The ADB Capacity Development Technical Assistance project Promoting Climate Resilient Rural Infrastructure in Northern Vietnam is demonstrating how non-conventional engineering solutions can strengthen rural infrastructure, resisting the hazards associated with climate change and providing opportunities to enhance community livelihoods. The project focuses on bioengineering as a low-cost alternative to conventional slope stabilization and protection techniques

1. Promoting Climate Resilient Rural
Infrastructure in Northern Vietnam
ADB TA 8102-VIE
“ Results of Bioengineered Rural Roadside
Slope and Riverbank Protection
Demonstrations”
Nguyen Dinh Ninh – David Rojas

2. I. INTRODUCTION
- “Promoting Climate Resilient Rural Infrastructure in
Northern Mountains of Vietnam” project was funded
by Global Environment Facility (GEF).
- The ADB-administered component supports the
construction of low cost, easily implementable
measures to reduce the vulnerability of rural
infrastructure to extreme climate events.
- The project was scheduled to last for 52 months,
from January 2013 to May 2017.

3. Project Purpose
• To assist Vietnam in taking steps to protect rural
infrastructure from the anticipated effects of climate
change ….
…by enhancing the capacity of stakeholders at local,
provincial and national level (i) to assess climate risks,
and (ii) to design and implement cost-effective,
sustainable, bioengineered solutions to mitigate
climate impacts.

4. Rural road erosion

5. Is this an effective approach?

6. Potential consequences

7. Riverbank erosion

8. Hard revetments do not ensure effective
protection

9. Hard revetments do not ensure effective
protection

10. Outputs
1. Climate change threats and impacts are assessed
and adaptation options identified.
2. Concept and detailed designs developed,
communities engaged, and demonstration
adaptation activities implemented.
3. Strengthened capacity of project stakeholders to
assess climate change impacts and select, design
and implement bioengineered solutions.

11. Bioengineering: definition
• “Bio-engineering is the use of plants to perform
technical surface protection (…) to control erosion or
help to prevent or stabilise shallow slope
movements” (Lao People’s Democratic Republic,
Slope Maintenance Manual, September 2008)
• " Soil bioengineering is the use of living plant
materials to perform some engineering function,
from simple erosion control with grass and legume
seeding or more complex slope stabilization with
willows and other plants ” (Schiechtl, 1980)”(D.F.
Polster, May 2003)

12. Comparative strength of bioengineering structure
and civil engineering structure over time*

13. II. RESULTS OF 4 DEMONSTRATIONS
Implementation procedure
Preparation
Implementation
Monitoring -
maintenance
Transfer

14. a. Preparation
• The Inception Workshop was held in April 2013.
• The proposed demonstration sites were reviewed and an
alternative road site (SP34 in Thai Nguyen province)
identified, proposed and formally approved.
• Baseline fieldwork and consultation were completed at all
four sites.
• Technical surveys of all four sub-projects were carried out,
specifically geotechnical and hydrological.

15. Preparation
• Concept designs for the demonstration measures were
developed.
• The TA’s training framework was developed and
reported .
• The Technical Core Group was approved and
established.
• The first formal training event was held in November
2013 involving core group members and others
(Vulnerability Assessment and Adaptation Response
Workshop)

16. Preparation
• The feasibility study and detailed design drawings for the
demonstration measures at Sub-project 4 in Bac Kan: submitted to
CPMU on 23 June 2014 and approved by MARD on 31 December
2014.
• The feasibility study and detailed design drawings for the
demonstration measures at Sub-project 32 in Son La: submitted to
CPMU on 10 November 2014 and approved by MARD on 9 March
2015.
• The feasibility study and detailed design drawings for the
demonstration measures at Sub-project 35 in Thai Nguyen: submitted
to CPMU on 18 December 2015 and approved by MARD on 27 April
2016.
• The feasibility study and detailed design drawings for the
demonstration measures at Sub-project 31 in Son La: submitted to
CPMU on 15 January 2016 and approved by MARD on 23 May 2016.

17. Results
b. Construction
Start Finish Maintenance
SP4 26 February
2015
26 April 2015 30 June 2016
SP32 15 April 2015 26 June 2015 30 August 2016
SP35 23 May 2016 23 July 2016 20 July 2017
SP31 28 June 2016 10 October
2016
01 November
2017

18. Measures applied at 2 riverbank demonstrations

19. Measures applied at 2 roadside slope
demonstrations

20. Cross-section

21. Cross-section

22. Construction of Thanh Mai riverbank revetment

23. Construction of Muoi stream revetment

24. Construction of embankment in Thai Nguyen

25. Construction of demonstration on cut slope
in Son La

26. Construction
• Short construction time, 2 months for a
demonstration.
• Only SP31- Son La took 2 months longer due to
rainfall and floods.
• Best time for construction: earthworks done in dry
season, installation of bioengineering measures
carried out in the middle or at the end of Spring.
• 12-month maintenance: appropriate duration

27. Thanh Mai revetment before construction

28. Thanh Mai revetment after construction

29. April 2015

30. May 2015

31. July 2015

32. July 2016

33. March 2017

34. April 2015

35. July 2015

36. July 2016

37. March 2017

38. Vegetated riprap

39. Muoi riverbank before construction

40. Muoi riverbank after construction

41. Local people engaged in construction

42. April 2017

43. April 2017

44. April 2017

45. Initial assessment
• Riverbank revetments in Thanh Mai, Bac Kan
and Thon Mon, Son La have gone through 2
rainy seasons with major floods, yet remained
intact.
• Revetment toe remains stable.
• Plants have had robust growth.
• Riverbed at the demonstration sites remains
stable.

46. Initial assessment
• Revetment toe was stabilized by riprap or
vegetated gabions, using Homonoia Riparia
(North-East), Salix tetrasperma (North-West).
• Stabilization measures used for semi-
inundated upper slope included Homonoia
Riparia (North-East), Salix tetrasperma (North-
West).
• Stabilization measures used for upper slope
included Vetiver grass or blanket grass.

47. SP35 before construction

48. Gullies on fill slope

49. SP35 after construction

50. October 2016

51. October 2016

52. October 2016

53. March 2017

54. March 2017

55. March 2017

56. SP31 before construction

57. SP31 after construction

58. April 2017

59. April 2017

60. April 2017

61. Initial assessment
• Roadside slope protection demonstrations have
only gone through one rainy season.
- Slope protection demonstration at Nhau Pass in
Thai Nguyen: stable, showing no signs of
erosion, plants have had good growth and
provided full coverage for cut and fill slopes.
- Flowers of Tiger grass have been harvested by
local residents and used for making brooms.
• Slope protection demonstration has not yet gone
through any flood seasons → further review
required.

62. Initial assessment
• Randia tomentosa used at toe slope, Tiger grass used
on upper slope are native plant species.
• Vetiver grass is highly effective in slope erosion
protection, yet relatively costly because it is not
locally available, hence incurring transportation cost.
• Further research of other native plant species for
slope erosion protection (Rhodomyrtus tomentosa or
Rose myrtle, Melastomataceae, Cortaderia selloana
or Pampas grass, Imperata cylindrical or Cogon
grass…) recommended.

63. Comparative cost

64. General comments
Advantages of bioengineering:
 Sustainable when properly applied
 Environmentally friendly
 Promotes livelihoods
 Easy to implement and time efficient
 Low cost

65. Lessons learned
1. Identify high-risk locations at early stage in a
project
2. Include bioengineering at earliest stage of
project planning
3. Use local knowledge of plants
4. Use low-cost investigation procedures

66. Lessons learned
5. The importance of integrating hard and soft
measures
6. The limitations of bioengineering – it cannot
fix deep-seated slope failures
7. The need for clear and simple design
guidance
8. The importance of quality control

67. Replication potential
- Mrs Ha Thi Huyen has used
Homonoia riparia for her
family’s field erosion
protection in reference to
demonstration measures used
at Thanh Mai riverbank
revetment.
- Lai Chau and Lang Son DARD
have contacted ICEM
consultants to obtain
reference documents and
discuss potential
bioengineering options for
local use.

68. Conclusions and recommendations
1. Generally, bioengineering measures can be
effectively applied for riverbank and roadside
slope protection.
2. Certain measures (e.g. live poles on riverbank,
jute net and grass seed) require revision or
improvement.
3. It is important to select appropriate plant
species and growing season in order to ensure
the success of bioengineering measures.

69. Thank you!