Monitoring human activity with high resolution SAR and optical imagery - a synergistic approach

Illegal traffic by off-highway vehicles (OHV) damages the salt crusts of Salton Sea Playa (California, USA) which then impacts air pollution and advances ground erosion. To mitigate the environmental impact of these threads a traffic management plan has been implemented which includes the monitoring of vehicle related disturbances on the Playa. This pilot study assesses the feasibility whether the application of Coherence Change Detection (CCD) technique to very high resolution Synthetic Aperture Radar (SAR) and optical imagery can be used to identify and to quantify OHV traffic. While the impacts on the interferometric coherence are well described, e.g. by atmospheric effects and temporal decorrelation, a quantitative interpretation of the observed signatures in the context of surface changes is still not fully understood. As a consequence, the feasibility of using CCD as a sensitive tool to evaluate subtle surface changes is limited. In this paper we describe a ground truth experiment at Salton Sea Playa and the corresponding analysis of CCD results and high resolution optical image stacks, which have been acquired as a synergistic data source. Goal is to provide a methodical scheme of CCD signatures in relation to known ground disturbance. The recommendations from this pilot study will inform how spaceborne monitoring methodologies can be used in the playa traffic management strategy and how a potential monitoring service should be implemented.