Slopes stabilization!

1. Ecotechnical methods in order to stop erosion of riverbanks and slopes
Răzvan Voicu
Method 1
Coconut fiber rolls or fascine rolls will be placed in a semicircle, on the slope, at a distance varying between 0.5 m and 3m. These rolls can be made in one piece (which is preferable) or more pieces, depending on the width of the slope. Being placed in a semicircle or half-buried in the soil, the rolls will redirect the water flow on the lateral side. (Fig. 1- fascine rolls or coconut fiber rolls, slope, drains, Positioning of fascine rolls – indicative scheme)This solution is viable for both a convex slope and a concave slope.
fascine rolls or coconut fiber rolls
slope

2. fascine rolls or coconut fiber rolls
slope
drains
Figure 1 Positioning of fascine rolls – indicative scheme
This solution is viable for both a convex slope and a concave slope. Some species of grass with fascicular root should be planted between the rolls, helping to fix the slope. Bamboo cuttings will be fixed at the top of the rolls, which in turn will form a drain that is connected to main drains(fig.2).

3. bamboo cuttings
system (hemp ring) for fixing bamboo cuttings to fascine rolls
fascine rolls or coconut fiber rolls
slope
drains
Figure 2 Positioning of bamboo cuttings – indicative scheme
After a while, the bamboo cuttings will fix their roots into the slope so that they could not ever slip down(fig.3).

4. system (hemp ring) for fixing bamboo cuttings to fascine rolls
bamboo cutting
fascine rolls slope
Figure 3 Fixing bamboo cuttings to fascine rolls – indicative scheme
With such a support system, the rolls can never slip down. The two outside drains should be ecotechnically arranged, where possible(fig.4).
riparian vegetation
wood
Figure 4 Ecotechnical arrangement of drains - indicative scheme

5. Method 2
Another method suggests fixing several lines of (willow, alder, bamboo, etc.) cuttings into the slope, perpendicular to each other(fig.1).
cuttings
hemp fixing system
cuttings
slope
Figure 1 Positioning of cuttings – indicative scheme
This fixing system on the slopes stops tangential efforts and eventual sliding of different pieces of the slope (action and reaction) (fig. 2).

6. cuttings
F1
F2
F3
F4
slope
Figure 2 Action force of the slope and reaction force of the cuttings – indicative scheme
The conditions of fixing these cuttings(fixing angle) diversify in function of land texture, the erosion of land, the angle of slope etc).
Method 3
Another method of stabilizing slopes would be drilling cylindrical holes in line where coconut fiber rolls to be fixed. These rolls are surrounded by 3 or 5 (alder, willow, bamboo, etc.) cuttings (fig. 1). Positioning of these cuttings is performed in line or rhomboidally.

7. cuttings
coconut fiber rolls
slope
Figure 1 Positioning of cuttings – indicative scheme
Method 4
Stopping pronounced erosion of watercourses is an important process for the dynamic of rivers, biodiversity and to protect the human settlements in their vicinity. Therefore, on the river bank, near the eroded area, wooden poles will be set parallel to the eroded area. Cuttings (alder, willow, bamboo, etc.) will be fixed to these wooden poles by using hemp canvas (fig. 1).

8. cuttings
watercourse
wooden poles to support the cuttings
Figure 1 Fixing the cuttings – indicative scheme
After the roots have been developed, cuttings will stabilize the bank directly, but they will also redirect the watercourse outside the eroded areas. First, to achieve these solutions, a channel along the eroded area must be done. After the channel has been performed, a wooden pole will be set crosswise or transversal to the channel, but on an inclined plane (fig. 2).
supporting pole
Figure 2 Fixing the supporting pole – indicative scheme

9. After that, the bank is drilled on the outside so that the three rows of cuttings to be fixed on the supporting pole. (fig. 1). After the cuttings have been fixed on the supporting pole using some hemp clothes, the channel is sealed. The bed is linearized before stabilizing, where possible.
Method 5
Another method of strengthening the slopes consists of their fixing by the means of straw rolls. Using cylinders of hemp, some cuttings will be laterally fixed on the straw rolls (fig.1).
straw rolls
cuttings cylinders of hemp
Figure 1 Fixing the straw rolls – indicative scheme
The straw rolls can be placed all over the slope or only in different areas (fig. 2).

10. straw rolls
Figure 2 Placing the straw rolls on the slopes – indicative scheme
The advantage of this solution is that it can successfully stop the massive dislocations of the slopes.
Method 6
This method consists in fixing the soil (slope) using wooden poles arranged longitudinally on the slope (fig. 1). The poles are arranged uniform all over the slope. Some cuttings with a branched root system will be fixed perpendicular to these wooden poles (fig. 2), which in turn will support the slope.

11. wooden poles
Figure 1 Placing the wooden poles on the slopes – indicative scheme
cuttings
fixing system for the cuttings
slope wooden pole

12. Figure 2 Positioning of cuttings – indicative scheme
Cuttings are fixed on the wooden pole using hemp canvases allowing their growth. Due to their elasticity, the wooden poles keep the soil under tension by fixing it (fig.3).
F1
F2
F4
F3
Figure 3 Action force and reaction force – indicative scheme
Method 7
The arrangement of the river banks can be achieved by using some pols and cuttings. Two horizontal wooden pols are attached to other two vertical wooden poles, which in turn are attached to the river banks in the eroded area. (fig. 1).

13. wooden poles
Figure1 Positioning of wooden fence – indicative scheme
The wooden bars are attached together by the means of a metal catching system in order to form a fence. The fence is in the form of an inclined plane and a set of compact cuttings are fixed on it by using hemp rings (fig. 2). These cuttings will fix the soil and stop the erosion. They will operate as a bank which cannot be eroded. As the method 4 presented above, a channel parallel to the eroded area must be developed in order to achieve these results.
erosion of the river bank
watercourse cutting wooden poles

14. Figure 2 Positioning of the cuttings on the river bank – indicative scheme
Method 8
Other possible solution against slope erosion consists in making exclusive wooden rectangular gabions. Cuttings are fixed to the horizontal sides (fig. 1). As presented before in other ecotechnical methods, the cuttings will be fixed on the gabions using some cylinders of hemp fixed by these gabions.
wooden gabion
cuttings
Figure 1 Positioning of a wooden gabion– indicative scheme
Fascine rolls for gabions stability will be set at the bottom of these gabions (fig. 2).

15. cuttings
wooden gabion
fascine rolls
Figure 2 Positioning of fascine rolls – indicative scheme
After a time period, the cuttings will fix their roots into the slopes. For greater effectiveness, the gabions are arranged rhomboidally all over the slope. (fig.3).
wooden gabion

16. Figure 3 Positioning of gabions on the slope – indicative scheme
Conclusions
All these ecotechnical solutions can be applied worldwide according to previous surveys on slopes or watercourses. Costs are lower than for traditional solutions; ecological materials are used in order to restore the study areas effectively.
Bucharest 2012