Riparian rehabilitation and bank protection design for a sand bed stream in the Upper Hunter Catchment, NSW, Australia
We present a set of laboratory experiments based on field site conditions along a reach of the Widden Brook, a sand bed stream in the Upper Hunter Catchment of south-eastern Australia that is currently being restored by reintroduction of lost riparian vegetation. Three experiments were conducted to investigate the impact of bank vegetation on flow and sediment dynamics. The first experiment contained no bank vegetation and was similar to the original state of the stream. The second experiment placed a series of three inline vegetation patches along the outer bank and the third experiment used a continuous strip along the outer bank. In each experiment a dense grid of velocity, water surface elevations and sediment transport masurements were collected.
Both arrangements of vegetation provided effective bank protection; however the patches used less vegetation and were thus more efficient. With continuous coverage the flow in the developed region of the vegetation zone was approximately constant. With patchy coverage there was some recovery of momentum which was reflected in the gradual increase in velocity between patches.
Dr. Jose Rodriguez is a senior lecturer at Civil, Surveying and Environmental Engineering, The University of Newcastle Australia.