At the Friends of Nelson public meeting on June 30, 2019, Anne Witt, a Geohazards Geologist from the Virginia Department of Mines, Minerals and Energy, presented her work on a VDEM-FEMA Pre-Disaster Mitigation Grant Project. This project is to develop a risk assessment of landslides in western Albemarle and Nelson counties based on previous landslide events that occurred largely during Hurricane Camille. According to Ms. Witt, previous landslide locations are prone to having future ones.
The Grant Project consists of 4 parts or stages:
- Remote sensing of landslides in the study area using LIDAR (Light Detection and Ranging) scanning technology
- Geologic field mapping of landslide prone areas
- Landslide Susceptibility Mapping
- Presentation of data products and results to the planning community and the public
The project is presently in its first stage, so mapping is preliminary. However, LIDAR has revealed a larger number and a more accurate depiction of these previous landslides in Nelson County than seen before.
Friends of Nelson has overlaid the draft mapping of these landslides on the proposed Atlantic Coast Pipeline route. Doing so reveals how many of these slides are on or proximate to the route. Given the number and concentration of these debris flows, we feel that landowners and county officials should be aware of these past events in assessing future risk and mitigating it. Risk awareness is important given the immense amount of ground disturbance that would happen during pipeline construction and the significant potential for pipeline ruptures and explosions resulting from possible slide events afterwards.
In the figure above, approximately 60 debris flows (green triangles) and 10 debris slides (blue triangles) are on or near the ACP proposed route (in gold).
The figure below illustrates how LIDAR reveals the scope and path of previous slides that is not visible even with aerial photography in winter with no leaves on the trees.
See the short summary of Anne Witt’s talk here. Many thanks to Ms. Witt for sharing some of the slides from her fascinating presentation, and to Charlie Hickox for the summary and for the overlay showing the ACP route.