Tuesday, 3 July 2018

New project about bedload sediment regime of torrent streams in Czech Republic was received

Within the fund program of the State Forest Service (LCR, s.p.) in Czech Republic, project about bedload sediment regime of Czech Republic torrent streams was received. Main members of Czech-Rivers research group, namely assistant professors RNDr. Václav Škarpich, Ph.D., RNDr. Tomáš Galia, Ph.D. and Associate Professor RNDr. Jan Hradecký, Ph.D. from Department of Physical Geography and Geoecology are participating in project which will be realized within cooperation of Masaryk University in Brno and the lead partner Envicons, s.r.o. from Pardubice (Czech Republic).
The main aim of the project will be focused to bedload sediment regime quantification of torrent streams in the area of the Moravskoslezské Beskydy Mts., Hrubý Jeseník Mts., Orlické hory Mts., České středohoří Mts., etc. Target of activity is to bring the outputs to management practice of bedload sediment material in torrential streams managed by the State Forest Service in Czech Republic.

Saturday, 30 June 2018

Ongoing research of instream wood in Carpathian headwater streams

Two our scientific papers were recently published, which deals with instream wood in the headwaters draining the highest peak of the Moravskoslezské Beskydy Mts, Czech part of Western Carpathians. The main aim of the article in Forest Ecology and Management was to find controlling factors of occurrence of large and small wood under mixed forest canopy. Deciduous trees significantly contribute to increasing number of observed small wood due to the recruitment of individual branches from these trees. However, higher frequencies of small wood did not turn into its larger active-channel volumes. On the other hand, conifers were important for the observed frequency of large wood pieces because of (i) recruitment of the whole trees and (ii) longer residence time of local conifers. Additionally, less-confined valley floor also led to increasing frequency of large wood, whereas highly confined valleys are prone to formation of large wood 'bridges' above the zone of bankfull flows. This paper was prepared under cooperation with colleagues from University of Geneve.

Conceptual model of LW and SW abundance and stability based on conifer/deciduous tree species and valley confinement. 

The second paper dealing with steps created by single wood pieces was published by Ecological Engineering. Detailed characteristics of 73 log steps in managed temperate Carpathian forests were assessed together with channel- and wood-based thresholds for log step development. The upstream threshold of log step occurrence can be assigned to those locations in stream longitudinal profiles, where transport capacity during ordinary high flows exceeds the critical value for the initiation of bedload movement (suspended-mode transport is usually not able to form sedimentary wedge upstream individual spanning logs). Downstream thresholds are controlled by stream transport capacity and wood dimensions, which also correspond to the limited recruitment of large wood pieces in local managed forests. The development of a log step at a particular channel width or basin area was controlled by the wood length, but the resultant step parameters (step height and width, length of upstream sedimentary wedge and volume of stored sediments) were better correlated with wood diameter. Nevertheless, the average sediment storage generated by a log step was only 0.51 cubic meters.      
Step created by a single wood piece. 

Empirical model of the potential development of log steps in the studied channels without debris flow or hyperconcentrated flow occurrence. 

Thursday, 28 June 2018

State of the geomorphologic research in 2018

Between 25th and 27th of April 2018, we participated on the 18th conference of Czech Association of Geomorphologists. The traditional State of the geomorphologic research in 2018 conference was held in Vílanec in the hearth of the Czech Republic close to the Vysočina Geopark. The Vysočina Geopark is spread out in the landscape of Bohemian-Moravian Highland. We presented our results from ephemeral channels of semi-arid European Mediterranean mountainous landscape in Crete (Greece) and from basins of the Outer Western Carpathians (OWC) in Czech Republic. Dr. Tomáš Galia discussed the importance of large wood in the geomorphic functions of rivers and streams of an ephemeral channel typical of semi-arid European Mediterranean mountainous landscape (Sfakiano Gorge, Crete, Greece). The conference was the first occasion to present the results of research of barchelor student Tereza Matušková from our Department of Physical Geography and Geoecology. She presented results about fine wood mobility in the Sučí Stream from the Ondřejník Massif (Podbeskydská pahorkatina Hilly land, OWC). Dr. Václav Škarpich and Mgr. Tereza Macurová referred about problematic of the possibilities of restoration measures to keep and protect the multiple-thread river pattern in the Skalická Morávka National Nature Monument in OWC.
  • Galia T., Škarpich V., Tichavský R., Vardakas L., Šilhán K.: Parameters, longitudinal distribution and dynamics of large wood in a Mediterranean ephemeral stream
  • Matušková T.: Fine wood mobility in the Sučí Stream.
  • Škarpich V., Galia T., Macurová T., Ruman S., Hradecký, J.: Possibilities for sustainability of the multiple-thread Morávka River channel in the Skalická Morávka National Nature Monument.
  • Macurová, T., Škarpich V., Galia T., Ruman S., Hradecký J.:  Gravel-bar dynamics of the protected multiple-thread reach of the Morávka River.
During this year we also plan to visit the conference RiverFlow 2018 in Lyon-Villeurbanne (France) between the 5th and 8th of September 2018.

Tomáš Galia during his presentation

Tereza Matušková during her poster presentation of fine wood mobility in the Sučí Stream

Tereza Macurová during her poster presentation about gravel-bar dynamics of the protected multiple-thread reach of the Morávka River

Friday, 9 March 2018

Research of large wood in a semi-arid stream

Our latest accepted article deals with the topic of instream wood in an ephemeral stream, which drains mountainous Mediterranean landscape of southwest Crete, Greece. We made a detailed inventory of large wood in the valley floor of 4-km-long reach. We analysed a total of 795 large wood pieces, and the mean observed abundance of instream wood was generally lower (ca. 14 m3/ha of active valley floor or ca. 20 pieces per 100 m of stream length) than is usually documented for more humid environments. The trees living in the valley floor acted as important instream wood supply agents (by tree throws or the supply of individual branches) and flow obstructions during large flood events, causing storage of transported large wood pieces in jams. On the opposite, the trees growing on adjacent, very steep hillslopes were less important in resulted instream wood budget. The geomorphic function of instream wood in the studied stream can only be perceived to be a spatially limited stabilising element for sediments, which was documented by a few accumulations of coarse clastic material by woody steps and jams.   

Studied stream

Large wood step with upstream sediment deposition

Living trees acting as flow obstructions during large floods. Note deposited large wood by these trees.

Thursday, 21 December 2017

How much gravel we need to have in a gravel-bed river?

In the past decades we observe gradual degradation of Czech and Polish Carpathian rivers. Whereas afforestation in Tatra Mts (reducing sediment supply), channelisation works and gravel mining are the main problems in Poland for channel incision (e.g., Zawiejska et al. (2010),  Wyzga et al. (2016),  Hajdukiewicz et al. (in press)), Czech rivers are often affected by the presence of water reservoirs stopping sediments from upstream and we noted more intensive channelisation works owing to the high population density in the Czech Carpathian forefields (e.g. Škarpich et al. (2013), Galia et al. (2016), Škarpich et al. (2016)). Unfortunately, this channel degradation (narrowing of channels, incision up to bedrock, loss of gravel bars) endangers also preserved wandering fluvial system in Skalická Morávka Nature Reserve. 

Presently, large volumes of gravels is stopped in the upstream part of the Morávka basin by a weir in Vyšní Lhoty, by Morávka Reservoir and we should also note the presence of check dams in small tributaries together with increase in forested area during 20th century. Therefore, Nature Conservation Agency of the Czech Republic is preparing a new management plan for the following decade, which includes management of gravels in the nature reserve. We have participated in calculations of missing gravels in the nature reserve, calculations of loss of bar habitats between 1950s and the present and we tried to determine dominant discharges, which would be able to sustain gravel bars and migration of channels in the reserve. It seems that huge volume of gravels (ca. 20 000 - 25 000 meters cubic) are missing in the upper part of the reserve. Much of this incision occurred during 20-50y flood in 2010. We expect that two-years daily discharges as well as large floods are important for preservation of the wandering system, reflecting natural hydrologic regime of streams based in flysch lithology. On the other hand, the river need to carry sufficient amount of gravels (up to several thousands meters cubic) during individual high-flow events to prevent from further incision. Other actions as artificial disturbations of gravel-bar surfaces, artificial flooding and close-to-natural bed stabilisation elements were suggested.       

Partially degraded wandering channel in Skalická Morávka Nature Reserve

Saturday, 11 November 2017

Proposal of universal symbology for detailed fluvial geomorphic mapping

With co-operation with cartographer Jan Miklín, we presented a proposal of universal symbology for geomorphic mapping of wadeable streams. The symbology includes individual channel and floodplain forms as well as selected important fluvial processes (i.e., erosion or deposition within a channel), grain-size characteristics of bed sediments or human interventions (e.g., several types of bank stabilisations or grade-control structures). The symbology has been recently published by Journal of maps, when we tested this mapping approach in three different locations (semi-confined valley with the presence of dumps from mining activity, confined high-gradient channel and mountain stream altered by bed sills). Individual symbols (prepared for ESRI ArcGIS) are ready for download  as supplemental material. 

Tuesday, 3 October 2017

New book: Open Channel Hydraulics, River Hydraulic Structures and Fluvial Geomorphology: For Engineers, Geomorphologists and Physical Geographers

On September 1, 2017 new book with name Open Channel Hydraulics, River Hydraulic Structures and Fluvial Geomorphology: For Engineers, Geomorphologists and Physical Geographers published by CRC Press.

The book presents practical hydraulic and river engineering research along with fluvial geomorphological concepts, and links the theoretical and practical knowledge of people working every day with rivers, streams, and hydraulic structures to fluvial geomorphology. The book also provides material for students to acquire the knowledge and skills to rehabilitate rivers, streams, and waterways.
The book was edited by Artur Radecki-Pawlik, Stefano Pagliara, Jan Hradecky and Erik Hendrickson and consist 508 Pages (20 Color) and about 257 illustrations.
We participated in three chapters with names: (i) Selected Principles of Fluvial Geomorphology (Jan Hradecky and Václav Škarpich), (ii) On Measurements of Fluvial Geomorphology Parameters in The Field (Vaclav Skarpich) and (iii) Geomorphology and Hydraulics in Steep Mountain Channels (Tomas Galia).