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

Abstract

Abstract:A topological representation of a rural catchment is proposed here in addition to the generally used topographic drainage network. This is an object-oriented representation based on the identification of the inlets and outlets for surface water flow on each farmer's field (or plot) and their respective contributing areas and relationships. It represents the catchment as a set of independent plot outlet trees reaching the stream, while a given plot outlet tree represents the pattern of surface flow relationships between individual plots. In the present study, we propose to implement functions related to linear and surface elements of the landscape, such as hedges or road networks, or land use, to obtain what we call a landscape drainage network which delineates the effective contributing area to the stream, thus characterizing its topological structure. Landscape elements modify flow pathways and/or favour water infiltration, thus reducing the area contributing to the surface yield and modifying the structure of the plot outlet trees. This method is applied to a 4Ð4-km 2 catchment area comprising 43 955 pixels and 312 plots. While the full set of 164 plot outlet trees, with an average of 7 plots per tree, covers 100% of the total surface area of the catchment, the landscape drainage network comprises no more than 37 plot outlet trees with an average of 2 plots per tree, accounting for 52 and 7% of the catchment surface area, when taking account of linear elements and land use, respectively. This topological representation can be easily adapted to changes in land use and land infrastructure, and provides a simple and functional display for intercomparison of catchments and decision support regarding landscape and water management.

Improving runoff prediction using agronomical information in a cropped, loess covered catchment

“…The runoff connectivity is controlled by K sat patterns (Harel & Mouche, ), as well as by macrotopography, for example, berms, embankments, ditches (Levavasseur, Bailly, Lagacherie, Colin, & Rabotin, ), hedges (Gascuel‐Odoux et al . , ), detention ponds (Chrétien, Gagnon, Thériault, & Guillou, ), and by microtopography resulting from tillage or wheel tracks (FpMasters, Rohde, Gurner, & Reid, ). The runoff dynamic, that is, the flow discharge, is controlled by the slope, the surface roughness and the hydraulic resistance expressed by the Manning's coefficient ( n ).…”

Integrating field measurements, a geomorphological map and stochastic modelling to estimate the spatially distributed rockfall sediment budget of the Upper Kaunertal, Austrian Central Alps

“…Wichmann et al, 2008). In the end, this approach is somewhat comparable to the study by Gascuel-Odoux et al (2011) who use a high-resolution DEM for overland flow routing and a map of agricultural fields which they link through flowpaths in order to create an object-oriented (rather than a pixel-oriented) drainage network. The rockfall production rates forming the basis of regionalisation and up-scaling currently depend on the surface area of the source cells in the DEM only.…”

Contrasting suspended sediment export in two small agricultural catchments: Cross‐influence of hydrological behaviour and landscape degradation or stream bank management

“…Not all cattle farmers have performed the work necessary to exclude cattle. In addition, even though much of the bocage is preserved in Moulinet, and grasslands cover much of its area, a small percentage of the catchment (3% in 2008) occupied by crop fields is nonetheless connected to the stream (Gascuel‐Odoux et al, ). In the same catchment, Vongvixay () analysed SS data (from October 2005 to September 2008) and concluded that soil erosion from hillslopes was another source of SS during certain storm events, especially in autumn and spring.…”

“…In 2008, grasslands and woodlands covered about 50% of the catchment. Croplands (mostly wheat and maize), covering 40% of the catchment, were located mainly in upslope and midslope areas (Gascuel‐Odoux et al, ; Figure ). In the Kervidy‐Naizin catchment, agriculture is dominated by intensive production of cattle (1.2 cows ha −1 UAA, mostly fed indoors) and pigs (9.2 pigs ha −1 UAA).…”