Spatial Prediction of Soil Carbon In a Desert Wetland Using WorldView-2 Imagery and Lidar.

Snake Valley, on the Utah/Nevada USA border, is currently at the center of a water resources dispute between stakeholders in Nevada and Utah. Snake Valley contains several rare desert wetlands that are organic carbon-rich hotspots in a regionally arid ecosystem typically low in soil organic carbon (SOC) and very high in inorganic carbon. Proposed groundwater pumping in this area may result in the drying of these wetlands and significant changes in soil carbon, particularly SOC.

Launched in October 2009, the Worldview-2 satellite has eight spectral bands and a spatial resolution of 2 meters. We used Worldview-2 imagery and 2m LiDAR elevation  data to model total, inorganic and organic soil carbon in a ~ 62 km² (~24 mi²) spatially heterogeneous desert wetland. Soil samples were collected in the field and total, inorganic and organic C were quantified in the laboratory. Random forest model accuracies were limited, but indicate that elevation, the red edge band and the red band were the most important variables for predicting total carbon. Elevation was the most important variable for predicting SOC. The red edge, yellow, coastal and red bands were the most important variables for predicting inorganic carbon. Additional statistical analyses of the data are underway.

Because of the high spectral and spatial resolution of WorldView-2 imagery, soil carbon predictions may be made at a previously unattainable scale. This research has broader application to soil carbon mapping in wetlands worldwide.