Sub-catchments

Traditionally research into stream water quality has be carried out on large, regional scales. This approach can allow a picture of water quality trends at the national level to be identified relatively quickly and also keeps costs down if measurement points are to be sampled at regular intervals. However, as Jason Galloway, ACP Hydrochemist explains in this article, a drawback of this approach is that processes and trends occurring at smaller scales can be masked by other trends occurring in the same area.