USDA Forest Service

Pacific Southwest Research Station

Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Mapping hard and soft impervious cover in the Lake Tahoe Basin using LiDAR and multispectral images: a pilot study of the Lake Tahoe Land Cover and Disturbance Monitoring

Principal Investigators:
Jarlath O’Neil-Dunne, Spatial Informatics Group, LLC
David Saah, Spatial Informatics Group, LLC

Proposal [pdf]

Final Report [pdf]

Spatial Informatics Group website

Please contact Jarlath O’Neil-Dunne with questions regarding the final report.

Project Summary

Conversion of land to impervious cover threatens the environmental quality of the Lake Tahoe Basin (LTB) (Bailey 1974) by reducing water percolation into the soil and increasing runoff, and thus sediment, nutrient, and pollutant transfer into Lake Tahoe (Arnold and Gibbons 1996). If impervious cover, both hard (e.g., paved or roofed areas) and soft (e.g., disturbed or compacted soil) expands to unsustainable or irreversible levels, many if not all of the environmental goals or “thresholds” central to management efforts within the basin could be adversely affected. Therefore, effective management and monitoring of impervious surfaces within the LTB requires an impervious cover data set that is detailed, accurate, and meaningful.

Spatial Informatics Group (SIG) mapped both hard and soft impervious surfaces in the LTB by leverage existing investments in high‐resolution multispectral imagery, Light Detection and Ranging (LiDAR), and vector geographic information system data. This was accomplished through a repeatable and cost‐effective analytical methodology, centered on Object‐Based Image Analysis (OBIA) techniques (e.g., O’Neil‐Dunne et al. 2012).

The end product consists of a spatially detailed, accurate, attribute‐rich, and realistic map of impervious cover within the LTB based on August 2010 ground conditions. Impervious surface information was summarized by varying geographic units of analysis, including ownership (e.g., parcels), environmental gradients/boundaries (e.g., watershed, soil type, soil capability class) and political boundaries (e.g., counties).

Finally, a pilot implementation of the Lake Tahoe Land Cover and Disturbance Monitoring Plan (SIG 2009) was carried out using the derived impervious surface cover. This analysis indicated that Land Capability Types 1b and 2 exceeded allowable coverage prescribed by Bailey (1974) to maintain the “environmental balance” for combined, LiDAR-derived hard and soft impervious cover types. Utilizing this approach to monitoring impervious surfaces may provide a repeatable, cost-effective approach to detecting watershed and LTB wide changes in impervious coverage in the future.