Economic analysis of wider benefits to facilitate SuDS uptake in London, UK

Abstract

Urban water management via Sustainable Urban Drainage Systems (SuDS) has been successfully applied in cities worldwide. This infrastructure has proven to be a cost efficient solution to manage flood risks whilst also delivering wider benefits. Despite their technical performance, large-scale SuDS uptake in many places has been slow, mostly due to reasons beyond the engineering realm. This is the case of England and Wales, where the implementation of SuDS has not reached its full potential. This paper investigates the strategic role of SuDS retrofit in managing environmental risks to urban infrastructure at a catchment level, through an economic appraisal of all benefits (i.e. flood reduction and wider benefits). The Decoy Brook catchment in London, UK, was used as a case study. Average Annual Benefits were used to monetise the value of SuDS in reducing surface flood risk, whilst a Value Transfer approach was used to appraise wider benefits. It was found that by including the latter, their economic feasibility improves considerably. This paper also shows how to split the investment amongst multiple stakeholders, by highlighting the benefits each one derives. Finally, recommendations regarding incentives and policies to enhance the uptake of SuDS are given. The proposed methodology for SuDS mapping and economic appraisal in the planning phase can be used in cities worldwide, as long as general principles are adapted to local contexts

Comparing cost‐effectiveness of surface water flood management interventions in a UK catchment

“…Water butts were estimated to cost £335.34/unit in 2018 prices (Stovin, Swan, Stovin, & Swan, ). It has been assumed that water butts will be replaced after 15 years at a discounted rate of £193.39, which represents the more conservative assumption from the available literature (Environment Agency, ; Ossa‐Moreno et al, ). Permeable paving costs are based on present day values in the literature of £74.52/m 2 (Environment Agency, ; Stovin et al, ; Woods Ballard et al, ).…”

Planning Nature-Based Solutions for Urban Flood Reduction and Thermal Comfort Enhancement

“…Several studies have investigated the effectiveness of NBS for different aspects in urban areas. In particular, several works focus upon the application of NBS to achieve multiple benefits at the same time, e.g., [10][11][12][13]. Furthermore, several studies have assessed the effectiveness of NBS measures separately on either urban flooding, e.g., [2,[14][15][16], or on heat stress, e.g., [17][18][19][20][21][22].…”

Applying the Systems Approach to Decompose the SuDS Decision-Making Process for Appropriate Hydrologic Model Selection

“…The multi-functionality of SuDS, spanning from hydrological [14] to environmental [33] and socio-economic [34] functions, results in a wide range of benefits for each of the relevant sectors. Due to this multifunctional nature of SuDS, the relationships between stakeholders are very complex.…”

“…Arrow et al [13] provided a good philosophical foundation for the role of CBA in the management of natural resources such as water. CBA was used by Ossa-Moreno et al [14] and Liu et al [15] to capture the broader benefits of SuDS and not focus only on the system's performance regarding flood management and water quality improvement. In those authors' studies, they tried to compare the different technologies of SuDS within the framework of a cost benefit analysis.…”