Abstract

Large improvements in flow estimation have been made the last decades. However, most, if not all, of the proposed algorithms have been developed and tested on mathematical, or manipulated natural, surfaces. There is an urgent need to develop algorithms dealing with natural artefacts in the landscape, like flat areas and depressions (sinks), caused by man, generalisation (of data type), or by errors in e.g. interpolation. The aim of this study is to present and test practical solutions making it possible to estimate drainage area over natural surfaces with a special focus on sinks and flat areas.Compared to other studies the main contributions of this research are that we have: adapted surface flow routing algorithms over flat areas to multiple flow algorithms, and developed algorithms letting the user decide which sinks to remove, either by beaching or filling. In both cases the user has the possibility to influence the result, by defining breaching points and deciding thresholds regarding area, volume or depth when filling sinks.In this study algorithms making it possible for the user to fill sinks depending on area, depth or volume have been developed. This increases the possibility to separate natural sinks from ones coursed by data or analysis errors. Also an interactive semi-automatic way of breaching break lines in the terrain is presented. This is needed instead of filling sinks caused by man-made artefacts, like road banks and train lines. Existing culverts are then replaced by used defined breach lines.Multiple flow functions to route overland flow over flat surfaces, caused by filled sinks or generalisation, are presented. The flat areas are classified as either 'flow-out' or 'flow-in'. Flow-out occurs when one or more cells on the flat area border have an elevation value lower than the flat area cells. A flat area is classified as 'flow-in' when all cells on the border of flat area have elevations higher than the flat area cells. These functions, together with the ones for sink removal, are exemplified and tested on real-world data. Results clearly indicate the benefits of the presented algorithms, making it possible to model overland flow and estimate flow accumulation/drainage area continuously in digital elevation models, without imposing vector hydrology covers (streamlines, lakes etc.).

Keywords

drainage area; flow accumulation; DEM; multiple flow distribution; flat areas; sinks

Published in

eISBN: 978-80-248-2667-7

Conference

9th International Symposium on Surface Models for Geosciences (GIS), 120123-120125, Ostrava, CZECH REPUBLIC

UKÄ Subject classification

Geosciences, Multidisciplinary


Permanent link to this page (URI)

https://res.slu.se/id/publ/117300