Dr. Joshua Viers to speak at the AWRA Riparian Specialty Conference


AWRA 2004 Summer Specialty Conference
Riparian Ecosystems and Buffers:
Multi-scale Structure, Function, and Management
June 28-30, 2004
The Resort at Squaw Creek
Olympic Valley, CA

Dr. Viers will be presenting the following paper:


Joshua H. Viers, James F. Quinn, Michael L. Johnson, and Susan L. Ustin

ABSTRACT: Methods for delineating riparian areas, as a function of both vegetation composition and ecological condition, are needed for regulatory and scientific analysis. Riparian areas are dynamic entities, both spatially and temporally, and are largely an outcome of geomorphic processes. We used spatial analysis techniques to develop a methodology for classifying stream networks by geomorphic confinement to analyze riparian vegetation composition for the Navarro River watershed in northern California. We classified stream reaches by source, transport, or depositional response processes using clustering of spatial terrain data. We used three primary variables to drive a K-Means clustering of segments: stream gradient, upstream accumulative area, and cross-valley gradient. Riparian vegetation was classified using high-spatial resolution, hyperspectral data from the NASA-JPL AVIRIS 2000 campaign to distinguish and classify vegetation cover within a riparian zone. The AVIRIS instrument is unique in that it has 224 contiguous, spectral channels allowing for species specific identification at 5m resolution. Leaf Area Index (LAI) derived from AVIRIS was examined by geomorphic confinement cluster. Our results indicate that depositional response reaches have the greatest percentage with an LAI of 0, or unvegetated, which reflects the hydrodynamic nature of watersheds. Furthermore, multi-storied canopies in source reaches were evidenced by significantly higher mean LAI values than other geomorphic types. Finally, variability of LAI was highest for response reaches, again reflecting perturbations on the landscape, natural and anthropogenic, which culminate in alluvial bottomlands and riparian areas. These methods and analyses are instructive for other watershed studies examining the riparian extent and riparian vegetation.

KEYTERMS: riparian vegetation; hyperspectral remote sensing; LAI; geomorphic confinement.