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REFRESH will push forward the science of integrated catchment modelling. Currently there are few catchment-scale models that link hydrology, hydrochemistry and ecology. REFRESH will address this knowledge gap, building on the progress made in Euro-limpacs and on the new experimental data from REFRESH to develop new catchment-scale models that not only simulate the transport of nutrients and organic matter to surface waters but also predict the ecological response, especially with respect to ecological functioning, biodiversity and thresholds. The integrated modelling will also be extended beyond the current state-of-the-art by:
Most critically the models will, for the first time, provide managers with a sophisticated tool to assess the effectiveness of adaptive management measures needed to protect surface waters from the adverse consequences of climate change. The modelling effort will focus on eight 'demonstration', or case study catchments representative of European climate types.
At the demonstration sites we will...
Right: Example of model chaining. From the Bjerkreim catchment, Norway (Kaste et al. 2006)
Data transfer between the models is indicated by the arrows. T= air temperature, P= precipitation, Q = water flow, HER= hydrologically effective rainfall, SMD= soil moisture deficit, RN= nitrogen immobilisation (as % of input).
HBV = Hydrologiska Byråns Vattenbalansavdelning model
INCA-N = Integrated Nitrogen in CAtchments model
MAGIC = Model of Acidification of Groundwaters In Catchments
FJORD = NIVA FJORD Mode
Integration of ecosystem models for rivers, lakes and wetlands with models of key ecological vulnerability indicators to determine interactions between climate and land-use management change and the freshwater ecology.
Ecological models developed for rivers, lakes and wetlands will be integrated with existing hydrochemical river, lake and wetland models to transfer knowledge acquired at field experiment scale to the demonstration sites. The most appropriate existing models will be chosen based on the issue to be modelled and data available. Specific ecological indicators will be determined following reviews but are likely to be both hydrochemical (nutrients, organic matter, sediment and oxygen) and ecological (gross primary production; system respiration; net primary production; chlorophyll a; and invertebrates, macrophytes, wetland plants, phytoplankton and fish functional groups and abundance). Data to develop and test the models will be collated from other projects (Euro-limpacs, REBECCA, WISER and national data) and from new data generated in REFRESH. Existing river models will be developed to include representations of the interactions of key ecological function and habitat indicators and the controlling environmental factors (temperature, flow, oxygen, organic matter, nutrients and hydromorphology). The models will be tested at sites in UK, Denmark, Finland, Turkey, Canada and REFRESH experimental sites. Selected lake models will be extended to include more functional groups of phytoplankton, invertebrates and fish and tested on data from the lakes used for modelling. Once developed, ecosystem models will be used to explore the effects of changes in the controlling environmental factors (temperature, water level, oxygen, organic matter and nutrients) on the functional groups and selected ecological indicators and compared with experimental and review data to test model behaviour.
Right: Coupling hydrochemical with ecological modelling.
Images redrawn from:
James, C., Fisher, J., Russell, V., Collings, S. and Moss, B. (2005), Nitrate availability and hydrophyte species richness in shallow lakes. Freshwater Biology, 50: 1049-1063. doi: 10.1111/j.1365-2427.2005.01375.x
Integrated and chained models to couple river, lake and wetland systems to the river catchment scale.
Both existing and the newly developed ecosystem models will be chained to create integrated catchment models of rivers, lakes and wetlands to simulate flow, water quality and ecological indicators throughout a catchment especially the connectivity, in terms of water, chemical and ecological transfers, between rivers, lakes and wetlands. This chaining will be done at the eight European demonstration sites, plus two sites in Canada for comparison.
Application of model chains at key demonstration sites to determine the ecological response to climate and land-cover change for different adaptation, mitigation and restoration options
The model chains applied to the demonstration catchments will be used to quantify the flow, hydro-chemical, ecological and habitat response to climate and land-use/management change for different adaptation, mitigation and restoration options. This assessment will determine the requirements, in terms of water- and land-use management, to maintain the ecological structure and function given changes in climate.
Left: Integrated modelling of ecological response, adaptive management and cost effectiveness strategies.
Uncertainty analysis and risk-based assessment of model outputs
Catchment scale modelling is difficult because of model structure, parameter and data uncertainty. Kolmogorov-Smirnov statistics, evaluated in a Monte-Carlo framework, and Extreme Value Theory will be used to assess parameter and input data uncertainty. Outputs from model chains based on different model combinations will be compared to assess structural uncertainty. The likelihood of different ecological futures at the demonstration sites will be determined from the modelled outputs based on the probabilities of different chemical and hydrological conditions, and the likelihood of crossing ecological thresholds.
Right: Uncertainty analysis used in catchment modelling