulations in 1D transport model TomSED and by observations of marked particle movement. Moreover, measurements of largest boulders occurred in channels gave information about competence of stream power during high-magnitude flood events to transport this coarsest fraction.
There was evident, that streams under low sediment-supply or high transport capacity were prone to occurrence of bedrock, bedrock-cascade and also step-pool morphology on the lower gradients. On the other hand, cascades and step-rapids without well-developed step-pool morphology were typical rather for high sediment-supply conditions. Differeneces in size of coarsest sediment fraction were assessed in longitudinal profiles under past debris-flow events and under prevailling fluvial processes. Occurrence of past debris-flows indicated much higher sized of largest boulders related to transport power of these colluvial events. Longitudinal profiles without debris-flow evidence in same cases indicated changes in boulder size trends with respect to fluvial processes, especially erosion (coarsening) and deposition (fining). Nevertheless, this fact was not evident in all investigated stream profiles. In addition, role of stream power was not important at all, when there was not observed any dependence between computed stream power and size of largest boulders.

The artificial boulder steps as a modern control works structure in mountain streams
Authors: Zdeněk Přibyla, Tomáš Galia

Torrent and gully control (currently regulated by ČSN 75 2106) in the Czech Republic landscape has influenced mountain streams since the 19th century. Mainly traditional control works are implemented, particularly staircase-like sequences of concrete check dams or bed sills. The main objective is to reduce the channel gradient, inhibit erosion of the channel bed and banks and limit sediment transport into the lower parts of the basin. Modern trends of control works abroad tend to conservation of natural channel morphology. In last two decades, sequences of artificial boulder steps alternating with pools are widely used in mountain streams restoration. Natural step and pool systems in mountain streams show high values of ​​flow resistance reducing sediment transport and they does not affect the channel connectivity and stream ecology by contrast to artificial check-dams. Often regulated stepped-bed channels in the Moravskoslezské Beskydy Mts. are characterized by lower size of bed sediments fraction, high transport capacity and bed incision. The natural stream morphology is usually presented by disordered channel bed with frequently alternating channel units such as cascades, steps, pools and bedrock.
An experiment of manual rebuilding of the channel bed was performed in the Malá Ráztoka stream. The 40 m channel reach (channel slope 0.09) is created by disorganized cascade and step units was rebuilt to regularly alternating units of steps and pools. Designated dimensions of steps high H (0.44 m) and steps spacing L (4.1 m) were calculated according to suggestions of foreign studies and considering the local channel slope S: 1<H/L/S>2 (Abrahamas et. al. 1995; Lenzi, 2002). Only boulders available in the channel or deposited along the banks were used for the steps construction. The key stones in boulder steps exceed 0.4 m and this corresponds to stability for the flood event >Q20 (Galia and Hradecký 2012). The rebuilt reach will be subjected to a detailed long-term monitoring focusing on effects of flood flows on sediment transport and changes in channel geometry (step and pool geometry). Construction of several other sections and starting their monitoring is planned for spring 2014.

Sunday, 11 May 2014

Monitoring of the Bílovka River restoration

We started the monitoring of state of the Bílovka River channel restoration. Bílovka River has undergone a rapid regulation works (with straightening and bank stabilization) in the last 40 years. Now, especially PLA Administration Poodří (link) and Povodí Odry Enterprise (link in Czech) are starting with returning of the Bílovka River to naturally meandering state of channel in the area of the PLA Poodří.
Bílovka River restoration project was realized between the years from 2011 to 2013. It was based on the amount of financial resources, the Operational Programme Environment (OPE, link) which is the second largest Czech operational programme. The project was projected to cost 480 million CZK and realized by Povodí Odry Enterprise (link in Czech) with cooperation of Talpa – RPF (link in Czech). Restoration of the Bílovka River was based on reconstruction of meandering channel.
The first part of monitoring is based on the measurement of channel morphology for modelling of hydrological situation, monitoring of channel changes morphology, etc.

Bílovka River channel morphology measurement