Section: New Results

Use of remote sensing data for hydraulic modelling

Participant : Carole Delenne.

Wetlands provide a vital resource to ecosystem services and associated rural livelihoods; but their extent, geomorphological heterogeneity and flat topography make the representation of their hydrological functioning complex. The main objective of this area of research is to assess the relevance of remote sensing data for the monitoring and hydraulic modelling of different hydrosystems. In [14] , a semi automated method exploiting 526 MODIS 8-day 500 m resolution images was developed to study the spatial and temporal dynamics of the annual flood across the Niger Inner Delta over the period 2000?2011. The flooded area is detected using band ratio indexes. Results were evaluated against classified Landsat images, previous studies and field stage data for a range of hydrological units: river stretches, lakes, floodplains and irrigated areas. Depending on the study area, its extent, and the objective to be reached, different kinds of remote sensing data may be interesting: RADAR, multispectral, high/low spatial/temporal resolution, etc. Several paths for research are currently considered to upgrade the use of remote-sensing data in hydrodynamic modelling:

• use of detected flooded area for model validation and for the calibration of parameters such as friction coefficient.

• topography assessment using the detection of the flooded area of a given wetland at different times.

• characterization of statistical properties of the geometry of the urban medium (useful for large-scale models): statistical, subgrid-scale properties of the topography, and information regarding the flow connectivity properties of the urban medium.