Geospatial analysis in natural hazard modelling: focus on landslide and sediment

1. School of Mathematical and Geospatial sciences Geospatial analysis in natural hazard modelling: focus on landslide and sediment Abdollah Alabdulaziz Mohammad Almohammad Mohammad Alasiri

2. Definition and Types • Natural Hazard definition: are natural processes that have negative effects on human life and properties. (There are different definitions from various literature) • They are classified as earthquakes, volcanic activity, mass movement (landslides, rock falls, avalanches), floods, erosion and sediment, storms (hailstorms, blizzard, rain, wind, tropical cyclones, storm surges), drought, desertification, heat waves, sand or dust storms, fire.

3. Lost statistics • In the past 20 years, In addition to causing billions of dollars of material damage. • Over 3 million people have been killed and over 1 billion people have been injured and become homelessness because of various natural hazards. http://www.scribd.com/doc/7305394/gisppt • Annual global economic costs related to natural hazards was estimated averagely US$435 billion per year at 2011. http://www.eturbonews.com/27313/2011-natural-disasters-cost-global-economies-435-billion • In 2003 there were about 700 natural disasters. http://www.scribd.com/doc/7305394/gisppt

4. Landslide (introduction) • small or large mass movements • Below schematics depict the landslide anatomy http://www.google.com.au/search?q=landslide+in+Australia+photos&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=KT9-T7y1J4WpiAew5qTiDQ&sqi=2&ved=0CCMQsAQ&biw=1680&bih=820 last visited on 6th April 2012.

5. Types of landslide http://c9geonaturalhazards.wikispaces.com/Paige

6. Landslide animation http://c9geonaturalhazards.wikispaces.com/Paige

7. Damages The total direct cost of landslides in Australia for the period from 1967 to 1999 is estimated at $40 million. Since 1842 there have been approximately 84 known landslide events, collectively responsible for the deaths of at least 107 people and injury to at least 141 people.http://c9geonaturalhazards.wikispaces.com/Paige last visit on 6th April 2012. Two sample photos of landslide damages : http://www.google.com.au/search?q=landslide+in+Australia+photos&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=KT9- T7y1J4WpiAew5qTiDQ&sqi=2&ved=0CCMQsAQ&biw=1680&bih=820 last visit on 6th April 2012 Big landslide damage report : http://www.liveleak.com/view?i=efc_1195154345 last visit on 6th April 2012.

8. Water soil erosion • The group of natural processes, including weathering, dissolution, abrasion, corrosion, and transportation, by which material is worn away from the earth's surface. http://www.thefreedictionary.com/erosion • There are two different types of soil erosion, Wind and Water. Water erosion happens because of rain and runoff. • The water soil erosion mechanism includes three steps; detachment, transport and deposition. • Types of water soil erosion are sheet erosion, rill erosion and gully erosion.

9. Water erosion Mechanism http://www.landfood.ubc.ca/soil200/soil_mgmt/soil_erosion.htm

10. Different types of water soil erosionhttp://www.landfood.ubc.ca/soil200/soil_mgmt/soil_erosion.htm

11. Different types of water soil erosionhttp://www.landfood.ubc.ca/soil200/soil_mgmt/soil_erosion.htm

12. Different types of water soil erosionhttp://www.landfood.ubc.ca/soil200/soil_mgmt/soil_erosion.htm

13. Problems • Water soil erosion has different side effects. It can destroy soil fertility and increase desertification. • Increasing in soil erosion means increasing in sediments. • Sediments can deplete the quality of water in watershed and also can make problem for man-made structures in downstream. • Sediments can stop the crop growth because of preventing of air to reach the plant root.

14. Landslide on satellite image http://blogs.agu.org/landslideblog/2011/10/06/a-first-look-at-nasa-satellite-imagery-of-the-landslides-from-the-sikkim-earthquake/ last visit on 6th April 2012 Satellite images captured the physical appearances of landslides occurrences after earthquake. Landslides were marked by red circles.

15. Landslide on satellite image Con. http://news.bbc.co.uk/2/hi/7404614.stm As it can be seen in the left image (before) river is flowing through open channel. After landslide, channel was blocked in part of river and water deposited behind the blockage and flood happened (next slide). Blocked area were marked by green circles.

16. Landslide on satellite image Con. http://news.bbc.co.uk/2/hi/7404614.stm Flooded area because of river channel blockage is marked by yellow circle in right photo.

17. Sediment particles reflectance on satellite images http://www.google.com.au/search?q=sedimentation+photos&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=aF9-T_TkNMOViQe-lNG6BA&ved=0CCMQsAQ&biw=1680&bih=820 As it can be seen in above image, areas near the sea that has more sediment are appeared in light blue colour.

18. Aerial view of soil erosion http://www.google.com.au/search?q=erosion+on+aerial+photo&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=PWR-T-H2AuutiQeXu5XNBA&sqi=2&ved=0CCwQsAQ&biw=1680&bih=820

19. Natural hazard management Process • Natural hazard management process includes detection, monitoring, modelling and mitigation. • Nature of natural hazard model depends on space and time. • Detection can use of the promised utility in different types of remote sensing. • Remote sensing can produce valuable time series information for monitoring the phenomena. • Spatially time series modelling can be done through GIS. GIS has the ability to store and retrieve all information from database during developing model or relevant analysis procedures.

20. Conclusion • Depend on the various types of hazard, likely affected regions should be predicted and mapped. • Spatial techniques and modelling can be used to assist relevant authorities to identify areas where mitigation efforts should be assigned. • Maps should be updated regularly in order to monitoring. • Therefore, comparing different periodically produced maps can reveal the trends. • Then, Action plans can be formulated to mitigate the hazard.