Team 09 Nguyen chau lan (Vietnam) Dilum Wannigasekara (Sri lanka)

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1 Team 09 Nguyen chau lan (Vietnam) Dilum Wannigasekara (Sri lanka)

2 contents Part I: Landslide in Vietnam Part II: Case study of Landslide in sri lanka

Part I: Introduction of Landslide in hoa binh province Vietnam The Hoa Binh province is located in the northwestern region of Vietnam. It covers an area of about 4,660 km 2.

3 Part I: Introduction of Landslide in hoa binh province Vietnam The Hoa Binh province is located in the northwestern region of Vietnam. It covers an area of about 4,660 km 2. The maximum elevation in the province is 1,510 m above sea level. an increasing frequency of landslide occurrences due to: Heavy rainfall Tectonic activity Steep terrain Extensive clear-cut logging Five major fracture zones (Hoa Binh, Da Bac, Muong La-Cho Bo, Son La-Bim Son, and Song Da) pass through the province causing rock mass weakness. Tien Bui et al., Nat Hazards (2013) 66:

4 Description of landslide in Hoa Binh province Time period Tan Mai and Phuc San February 16, 2012 September 13, 2012 March 2, 2012 Place Damage Remark Phieng Sa, Tan Son Tong Dau and Dong Ban 350 families had to relocate due to large landslide Large destroying a section of the national road number 6 and killing two people destroyed the road section and blocked traffic for some days Large landslide (more than 40,000 m 3 ) collapsed destroying more than 100 m of the road section and caused serious traffic problems.

5 Damage due to landslide Landslide Phieng Sa, Tan Son areas Landslide destroyed road in Hoa Binh province

threshold for the Hoa Binh province, RTH is the threshold rainfall, and

6 Threshold Rainfall in hoa binh province Distribution of rainfall at the 12 rain gauges of the Hoa Binh province of the period Rainfall threshold for the Hoa Binh province, RTH is the threshold rainfall, and R15Ad is the 15-day antecedent rainfall Tien Bui et al., Nat Hazards (2013) 66:

7 Counter measure for landslide

8 Conclusion part I An example photograph of a landslide risk area at Dong Tien, Hoa Binh city. Photo courtesy of the Hoa Binh newspaper 2012

9 Conclusion part I There are many of permanent retaining walls and anchor system for increase stability of slope and landslide prevention in Hoa binh. However, because of limited technology and budget for landslide prevention, there are issues for research and development in Vietnam beside achievements including: Technologies of landslide inspection, monitoring and forecast; Technologies of groundwater moving monitoring and control; Landslide mapping for Vietnam; Completion of experiments, analysis and selection of calculated data; Model technologies with data calculation and analysis and designing softwares;

10 Present by: Dilum Wanigasekara Engineering Geologist National Building Research Organization Sri Lanka 14/08/2013

11 Location Peradeniya town is located in Kandy district, Central province of Sri Lanka.

12 Importance of the area: The gateway to the historical city of Kandy. City is situated in the middle of two most important interchanges in the country A1 (Kandy Colombo) & A5 (Kandy- Nuwara Eliya) Highway roads and the most busiest road in the country. Some important places in the area: -Peradeniya Botanical Garden -University of Peradeniya -Peradeniya teaching hospital Mahaweli River (Longest river in Sri Lanka) flowing through peradeniya. Large scale commercial town.

13 Location map of the area: (Source-Google image 2013) Landslide location

14 INTRODUCTION Landslide Hazard in Peradeniya (November 2006) Landslide Hazard Zonation map of the area

15 Side view Front view

16 Occurred in November 2006 Large scale landslide and Rock falling 04 people were killed and 10 commercial buildings/shops were completely destroyed. interrupting road traffic for 03 weeks Sri Lankan government planed to resettle the town into a new location-iriyagama where1.5km away from the existing location. Not success as, -The commercial community rejected. -Very important and an attractive area in the country. -High cost involving for the proposed new town for a developing country

17 Geology of the area: Consisting with Reddish brown/yellowish brown Sandy clayey soil. Bed rock: Quartzo feldspathic gneiss Highly jointed/ fractured rock. Scarpment slope. Overburden soil thickness approximately 2.50m- 5.50m

18 National Building Research Organization (NBRO) carried out an extensive study of this area, culminating in a project proposal submitted to the Government in Since the year 2009, the Government of Sri Lanka has allocated Rs. 102 Million to mitigate this landslide.

19 Mitigation Process The mitigation work started in December 2009 by the Landslide Research and Risk Management Division (LRRMD) in NBRO under the Ministry of Disaster Management. The applied and proposed structural mitigation measures for mitigating this landslide include, trimming and benching, rock blasting, soil nailing, rock bolting, Construction and Improvement of surface drainage. turfing.

20 Trimming and benching:

21 Rock blasting

22 Soil nailing, rock bolting

23 Construction and Improvement of surface drainage

24 Turfing

25 Comparison Before Now

26 So far. 75% of the mitigation activities are completed under phase no-01. Two unstable potential landslide areas located besides the location. New Proposal: Extend the number of tracks on the main road and to upgrade the city with latest infrastructure facilities and recreational Facilities to function as a commercial and leisure area and to attract more local and Foreign People.

27 New Proposal

28 Landslide potential area-02 Mitigating area Landslide potential area-01

29 My recommendations: Continuous monitoring system for the potential area. Rain gauge Inclinometers Extensometers Monitoring camera Landslide early warning system with commercial building owners as the volunteers.

National Platform for Disaster Risk Reduction in Sri Lanka

National Platform for Disaster Risk Reduction in Sri Lanka Eng.(Dr) Asiri Karaunwardena Director General / National Building Research Organization Ministry of Disaster Management Sri Lanka National Platform