Creating a catchment scale perspective for river restoration

摘要

One of the major challenges in river restoration is to identify the naturalfluvial landscape in catchments with a long history of river control.Intensive land use on valley floors often predates the earliest remotesensing: levees, dikes, dams, and other structures alter valley-floormorphology, river channels and flow regimes. Consequently, morphologicalpatterns indicative of the fluvial landscape including multiple channels,extensive floodplains, wetlands, and fluvial-riparian andtributary-confluence dynamics can be obscured, and information to developappropriate and cost effective river restoration strategies can beunavailable. This is the case in the Pas River catchment in northern Spain(650 km2), in which land use and development have obscured the naturalfluvial landscape in many parts of the basin. To address this issue we usedcomputer tools to examine the spatial patterns of fluvial landscapes thatare associated with five domains of hydro-geomorphic processes andlandforms. Using a 5-m digital elevation model, valley-floor surfaces weremapped according to elevation above the channel and proximity to keygeomorphic processes. The predicted fluvial landscape is patchilydistributed according to hillslope and valley topography, river networkstructure, and channel elevation profiles. The vast majority of the fluviallandscape in the main segments of the Pas River catchment is presentlymasked by human infrastructure, with only 15% not impacted by rivercontrol structures and development. The reconstructed fluvial landscapeprovides a catchment scale context to support restoration planning, in whichareas of potential ecological productivity and diversity could be targetedfor in-channel, floodplain and riparian restoration projects.