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Communication Dans Un Congrès Année : 2011

Remotely sensed riparian corridor indicators in relation to ecological status of rivers

Résumé

The definition of restoration strategies on riparian corridor requires an improved understanding at regional scale of the relative influence of both human surrounding pressures (at different scales, from watershed to local riparian corridor) and riparian vegetation on river ecological status. This work brings new routine methodologies for (i) accurate and fine-scale mapping of land cover within riparian corridors over large extent in combining information from remotely-sensed images at very high spatial resolution and ancillary data; (ii) building spatial indicators reflecting impact mechanisms on river ecological status of both human pressures along rivers and riparian vegetation; (iii) building spatialized pressure/impact models at regional scale. These methodologies were developed and implemented over the Herault watershed (1150 km, 2650 km², 3 ecoregions, southern France) and rivers of the Normandy Region (6000 km, 25000 km², nordwest France). First, detailed fine-scale riparian corridor land cover maps were produced on the two studied areas with high accuracy (89%) from an object-oriented classification procedure combining information from orthophotos (0.5 m pixels), Spot 5 XS (10 m pixels) satellite images, and complementary spatial thematic data. Then, several spatial indicators were defined and built. For example, six types of indicators specific to the role of riparian forest have been defined: (1) length and (2) area indicating the presence and intensity of this vegetation along the river; (3) connectivity (number of gaps/km of river) and (4) length of gaps reflecting the role of thermal regulation related to the shadow cast by the vegetation, and (5) the average width and (6) uniformity (varying width) reflected with the connectivity indicator the ability of this vegetation to act as a buffer. Finally, introduction of these indicators in Pressure/Impact models highlights the influence of herbaceous and tree riparian vegetation on a 20 m buffer width on macroinvertebarte community. Remotely sensed riparian corridor indicators are a key issue to monitor and manage riverine landscape.
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Dates et versions

hal-02596881 , version 1 (15-05-2020)

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T. Tormos, Pascal Kosuth, K. van Looy, Yves Souchon, Bertrand Villeneuve. Remotely sensed riparian corridor indicators in relation to ecological status of rivers. IAVS Lyon 2011, special session Biodiversity and functioning of riparian habitats: indicators of change, Jun 2011, Lyon, France. pp.15. ⟨hal-02596881⟩
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