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Suburban areas are subject to strong anthropogenic modifications, which can influence hydrological processes. Sewer systems, ditches, sewer overflow devices and retention basins are introduced and large surface areas are sealed off. The knowledge of accurate flow paths and watershed boundaries in these suburban areas is important for storm water management, hydrological modelling and hydrological data analysis. This study proposes a new method for the determination of the drainage network based on time efficient field investigations and integration of sewer system maps into the drainage network for small catchments of up to 10 km 2 . A new method is also proposed for the delineation of subcatchments and thus the catchment area. The subcatchments are delineated using a combination of an object-oriented approach in the urban zone and geographical information system-based terrain analysis with flow direction forcing in the rural zone. The method is applied to the Chaudanne catchment, which belongs to the Yzeron river network and is located in the suburban area of Lyon, France. The resulting subcatchment map gives information about subcatchment response and contribution. The method is compared with six other automatic catchment delineation methods based on stream burning, flow direction forcing and calculation of subcatchments for inlet points. None of the automatic methods could correctly represent the catchment area and flow paths observed in the field. The watershed area calculated with these methods differs by as much as 25% from the area computed with the new method.Method 1 is the proposed method, method 2 uses flow direction forcing, method 3 contains subcatchments for inlet points and methods 4a-4d use different kind of stream burning: method 4a uses just variable road burning, and methods 4b-4d use variable road burning and the burning of the drainage network of 1, 5 and 10 m, respectively. 3756 S. JANKOWFSKY ET AL.

Land cover mapping using aerial and VHR satellite imagesThe rapid progression of urbanization in periurban areas affects the hydrological cycle 3 of periurban rivers. To quantify these changes, distributed hydrological modelling tools 4 able to simulate the hydrology of periurban catchments are being developed. Land cover 5 information is one of the data sources used to define the model mesh and parameters. 6The land cover in periurban catchments is characterized by a very large heterogeneity, 7

Flowpaths are significantly affected by land use change and engineered elements across urban catchments. Conventional GIS-based tools for extracting drainage networks were not developed for urban terrains. This work presents Geo-PUMMA, a GIS toolbox to generate vectorial meshes for terrain representation in distributed hydrological modeling, and to extract drainage patterns in urban and peri-urban catchments. Geo-PUMMA generates wellshaped Hydrological Response Units (HRUs) and Urban Hydrological Elements (UHEs). The toolbox was used in peri-urban catchments of Chile and France to generate three model meshes with different levels of treatment, and extract and compare their corresponding drainage networks. A recommended mesh is identified, which replicates the main morphological and hydrological features of the reference drainage network, and is able to preserve features at small to medium spatial scales (~ 80-150 m). Overall Geo-PUMMA can be used to represent the terrain in distributed hydrological modeling applied to urban and peri-urban scales. .

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