Landslide susceptibility mapping of the mountainous area in a Luoi district, Thua Thien Hue province, Vietnam

Long Nguyen Thanh

Onderzoeksoutput: PhD Thesis

Samenvatting

A Luoi is a Vietnamese-Laotian border district situated in the Western part of Thua Thien Hue province, Vietnam. Landslides occur frequently in the area and seriously affect local living conditions. Therefore, spatial analysis of landslide susceptibility in the mountainous regions of the A Luoi is very important. Hence, this study focuses on a particular mountainous region of about 262.7 km2 in the A Luoi district. In the study area, recently 181 landslides have been observed. In order to explain these landslides, various factors, i.e. slope, landuse, weathering, geomorphology, geology, soil, elevation, distance from streams or rivers, long-term annual total precipitation, and fault density, were selected and prepared in GIS for landslide susceptibility mapping. Four types of approaches for landslide susceptibility mapping are applied: landslide inventory analysis, heuristic methods, statistical analysis, and process-based or deterministic modeling. In each approach, several methods are applied, i.e. index-based and analytical hierarchical process in the heuristic approach, statistical index, certainty factor, conditional analysis, weight of evidence modeling, landslide susceptibility analysis, probability, multiple linear regression and logistic regression method in the statistical analysis approach, and slope safety factor modeling based on static or dynamic hydrological condition in the deterministic approach. The goal is to learn about the difficulties to apply a certain technique and to select the best technique for application in central Vietnam. In total ten different methods are tested to determine the landslide susceptibility in the study area. The results are discussed and compared in order to evaluate the agreement or disagreement between these methods. The analysis and comparison of these results show that: - There are large differences of results between the three approaches: heuristic, statistical, and deterministic analyses. - The certainty factor is the best method for landslide susceptibility mapping in the study area because it can indicate the zones that are susceptible to landsliding most accurately. Hence, the map based on the certainty factor method is selected as the final result of this study. The final landslide susceptibility map of the study area indicates that the low, moderate, high and very high landslide susceptibility classes are respectively covering 107.5 km2 (40.9%), 48.5 km2 (18.5%), 44.5 km2 (16.9%), and 62.1 km2 (23.6%) of the study area. The detected landslide areas in the low, moderate, high and very high landslide susceptibility classes are respectively 0.47 km2 (6.7%), 0.93 km2 (13.3%), 1.88 km2 (26.7%), and 3.75 km2 (53.3%). The high and very high landslide susceptibility zones are predominant characterized by: - Slope angles higher than 150, and predominantly higher than 250. - The landuse features are mostly afforested land. - The geological features are mainly Dai Loc complex or the Lower A Vuong formation. - The geomorphological units Quaternary-Neogene slow gravity slopes, and Quaternary-Neogene erosional-denudational slopes, are the most prominent. - The weathering features are mostly Sialfelite or Sialite. - The fault density is larger than 1500 m/km2. On the basis of these results, recommendations about landslide risk in the study area are formulated for administrators and local inhabitants.
Originele taal-2English
Toekennende instantie
  • Vrije Universiteit Brussel
Begeleider(s)/adviseur
  • De Smedt, Florimond, Promotor
Plaats van publicatieBrussels
StatusPublished - 2008

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