Recent Developments in Hydroweb. Water Level Time Series on Rivers and Lakes
Cretaux, Jean-Francois¹; Gennero, Marie-Claude¹; Arsen, Adalbert¹; Bercher, Nicolas²; Calmant, Stephane³; Berge-Nguyen, Muriel¹; Drolon, Vanessa⁴; Maisongrande, Philippe^2
1CNES/legos, FRANCE; ²CNES, FRANCE; ³IRD/Legos, FRANCE; ⁴Legos, FRANCE

We present the current state of the database as well as developments in progress. HydroWeb (http://www.legos.obs-mip.fr/soa/hydrologie/hydroweb/) provides offline water level time series on rivers, lakes and floodplains based on altimetry data from several satellites (Topex/Poseidon, ERS, Jason-1&2, GFO and ENVISAT). The major developments in Hydroweb concerns automatic acquisition and processing of IGDR data for updating time series in near real time (both for lakes & rivers) and also use of additional remote sensing data, like satellite imagery allowing the calculation of lake's surfaces.
A lake data centre is under development at the Legos in coordination with Hydrolare Project leaded by SHI (State Hydrological Institute of the Russian Academy of Science). It will provide the level-surface-volume variations of about 150 lakes and reservoirs, calculated through combination of various satellite images (Modis, Asar, Landsat, Cbers) and radar altimetry (Topex / Poseidon, Jason-1 & 2, GFO, Envisat, ERS2). The final objective is to propose a data centre fully based on remote sensing technique and controlled by in situ infrastructure for the Global Terrestrial Network for Lakes (GTN-L) under the supervision of WMO and GCOS. Further additional products are planed in Hydroweb, in particular floodplains extent variations from the Modis instruments.
In a longer perspective, the Hydroweb data base will integrate data from future missions (Jason-3, Altika, Sentinel-3) and finally will serve for the design of the SWOT mission. In particular the products of hydroweb will be used as imput data for simulation of the SWOT products (water height and surface variations of lakes and rivers).