Footprint recently took part in a working lunch on the topic of drought. The event was organised by Neil Landsburg of the Sustainable Water Industry Group (SWIG) and hosted by David Lewis, Head Gardener at The Roof Gardens, Kensington
Speakers Neal Landsburg and Colin Green, Professor of Water Economics at IET, were followed by a panel discussion.
Colin’s discussed the drought and ‘why it need not have happened?’ He distinguished between rainfall conditions in drought and flooding.
Definitions of water types:
- Blue water – surface water and ground water
- Green Water – water stored in the soil, soaked into the ground
His conclusion to dealing with variability, is to either store flood water or reduce demand to match supply. He cited Germany as at the forefront of sustainable water retrofit, highlighting a number of measures taken there:
- 30% of municipalities have separate charges for foul and surface water
- In North Rhine-Westphalia over an eight year period, 6 million m2 of surface area was disconnected from sewer system, including 825,000 m2 to green roofs.
- 13.5 million m² of green roofs were constructed in 2001 alone. This makes up around 14% of total roof space in Germany.
- 35% of new builds have rain water harvesting fitted
- Combined sewer overflow tanks (CSO-tanks) store 33 billion m3/ 400 litres per German citizen of water
This has led to domestic water consumption at 127 litres per person per day (l/p/d). These results are down to better legislation, combined land and water planning and a local responsibility for water planning. UK targets set in the CSH are at 120l/p/d minimum reduction, while current consumption figures for the UK are around 150 l/p/d.
There is doubt as to whether these strategies could work in the UK where a privatised water industry means there is little incentive to reduce demand. Policy change and behaviour change are key components, however Colin noted ‘one cannot work without the other’.
Suggestions for moving forward and the challenges ahead included retrofitting, integration of land and water management, incentive change for industry, and generally pushing water management higher up on the agenda.
The panel discussion which followed raised a number of issues:
- Lack of plumbing skills to deal with new technologies
- The ‘technology over behaviour change’ approach was questioned, the required 30 l/p/d reduction considered achievable by simple solutions made by occupants. This however is still the minimum CSH standard; more will have to be done to achieve CSH 5 and 6 at 80 l/p/d.
- The key relationship between cities and water was highlighted and a ‘larger pipe’ approach discouraged. Rain going directly into rivers was cited as an old-fashioned technology.
- The Government’s Green Deal scheme does not currently include green roofs or walls. It was suggested that they may be included as insulation, due to their good insulation value. A green roof was clarified as not necessarily green but one which is vegetated.
- David Lewis and Chris Collins, Blue Peter’s gardener, also briefly presented a brief explanation of the garden’s condition and history. The garden is manually watered but retains a number of redundant irrigation systems. David has reduced water demand by a third by simply changing the planting. Renevotions to the roof gardens were not needed in places with planting as lack of temperature variations limited damage to the bitumen roof.
- Chris highlighted the bottom up approach to water management; working with children to encourage homes to re-use grey water for watering plants.
The event suggested many ways to move forward, with an emphasis on practical action timed with the announcement of an official drought in the south east. It was agreed that this should be used as an opportunity to raise awareness of water management issues and push forward solutions to those responsible for the construction of the built environment. It is also important to redress the misconception that ‘drought is not the same as water shortage’. Droughts need to be dealt with before they occur.
All images (c) Professor Colin Green
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