Tim is a physical geographer with expertise in environmental hydrology, palaeolimnology, aquatic and wetland environments. His research focuses on anthropogenic impacts on upland landscapes and the management and restoration of degraded freshwater and peatland landcapes.

Research on water quality changes in upland freshwaters has focused on the impacts of air pollution and the extent to which acidified and metal polluted streams and lakes can recover. This has included early evidence that acidification is a reversible process, evaluations of the impacts of nitrogen deposition on upland waters, and new understandings of the mobility of metal pollution in freshwaters. Work on the degradation and restoration of blanket peat systems has led to assessments of peat revegetation processes, evaluations of the hydrological impacts of erosion and restoration and assessments of the role of fluvial carbon fluxes to greenhaouse gas budgets.