韓國의 山沙汰 發生要因과 豫知에 關한 硏究 = Landslides occurrence and its prediction in Korea

다국어 초록 (Multilingual Abstract)

In order to reduce the damage from landslides, this study was undertaken;
* to classify landslide-prone areas,
*to find out the factors of landslides occurrence,
*to investigate and predict landslides.
Data about landslides were collected from records and literature to identify landslide-prone areas. For investigation of landslides condition, both forest and site conditions were inverstigated in 317 plots in Anyang,pyeongchang, Jinhae, Boeun, Jeongseon, Yeongweol, Gwangyang, Bosung, Habcheon and Changweon where landslides occurred from 1977 to1982.
All data pertaining to the occurrence of landslides were analyzed statistically and the results are as follows;
1. Landslide-prone areas in Korea are divided into 4 regions including surrounding and central Hwacheon, Gwangreung and Anyang districts(region1); surrounding and central Yangyang, pyeongchang, Boeun and Geumsan districts(region2); surrounding and central Euichang and Jinhae districts(region 3); and surrounding and central Hadong and Boseong districts(region4).
The bed rocks consist of granite and granite-gneiss, metamorphic sedimentary rock, silla group, and granitic gneiss in region 1,2,3 and 4 respectively.
2.The frequency and acreage of landslides occurrence from July to September for 81 years(1904~1985) were 84 and 98 respectively.
The probability of landslides was very high when continuous rainfall exceeded 200mm and maximum rainfall intensity was more than 32mm per hour.
3. The types of landslides by shape could be categorized into 4 types: A type(dendroid shape), B type(file, omega, dome, shell and fishtrap shape), C type(straight shape) and D type(board shape). Among four types the most frequent was C type, A and C type were also found to occur in large scale.
4. It was observed that the smaller the size of the landslides, the greater the frequency of landslides as demonstrated by the results that 86% of landslides were less than 100m long,
90% of landslides were less than 20m wide and
91% of landslides were less than 2,000m^(2) in acreage.
5. Landslides occured most often in coniferous stands, less in hardwoods and least in mixed forest, and most prevalent in stands with open crown density and small diameters.
6.It was observed that landslides occured in 225 plots per 1,000ha of unstocked forest stand and 136 plots per 1,000ha of stocked forest stand.
7.On mountainsides occurred 40% of landslides and 77% at concave areas with high soil water concentrations due to the shape of cross section of topography. Also it was observed that landslides occurred more frequently at concave or rectilinear slope than convex slopes due to the slope form, and mostly on a slope between 30~35˚
8.Among the various causes of landslides occurrence, surface discontinuities accounted for 16%, underground discontinuities for 81%, and stream erosion for3% of the total plots. These results strongly demonstrated that landslides were influenced by soil characteristics.
9.It appears as though the main factors which influence the occurrence of landslides were the length of slope, bed rock, position of slope, topography, shape of cross section, slope gradient, average stem diameter of stand, stoniness, forest type, depth of landslide and slope form in this order of partial correlation coefficient.
Among these factors, shape of cross section, length of slope, bed rock, slope gradient, position of slope, average stem diameter of stad and slope form were selected to prepare the score table for prediction of landslide susceptibility on the small area; and this score table was prepared by multivariated statistical analysis.
10. In accordance with landslide size and factors which influence their occurrence, the following relationships were establsihed.
(1) large scale landslides occurred generally on slopes of concave shape and straight shperather than on convex shape.
(2) in accordance with length of slope, the longer the slope, the larger the landslide area.
(3)bed rock composition affected landslide size in the following order of magnitude; granite-gneiss, phyllite, slate or passmmite, granite and lime-stone.
(4)the steeper the slope, the smaller the landslide occurred on the hillside.
(5)position of slope played an integral role in landslides occurrence;that is, higher the position of slope increased the larger the landslide area.
(6)large scale landslides occurred in small diameter stands, but rarely in stocked stands.
(7)large scale landslides occurred more often on concave slopes than on rectilinear slope.
11.In applying the information for the prevention of landslides, a basic and preliminary landslide overview map was developed, preliminary landslide overview maps are necessary for 69 districts in Korea in the future.
12. For practical use of landslides investigation relevant to disaster prevention and countermeasrus, preliminary landslide overview maps were prepared for the three districts such as Jinhae, Boeun and Pyeonchang with a total area of 27,009 hectares.These districts were found to be relatively susceptible to landslides occurrence among the landslide-prone areas and should be divided into 3 categories for landslide susceptility class by district.

목차 (Table of Contents)

• I. 서론 = 2
• II. 연구사 = 2
• III. 재료 및 방법 = 6
• 1. 조사지 개황 = 6
• (1) 안양지역 = 6
• (2) 평창지역 = 6
• (3) 진해, 창원지역 = 7
• (4) 보은지역 = 7
• (5) 정선, 영월지역 = 7
• (6) 광양, 보성지역 = 7
• (7) 협천지역 = 7
• 2. 조사내용 및 방법 = 8
• (1) 산사태지 조사 = 8
• (2) 산사태 발생 위험도 조사 = 9
• 3. 자료 분석 = 9
• (1) 산사태 발생 요인 = 9
• (2) 산사태 예비 방법 = 9
• IV. 결과 및 고찰 = 13
• 1. 산사태 우심지도 작성 = 13
• 2. 산사태 발생 요인 = 13
• (1) 산사태 유형 및 유형별 산사태 발생 모색 = 13
• (2) 산사태 발생빈도와 환경인지와의 관계 = 16
• (3) 요인별 산사태 발생 빈도 = 21
• 3. 산사태 예지 방법 = 21
• (1) 산사태 발생면적과 환경인자와의 관계 = 21
• (2) 지황, 임황인자에 의한 산사태 발생 위험도 점수표 작성 = 24
• 4. 산사태 발생 위헌도 조사 = 27
• (1) 산사태 발생 위험지 조사도 작성 = 28
• (2) 위험도별 임지개황과 예상 대책 = 28
• V. 결론 = 31
• 참고문헌 = 32
• Summary = 37
• Appendix = 40