A MOVE FROM ANALOG TO DIGITAL GEOHAZARD MAPPING IN PENNSYLVANIA

As technologies and software advance, digital methods of mapping are becoming the norm. The Pennsylvania Geological Survey (PaGS) is developing techniques to meet the needs of both the Survey and the communities it serves.

Landslides have been tracked and recorded through air photos, reports, newspaper articles, and direct accounts, while sinkholes have been mapped since the 1980’s with air photo analysis, and when available, from consultants, PennDOT, and municipality reports, as well as PaGS service requests. Data points of sinkholes were transferred to topographic maps and later digitized to a point feature database. Landslide reports are a collection of PDFs and an excel file. Sinkhole data points can be accessed in PaGS’s digital interactive map, though the data is often not in an accessible format for the general public. Landslide data is not available to the public in any form.

New ways of mapping geohazards in Pennsylvania are needed. Modern karst feature density maps are being created through semi-automated digital mapping techniques using 1-meter resolution lidar digital elevation models (DEM). Polygons of the closed depressions with characteristic attributes and metadata are published along with feature density maps. These maps better show the users the level of geohazard in their area compared to simple point data.

Landslide potential maps will be created using landslide inventories derived from the 1-meter resolution lidar DEMs and field verified. Landslide controlling factors will also be explored and correlated to surficial and bedrock geology maps, creating layers which have metadata and attribute tables containing data about the suspected causes of landslides in a particular area.

Our goal is to provide updated geohazard maps that are more easily consumed by the users and that will guide municipal planners and developers in the future.