Priority River Habitat - Headwater Areas

One of the two datasets that make up the Priority River Habitat Map. Under the UK BAP definition all headwaters potentially form part of the priority habitat definition. The headwater resource can be a significant proportion of the river habitat network, accounting for the large majority of total river length. The headwater areas selected as most natural by land cover comprise a relatively large proportion of the upland headwater resource but a very small proportion of the lowland resource. The headwater analysis is the least certain component of the naturalness analysis – for example, highly natural headwater streams running through very small catchment areas, often wooded, would not be detectable by the analysis that has been undertaken. Equally, land cover is a crude measure of naturalness and various types of impact on river habitat are not well correlated with it (e.g. abstraction pressure, point source pollution). These issues can only be addressed through local interpretation of the final priority habitat map.