Supplementary material

Title

Monitoring methodology of interventions for riverbanks stabilization: assessment of technical solutions performance

Authornamesandaffiliations

António Pinto1, L.F. Sanches Fernandes2, Rodrigo Maia3

1, 3 Faculty of Engineering of University of Porto - Hydraulics, Water Resources and Environment Division, Civil Engineering Department. Postal address: Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal. Tel.: +351 225 081955, Fax: +351 225 081446

2 Centre for the Research and Technology of Agro-Environment and Biological Sciences, Vila Real, Portugal. Department of Engineering, UTAD, Portugal. Postal address: Ap. 1013, 5001–801 Vila Real, Portugal. Tel.: +351 259 350397

E-mail: (corresponding author);

Supplementary material

Table A1 – Summary table of the monitoring application and evaluation of the observed performance of the riverbank stabilization technical solutions implemented in the Algibre river stretch based on the monitoring action carried out in June2016.

Proposed monitoring methodology / Algibre River
1. Preliminary characterization
Intervention causes
Intervention year
Intervention objectives
Used techniques (Bank)
Used techniques(Embankment)
Monitoring/Maintenance actions / High level of erosion of theright bank, endangering the adjacent area used for recreational and tourist activities.
2006.
Implementation of a demonstration center and technical solutions of natural engineering development; Control of the erosion on the bed and banks; and,Implementation of a monitoring system.
Gabion box; Riprap; Sack gabion; Log vegetated cribwall.
Live slope grid; Organic matter; Live staking.
No actions of monitoring/maintenance were carried out since the date of the intervention.
2. Materials (analysisanddiagnose)
Live vegetable material (Bank)
Vegetation type
Length/Diameter (cm)
Revegetation (pruning)
Tree cover uniformity
Roots system
Exotic/Invasive vegetation
Live vegetable material (Embankment)
Vegetation type
Length/Diameter (cm)
Revegetation (pruning)
Tree cover uniformity
Roots system
Exotic/Invasive vegetation
Dried and treated wood (Bank/Embankment)
Resistance/Durability
Technical installation/application
Stones (Bank)
Resistance/Durability
Quantity
Shape
Dimension (D50)
Stones detachment
Geosynthetics(Bank/Embankment)
Integrity
Fixing system
Wire; Staples; Wire netting (Bank/Embankment)
Corrosion and degradation points
Technicalinstallation/application / Gabion Box / Riprap / Log vegetated Cribwall / Live Slope Grid / Live Staking
Non-existant / Non-existant / Non-existant
Salix salvifolia
150(±30)/2(±1)
New shoots
20%
Unstable
Arundodonax / Non-existant / Salix salvifolia
200(±50)/2(±1)
New shoots
30%
Stable
Arundodonax
Non-existant / Non-existant / Non-existant / Salix salvifolia
150(±50) / 2(±1)
New shoots
20%
Unstable
Arundodonax / Salix salvifolia
200(±50)/2(±1)
New shoots
30%
Stable
Arundodonax
Non-existant / Non-existant / High state of degradation (wooden trunks practically non-existant) / Non existant
Good behaviour
Effective
Angular
Gabion box, Riprap (40-60cm)
Not detected / Non-existant / Non-existant / Non-existant
Non-existant
Good state
Wire staples fixing system / Non-existant / High state of degradation
Wire staples fixing system / Non-existant
3. Adaptation of the technical solutions to the intervention site requirements / Gabion Box
(Base conditions) / Riprap
(Base conditions) / Log vegetated Cribwall
(Base conditions) / Live Slope Grid
(Base conditions) / Live Staking
(Base conditions)
Height (m)
Angle (˚)
Material type
Instability mechanism
Mechanism of failure
Shear stress (Pa)
Velocity flow (m/s)
Vegetable revetment
Erosion type
Accessibility for construction / 1.0
90
Granular
Bend
Toe erosion
<200
<2.0
------
Isolated
Yes / OK
OK
OK
OK
OK
OK
OK
-----
OK
OK / 1.0
90
Granular
Bend
Toe erosion
<200
<2.0
------
Isolated
Yes / OK
OK
OK
OK
OK
OK
OK
----
OK
OK / 1.0
90
Granular
Bend
Toe erosion
<200
<2.0
Exotic
Isolated
Yes / OK
OK
KO
OK
OK
OK
OK
KO
OK
OK / 1.0
90
Granular
Lack root
Mass failure
<200
<2.0
Exotic
Isolated
Yes / OK
OK
KO
OK
OK
OK
OK
OK
OK
OK / 1.0
90
Granular
Lack root
Toe erosion
Mass Failure
<200
<2.0
Exotic
Isolated
Yes / OK
OK
KO
OK
OK
OK
OK
KO
OK
OK
4. Strengths and Weakness of the intervention
Strengths
Weakness / The bank toe was strengthened against erosion by the application of gabion box, riprap and sack gabion techniques.
The embankment is at high erosion potential state. This is due to the low performance of the vegetation that did not achieve the expected protection.
5. Assessment of the current observed performance of the techniques used (Qualitative Classification)
Gabion box / IV – Good
Riprap / IV – Good
Log Vegetatedcribwall / I – Weak
Live slope grid / I – Weak
Live staking / III – Fair
6. Comparative performance analysis

Table A2 – Summary table of the monitoring application and evaluation of the observed performance of the riverbank stabilization technical solutions implemented in the Odelouca river stretches based on the monitoring action carried out in June 2016.

Proposed monitoring methodology / Algibre River
Stretch 1 / Stretch 2 / Stretch 3
1. Preliminary characterization
Modifications/Alterations/
Constructions
Intervention causes
Intervention year
Intervention objectives
Used techniques (Bank)
Used techniques(Embankment)
Monitoring/Maintenance actions / The Odelouca dam construction (2010), by means of the high retention efficiency created, does not allow the sedimentological replacement necessary in order to maintain a dynamic balance of the river sections downstream.
High erosion of the right bank / Lack of autochthonous vegetation on the right bank / High erosion of the left bank
2012
Fluvial erosion control, with prevalence to striking and potentiate measures of habitat restoration; Riparian vegetation rehabilitation; Reduction of invasive/exotic plant species (especially - Arundodonax) in the riverside corridor.
Live gabion box / Live riprap / Riprap; Log vegetated cribwall
Live staking; Geomats; Organic matter.
Two years after the intervention (2 actions per year)
2. Materials (analysis and diagnose)
Live vegetable material (Bank)
Vegetation type
Length/Diameter (cm)
Revegetation (pruning)
Tree cover uniformity
Roots system
Exotic/Invasive vegetation
Live vegetable material (Embankment)
Vegetation type
Length/Diameter (cm)
Revegetation (pruning)
Tree cover uniformity
Roots system
Exotic/Invasive vegetation
Dried and treated wood (Bank/Embankment)
Resistance/Durability
Technical installation/application
Stones (Bank)
Resistance/Durability
Quantity
Shape
Dimension (D50)
Stones detachment
Geosynthetics(Bank/Embankment)
Integrity
Fixing system
Wire; Staples; Wire netting (Bank/Embankment)
Corrosion and degradation points
Technical installation/application / Live Gabion Box / Live Riprap / Log Vegetated Cribwall / Live Staking / Riprap
Salix salvifolia
450(±50)/ 10(±5)
New shoots
>90% (Excellent)
Stable
Arundodonax / Salixsalvifolia(1)
Fraxinusangustifolia(2)
Neriumoleander(3)
Tamarixfricana(4)
(1) 150(±50)/4(±1)
(2) 120(±30)/2(±1)
(3) 120(±30)/3(±2)
(4) 100(±30)/3(±2)
New shoots
>60% (Fair)
Stable
Arundodonax / Salix salvifolia
350(±50)/ 7.5(±1) / Non-existant / Non-existant
Non-existant / Non-existant / Non-existant / Salixsalvifolia(1)
Fraxinusangustifolia(2)
Neriumoleander(3)
Tamarixfricana(4)
(1) 150(±50)/4(±1)
(2) 120(±30)/2(±1)
(3) 120(±30)/3(±2)
(4) 100(±30)/3(±2)
New shoots
>40% (Poor)
Stable
Arundodonax / Non-existant
Non-existant / Non-existant / Good behaviour
Trunks fixed by iron staples / Non-existant / Non-existant
Good behaviour
Effective
Angular
Gabion box (40-60), Riprap (30-40cm)
Not detected / Non-existant / Non-existant / Good behaviour
Effective
Angular
30-40cm
Geotextile and Coconut fibers (decomposition state); Geomats (good state)
Stones placement to cover the geotextile;Geomats and coconut fibers fixed with iron staples
/ Non-existant / Good behaviour
3. Adaptation of the technical solutions to the intervention site requirements / Live Gabion Box
(Base conditions) / Live Riprap(Base conditions) / Log Vegetated Cribwall
(Base conditions) / Live Staking
(Base conditions) / Riprap
(Base conditions)
Height (m)
Angle (˚)
Material type
Instability mechanism
Mechanism of failure
Shear stress (Pa)
Velocity flow (m/s)
Vegetable revetment
Erosion type
Accessibility for construction / 2.5
90
Granular
Lack root
Toe erosion
<200
<2.0
------
Isolated
No / OK
OK
OK
OK
OK
OK
OK
---
OK
KO / 1.0
30
Granular
Bend
Toe erosion
<200
<2.0
------
Isolated
Yes / OK
OK
OK
OK
OK
OK
OK
--
OK
OK / 1.5
90
Granular
Lack root
Toe erosion
<200
<2.0
Exotic
Isolated
Yes / OK
OK
KO
OK
OK
OK
OK
KO
OK
OK / 3.0
20
Granular
Lackroot
Mass failure
<200
<2.0
Exotic
Isolated
Yes / OK
OK
KO
OK
OK
OK
OK
KO
OK
OK / 0.50
90
Granular
Smooth
Toe erosion
<200
<2.0
------
Isolated
Yes / OK
OK
OK
OK
OK
OK
---
OK
OK
4. Strengths and Weakness of the intervention
Strengths
Weakness / The live staking placed in the gabion box has anexcellent result. / The embankment renaturalization with native vegetation and exotic vegetation removal was succesfull. / The live staking placed in the cribwall have excellent results, and the wooden trunks are imperceptible.
The isolated spots of exotic vegetation (Arundodonax) and the low density of the stakes (spaced 1.5m). Only 40% success rate in live staking applied to the embankment. / The live staking under-developement. The strong presence of grazing animals in the intervention site and the low density of the stakes (spaced 1.5m). / The isolated spots of exotic vegetation (Arundodonax) and the low density of the stakes (spaced 1.5m). Only 60% success rate in live staking applied to the embankment.
5. Assessment of the current observed performance of the techniques used (Qualitative Classification)
Live Gabion box / V – Excellent
Live Riprap / III – Fair
Riprap / V – Excellent
Log Vegetatedcribwall / V – Excellent
Live staking / III – Fair
6. Comparative performance analysis

1