A2-D reservoir routing model: sedimentation history of Abbeystead reservoir, U.K.

A physically based two-dimensional model is applied to the case-study site of Abbeystead Reservoir, UK. The model, developed for density currents, solves the Navier-Stokes equation coupled to a general sediment transport equation. Water flow and sediment motion are determined by reference to dimensionless Reynolds and Richardson numbers. An additional dimensionless parameter, a, determines suspended and/or bedload sediment transport rates. The performance of the model is considered in relation to data obtained from repeated bathymetric surveys (1876-1991) for Abbeystead Reservoir, which provides an exceptionally detailed long-term record of sedimentation rates and deposition patterns. The suitability of the adopted two-dimensional scheme is related to the local morphology of the reservoir and the time-scale of the delta propagation process. First results show good agreement between the numerical simulations and the field data. The model is able to reproduce both the dynamics of delta growth and the quasi-equilibrium delta form reached as the infilling process nears completion.