Determination of surface flow paths from gridded elevation data

Abstract

[1] Surface flow paths are obtained from gridded elevation data by connecting grid cell centers along predetermined flow directions. These flow directions are commonly determined using single and multiple flow direction algorithms. It remains, however, unclear whether multiple flow direction algorithms, which introduce artificial dispersion, can be used to describe surface flow paths and gravity-driven processes across a terrain without causing unrealistic flow dispersion. To explore this issue, a unified algorithm for the determination of flow directions has been developed, and new methods for the validation of the resulting surface flow paths are introduced. The unified algorithm makes it possible, by setting appropriate parameters, to perform local or path-based analyses and to experiment with different combinations of single and multiple flow directions in a morphologically significant manner. The new validation methods use drainage systems delineated from contour elevation data as a reference and take into consideration the overlap between these systems and those obtained from gridded elevation data. The unified algorithm is presented, and the results are evaluated for selected case studies in order to provide guidance on the use of surface flow path algorithms based on gridded elevation data.

Deriving a global river network map and its sub-grid topographic characteristics from a fine-resolution flow direction map

“…In this case, the upstream area is overestimated for River A and underestimated for the downstream stretch of River B. In fact, an accurate reproduction of the upstream area is a necessary, but not sufficient, condition for the validation of river networks, because upstream area does not represent the shape of a basin or sub-basin (Orlandini and Moretti, 2009). Nevertheless, the comparison between the original and upscaled upstream areas is considered to be adequate for validating the accuracy of the upscaling.…”

“…The FLOW method requires two fine-resolution topographic datasets, i.e., a flow direction map and a surface elevation map, at the same resolution, to generate a coarse-resolution river network map as well as supplementary maps of river network parameters. It was previously established that flow directions can be determined from a sufficiently precise surface elevation map (Orlandini and Moretti, 2009). However, precise elevation maps on a global scale are still limited.…”

Impact of grid resolution on the integrated and distributed response of a coupled surface–subsurface hydrological model for the des Anglais catchment, Quebec

“…The increasing availability of digital elevation models (DEMs) and the development of tools that allow rapid analysis of topographic attributes for watershed delineation (e.g., Wise, 2007; Orlandini and Moretti, 2009) have contributed to advances in hydrological modelling and to the ease with which a wide diversity of models can be applied over a broad range of scales. Discretization issues related to DEM cell size are consequently quite important, and several studies have investigated this problem.…”

Effects of watershed subdivision level on semi-distributed hydrological simulations: case study of the SLURP model applied to the Xiangxi River watershed, China

“…This is partly attributed to the increasing availability of digital elevation models (DEMs) and terrain analysis tools over a broad range of scales (Wise 2007, Orlandini and Moretti 2009, Eldrandaly and AbuZaid 2011, Mao et al 2011, Sulis et al 2011. Meanwhile, the use of hydrological models raises issues related to spatial parameterization and watershed discretization.…”