Early Detection System for Landslides using WSN

2. Outline • Background on Landslides • Landslides Prediction • System Architecture • Solution • Evaluation

3. Landslides • A landslide is an catastrophic event where a block of earthen mass slides downhill. • Cause significant loss of life and billions of dollars each year.

4. Landslides Prediction • Although a basic understanding of the landslides is available, system that predict the occurrence of a landslide do NOT exist. • Why? • The lack of field measurements over large temporal and spatial scales.

5. Landslides Prediction • The development of a landslide is a temporal process • takes as long as a year to develop • Movement speed, several cm per month • Landslides are spatial in nature. • Position • Movement direction This paper propose a WSN to detect the early signals preceding a landslide.

6. System Architecture • Sensor Column • Geophone • Strain Gauge • Pore Pressure Transducer • …

7. System Architecture • Deployment • A network of sensor columns • Placed in vertical holes drilled over the hill surface • Using sensor columns to detect movements

8. Solution Outline • Geophones estimate displacement dij(t) • Based on distance matrix D=[dij(t)] • Detection • Determine whether slip surface has formed • Classification • Estimate subset of sensors that moved • Localization • Compute location of slip surface

9. Example • Detection & Classification & Localization

10. Detection • Use strain gauges on each sensor column • Can measure changes in their length due to deformation

11. Classification • Determine which sensors are above and below the slip surface • Basic principles: Distance between two nodes • Below the slip surface should not change • Across the slip surface is likely to change • Above the slip surface would see a small change • The nodes located closest to the known rigid part are unlikely to move. (anchor nodes)

12. Classification • Voting Algorithm • Note state: {0, 1, U} • Initially: anchors=0, rest=U • Repeat until all nodes classified • Update node i’s state based on votes from neighbors j • If j in U, no vote • If Δdij=0, vote is equal to j’s state • If Δdij≠0, vote is equal to complement of j’s state

13. Localization • Localize moved nodes using trilateration • Slip surface estimation

14. Evaluation • Evaluation metrics • Average and std. dev of localization error • Max. distance between actual and estimated slip plane • Abstract network model • Communications are error-free • Nodes do not fail

16. Prediction Finite Element Analysis Temporal & Spatial Measurement Simple Measurement Summary • Propose a WSN for the prediction of landslides • Design a system to detect the early signals preceding a landslides. WSN Civil Engineering

17. Remarks • Localization for a specific application (landslides prediction) • NOT for general purpose. • Localization for a group of sensors (sensors above slip surface) • NOT for a single sensor node. • Localization for moving sensor • although there is only a little movement

18. Thanks!