Integrated water management –
The blue green grey (BG2) city

By Martin Shouler

Research and Innovation Steering Group Member, UK Water Partnership

Water plays an essential part in the life of our cities. It is required to provide our basic needs for drinking water and sanitation, for industry and commerce and plays an important part in our health and well-being. Water is both an enabler for allow of cities to work but can also present a risk in the form of flooding and surcharging.

Worldwide, cities are growing at a tremendous rate (ref). Our modern conurbations of high density living are placing an ever increasing strain on their associated water infrastructure assets as well as the aquatic environment of the wider catchment.

We are facing problems caused by both too little and too much water. As well as climate change, this is being exacerbating by increasing population growth and urbanization. In addition, for many cities, existing urban water infrastructure is often at or approaching its maximum capacity.

When considering water in cities it is often helpful to look at the constituent elements of man-made, natural and semi-natural systems. Man-made systems will include above and below ground water infrastructure including water supply, wastewater and flood defence systems. This is so-called ‘grey’ infrastructure and is typically managed by a private or public water company. Natural and semi-natural systems (partially engineering) encompass both ‘green’ systems, such as sustainable urban drainage systems (SuDS), managed land and green roofs and ‘blue’ systems such as rivers and water bodies. Often these BG2 systems are incoherent and not integrated being managed by a range of agencies both public and private.

By considering blue, green and grey systems together, an optimized approach to water to integrated water management (IWM) for cities can be achieved. For example, green infrastructure such a swales and parks can absorb and infiltration stormwater locally that otherwise would need to be conveyed in piped ‘grey’ drainage systems. This reduction and the slowing of stormwater flows can help reduce the risk of flooding. Rivers and streams that have often been canalized or channeled undergrown can be opened up and with careful design provide areas to manage surcharging during high intensity rainfall.

In our congested cities, access to blue and green spaces, as well as contributing to the management and control of water, can provide multiple health benefits. These range from reduced exposure to pollution and high urban temperatures through to improved mental wellbeing and providing opportunities for outdoor physical activity. Integrating these spaces with communication routes provide safe and appealing cycling, walking and running routes to allow citizens to travel more simply.

For this to work the true cost and benefits of these BG2 systems need to be taken into account; this is especially in the case for natural and semi-natural systems which can be difficult to fully quantify and further work is required here on valuing ecosystem services. An example of this is Granger Town…

The technical and engineering requirements to develop an integrated for solution for a city to work are relatively straightforward to achieve. However, we need to rise to the challenge of:

  • Working with multi-stakeholders across of range of agencies together with the commercial and industrial communities.
  • Developing financial models that identify the true costs of the solutions and value the benefits of blue and green infrastructure, and
  • Allocating the costs to the beneficiaries in a fair and equitable manner.

The BG2 city provides a cost efficient, environmental sensitive and will contribute to the health and well-being of its citizens.

Biography – Martin Shouler

Martin is the Global Environmental Services Engineering and Public Health Engineering Skills Leader at Arup. Working on water and related projects across both Building Engineering and Infrastructure; focusing on design, research and consultancy across the world. Particular expertise includes water supply, sanitation, sewerage, water conservation and efficiency, water quality, water treatment, wastewater engineering and infrastructure services. In addition, he has a keen interest in sustainability particularly related to minimising water use and energy associated with its use.

Previous involvement has included the role of Chairman of the UK’s Society of Public Health Engineers (SoPHE) and also serving as an advisor to the Environment Agency with a special interest covering the water and construction industries. Martin has also been part of the Expert Group advising the Department of Communities and Local Government (DCLG) on the revision of water related Building Regulations. In addition he is a member of British Standards Institution (BSI) committees, responsible for a number of water sector standards, and has been involved in developing many British and European standards.

Recently Martin has worked for the Water Resources Group 2030 on Managing Water in Scarce Environments. He is also a Liveryman of The Worshipful Company of Plumbers and serves on their Technical Committee.