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Soda-Mattress Riverbank Protection Measures

5 th World Water Forum, Istanbul, Turkey 16 – 22 March 2009. Soda-Mattress Riverbank Protection Measures. Ministry of Public Works and Transport Department of Waterways Lao, PDR Mr. Houngla SENGMUANG Mr. Phaknakhone RATTANA Ms. Vanh DILAPHANH Mr. Kazumitsu MURAOKA.

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Soda-Mattress Riverbank Protection Measures

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  1. 5th World Water Forum, Istanbul, Turkey 16 – 22 March 2009 Soda-Mattress Riverbank Protection Measures Ministry of Public Works and Transport Department of Waterways Lao, PDR Mr. Houngla SENGMUANG Mr. Phaknakhone RATTANA Ms. Vanh DILAPHANH Mr. Kazumitsu MURAOKA

  2. Contents: • 1) Introduction (Background of Lao PDR and Mekong River) • 2) The Condition in the Activity Area • 3) Design of Riverbank Protection Works • 4) Features and Installation of Soda Mattress • 5) Construction Cost • 6) Conclusion

  3. Lao Peoples Democratic Republic  Area: 236,800 sq km.  Population: 5.6 million (2005).  GNP or GDP: 491 US$ (2005)  Capital city: Vientiane.  Bordering: China, Myanmar, Thailand, Cambodia and Vietnam.  Altitude: 90 - 1500 m above MSL  Climate: Tropical, monsoon.  Temperature: 15C to 38C • Mekong River • The world’s twelfth longest river, length of mainstream 4,825 km, runs through the Lao territory with a length of 1,865 km. • The tenth largest in terms of annual flow with total drainage area 795,000 sq km. • Runs through six countries: China, Myanmar, Lao PDR, Thailand, Cambodia and Vietnam.

  4. Water Level of Mekong River

  5. Mechanism of bank erosion • Due to scouring at foot of riverbed(Most of the eroded vertical riverbank cliffs are of this type)Due to lowering river water level • Due to slope failure • Severely eroded riverbanks form Vertical Cliffs mostly. • Damage by the erosion extends to many facilities (such as road, houses, oil bases, factories, electric cables).

  6. Design Philosophy of Riverbank Protection Work • Using local construction material as much as possible. • Using manpower of Lao P.D.R. as much as possible. • Construction and maintenance work can be done by people of Lao P.D.R. as much as possible. • To pay attention to keep riverine environment

  7. Japanese Traditional River Works • Japanese traditional method of river works are suitable for Mekong River around Vientiane City, those are ; • “SODA” Mattress esp. for foot protection works • Cobble-Stone with Willow Branches Work • Wooden Pile Dike Groyne Work

  8. WHAT IS “SODA” ? “SODA” IS BRANCHES OF BRUSH WOOD CUT FROM MISCELLANEOUS SMALL TREES IN FIELDS AND FORESTS • MAY TIOU NAM, MAY POHOU, MAY PAO, MAY MOUK, etc. TREES WITH STRENGTH AND TENACITY FOR HURDLE WORK: FLEXISIBILITY STRUCTURE OF SODA MATTRESS

  9. Foot Protection Work- Assembling and installation of Soda Mattress 5) Piling short wooden piles to combine upper and lower lattice structures and for hurdling work 2) Making ‘Rensai’ (connection beam made of fascine) 3) Fixing node of Rensai lattice 4) Flooring ‘Siki-Soda’ work 1) Preparation of Soda bundles 6) Placing floating Soda mattress at the planned position by boat 7) Connecting Soda mattresses by manpower 8) Row of connected mattresses

  10. Riverbank Protection Works Activities Location of Material Collection Sites Laksamsip Danxi Ban Sakai (50 km from city center) Donloun Nong Teng Kao Liao Sibounheuang Nongpen Xiangkhouan • : Quarry site Wat Chom Cheng • : Fascine material site • Ban Dongphosi 2 km : Stockyard 2 km : Borrow site of sand, gravel and laterite

  11. Features of SODA Mattress • Flexible and Durable in water • Porous for good habitat of aquatic life • Suitable to sandy riverbed as foot protection • Effective against sand suction • Mainly adaptable to mild slope river of less than 1/2000. • Setting condition: Below low water level

  12. Plan Total Length=156 m Typical Cross Section Slope Protection Work (Cobble stone with willow branch work) Foot Protection Work (Soda mattress work:23 sheets) Foundation Work (Log Hurdle work)

  13. Average Construction Cost

  14. January 2004 Before construction (Oct. 2002) Pilot Work at Ban Dongphosi (completed in May 2003) March 2005 June 2005 Continuous Monitoring • The Climate in Laos is very much different from that in Japan (especially very long dry season in Laos). • It is essential to monitor the completed works at least 5 years • to verify the appropriateness of Japanese method such as the effect of protection, growth of vegetation, sedimentation • to find the issues to be improved for localization.

  15. Conclusion - Importance of a appropriate technology, the project has introduced the Japanese traditional methods on the riverbank protection (particularly Soda Mattress Method) instead of high technology. - One of the characteristics of the method is low cost, it is easy to maintain by local people and can use of existing material, it is suitable for developing country like Lao PDR. - Therefore, the appropriate techniques is very effective to make counterpart agencies to aware and strengthen partnership with relevant organization and local people to take the ownership.

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