Friday, 26 May 2017

Our participation on the traditional Czech conference of geomorphologists

Between 17th and 19th of May, 2017, we participated the 17th international conference State of geomorphologic research in 2017, which was held this time in Pec pod Sněžkou (Krkonoše Mts). Dr. Galia presented the present stage of instream wood research in Carpathian headwaters, whereas Dr. Škarpich demonstated the relations between the bar grain-sizes and local flow hydraulics in the gravel-bed Bečva River. Moreover, the poster proposing map symbology for small channels was prepared by co-operation with our department colleague Jan Miklín. The conference was also the first occasion to present the research of our new PhD student Tereza Macurová for scientist community. She showed the results of her magister thesis dealing with channel geometry, bed grain-sizes and fluvial processes in the Kobylská Stream (Moravskoslezské Beskydy Mts, Western Carpathians).

  • Galia, T., Šilhán K., Ruiz-Villanueva, V., Tichavský R.: Geomorphic function and residence time of instream wood in steep headwater channels: a case study from the Mazák Basin, Moravskoslezské Beskydy Mts.
  • Macurová, T., Škarpich, V.: Downstream variation in bed sediments in the Kobylská mountain stream based in flysch geologic structures (Vsetínské vrchy Mts)  
  • Miklín, J., Galia, T.: Detailed fluvial-geomorphologic mapping of wadeable streams: a proposal of universal map symbology
  • Škarpich, V., Galia, T., Ruman, S., Máčka, Z.: Downstream variations in bar grain sizes in the context of managed and re-naturalized channel reaches of the Bečva River
The conference proceedings with abstracts will be prepared for download here.
Václav Škarpich during his presentation.

Thursday, 4 May 2017

Instream wood dynamics in Carpathian headwater streams

New results were published from ongoing research of instream wood in Czech Carpathian headwaters. Our recent article in Geomorphology prepared in co-operation with colleagues from the University of Geneve (Dr. Ruiz-Villanueva and Prof. Stoffel) deals with the residence time of typical tree species of Carpathian forests (Norway spruce and European beech) in small channels of Mazácký Grúnik Natural Reserve, Moravskoslezské Beskydy Mts (Fig. 1). We investigated that spruce logs indicated more than two times longer mean and maximal residence times as compared to European beech based on the successful cross-dating of 127 logs (Fig. 2). Maximum obtained residence time in the headwaters was 128 years for spruce and 59 years for beech, whenlog age and log diameter played the most important role in the preservation of wood in the fluvial system.Instream wood creating steps or logs accumulated in jams did not show any differences in residence time as compared to nonfunctional pieces. Shorter residence time was found for hillslope-stabilized wood when compared to unattached wood entirely located in the channel or pieces stabilized by other wood or sediments. We also documented that large flood events recorded by nearby gauging station or by dendogeomorphic methods (dating of exposed roots by channel erosion) were not always responsible for tree mortality and delivering of wood into local channels and thus, another important agents of wood recruitment than lateral erosion (e.g. windthrows, mass movements) should be considered.

During last days, we measured topography of the Mazák Stream and installed RFID pit-tags into fifty logs in order to observe their movement during future hydrogeomorphic events (Fig. 3). To compare wood and sediment dynamics, we also added ca. 70 stones with pit-tags (ca. D50 grain-size) on channel bed.

Fig. 1. Cross-dating performed in the headwater channel

Fig. 2. Depletion rate of European beech and Norway spruce in the studied channels

Fig. 3. Geodetic measurements and pit-tags installation