THE DATA ASSIMILATION OF WATER SURFACE PROFILES BY USING ENSEMBLE ADJOINT METHOD FOR UNCERTAIN CONDITIONS

This paper discusses the influence of river bed variation and uncertain conditions on the assimilation results in the adjoint model analysis applied in Tone river reach (133km-152km). Although the bed variation during the flood in 2007 was small, it is shown that this model can assimilate the water surface profiles with movable bed. For the flood in September 2011, we attempted an ensemble analysis with the adjoint method, and estimated the expected values and distribution of the parameters and the flow rate. This adjoint model has the similar repeatability with the particle filter model, comparing results of both methods.