GIS IN GEOLOGY Miloš Marjanović Lesson

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: (1: 5000 for the second case study) − Digital geological map 1: (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 HazardsClimatic HazardsEnvironmental Hazards Special types Earthquakes Tsunamis Volcanic eruptions Landslides Tropical storms Floods Droughts Pollution Deforestation Desertification Pest 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·SR=H·V(ER) 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)

 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 area acc. 40 km 2 landslide occurrences

 Case study: Fruška Gora Mountain, Serbia GIS in Landslide assessment (basic)

 Scale and level selection: mid-scale of1: (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 (P e )  suggesting the concept of Ep  derived from DEM  reclassified into 4 classes  normalized DN norm =(DN – DN min )/(DN max – DN min ) GIS in Landslide assessment (basic)

 Geo-parameters modeling  Slope angle (P s )  suggesting the physical relation  derived from DEM  reclassified into 4 classes (5 degrees intervals)  normalized GIS in Landslide assessment (basic)

 Geo-parameters modeling  Aspect (P a )  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 (P ds )  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 (P v )  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 (P l )  suggesting different stability conditions in different materials  digitized and simplified after geological map 1:  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 (P r )  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-parameters S = 0,29 ⋅ P l +0,27 ⋅ P s +0,15 ⋅ P r + 0,14 ⋅ P ds +0,08 ⋅ P v + 0,05 ⋅ P e +0,02 ⋅ P a 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 Marjanović Exercise

Exercise 4 – AHP-GIS extension