Green infrastructure: supporting green river engineering
Responding to the needs of the Environment Agency, Natural Resources Wales, the Welsh Local Government Association and Natural England, HR Wallingford led the development of decision making frameworks that identify the critical success factors to support the selection and application of green engineering approaches in rivers.
What is a green infrastructure (GI) network?
The green infrastructure (GI) network is made up of natural and semi-natural features that connect and run through our urban spaces. Rivers form a key part of this green network, and GI approaches can be used to help conserve and restore these natural features by improving water quality, morphology and natural habitats.
Making the case for Green Infrastructure approaches
GI approaches strengthen the functionality of river ecosystems by greening new and existing river infrastructure. They also help compliance with the environmental aspects of the Floods and Water Framework Directives. However, despite these obvious benefits, a number of obstacles exist that prevent green infrastructure approaches from being used as part of river engineering schemes. These often softer approaches can be perceived as having higher risk of failure, which is possibly partly attributed to a lack of design and maintenance guidance available to support their use. It has also been previously unclear to stakeholders how to demonstrate and communicate the multiple benefits of GI. Three actions were identified in this project as essential to overcome these barriers:
- gathering existing guidance and literature to provide sound arguments as well as advanced, technical knowledge to promote the informed selection of Green or Green-Grey solutions in river engineering;
- compiling and communicating a series of case studies that provide reliable evidence on key aspects of GI implementation, including constructability, engineering performance, environmental functions and social benefits; and
- identifying critical success factors (motivation, engineering performance, costs and ecosystem services) and assessment of their impact on decision making.
Our decision support framework addresses both the business case and the technical requirements for GI approaches. We give regulators and planners authoritative material to share with designers and contractors at the early planning stages of a project to help support the selection of suitable green or green-grey measures.
Developing decision support frameworks
The above actions ultimately led to a decision support framework at two different levels:
- the Business Case, which provides arguments to support the decision to implement a GI approach,
- the Technical Support, which provides the technical information base from which to select an appropriate Green or Green-Grey measure or technique.
We produced a new publication ‘Green approaches in river engineering: supporting implementation of Green Infrastructure’ which brings together the strategic arguments and the technical information needed to support the selection of GI approaches and, through a series of case studies, provides sound evidence on constructability, engineering performance and environmental and social benefits.
This publication is available as a free ebook from HR Wallingford (https://eprints.hrwallingford.com/1250/) and is hosted also at CIRIA (www.ciria.org) and RRC (www.therrc.co.uk).
Paper copies are also available.
Funding and partners
The work was carried under a NERC-funded project (Natural Environment Research Council) led by HR Wallingford.
Partners included the River Restoration Centre, Environmental Policy Consulting, CIRIA, University of Liverpool and University of Nottingham.
The project was driven by the needs of the Environment Agency, Natural Resources Wales, the Welsh Local Government Association and Natural England.