Understanding riverine hydroecological response to climate change : development of a coupled modelling framework

Abstract

Described as the most essential natural resource, rivers rank amongst those ecosystems most sensitive to climate change. The 2018 Brisbane Declaration highlights the pressing need to consider the resultant hydroecological impact. To this end, this thesis looks to develop a coupled hydrological-hydroecological modelling framework, an exciting first step under the new research agenda. Initially, the focus lies on developing current understanding of the hydroecological relationship through consideration of potential delays in hydroecological response, alongside refinement of current modelling practice. There follows consideration of whether hydrological models can preserve ecologically relevant characteristics of the flow regime, as determined through hydroecological modelling efforts. Limiting factors are identified and an alternative hydrological modelling approach established. A holistic depiction of uncertainty is central to all developments. The framework is developed with reference to a principal case study, the groundwater-fed River Nar, Norfolk; validation of the component models is achieved through additional case-studies. The hydrological model, forced with climate change projections, is used to simulate changes in the flow regime. This output then serves as input to the coupled hydroecological model. It is thus possible to assess the impact of climate change on hydroecological response in a quantitative manner. Given data limitations, the framework is best suited to applications at the regional scale or by flow regime type. Its importance lies in the potential to inform water resources adaptation, as well as advancing the fields of hydroecological and hydrological modelling. Scope for further research centres around the wider socio-economic context, as recommended under the Brisbane Declaration.