1. Page 1 Landslide hazard analysis for Hong Kong using landslide inventory and GIS 7099042005 鄭育騰 7099042023 何俊賢 7099042025 張台聖

2. Page 2 Index Abstract Geology and Climate of Hong Kong Comprehensively consider the landslide hazard Using GIS to analyzing landslide hazard Conclusion

3. Page 3 1.By using GIS and employing historical landslide data in Hong Kong to analyze where is the susceptible area. 2.There are four main categories we consider as our parameters : a. Terrain b. Geology c. Landslide d. Environment Each of those categories contains one or more GIS layers. Abstract

4. Page 4 3.By using the "zonal statistics" and "raster calculator "we can obtain the correlation of each layer with the number of Landslide and the hazard map. 4.Combining the hazard map with "Exposure Index" we can obtain the risk map. Abstract

5. Page 5 Index Abstract Geology and Climate of Hong Kong Comprehensively consider the landslide hazard Using GIS to analyzing landslide hazard Conclusion

6. Page 6 Geology and Climate of Hong Kong 名稱高度 (m) 行政區 太平山 554 中西區 柏架山 532 東區 奇力山 501 中西區 西高山 494 中西區 歌賦山 479 中西區 金馬倫山 439 灣仔區 畢拿山 436 東區 紫羅蘭山 433 南區 渣甸山 433 灣仔區 聶高信山 430 灣仔區 歌連臣山 340 南區 南朗山 284 南區 摩星嶺 269 中西區 龍虎山 253 中西區 壽臣山 140 南區

7. Page 7 3.Lithology : a. volcanic rock(tuff) b. intrusive rock(granite) 4.Deposit : a. weathered from volcanic rock b. the average thickness is 2m Geology and Climate of Hong Kong

8. Page 8 Geology and Climate of Hong Kong

9. Page 9 Index Abstract Geology and Climate of Hong Kong Comprehensively consider the landslide hazard Using GIS to analyzing landslide hazard Conclusion

10. Page 10 Diurnal and seasonal distribution for landslides Fatalities and injuries rate Facilities risk rate Landslide in different geological formations Frequency and volume relation of landslides Landslide inventory Comprehensively consider the landslide hazard

11. Page 11 Diurnal distribution :  Landslides often occur during daytime from 7 till 18 o’clock.  The peak hour is at noontime. Diurnal and seasonal distribution for landslides

12. Page 12 Seasonal distribution :  The average monthly rainfall correlates well with landslide occurrence. EXCEPT MAY!!!  May has an abnormal high frequency of landslides from 1991 to 1992. Diurnal and seasonal distribution for landslides

13. Page 13 Seasonal distribution :  We delete the data of MAY and re-plot the figure.  Clearly! We can observe the correlation between rainfall and landslide. Diurnal and seasonal distribution for landslides

14. Page 14 Diurnal and seasonal distribution for landslides Fatalities and injuries rate Facilities risk rate Landslide in different geological formations Frequency and volume relation of landslides Landslide inventory Comprehensively consider the landslide hazard

15. Page 15 Cumulative casualties from 1948 till 1996 :  The total number of fatalities and injuries are 556 and 570. This data means that there are 23 casualties per year. Fatalities and injuries rate

16. Page 16 Fatalities and injuries rate Cumulative casualties from 1948 till 1996 :  There are jumps in 1972.  In recent year, the casualties have decreased to 8 due to the LPM program.

17. Page 17 Diurnal and seasonal distribution for landslides Fatalities and injuries rate Facilities risk rate Landslide in different geological formations Frequency and volume relation of landslides Landslide inventory Comprehensively consider the landslide hazard

18. Page 18 Cumulative number of landslides facilities :  Double count of influences is allowed in our analysis.  In resent years, landslides hazard on squatter is dropping. Facilities risk rate

19. Page 19 Facilities risk rate Cumulative number of landslides facilities :  Landslide hazard on road and footpath is increasing.

20. Page 20 Percentage distribution of landslide on each facilities :  Only 1% of landslide hazards directly hit on cars. Facilities risk rate

21. Page 21 Diurnal and seasonal distribution for landslides Fatalities and injuries rate Facilities risk rate Landslide in different geological formations Frequency and volume relation of landslides Landslide inventory Comprehensively consider the landslide hazard

22. Page 22 Percentage distribution of geological formation :  Volcanic formation : tuff. Igneous formation : granite.  It is normally speculated that the occurrence of landslide should depend on the local geological formation. Landslide in different geological formations

23. Page 23 Percentage distribution of landslide on soil types :  There seems no strong correlation between landslide occurrence and geological formation. Landslide in different geological formations

24. Page 24 Diurnal and seasonal distribution for landslides Fatalities and injuries rate Facilities risk rate Landslide in different geological formations Frequency and volume relation of landslides Landslide inventory Comprehensively consider the landslide hazard

25. Page 25 Cumulative number of landslides per year & volume of landslide :  It is very unlikely that the data set for small events is complete. Frequency and volume relation of landslides

26. Page 26 Frequency and volume relation of landslides

27. Page 27 Diurnal and seasonal distribution for landslides Fatalities and injuries rate Facilities risk rate Landslide in different geological formations Frequency and volume relation of landslides Landslide inventory Comprehensively consider the landslide hazard

28. Page 28 Contour map and landslide data :  One way to generate hazard map is the use of historical data.  We divide the Hong Kong map into square grids. Landslide inventory

29. Page 29 Contour map and landslide data : Landslide inventory  Counting the number of landslides in each grid, using the curve to combine the grid with the same number.

30. Page 30 Contour map and landslide occurrence :  The six levels of contour lines are : (1)0.25 (4)2 (2)0.75 (5)4 (3)1.25 (6)5 Landslide inventory

31. Page 31 Index Abstract Geology and Climate of Hong Kong Comprehensively consider the landslide hazard Using GIS to analyzing landslide hazard Conclusion

32. Page 32  The limitation of the hazard map introduced just now is that only landslide data has been used in generate the map.  A useful hazard zonation map should also depend on other factors. Such as geology, geomorphology, hydrology, vegetation and climate. Using GIS to analyzing landslide hazard

33. Page 33  Before combining those parameters, we use zonal statistics in ArcGIS 8.2 to generate the correlation of any two layers.  These plots are useful for identifying the important parameters affecting landslide occurrence. Using GIS to analyzing landslide hazard

34. Page 34  Seven layers of information have been used in this analysis.  More layers can also be added to this hazard analysis if their correlations with landslide occurrences are clear and measurable. Using GIS to analyzing landslide hazard

35. Page 35 Using GIS to analyzing landslide hazard

36. Page 36 Using GIS to analyzing landslide hazard

37. Page 37 Using GIS to analyzing landslide hazard

38. Page 38 Using GIS to analyzing landslide hazard

39. Page 39 Index Abstract Geology and Climate of Hong Kong Comprehensively consider the landslide hazard Using GIS to analyzing landslide hazard Conclusion

40. Page 40  ArcGIS makes the landslide risk analysis more efficiently and quickly.  There are things that we should bear in mind : a. Unreliable prediction on parameters can lead to misleading hazard estimation. b. The Exposure Index we considered should be more comprehensive. Conclusion

41. Page 41 Thank You For Listening