This is the publisher's version, also available electronically from "http://onlinelibrary.wiley.com".In many near-surface applications, detailed subsurface characterization is important. Characterization often is obtained using ground-penetrating radar (GPR) or shallow seismic-reflection (SSR) imaging methods, depending upon depth of interest and surficial geology. Each method responds to different physical properties; thus, each may produce different images of the same near-surface volume. By incorporating the two methods, we generated a cross-section of the subsurface at an alluvial test site and identified the depths of three interfaces accurately to ±5 cm. We present here experimental results and examples of SSR and GPR images obtained ...