Abstract
<title>Abstract</title> <p>Large, deep-seated and slowly moving landslides encountered across the Western Canada Sedimentary Basin (WCSB) are crossed by all types of linear infrastructure and impact on populated areas on river valley slopes in the region. While these landslides do not lead to sudden or catastrophic loss they have historically lead to significant economic losses associated with mitigations caused by ongoing strain. While there is tolerance for movement built into the design of linear infrastructure crossing these landslides, there are maximum tolerances for the total amount of movement that can be accommodated before permanent damage occurs. If those movements occur quickly it reduces the opportunity for early identification and proactive mitigation. With this, infrastructure owners in the region contributed a large amount of regional displacement data (Froese et al, submitted) to support developing an understanding of spatial and temporal displacement trends over many decades. These displacement trends were then coupled with data on hydroclimatic drivers obtained from the ERA-5 Land global re-analysis model in order to better understand the specific components of wetting that correlated with increased landslide activity in order to identify key drivers that could be utilized to develop a warning model that could be calibrated with historical performance. This paper outlines how these various data were integrated, the development of the concept of a regional landslide activity index, the development of a forecast model and demonstration as to how the model performed as a hindcast when assessed against known events. The initial approach to utilize the model as a forward-looking forecast for the 2026 landslide season is also demonstrated.</p>