gis in geology miloš marjanović lesson 4 21.10.2010
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GIS IN GEOLOGY
Miloš MarjanovićLesson 421.10.2010.
GIS in Landslide assessment (basic)
Introduction to landslides and landslide risk assessment
Case studies: Landslide susceptibility analysis on Fruška Gora Mountain, Serbia example of GIS application in Engineering Geology
Methods applied:− Raster modeling− Multi-criteria analysis− Entropy model− Statistical analisis
Data resources:− Topographic map 1: 50 000 (1: 5000 for the second case study)− Digital geological map 1: 50 000 (1: 5000 for the second case study)− Satellite imagery LANDSAT TM 7− Hydrometeorological data
Accent on analytical potential of GIS environment in basic landslide assessment
Contouring and surface modeling
Geostatistics
Desktop and Web
publishing
Desktop mapping
Artificial Intelligence(AI)
Database Management Systems
(DBMS)
General statistics
Spread- sheets
Image Processing
(IP)
Computer Aided
Drawing (CAD)
Geographic Information
System (GIS)
GIS in Landslide assessment (basic)
Geological Hazards
Climatic Hazards
Environmental Hazards
Special types
EarthquakesTsunamisVolcanic eruptionsLandslides
Tropical stormsFloodsDroughts
PollutionDeforestationDesertificationPest infestation
Epidemics
Industrial & chemical accidents
GIS in Landslide assessment (basic)
Natural “hazards”
Landslide phenomena – theoretical background Definition Typology
Slides Falls Topplings Flows Lateral spreads
GIS in Landslide assessment (basic)
Landslide phenomena – theoretical background
Classification by velocity: High Medium Low
GIS in Landslide assessment (basic)
Landslide phenomena – theoretical background
Genesis and factors: Predisposition factors:
Geological – Geo-mechanical
weak & sensitive materials, sheared materials, weathered materials, fissured and jointed or inconvenient by other structural entity, contrast in permeability (heterogeneous materials), contrast in deformability…
Morphological
Triggering factors: Increase of shear stress: erosion/excavation at the toe, loading at the
crown, earthquake, rockfall Decrease in strength: rainfall/meltdown/leakage, cyclic loading, Phys-
Chemical changes Combination: earthquake + liquefaction, vegetation removal…
GIS in Landslide assessment (basic)
Landslide phenomena – theoretical background
Stage of activity
GIS in Landslide assessment (basic)
Landslide Qualitative Risk Assessment terminology:
Susceptibility (S): intensity classification, volume/area and spatial
distribution of existing or potential landslides
Hazard (H): spatial (Ps) and temporal (Pt) probability of landslide
occurrence over an area in a given time sequence
Vulnerability (V): measure of exposure to adverse phenomena (0-100%)
Element at risk (ER): population and constructions (buildings,
infrastructural objects) measured in units (#, $)
Risk (R): probability and severity for adverse phenomena to take effect
ER
H=WPs·WPt·S R=H·V(ER)
GIS in Landslide assessment (basic)
GIS in Landslide assessment (basic)
Landslide risk framework – from analysis to management
GIS in Landslide assessment (basic)
Management has to deal with:
Scientific uncertainty
Acceptable and tolerable risk ($, # of casualties)
General risk (not only landslides)
Territory issue
Science vs. decision
GIS in Landslide assessment (basic)
models of the past uncertainty time-consuming terminology success problems
scientist
models of the future decision immediate action common or regulation
language limitations solutions
decision maker
GIS in Landslide assessment (basic)
GIS in Landslide assessment (basic)
Inventory (location, volume/area, travel distance) Susceptibility zoning
Heuristic (basic) Statistical: univariate, bivariate (weights of evidence, information
value, frequency ratio), multivariate (discriminant, regression, Likelihood ratio cluster analysis, AI)
Deterministic
Hazard – frequency analysis Probabilistic based on the historical data on landslides, data on
landslide triggers, dendrochronology, lichenometry Modeling the primary variable (the triggering variable)
Risk Appending the individual, societal, and economic risk analysis
GIS in Landslide assessment (basic)
Case study: Fruška Gora Mountain, Serbia
GIS in Landslide assessment (basic)
study areaacc. 40 km2
landslide occurrences
Case study: Fruška Gora Mountain, Serbia
GIS in Landslide assessment (basic)
Scale and level selection: mid-scale of1:50 000 (in accordance to resources), preliminary zonation
Classification selection: for landslides according to Varnes et al. only slide movements, for susceptibility classes own system is developed
Method selection: heuristic – multi-criteria analysis Input data type and region type selection: raster, pixel
GIS in Landslide assessment (basic)
Overlaying and spatial analysis are easily feasible over referenced layers
Classification could be adjusted in bigger detail
The exporting to ASCII format provides excellent communication with GIS-coupled engines (for different modules generation, as well as for the machine learning algorithms)
Pros for raster data type
Bulky and demanding in terms of memory capacity, and processing speed
Cons for raster data type
GIS in Landslide assessment (basic)
Multi-criteria analysis
GIS in Landslide assessment (basic)
Geo-parameters modeling
Elevation (Pe) suggesting the concept of Ep derived from DEM reclassified into 4 classes normalized
DNnorm=(DN – DNmin)/(DNmax – DNmin)
GIS in Landslide assessment (basic)
Geo-parameters modeling
Slope angle (Ps) suggesting the physical relation derived from DEM reclassified into 4 classes
(5 degrees intervals) normalized
GIS in Landslide assessment (basic)
Geo-parameters modeling
Aspect (Pa) suggesting the influence of
moisture content, soil thickness derived from DEM reclassified into 4 classes
(SE, SW, NE, NW) weighted and normalized
GIS in Landslide assessment (basic)
Geo-parameters modeling
Distance from streams (Pds) suggesting the influence
of the linear erosion pattern buffered from drainage
network vector filtered for the erosional
preference reclassified into 4 intervals normalized
GIS in Landslide assessment (basic)
Geo-parameters modeling
Vegetation cover (Pv) suggesting the influence of
root system on the slope stability mapped by NDVI by using
3,4 Landsat 7 TM chanel,
due to chlorophyll spectra
authenticy reclassified into 2 classes normalized
GIS in Landslide assessment (basic)
Geo-parameters modeling
Lithological composition (Pl) suggesting different stability
conditions in different materials digitized and simplified after
geological map 1:50 000 weighted reclassified into 4 classis
a-alluvions
b-loess sediment
c-calcareous sediments
d-clayey soils
normalized
GIS in Landslide assessment (basic)
Geo-parameters modeling
Rainfall (Pr) suggesting the moist distribution
governed by heavy rains interpolated from sample point
data set (tables from HMSS)
by normal kriging with fitted
parameters (sill/nugget) reclassified into 4 classes normalized
GIS in Landslide assessment (basic)
Computing the weights of influence of geo-parameters
Analytical Hierarchy Process Pair-wise matrix
Comparing relative weights of influence of geo-parameters against each other and summing the columns
Eigenvector matrix
Normalizing all members of the first matrix by the column sum and averaging the values by rows. The last column gives eigenvector – weights distribution function
GIS environment uses eigenvector to calculate the susceptibility raster map
GIS in Engineering Geology
Computing the weights of influence of geo-parametersS = 0,29⋅Pl +0,27⋅Ps +0,15⋅Pr + 0,14⋅Pds +0,08⋅Pv + 0,05⋅Pe +0,02⋅Pa
GIS in Landslide assessment (basic)
Calibration of classes
Entropy model
optimal increase of information
gain at 4 – 9 classes Calibration using
geomorphological reference map
optimal error at 4 class intervals
GIS in Landslide assessment (basic)
Final output map as an interpretation of landslide susceptibility
Susceptibility map
1. lowest zone
2. mild zone
3. moderate zone
4. highest zone
GIS in Landslide assessment (basic)
Purpose:
Regional planning Preliminary assessment for further detailed analysis Base for hazard and risk mapping
GIS in Landslide assessment (basic)
GIS IN GEOLOGY
Miloš MarjanovićExercise 44.11.2010.
Exercise 4 – AHP-GIS extension
Exercise 4 – AHP-GIS extension
Exercise 4 – AHP-GIS extension
Exercise 4 – AHP-GIS extension