Interest of spatially distributed data to evaluate the object-oriented PUMMA model on the semi-rural Mercier catchment (Yzeron basin, France)

Musandji Fuamba, Flora Branger, Isabelle Braud, Pedro Sanzana Cuevas, Benoit Sarrazin, Sonja Jankowfsky

Thursday 2 july 2015

12:36 - 12:39h at Central America (level 0)

Themes: (T) Water resources and hydro informatics (WRHI), (ST) Catchment hydrology, Poster pitches

Parallel session: Poster pitches: 11H. WRHI - Catchment

Urban growth affects mostly the periphery of large cities, leading to catchments which are a mixture of rural and urban areas, so-called periurban catchments. Increase imperviousness and the setup of various networks (drinking water, sewer systems) lead to the modification of the hydrological cycle components and of water pathways in those catchments. In this paper, we assess the relevance of the The Peri-Urban Model for landscape MAnagement (PUMMA) to represent the hydrological cycle in the Mercier sub-catchment (6.8 km2), located close to Lyon city, France, with 10% of artificialized areas. The model is tested in more rural conditions than in a previous application to the Chaudanne neighbour sub-catchment (2.2 km2), characterized by 24% of artificialized areas. The model mesh is based on an object-oriented approach. It is composed of polygons, as derived from a detailed land use map (forest, agricultural fields, urban cadastral units and lakes). The river network is composed of the natural river, ditches and the rain water network. All the units are interconnected for surface and sub-surface flow transfer, and river routing. Model parameters are specified using in situ information or the results of previous studies, without any calibration, in order to assess the relevance of various functioning hypotheses. The model is run for two contrasted years: 2008 (wet) and 2009 (dry) with a variable time step for rainfall and an hourly time step for reference evapotranspiration. Simulated discharge is compared to measurements at the outlet and statistical performance criteria are computed. The model is able to represent the contrast between higher values of base flow in winter and very low flow in summer. Annual runoff volume is underestimated (-21%) in 2008 and overestimated (+10%) in 2009.