Remote Sensing and Field Mapping: Requisite Bed Fellows for Assessing River Systems

Mapping channel geomorphology, riparian vegetation and the extent of anthropogenic disturbance of river corridors has traditionally been conducted laboriously in the field. With the implementation of the EU Water Framework Directive (WFD), member states are mandated to complete river basin management plans requiring such fieldwork in order to achieve good ecological status by 2015. Thus, deriving wider land cover information from remotely sensed data will be an integral addition to fieldwork in order to meet the requirements of the WFD. The objective of this study was to use two types of remote sensing data, LiDAR and ortho-imagery, to delineate channel morphologies and to field check the analysis in the field to test the accuracy of the remote sensing techniques and assess their applicability for the WFD. Using Carneros Creek, in Napa, CA as a testing ground because of the publicly available LiDAR and ortho-imagery datasets, I achieved 80% accuracy in identifying large terrace features from the Digital Elevation Model (DEM), and a lower percentage at 66% accuracy in identifying steep or vertical banks. Field checking the data not only helped clarify existence of the morphological feature but it also allowed for more complex data gathering such vegetation patterns and species, bedrock outcroppings and land use evidence such as outlets of drainage systems and in-stream pumps, all of which I could not see from the DEM. Preliminary conclusions point towards effective usage of remote sensing data in the WFD. LiDAR scans portend to be specifically useful in Mediterranean climates that are dry most of the year, as opposed to wetter climates where water impedes accuracy of LiDAR mapping