Incorporating landscape features to obtain an object-oriented landscape drainage network representing the connectivity of surface flow pathways over rural catchments

摘要

A topological representation of a rural catchment is proposed here in addition to the generally used topographic drainagennetwork. This is an object-oriented representation based on the identification of the inlets and outlets for surface water flownon each farmer’s field (or plot) and their respective contributing areas and relationships. It represents the catchment as anset of independent plot outlet trees reaching the stream, while a given plot outlet tree represents the pattern of surface flownrelationships between individual plots. In the present study, we propose to implement functions related to linear and surfacenelements of the landscape, such as hedges or road networks, or land use, to obtain what we call a landscape drainage networknwhich delineates the effective contributing area to the stream, thus characterizing its topological structure. Landscape elementsnmodify flow pathways and/or favour water infiltration, thus reducing the area contributing to the surface yield and modifyingnthe structure of the plot outlet trees. This method is applied to a 4D4-km2 catchment area comprising 43 955 pixels andn312 plots. While the full set of 164 plot outlet trees, with an average of 7 plots per tree, covers 100% of the total surfacenarea of the catchment, the landscape drainage network comprises no more than 37 plot outlet trees with an average of 2nplots per tree, accounting for 52 and 7% of the catchment surface area, when taking account of linear elements and landnuse, respectively. This topological representation can be easily adapted to changes in land use and land infrastructure, andnprovides a simple and functional display for intercomparison of catchments and decision support regarding landscape andnwater management. Copyright  2011 John Wiley & Sons, Ltd.