Modélisation géostatistique des débits le long des cours d'eau
Résumé
Estimating discharges along a stream network requires specific models of random function because usual covariance model are no longer valid on such structures. Moreover, variables are generally highly non stationary because of the discontinuity at each confluence but also because of relationships with soil properties, that have to be taken into account. We propose a global model of random functions along a tree graph introducing the concept of ¿elementary thin streamsÀ, defined by the whole set of paths between sources and outlet (de Fouquet and Bernard-Michel, 2006). At each point of the network, the river is considered to be the linear combination of these streams on which one dimensional stationary random functions are defined. In practise, the coefficients of the linear combination are determined according to the conservation equation of discharge and flux at the forks. An application to water discharge on the Moselle Basin (north-east of France) is presented. The hydrographic network of this Basin is made of about 100 important nodes and 100 monitoring stations are available for the last 10 years.