Contemporary reach restoration efforts focus heavily on returning streams to natural states, though increasing meander and bedform features in streams.  This approach is targeted to foster enhanced connectivity with the riparian and hyporheic zones. Regarded as a streams ‘liver’, exchange with the hyporheic zone not only filters and purifies stream water, but also provides nutrients and dissolved oxygen to benthic organisms, which are vital to the overall ecological health of a stream. At the patch scale, hyporheic exchange is characterised by periodic downwelling and upwelling, facilitating biogeochemical treatment in the streambed at a characteristic residence-time distribution. However, modelling beyond this scale remains a challenge, because of the interplay of a greater number of physical processes. We present work to show how hyporheic exchange can be quantified in terms of a mass transfer coefficient, which expresses the stream averaged advective transport into the stream. Using this approach, we provide examples of how regional groundwater fluxes at larger scales, along with processes occurring at different temporal scales can be combined through additive mass transfer coefficients.  It is envisaged that this will provide an invaluable framework for predicting rates of hyporheic exchange and in turn assessing the effectiveness of reach rehabilitation and restoration.­­