This paper reports an application of data-based mechanistic (DBM) modelling to the study of reservoir sedimentation. A detailed monitoring programme in the catchment of the Wyresdale Park reservoir was used to calibrate a two component DBM sedimentation model. The first component was a non-linear rainfall to suspended sediment load (SSL, kg s−1) model, the second dealt with sediment routing and the trap efficiency of the reservoir. Daily precipitation data for the period 1911–1996 were used to simulate the sedimentation history of the reservoir. The synthetic accretion sequence evidences the effects of climatic forcing and was compared to lake-bed sediment cores independently dated using 137Cs. The synthetic stack showed general agreement with the observed accretion data. Departures in model performance most likely reflect non-stationarity in the system due to local changes in land use and reservoir regulation.