| Main results | On the basis of results from assessment, detail risk zoning and proposal of mitigation methods for ground rapture-landslide and flash flood - debris flow hazards in Son La- Dien Bien - Lai Chau provinces, we can have some conclusions as followed:
- Geohazards such as: ground rapture-landslide and flash flood - debris flow hazards are complex in Son La- Dien Bien - Lai Chau provinces. The most serverly damaged areas are Muong Lay, Son La, Muong La, Muong Te, Phong Tho, Dien Bien, Tuan Giao, Tan Uyen, Than Uyen and ect…. In the area, there was an occurrence of the most serverly damaged debris flow events in Muong Lay, 1999.
- The occurrence of ground rapture-landslide and debris flow hazards are closely related to large active faults such as: Lai Chau - Dien Bien, Pac Ma - Muong Te, Sin Thau - Muong Nhe, Phong Tho - Than Uyen, Muong La - Cho Bo, Song Da, Son La - Bim Son, Song Ma and Sop Cop - Lang Chanh; strongly raptured zones: Nam Ma, Binh Lu - Than Uyen, Muong Mo, Yen Chau; or uplifted structures in Neo-tectonics such as Phu Si Lung, Hoang Lien Son, Phu Sam Cap... Flash flood occures mainly along slope of positive structures and valleys, such as mountains of Phu Si Lung, Hoang Lien Son, Phu Sam Cap, Phu Den Dinh and low structures such as Muong Te, Muong Nhe, Nam Ma, Binh Lu - Than Uyen, Muong Mo, Yen Chau, Muong Lay, Muong La, Ta Khoa...
- Ground rapture-landslide and flash flood - debris flow hazards are mutual hazards. Ground rapture cause rapturing and deep weathering layers and enhancing landslides. Landslide in turn, supply materials for debris flow. Debris flow damps streams and rivers which cause flash flood. Flash flood - debris flow hazards encourage erosion. So, in one area, it is usual that landslide and flash flood - debris flow hazards occures silmutaneously (in 1996: Huoi Leng, Nam He, Pa Ham, Nam Mo, Nam Hang, Muong Lay, Lai Chau city).
- The formation and development of landslides is mainly affected by ten factors. Dipping, rain fall are the most important factors, followed by weathering crust, geo-technical, dynamic-rapture zones, geo-hydrology, vegetable cover and human activities.
- Using approach of integration of factors which effect to causing, forming and developing mechanisms of ground rapture-landslide and flash flood - debris flow hazards Son La- Dien Bien - Lai Chau provinces, allow us to assess the risk from low level area to high one.
- Synthesizing and selecting to give managing and technical solutions help us reducing the damage caused by the hazards and mitigating ground rapture-landslide and flash flood - debris flow hazards. The human managing solutions are firstly recommended. Simply technical solutions can be applied. |
| Recommendations | - Archived results of the project have deeply scientific and actual significance. That is the importantly actual basis which is useful with scientists, administrators, managers from various ministries, and departments in constructing, developing social-economics in Son La- Dien Bien - Lai Chau provinces.
- Mitigation of ground rapture-landslide and flash flood - debris flow hazards must be recognized as the task of each individual, each family and every administration levels. In mitigating geo-hazards, two important contents can not be decoupled: managing every human action and applying suitable technical solutions.
- Afforesting and managing watershed must be also recognized as the task of each individual, each family and every administration levels in Son La- Dien Bien - Lai Chau provinces.
- Constructing of cities, towns, residential areas and economic facilities is indispensable trend for study area It is imperative to enforce forecasting networks of geohazards, especially such as ground rapture-landslide and flash flood - debris flow hazards. Establishing of advanced early-warning systems as well as emergency rescue in order to reduce hazard damages. For residential areas where occurrence of hazards is complicated and hazardous, civilian must be moved to safe areas.
- It is imperative to enforce forecasting networks of geohazards, especially such as ground rapture and landslide hazards. Establishing of advanced early-warning systems as well as emergency rescue in order to reduce hazard damages. For residential areas where occurrence of hazards is complicated and hazardous, civilian must be moved to safe areas.
In progress of the project, we always receive guidance and favorable conditions from many different administrators. Vietnam Academy of Science and Technology’s directorate, Department of Planning and Finance, Institute of Geological Science’s directorate, Department of Science and Technology of Lai Chau, Dien Bien and Son La provinces are really appreciated. |
