Ireneusz Malik, Małgorzata Wistuba, Damian Absalon, Michał Habel, Sergey Chalov, Ruide Yu, Hydrodynamic parameters of floods and related bank erosion events indicated from tree rings and 2D hydrodynamic model for a small ungauged catchment (Sudeten Mts., Poland), Ecological Indicators - 2021, Vol. 129, art. no 108021, Punktacja całkowita MEiN: 140.000

W ramach badań opracowano podejścia do integracji dendrochronologii i modelowania 2D w celu wskazywania i oceny przeszłych zdarzeń powodzi i erozji brzegów na małej górskiej rzece Łomniczka w Sudetach w Polsce. Wydatowane zostały zaburzenia wzrostu wynikające z przechylania pni świerków rosnących na zerodowanych brzegach rzek, tj. mimośrodowość słojów i drewno ściskane. Badania dendrochronologiczne  pozwoliły na wskazanie wystąpienia 28 powodzi od lat 30. XX w., w tym 11 powodzi, kiedy na badanych stanowiskach odnotowano również erozję brzegów. Zaproponowane w publikacji podejście pozwala na określenie tempa erozji brzegów podczas określonych powodzi. Model 2D pozwolił wskazać na prędkości przepływu wody oraz naprężenia ścinające jakie działały na brzeg podczas badanych wezbrań. Zaproponowane w niniejszym opracowaniu podejście może być wykorzystywane jako narzędzie do zarządzania powodzią, zagospodarowania przestrzennego i planowania.

Abstrakt

Small mountain catchments usually lack hydrological monitoring and gauges. Therefore, in such areas, data on past flood and bank erosion are often missing, which makes assessing flood and erosion hazards very limited. We attempt to fill in this gap by dating individual flood and erosion events from growth disturbances produced by trees after their stems are tilted, and their roots are exposed and wounded by transported material. We aimed to develop a conceptual approach to integrate dendrochronology and 2D modelling for indicating and assessing past events of floods and bank erosion on a small mountain river Łomniczka, Sudeten mountains, Poland. We dated growth disturbances resulting from tilting of stems of spruce trees which grow on eroded riverbanks, i.e. tree-ring eccentricity and compression wood. We also dated disturbances resulting from the exposure of roots from under the soil cover, i.e. sudden decreases of cell lumen, and root injuries by debris transported by floods, i.e. scars and traumatic resin ducts. Dendrochronology allow to indicate the occurrence of 28 floods since the 1930s, including 11 floods when bank erosion was also recorded at study sites. The approach enables to identify rates of bank erosion during specific floods which ranged at study sites from 20 to 120 cm. The largest discharge was determined for the 1997 flood (106,7 m3 s−1), and the highest flow velocities were obtained for the 1930 floods (4.59 m/s). Results show that the highest shear stress occurred during the floods in 1943 and 1977 (510,3N/m2) and in 1997 flood (469.1 N/m2). We conclude that dendrochronology combined with 2D modelling allowed us to indicate past floods and bank erosion, and to prepare reliable inventories for analyses of flood and erosion hazard. The approach proposed in this paper can also be used as a tool for flood management, spatial management and planning.

  

Link: https://doi.org/10.1016/j.ecolind.2021.108021