Soil-Root System Withholding Strength for River Bank Stability

The ability of vegetation to stabilise soils is frequently employed in slope stabilisation projects including riverbank restoration activity. Soil block samples permeated with roots of Bermuda Grass commonly used for remediation and riverbank restoration were tested in a direct shear apparatus. Shear stress results of rooted soils were compared with results of un-vegetated soil bloc—s with similar soil types. The increase of shear strength was determined by comparing shear stresses at speciic horizontal displacements. The relative strength increase at the same displacement was 27.3 kPa compared to 19.1 kPa for un-vegetated soil at a displacement of 13.3cm (Location 3). The relative strength increase at the same displacement of 13.3cm was 43.5% for Location 1 and 42.4% for Location 2. The shear stresses in most of the blocks with roots were still increasing at the end of the test (maximum displacement of about 15cm). These conservative root biomass values and the shearing resistance obtained can be used in the assessment of the stability of the existing vegetated slopes and in the design of vegetated riverbanks.

Soil Bioengineering - A New Technique to Generate Riverbank Restoration

Soil bioengineering is a kind of engineering by using living plant materials to construct the structures with some engineering and ecological functions, which can provide an effective means for the slope stabilization and site restoration of river banks. Experimental site in Liuli River proves that Salix cheilophila Schneid and Salix alba var. tristis are good materials to obtain near-natural riverbank restoration. Soil bioengineering measures of live staking, live fascines and brush layers are effective. After periods time of project implementation, significant effectiveness was obtained on slope stability, habitat improvement, and ecological restoration of river banks. This can provide guidelines for selecting materials and methods to control riverbank erosion. It was concluded that the approach could be widely applied in ecological riverbank restoration in China.