This paper proposes an approach for combining device-scale and basin-scale simulation methods to provide realistic in-situ performance analysis of turbine arrays and with the eventual goal of determining basin-scale effects from large turbine arrays. The present state-of-the-art basin-scale simulation methods represent turbines as sub-grid-scale objects, typically using semi-empirical/semi-analytical turbine models. Device-scale CFD simulation methods can resolve flows around turbines and can predict turbine performance outside the idealized assumptions of analytical methods. Thus, combining the capabilities of these two types of simulations is desirable for accurate in-situ performance analysis with the correct influence of turbines on the basin flow. The approach is to parameterize turbine thrust and power using a reference velocity available to both types of model. This is a volume average over a region in space that can be resolved by the basin-scale model. The approach is accurate provided both methods predict a consistent reference velocity. This paper presents preliminary studies testing such consistency for simplified channel scenarios, finding that as long as the averaging volume has length scales twice the turbine diameter, relative error in power is typically under ≈5%. When applied to a complex real-world flow, the relative error was larger. It is thought that at present, the method is suitable for approximate power prediction and further improvement is required for accurate turbine performance studies.