An Adaptive Approach for Channel Network Delineation from Digital Elevation Models

A. Afana1, G. del Barrio2
1 Desertification and Geo-Ecology Department, Arid Zones Research Station (CSIC),
C/ General Segura, 1, 04001, Almeria, Spain.
Tel. +34 950 281045
Fax. +34 950 277100
E-mail: ashraf@eeza.csic.es
2 Desertification and Geo-Ecology, Arid Zones Research Station (CSIC),
C/ General Segura, 1, 04001, Almeria, Spain.
Tel. +34 950 281045
Fax. +34 950 277100
E-mail: gabriel@eeza.csic.es

The quantitative description of land surface parameters is one of the essential tasks in hydrologic and geomorphologic studies, mainly river system structure and its related geomorphometric properties (Hancock 2005). Digital Elevation Models (DEMs) are generally used to delineate basin’s limits and to extract its corresponding channel networks, using either automatic or semi-automatic approaches for such depiction. In many cases, methods for stream-limits delineation are broadly based on a constant threshold area that defines channel initiation in relation to upslope contributing area. However, the majority of these approaches fail to detect an appropriate threshold value, mainly when the basin is made up of heterogeneous sub-zones, as they only work lumped. In this work, a new approach is proposed to define an optimum threshold value (As) based on the intrinsic properties of the drainage network structure. Such technique provides various critical thresholds in relation to DEM-data resolution and to the heterogeneity of the dominant landform structures.

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