This paper suggests that computer simulation modelling can offer
opportunities for redistributing expertise between science and affected
publics in relation to environmental problems. However, in order for
scientific modelling to contribute to the coproduction of new knowledge
claims about environmental processes, scientists need to reposition
themselves with respect to their modelling practices. In the paper we
examine a process in which two hydrological modellers became part of an
extended research collective generating new knowledge about flooding in
a small rural town in the UK. This process emerged in a project
trialling a novel participatory research apparatus-competency
groups-aiming to harness the energy generated in public controversy and
enable other than scientific expertise to contribute to environmental
knowledge. Analysing the process repositioning the scientists in terms
of a dynamic of `dissociation' and `attachment', we map the ways in
which prevailing alignments of expertise were unravelled and new
connections assembled, in relation to the matter of concern. We show how
the redistribution of knowledge and skills in the extended research
collective resulted in a new computer model, embodying the coproduced
flood risk knowledge.