Effects of climate and land use changes on river ecosystems and restoration practices

Rivers are highly complex ecosystems with interrelated processes between physical, chemical and biological components. River restoration efforts are put in place to overcome pressures from the development sector to improve river process and function, nevertheless, river restoration tends to encounter obstacles as a result of these societal demands. To stop restoration projects falling short of their objectives, there is a need to demonstrate and predict the effects of human activities on these components spatially and temporally.

The overall aim of this document is to provide guidance and tools for river managers to analyse the potential effects of degradation, restoration, climate and land use change to optimise benefits between cross-sectoral river services and ecological requirements whilst considering climate change effects. Failure to plan across the full array of ecological and socioeconomic co-benefits can have undesirable and unanticipated consequences.

The motives, pressures and restoration measures for the dominant sectors are summarised in this document to identify the potential for interactions between pressures and restoration measures (benefits and losses for different conservation features). Guidance, tools and models to identify options for restoration and multiple-benefits are overviewed with focus on the potential effects of climate and land use changes on river processes. Specific emphasis is on synergistic strategiesto assist project managers with decision making, problem solving and planning strategies to identify suitable Programme of Measures (PoM) to support future RBMP cycles and the tuning of the WFD with other directives (Habitats, Birds, Flood, Groundwater, Renewable Energy, Sustainable Transport).

Synergies in river restoration occur when benefits can be found for both ecosystem services and the environment, whereas a trade-off occurs when one changes at the expense of another. Adopting a ‘synergy and trade-off’ approach to river restoration is discussed with specific focus on soft engineering techniques in relation to climate change enabling planners to consider the links in integrated freshwater conservation planning and overcome constraints that might hinder other (or multiple) sectors. Synergistic approaches are now emerging in river restoration and cross-sectoral interactions, and are supported by various policy documents. For example, synergies between flood-risk and river management or between hydropower development and restoration of longitudinal connectivity for fisheries. Flood-risk management is perhaps the policy with the best potential for synergies with other aspects of water management, provided that adequate strategies are implemented (CIS 2007). Working with natural processes & nature-based restoration are key features of the strategy to overcome climate change impacts whilst providing multiple-benefits thus, allowing important opportunities for synergies between directives such as EU Floods Directive, WFD, Habitats Directive and Birds Directive, amongst others.

The main methods promoted in this document are hydro-economic models, cross-impact balance analysis and the nested-DPSIR framework.

  • Hydro-economic modelling can support integrated river basin management and they represent regional scale hydrological, engineering, environmental and economic aspects of water resources systems within a single framework. The complexity of interactions between water and the economy can be captured through formal, mathematical models linking relevant hydrological and biogeochemical processes to economic ‘laws’ of supply and demand underlying the provision of scarce water services (Brouwer & Hofkes 2008). Integrated hydro-economic models can suggest least-cost combinations of actions to attain specified goals and examine how alternative choices will affect different interests. In summary it can be argued that hydro-economic modelling is especially suitable to address water quantity issues, but that it is much more difficult to make the link with WFD environmental objectives that are ecological in nature. The main bottleneck in full application of hydro-economic modelling is to integrate type-specific pressure-impact relationships where hydrological regime is linked with ecological status.
  • Cross-impact Balance Analysis creates a hypermatrix and can be applied by river managers to anticipate the potential impacts of possible hydrological changes on stream channel morphology, ecological function and services provision (Slawson 2014). CIB analysis is a helpful approach that can give a number of options for plausible future scenarios. It is based on a qualitative judgement scale and relies on expert judgement across a number of disciples, the benefit here is that CIB is not data dependant, however, expert judgement can result in bias and strongly influence any outcome.
  • The nested-DPSIR framework is a conceptual tool that identifies key relationships between society and the environment and should be applied in the early stages of project planning. It aims to reconcile conflicting interests between societal and the ecological needs of rivers, in addition to land uses change by capturing key relationships between society and the environment, encouraging decision-makers to think about the challenges at a larger scale, across multiple sectors. At a catchment scale the nested-DPSIR can identify restoration potential and aid decisions for PoM objectives. The outcome from a CIB Analysis can be used alongside DPSIR to explore synergies and new opportunities.

Weighted prioritisation matrices are easily understood, simple to apply and have the advantage of allowing various alternatives to be compared numerically. Scoring is based on existing information, both quantitative and qualitative, and incorporates the opinions of stakeholders, ecological specialists and economists. Physical, chemical and biological aspects of broad-scale processes of freshwater rivers and interfaces between connecting ecosystems, such as natural habitat continuum from upstream to downstream catchments and between river and its surrounding land use are considered during the scoring. Nevertheless, there are a few disadvantages to this method, mainly because the evaluation procedure depends heavily on the weightings assigned and these can be subjective and open to bias.

Conclusions and recommendations from this document are:

Ø  In many scenarios the domains of environment, society and institutions are disconnected and sustainability is compromised

Ø  Identifying relevant political and economic incentives can help overcome the inadequate budget situation for restoration

Ø  Simple decision support methods are generally easier to use, but lack a full understanding of the economic and social interactions, while complex models incorporate these aspects but suffer from data paucity and need huge investments to achieve the required input

Ø  Optimising ecosystem services in conjunction with the ecosystem approach appears to be a useful mechanism for selecting the best management options, but to convince other users of the importance of ecological services requires ecological and socio-economic information at a catchment scale and the more fundamental economic data to support the dialogue.

Ø  Adopting a synergy approach to river restoration will maximise multiple benefits between sectors and ecosystem form and function, tools such as DPSIR help identify synergies but its application by river managers is generally lacking

Ø  The consequences of climate change e.g. through more extreme discharge regimes create a moving target for planning and implementation and require an anticipating and adaptive strategy

Ø  Identifying the impacts of different sectors and the potential synergies should be part of the project planning cycle and be inherent in the identification and formulation phases of the project development.

Case studies to support the processes described are provide in Part 2 of the deliverable.

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