Landslide and erosion risk is calculated as the weighted sum of the number of landslide events recorded from 1985 to the present, each multiplied by a severity factor of 1 to 2. The final risk level ranges from 1 (minimum risk) to 5 (maximum risk).
Landslides constitute one of the most significant geomorphological hazards globally, with consequences including loss of fertile soil, destruction of natural habitats, destabilisation of riparian ecosystems, and direct impact on human safety and infrastructure. Risk is influenced by predisposing factors such as slope, soil type, vegetation cover and rainfall regime, and is amplified by climate change through intensification of heavy rainfall events (Kirschbaum et al., 2015).
The KPI integrates two complementary datasets: the Global Landslide Catalog (NASA) for global coverage and the ISPRA IdroGeo database for higher-resolution detail on Italian territory.
Risk classification algorithm:
Future probability calculation (Poisson distribution):
The probability of at least one event in the next 2 years is calculated using the Poisson distribution:
P = 1 − exp(−λ × 2)
where λ = historical events / years observed represents the mean annual event rate in the area. This formulation assumes that landslide events are independent and uniformly distributed over time, which is a reasonable approximation for short-to-medium-term risk estimates.
| Code | Name | Provider | Temporal coverage |
|---|---|---|---|
WRD_GLDSL_99 | Global Landslide Catalog | NASA / Goddard Space Flight Center | 1970 – 2019 |
ITA_ISPRA_99 | IdroGeo ISPRA — Landslide Inventory | ISPRA / National IFFI System | 1960 – 2017 (continuously updated) |
| Indicator | Unit | Range | Inverted |
|---|---|---|---|
landslides | — | [1, 2, 3, 4, 5, 5] | Yes |
Inverted = Yes: a lower value indicates lower risk and safer conditions for the site.
| Level | Value | Interpretation |
|---|---|---|
| E (Critical) | 5 | Extreme landslide risk; numerous severe events historically recorded |
| D (Poor) | 4 | High risk; multiple significant landslides documented |
| C (Moderate) | 3 | Moderate risk; some landslide events in the area |
| B (Good) | 2 | Low risk; rare or minor events |
| A (Excellent) | 1 | Minimal risk; no relevant landslide events recorded |
The KPI provides:
landslides
Landslide risk calculated from the weighted sum of historical events since 1985. Sources: NASA Global Landslide Catalog (WRD_GLDSL_99, 1970–2019, Kirschbaum et al., 2015), ISPRA IdroGeo (ITA_ISPRA_99, Italy, 1960–2017). Severity 1–2 per event (1=limited, 2=significant). Level 1–5 classification based on index Σ(severity × events). 2-year probability computed with Poisson distribution: P = 1 - exp(-λ × 2), where λ = events/observed years.