In river landscapes subject to prolonged and high population pressure, the impact of human actions is usually so pervasive that re-establishment of 'natural' river conditions is not possible. However, understanding the impacts of humans on river ecosystems is essential to identify how degradation of condition may be slowed or reversed and may also lead to the recognition that some human activities may be crucial for maintaining highly valued and sensitive river ecosystems. To achieve the necessary understanding for such judgements, it is essential to assemble, synthesize and analyse information on human actions, river environments and their interactions. In this paper, we focus on three commonly available information sources (historical records/archives, topographic and geomorphological maps, river habitat surveys) that can deliver relevant information over three timescales (centuries, decades, years). We illustrate the potential of these three data sources to assemble thematic and quantitative knowledge about how river systems function under a history of different human pressures and interventions, by exploring an example river landscape: the New Forest, southern England. We use this illustrative example for three reasons. First, for more than 1000 years, the New Forest has been affected by a complex range of land use and management practices which have heavily influenced the contemporary river landscape. Second, many of these human actions have degraded the landscape but others sustain highly valued landscape characteristics and ecosystems. Understanding the relative negative and positive impacts of different human actions is essential to understanding any river landscape with a long history of human use, and thus to designing balanced and appropriate management approaches. Third, in this special issue in memory of Professor Ken Gregory, we focus on an example landscape where he conducted research, allowing us to incorporate insights and data from his observations.
