Green Infrastructure is the network of natural environmental components and green and blue spaces that lies within and between the cities, towns and villages which provides multiple social, economic and environmental benefits. In the same way that the transport infrastructure is made up of a network of roads, railways, airports etc. green infrastructure has its own physical components, including parks, rivers, street trees and moorland.
Case study: ERITH MARSHES & BELVEDERE LINKS, BELVEDERE, London Thames Gateway
London Borough of Bexley Belvedere and the nearby towns of Erith and Thamesmead lie in the London Thames Gateway growth area. They are characterised by a low skill, low wage economy that struggles to sustain a retail and wider amenity offer. The area’s main employment location of Belvedere is blighted by 70ha of vacant or derelict land. In order to attract new businesses a new link road has been planned, with the intention of opening up the area.
The site enjoys a unique environmental setting. It is immediately adjacent to the Erith Marshes, a site of regional importance for nature conservation. Under investment in the environment of the area needed to be addressed in order improve access, flood prevention, recreation and biodiversity as a way of maximising the functionality of the green infrastructure. The local network of drainage dykes has received little or no maintenance in recent years and its restoration is considered vital in preventing the flooding of low-lying residential areas. Pedestrian and cycleway improvements (green links) are also planned.
The Erith Marshes and Belvedere Links project aims to enhance the environmental quality of the marshland and to improve its accessibility from the surrounding area. In turn, this is expected significantly to increase the attractiveness of the Belvedere employment site to higher value businesses. The green infrastructure valuation toolkit has been used to evaluate the benefits of this significant investment in the marshes and adjacent area. As recommended in this guide, a three stage process was applied. Preparation: Understanding physical characteristics and beneficiaries The project would be focused on 156 ha of existing marshland, including 15km of drainage dykes, and the redevelopment of 12.5 ha of derelict land, which would be made possible by the construction of the new link road.
The works will greatly improve access, security and sustainability in Belvedere, with a range of long term benefits for local employers, staff and residents. The main direct beneficiaries of the new access and enhanced greenspace are expected to be local residents. Based on an analysis of the number of households, the number of residents living within 300m and 1200m of the project were estimated to be over 5,000 and around 47,500, respectively. [Actual figures are 5,164 and 47,518, but this sounds too precise!] The number of recreational users is predicted to be 237,600 (based upon a likely 10 visits each year, 50% of which are assumed additional to the existing baseline figure).
Assessment: Identifying potential benefit areas and applying relevant tools As a natural green-space area, the marshes are considered likely to have a positive impact on climate change adaptation, flood alleviation and general quality of place. The green corridor element of the project (paths and cycleways) is likely to have tourism, transport [it seems obvious we that we should mention it, although Genecon haven’t costed transport benefits] and public health and well-being benefits. The different elements of green infrastructure within the project (exact area of canal, wetland, different types of grassland, woodland and length of footpaths and cycleways) have been analysed in the context of the likely beneficiaries. The relevant tools were applied to assess the value of the benefits identified in monetary terms (for those benefits that could be costed) quantitative terms or qualitative terms. Some valuations were expressed as a precise figure, whereas others were expressed as falling within a range of figures. For valuation purpose, most benefits were deemed to last for 10 years, although some were deemed to last for longer periods. In each case, the valuations were discounted to give a present value (PV) figure, so that benefits which accrued for different lengths of time could be easily and directly compared.
The benefits were calculated as follows:
- Climate change adaptation and mitigation – The marshes and other areas of greenspace exhibit a significant urban cooling effect. This benefit, though uncosted, is recognised as having an impact on 2,000 to 2,500 households within 300-450m of the marshes.
- Water management and flood alleviation – Energy costs and carbon emissions relating to water treatment will be reduced through improvement of the natural drainage system on the marshes. The value of these benefits were calculated to be £0.6 million and £0.3 million, respectively, at present value (PV).
- Health and wellbeing – The calculation of reduction in mortality rates from increased take-up of moderate exercise (walking and cycling) was estimated to be £7.4million (PV) for walking and £1.5 million (PV) for cycling. Land and property values Residential land and property uplift within a 450m radius of the site was estimated to be £9.5 million (PV).
- Investment – An earlier study considered employment and environmental outputs from the Belvedere Link road on its own, from the marshland improvement and green links on their own and from a combination of the two. For employment, by 2016 the link road alone might provide an additional 2,200 jobs, and the green links 650, but together the increase is predicted to be a net 8,700. Adjusted for the relative importance of the green infrastructure, the estimation of site employment capacity and employment based GVA assessment was £31 million (PV).
- Labour productivity – Reduced absenteeism was calculated to be worth between £0.1 million and £0.5 million (PV).
- Recreation and leisure – Based on a “willingness to pay” measure, the recreational benefits were estimated to be £1.64 million (PV).
- Biodiversity – Erith Marshes are some of the last remnants of grazing marshes in south London. It is recognised that their enhancement through this project will bring increased qualitative biodiversity benefit, especially the promotion of rare and specially protected species such as the water vole.
- Land management – Direct management of the land was estimated to generate employment for three people, calculated at a benefit value of £0.6 million (PV).
The total value of the benefits generated by the improvements was estimated to be £53.1 million – £55.8 million (PV). Just over half of this (56%) was accounted for by that aspect of the site’s increased employment potential which was considered attributable to the green infrastructure. The other significant benefits included land and property uplift, improved labour productivity from fewer working days lost, enhanced health and well-being, recreation and flood alleviation. The capital investment is to be made by regeneration and economic development agencies. The total cost of £10.54 million includes the road construction and just £1.84 million of this relates to the landscape improvements. This case study illustrates the challenge of how best to capture the relative impacts of green and grey infrastructure. Without the link road, the number of jobs attracted would be low, but with improved access, the importance of improved environment becomes much greater. This project therefore shows a very good rate of return on investment in the natural