Author(s)

F. Delclaux & C. Depraetere

Abstract

Quantitative approach for the determination of hydrological landscapes F. Delclaux* & C. Depraetere^ *UMR HydroSciences Montpellier, IRD, France ^Hydrologie, IRD Cotonou, Benin Abstract Due to spatial heterogeneity of watersheds hydrologists segment the landscape in homogeneous zones. Then, two points are explored: the homogeneity validation and the role of data quality. The concept of homogeneous units is validated in terms of texture metrics. These indices are calculated with a co- occurence matrix whose elements define the probability of pixel adjacency within a raster map. Data and computational tools are handled by the GRASS GIS. First, the index sensitivity is tested with two types of data: (1) linear and sinusoidal virtual landscapes, (2) 314 West African watersheds characterised by the Mean Quadratic Curvature parameter of the relief. The inter—comparison shows a great dispersion in the heterogeneity description. Moreover, the study highlights the correlation between me

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