Landslide Prediction Software NOVEMBER 19, 2010

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1 Landslide Prediction Software NOVEMBER 19, 2010

2 Scenario Rainfall-triggered landslides in shanty-town communities are an everyday occurrence, and large events can cause loss of life, require community relocation, and cost millions of dollars. The MoSSaiC project in the Eastern Caribbean has shown that mapping hillsides can reveal the local landslide triggers The mapping is done by the community and local government engineers or local geotechnicians. In this context dynamic slope hydrology is often found to be the dominant landslide mechanism at a highly localised scale water entering the slope material reduces its strength and can result in a landslide

3 Scenario (continued) If the amount of surface water (from rainfall and houses) can be reduced, this means that less water will soak into the soil and hence the stability of the slope will be increased This diagnosis can be tested using slope stability software (CHASM, in this case) the subject of this exercise. Drains can then be designed and constructed to capture surface water This has already been done in several vulnerable communities and is proven to have reduced the landslide hazard

4 Existing Solution CHASM (Combined Hydrology & Stability Model) is an integrated slope hydrology/slope stability software package that aids the assessment of slope stability conditions. It is designed to help the user estimate the effects on slope stability of selected storm events, surface vegetation cover, slope plan curvatures and other important slope and material properties it was the first slope stability code to incorporate dynamic hydrology (the key mechanism in rainfalltriggered landslides).

5 The Need To use models like CHASM requires a certain level of modeling and geotechnical expertise in order to make a realistic analysis of a slope. The aim of this development is to make the technology available to government technicians and engineers who don t have any modeling expertise but who have knowledge of the local slopes, basic field data and community accounts of slope processes.

6 Approach A Web Portal A web-portal for CHASM would make the software accessible to local government technicians/ engineers and provide some top level checks on model inputs. This could be done as 3 or 4 page webform for field data entry with onthe-fly error checking and access to database of key parameters. It would be handy to give the user the option of point and click drawing of the slope, with subsequent editing of these geometric parameters (graphics are helpful for non-experts!). The next stage would then involve generating 5 input files (.txt) for CHASM and submitting the job to the remote server for the model to be run.

7 Approach B Visualizer Front-End When the simulation is complete the engineer will need to look at the outputs change in slope stability over time (a graph) and identify the critical conditions for slope failure this requires visualization of the slope profile (a regular mesh) and the value of different slope variables at each time-step. The raw model outputs are text files and are currently interpreted using scientific visualization software such as Matlab, R or IDL (which requires knowledge of the CHASM output file formats and slope parameters). For this project a new postprocessing GUI is needed to automate this process for the user. This could for example be based on the Open Source tools R or Python (using matplotlib).

8 Relevant Links Find out about the software and its applications. Understand the wider context, and see the difference a understanding slope processes can make when it comes to reducing the risk to communities.