22. Modelling Environmental Change: Quantification of Impacts of Land Use and Land Management Change on UK Flood Risk

Hydrological models have an important role to play in supporting water management. In this paper we consider the insights developed from Pater Young’s research in the context of the particularly challenging problem of predicting the effects of land use and land management change across multiple scales. The strengths and weaknesses of alternative modelling approaches are reviewed. We then consider the utility of physics-based models, firstly applied to issues of upland grazed pasture and the effect of tree shelter belts, supported by an extensive multi-scale field experimental programme at Pontbren, Wales. The models provide useful quantification of local (field-scale) effects; we use meta-modelling emulation to extend the simulations to catchment scale. Secondly we consider the problem of upland peatland management, in the absence of detailed local data. Physics-based modelling provides generic guidance on the effects of drainage and drain blocking on flood risk. We then consider the potential of conceptual models, conditioned by regionalised indices—in this case a Base Flow Index and the US SCS Curve Number. BFI has considerable power in constraining ungauged catchment simulations, and with speculative adjustment of soil categorisation, catchment-scale effects of land management can be simulated. The CN approach is applied through subjective mapping of US to UK soils; although derived for the US, results show that it has considerable utility for UK regional application. Finally, we reflect on the role of Data Based Modelling, and, in application to our detailed experimental data, show its usefulness in identifying appropriate model structures to guide hydrological application.