Because much ecological research in rivers applies theories developed elsewhere to a diverse array of habitats renowned for their spatial and temporal complexity, riverine ecology lacks a clear conceptual cohesiveness (Fisher 1997). Hence, the quest to identify, explain, and predict dominant ecological patterns and processes has led to the proposition of many conceptual models that also vary across spatial and temporal scales. These models range from the structure of river networks through to reach-scale models of flow regimes, patch dynamics, sediment organization, and stream hydraulics. Not surprisingly, the explicitness of these conceptual models to specific river types (e.g., headwaters, alluvial rivers, floodplain rivers) contributes significantly to the processes and linkages emphasized by the models. Despite the obvious lack of cohesion in conceptual models of river function, three themes are common to all such models and these are fundamental to riverine ecology: (1) identifying interactions between structure and function; (2) understanding the processes driving the arrangement of structural components in space and time; and (3) identifying how specific habitats and processes are connected in space and time. Critical reviews of conceptual models of river function are given elsewhere (see Thorp et al. 2006). Our aim here is to discuss these three themes as they relate to understanding river function.

Many river restoration projects fail. Inadequate project planning underpins many of the reasons given for failure (such as setting overly ambitious goals; selecting inappropriate sites and techniques; losing stakeholder motivation; and neglecting to monitor, assess, and document projects). Another major problem is the lack of an agreed guiding image to direct the activities aimed at restoring the necessary biophysical and ecological processes within the logistic constraints of on-ground works. Despite a rich literature defining the components of restoration project planning, restoration ecology currently lacks an explicit and logical means of moving from the initial project vision through to on-ground strategies. Yet this process is fundamental because it directly links the ecological goals of the project to the on-ground strategies used to achieve them. We present a planning process that explicitly uses an interdisciplinary mechanistic model of disturbance drivers and system responses to build from the initial project vision to the implementation of on-ground works. A worked example on the Upper Hunter River in southeastern Australia shows how understanding catchment history can reveal disturbance and response mechanisms, thus facilitating process-based restoration.