There have been numerous fluvial studies of flow resistance in alluvial channels during the last few decades. Significant progress has been made towards predicting flow resistance (and therefore velocity) for a given discharge. These past applications rely heavily on the characterization of particle sizes and the effects of changing relative submergence on flow resistance estimates. Different types of equations have been shown to provide reasonably good estimates in specific environments. Major difficulties arise from characterizing mobile beds, bed topography and its evolution and how these factors control rates of change of average velocity as discharge rises along a given river reach. Different issues can be recognized as a function of the spatial and temporal scales of investigation. A case can made that more emphasis should be placed upon reach-scale investigations. Detailed studies of bed topography, its maintenance, its evolution (at the reach scale) and its interactions with macroturbulence structure and sediment transport would ultimately provide valuable information and improved knowledge on both flow resistance processes and applications (predictions). Moreover, technological means now allow detailed characterization of bed topography and flow fields of large river systems. Such promising avenues should be further pursued with the goal of providing not only a better understanding of flow-bed-sediment transport interactions in large river systems but also a better understanding of flow stage variations, flood hazards, flow resistance estimates and therefore partitioning of depth and velocity as discharge rises along major river systems.

During recent decades, the use of high-resolution light detection and ranging altimetry (LiDAR) data in fluvial studies has rapidly increased. Airborne laser scanning (ALS) can be used to extensively map riverine topography. Although airborne blue/green LiDAR can also be utilized for the mapping of river bathymetry, the accuracy levels achieved are not as good as those of terrain elevation measurements. Moreover, airborne bathymetric LiDAR is not yet suitable for mapping shallow water areas. More detailed topographical data may be obtained by fixed-position terrestrial laser scanning (TLS) or mobile terrestrial laser scanning (MLS). One of the newest applications of MLS approaches involves a boat/cart-based mobile mapping system (BoMMS/CartMMS). This set-up includes laser scanning and imaging from a boat moving along a river course and may be used to expand the spatial extent of terrestrial scanning. Detailed digital terrain models (DTMs) derived from LiDAR data can be used to improve the recognition of fluvial landforms, the geometric data of hydraulic modelling, and the estimation of flood inundation extents and fluvial processes.

Few publications may claim to have transcended the original field in which they were written, by shaping a wide range of research areas and philosophies. In this short paper we reflect on the manner in which Gilbert F. White’s 1945 publication ‘Human adjustment to floods’ has not only shaped how we study and perceive flooding, but has also had a significance beyond its original aims, revolutionizing the ways in which hazard and risk are conceptualized more generally. Before considering the impact of ‘Human adjustment to floods’, we briefly review academic understanding of floods in the decades leading up to the 1940s and later place the 1945 paper in the context of White’s subsequent contributions to research which both developed and built on his ideas.