LiDAR‐based fluvial remote sensing to assess 50–100‐year human‐driven channel changes at a regional level: The case of the Piedmont Region, Italy

Abstract

Remote Sensing (RS) technology has recently offered new and promising opportunities to analyze river systems. In this paper, we present a calibration of characteristic Hydraulic Scaling Law (HSL) using a regional database of river geomorphic features. We consistently linked discharge with channel geometry features for estimated Bankfull Channel Depth (eBCD), Active Channel Width (ACW), and Low Flow water Channel Width (LFCW), which are continuously available from RS data along the river course. We then used historical information and external sources of information on channel reaches that were relatively unaffected by human pressure over periods ranging from a few decades to a century (measured in comparable geographical areas) to infer relatively Unaltered HSLs (rUHSLs). Adopting rUHSL validated with available local historical evidence on channel geometry, we were able to assess historical changes in channel geometry consistently over the entire region and within the studied temporal window. The case study was conducted for the Po basin in the Piedmont Region, north‐west Italy. From our analysis, it emerges that regionally 74% of the river network has riverbed incisions exceeding 1 m, while 66% of channels have halved their historical widths with a total of 617 ha of land subtracted from the active channel. LFCW is, on average, wider in Alpine rivers compared with those located in the North Apennines. Although it is currently not possible to measure the accuracy of these estimates, the evidence generated is coherent with available historical information, characteristic hydraulic scaling laws, evidence from relatively unaltered reaches and the available literature on local fluvial systems. This methodology provides robust, novel and quantitative information regarding decadal to secular channel changes that have occurred on a regional scale. This new layer of information enriches our ability to rationally address assessments of large‐scale past and future channel trajectories. © 2018 John Wiley & Sons, Ltd.

Mapping valley bottom confinement at the network scale

“…This presents an opportunity for wide-ranging, comparative geomorphic assessment across different settings, thereby supporting, for example, region-wide analyses of river diversity (e.g. Demarchi et al, 2017;Bizzi et al, 2019).…”

“…For example, the tool can support regional-scale analyses of controls upon river diversity and morphodynamics (cf. Demarchi et al, 2017;Bizzi et al, 2019). Figure 14 demonstrates variability in valley setting across the four watersheds analyzed in this study.…”

“…Demarchi et al, 2017;Bizzi et al, 2019). Numerous scientific and management applications emerge from this work.…”

“…While coverage of HRT is ever growing (with nationwide coverages emerging in some smaller nations), the reality in most locations on earth (including most of the United States) is that HRT is on the horizon as opposed to being readily available today. Demarchi et al, 2017;Bizzi et al, 2019). > 100 km 2 ).…”

Object-Based Ensemble Learning for Pan-European Riverscape Units Mapping Based on Copernicus VHR and EU-DEM Data Fusion

“…The RS classification map was then used in support of a quantitative river type classification and characterization of fluvial forms across the region. The utility of such type of objective and continuous mapping was also demonstrated by the subsequent work of Bizzi et al [18], in which a consistent assessment at the regional scale of human-induced 50-100-year channel changes was provided for the first time, thanks to the exploitation of the RS-based riverscape units map.…”