Friday, 23 November 2018

Our research of instream wood in Mediterranean environment

This year, we continued with investigations of the abundance and geomorphic effect of instream wood in Mediterranean fluvial systems. In June, we again visited the Lefka Mts (the highest mountain range in Crete, Greece) to assess predictors of instream wood loads in intermittent and ephemeral streams draining this mountain range. We measured parameters of wood together with channel geometry and riparian forest characteristics in ca. 40 channel reaches. The preliminary results show that the frequency of instream wood has rather a random character, whereas the biomass in riparian forests is important for instream wood volumes in small Mediterranean channels. 

Wood deposited by a previous flood outside the bankfull channel.

Step consisted of instream wood acting as sediment retention element.
During late September, we also investigated characteristics of instream wood in larger intermittent river (the Evrotas) draining the Peloponnese peninsula. Together with colleagues from Hellenic Center of Marine Research (Dr. Vardakas, Prof. Kalogianni) we also tried to find connections between the occurrence of instream wood and local endemic fish species. The examined river is interesting by alterations of hydrologic (dry vs. wet channels) and geomorphic (single thread vs. wandering) patterns. These alterations are reflected in the abundance of instream wood together with the character of riparian trees and occasional removal of instream wood by local people.

Instream wood in a single-thread wet reach.

The stump transported by a previous flood into dry wandering channel.
Now we are processing field data from both studied areas and we are planning to prepare related scientific articles during the first moths of 2019.      

Monday, 12 November 2018

Field excursion about river restoration projects in Upper and Lower Austria

The field excursion trip took place for students of our Department of Physical Geography and Geoecology from 5 to 8th September 2018. The main idea was showing river restoration projects in Lower and Upper Austria, namely on the Danube River and its tributaries, e.g. on the Traun River or the Ybbs River.
On Tuesday 6th of September, the first day of field excursion trip was focused on river restoration projects in urban area of Linz City. Especially, on the restoration of gravel bars on the left-side bank of the Danube River and future vision of river restoration of Danube River, e.g. creating of islands and side-channels in Urfahr District.
The second day of excursion was focused on the river restoration projects in downstream part of the Ybbs River. We visited reaches between Greinsfurth and Winklarn villages where river restoration were realized, e.g. fishpass through Greinsfurth hydropower dam (or weir), distributary of the Ybbs River near Winklarn for increasing of biodiversity and heterogeneity of channel, or restoration of mouth of the Ybbs River to the Danube River.
The third day, we visited hydropower dam in Melk with lock chamber for river navigation on the Danube River. The last stop was close-to-natural fishpass through hydropower dam in Melk.

Restored gravel bars on the left-side bank of the Danube River in Linz.

Fishpass through Greinsfurth hydropower dam.

Greinsfurth hydropower dam.

Presentation of river restoration of distributary near Winklarn.

Crossing through the restored reach Ybbs River near Winklarn.

On the hydropower dam in Melk.

Field Excursion was supported by Moravian-Silesian Region