DEMs of Difference

A key aspect of geomorphological enquiry is concerned with quantitatively monitoring the development of the Earth’s surface, in a diverse set of environments, and at a range of spatial scales and temporal frequencies. A variety of geomatics technologies facilitate the acquisition of multitemporal survey data that can be used to construct Digital Elevation Models (DEMs). The
technique of producing a DEM of Difference (DoD) involves quantifying volumetric change between successive topographic surveys. Whilst the essence of the technique is relatively simple, distinguishing between real geomorphic change and survey noise requires appropriate approaches to error analysis to ensure that DoDs are reliable. This is especially important when DEMs have
been constructed from fusions of data acquired using different survey or analysis techniques, causing vertical error to be spatially and/or temporally variable across component DEMs. This book chapter reviews example applications of DoDs from across the geomorphological discipline and then focuses upon examining morphological sediment budgeting in fluvial geomorphology. The chapter summarises approaches to error analysis, provides guidance on DEM acquisition, and reviews available software.