Morphodynamic effects of stone and wooden groynes in a restored river reach

Abstract

Restoration works on an 11 km long reach of the Spree River near Cottbus in Germany were accomplished in 2014. The overall objective was to improve the biodiversity, changing the morphological structure from a straight single-thread river to a braiding one with reshaped thalweg, and creating zones with varying flow velocities required for fish spawning. Several interventions were made, among which also two types of groynes were constructed along the reach: impermeable stone groynes, with an inclined crest so that only the tip is typically submerged during normal flow conditions, and wooden groynes made of several large trunks, which are mainly submerged at normal flow conditions. To compare local morphodynamic effects caused by the different types, flow velocities and bed topography were measured at distances of 12 m upstream and 16 m downstream of two selected groynes. The vertical profile was captured by measuring at five levels above the bed. Bed material was sampled at several locations around the groynes. The analysis of the measurements showed the effect of each groyne type on the flow velocity, bed topography and bed material. Furthermore, the differences in the effects of each groyne type on the flow, bed topography and bed material were highlighted.

Investigation of Flow, Erosion, and Sedimentation Pattern around Varied Groynes under Different Hydraulic and Geometric Conditions: A Numerical Study

“…For example, Vaghefi, et al [2] investigated the effect of the shape of groynes on flow pattern. Zaid, et al [3] looked into groyne materials by studying the effects of stone and wooden groynes in a restored river reach. Uijttewaal [4] tested four types of groynes found among the largest rivers in Europe to determine efficient alternative designs, while considering the physical, economical, and ecological aspects [4].…”

Microbiological community structure on logs used for groynes in a riverbank system

“…A river groyne is a civil engineering structure that is used for the control of water flow by installing huge stones and concrete blocks in the bank of the river. The structure enables the control of riverbank erosion at a bend in the river and protects the bank from the action of running water [11][12][13][14]. In addition to stones and concrete blocks, water control technology using logs has been also used in many parts of the world.…”