Raise of Slopes — User Guide

This QGIS plugin performs slope stability analysis based on the Limit Equilibrium Method (Bishop, Spencer, Morgenstern-Price) with circular slip surfaces. Starting from a DEM, it extracts an elevation cross-section, models the subsurface stratigraphy and phreatic surface, and finds the critical slip surface that minimises the Factor of Safety (FoS) using either an exhaustive grid search or a Nelder–Mead simplex optimiser.

Quick-start workflow

1. Load a DEM raster into QGIS.
2. Open the plugin and go to Elevation Profile: select two points on the map to extract the cross-section.
3. Go to Soil Parameters and enter the geotechnical properties.
4. Optionally configure a second layer and / or water table in Stratigraphy & Water Table.
5. Run an analysis from Grid Analysis or Simplex Analysis using the Run button at the bottom of the window.
6. Repeat for multiple cross-sections and accumulate results into a Hazard Map.
7. Export results (chart, CSV, DXF, text report) from the Export menu.

Acknowledgements

This study was funded by the European Union — NextGenerationEU and by the Ministry of University and Research (MUR), National Recovery and Resilience Plan (NRRP), Mission 4, Component 2, Investment 1.5, project “RAISE — Robotics and AI for Socio-economic Empowerment” (ECS00000035). Andrea Bressan, Simone Pittaluga, Lorenzo Tamellini and Domenico Gallipoli are part of the RAISE Innovation Ecosystem.

How to cite

If you use this plugin in your research or professional work, please cite the underlying methodology:

Lalicata, L.M., Bressan, A., Pittaluga, S. et al. An Efficient Slope Stability Algorithm with Physically Consistent Parametrisation of Slip Surfaces. Int J Civ Eng 23, 671–682 (2025).
https://doi.org/10.1007/s40999-024-01053-1

Tab: Elevation Profile

All analyses are anchored to the elevation profile. Compute this first.

Profile extraction

• DEM: choose any raster layer loaded in QGIS. Press Refresh to update the list after loading new layers.
• Select 2 points: activates the map tool. Click P1 (upslope end) then P2 (downslope end). The profile is sampled automatically at the native DEM pixel size using bilinear interpolation.
• The profile chart updates immediately. Slip surfaces computed in subsequent analyses appear as coloured arcs overlaid on the terrain.

Chart controls

• Clear surfaces: removes all computed slip surfaces from the chart without re-computing the profile.
• Surface visibility list: check or uncheck individual surfaces to show or hide them. Useful when many surfaces are computed.
• Open Report: opens a detached window with a full-size chart, colour legend, and geotechnical parameter table — formatted for printing or screenshots.

Export menu

Project menu

Save or load the complete plugin state to a .rslope file (JSON). The file stores the sampled profile data, all parameters, computed surfaces, surface visibility, and hazard-map configuration. On load, any raster layers referenced by the project are looked up in the current QGIS project by name; missing layers are reported with an option to continue.

Tab: Soil Parameters

Geotechnical properties for the primary (surface) soil layer. These values are shared between the Grid and Simplex analyses.

The Second Layer parameter block (γ₂, c₂, n₂, φ₂) is used when a second stratum is enabled in the Stratigraphy & Water Table tab.

Tab: Stratigraphy & Water Table

Second layer

Enables a two-layer model. The interface between layer 1 (surface soil) and layer 2 (deeper formation) can be defined in three ways:

• Constant depth from ground surface: the interface is at a uniform depth below the terrain everywhere.
• Depth from raster: a raster layer provides the depth of the interface at each point along the profile (sampled with bilinear interpolation).
• Absolute elevation: the interface is at a fixed elevation (m a.s.l.), regardless of terrain height.

The interface is drawn as a dashed brown line on the profile chart when the second layer is active.

Water table

Enables pore-pressure calculations. The water table can be defined using the same three modes as the second layer. When active, the phreatic surface is drawn as a blue dashed line on the chart, and pore pressures modify the effective stresses in the LEM solver.

Tab: Grid Analysis

Evaluates the Factor of Safety for a large discrete set of circular slip surfaces sampled on a regular grid of (entry, exit) pairs. Provides a global view of the stability landscape at the cost of computation time.

Tab: Simplex Analysis

Uses a Nelder–Mead optimiser seeded from a coarse grid to find the minimum-FoS surface. Much faster than a full grid for the same resolution, and well-suited for fine-tuning around a known critical zone.

Tab: Hazard Map

Accumulates stability results from many profile analyses into two georeferenced GeoTIFF rasters covering the study area:

• Min FoS raster: each cell stores the lowest FoS found across all profiles that cross it.
• Slip depth raster: each cell stores the depth of the corresponding critical slip surface.

The rasters are styled automatically when loaded into QGIS: FoS uses the red–yellow–green colour ramp; depth uses a white–blue ramp.

Workflow for a multi-profile hazard map

1. Analyse the first cross-section and switch to Hazard Map.
2. Select Create new rasters, define the output extent, cell size, and output paths, then click Add current result to map.
3. Enable Update rasters automatically after each analysis for subsequent profiles.
4. Analyse each additional cross-section; the rasters update automatically.
5. To restart from scratch, switch to Update existing rasters and enable Overwrite.

Stability methods

Results interpretation

On the chart, slip surfaces are coloured on a continuous red–yellow–green scale spanning the FoS range of all currently displayed surfaces. The critical surface (lowest FoS) is drawn with a thicker line and labelled #1.

File formats