» Issue 3: Autumn 2005

Ramblings of a rambler

Flood defence and water sustainability expert Jean Venables comes to some valuable conclusions for the future during a summer walk by the Thames

FLOOD RISK IN THE THAMES was one of the many topics of conversation on the recent CGCA summer event in the series ‘Walks with a Past President’, organised by David Hattersley. I led the 20 keen walkers from the Thames Barrier to Greenwich, ending up as guests of civil engineering contractor, Dean and Dyball, at their construction site at the confluence of the Thames and Deptford Creek. They are building new river walls for a development site that may, one day, become an international cruise terminal and make a significant addition to the regeneration of the area. The walk was five miles of the 180 mile long Thames Path which runs from the Barrier to the source in Gloucestershire. We passed through sections of extreme contrasts: historic buildings, industrial activity, dereliction, new development, ecological wetland and the Quantum Cloud sculpture by Anthony Gormley, viewed whilst going from east to west across the Meridian.

Contrasting

The group commented in particular on the contrast between the Trinity Hospital built in 1614, for ‘Twenty One Retired Gentlemen of Greenwich’ and run by the Mercers’ Company, with the new flats and houses on the Greenwich Peninsular near the Dome.

The Dome is an excellent example of use of grey water, as it was designed to capture and store rainwater for flushing toilets to reduce the demand for potable water. The flood defences here are also of sound environmental design, being set back from the river’s edge to provide inter-tidal habitat.

It was high tide and the established reed bed gave a soothing, and welcoming rustling sound as it moved in the currents in the water. Further ecological habitat is provided by some of the redundant jetties being grassed and planted for invertebrates and as safe roosts for birds.

Another topic about which I was asked many questions was water quality, as the natural silt content of the estuary belies the increasing water quality evidenced by a total of 121 species of fish, including salmon, having been identified in the river. Some say there are 121.5 as a roach/bream hybrid has been caught! The estuary acts as an important nursery for commercial fisheries in the North Sea with sea bass, in particular, being of economic significance to both commercial and recreational fishing.

However, we cannot afford to be complacent over water quality whilst there are many combined storm overflows (CSOs) that operate when the runoff from rain exceeds the capacity of the system, because they cause pollution and reduce the dissolved oxygen. Thames Water mitigates these incidents by injecting air, or hydrogen peroxide, from barges, but severe storms frequently give rise to a fish kill.

Disappointed

A proposal to build a tunnel under the Thames to avoid these incidents has been put forward by Thames Water. Many were disappointed that this item was not included by OFWAT in the recently agreed capital programme.

Investment to renew and upgrade the drainage network – to meet both current and future requirements – is required, even if it is a subject ‘out of sight and out of mind’ until it does not work. It is a truism to say that there are no votes in sewers.

Another area where the country has benefited from the investment of previous generations is in the drainage networks now operated by the Internal Drainage Boards. Low-lying, waterlogged but very fertile land was drained and the water levels in the ditches managed by appropriate use of the pumping stations to maintain good growing conditions for the crops.

The need for agricultural efficiency is as strong now as it was in wartime as we have come to recognise that by reducing food imports, ‘food miles’ are reduced, with the consequential benefit of reducing greenhouse gases.

We all know that water is vital for life – but so many people have too little of the right kind of water, and are frequently at increasing risk of getting too much of the wrong kind of water. This does not only apply to developing countries but also to the developed.

For example, in densely populated areas, we consume so much water in comparison to the rainfall that ‘semi-arid’ is a description that can be applied to parts of South East England – often much to people’s amazement. At the same time climate change is predicting increasing sea levels and storminess and an increasing risk of inundation from the sea – too much of the wrong kind!

So, what do I mean by right and wrong kinds of water, right and wrong in terms of quality or quantity?

Appropriate

We need water of the appropriate quality for its use whether that is potable or for irrigation, rivers and canals. We also need to consider the spatial distribution of water. How much of the rainfall soaks into the ground and how much flows into the drainage and river systems?

Changes in land management processes and an increasing use of hard landscaping have increased the rate of runoff and reduced the natural recharge of the ground water system. In many areas rivers rely on the flow from ground water, replenished in the winter, to maintain the flow in the drier summers. In England, the winter of 2004/2005 was particularly dry, resulting in pressure on maintaining water supplies in the summer of 2005.

So what is being done to manage these risks? For the longer term, the Environment Agency has set up the TE2100 Project to investigate strategies for managing flood risk in the Thames Estuary over the next hundred years.

This very exciting, broad-based study is currently collecting data and will soon be reviewing strategies. As Chair of the Expert Panel for the Project, I appreciate the efforts of the multidisciplinary team examining an extremely complex set of issues. In addition, the recent DEFRA document ‘Making Space for Water’ is causing new methodology to be developed to meet the current philosophy.

On our walk, we benefited from the creation of the far-sighted concept of the Thames Path. The City to Sea Project, being promoted by the Thames Estuary Partnership, seeks to extend the Thames path, on both north and south banks all the way along the estuary from the Barrier to the sea.

Most of us take the provision of essential services for granted. Few, I’m sure, stop to think about energy or realise that reducing water use reduces the energy needed for pumping, which in turn reduces emissions of the greenhouse gases. Using less water can, at certain times of the year, also mean conserving a scarce resource. We Londoners have few hose pipe bans; we have been spoiled, thanks largely to the foresight of our Victorian forefathers. Much of this infrastructure may be out of sight – and therefore out of many people’s minds – but we need to keep investing in its upkeep and updating.

By the way, weren’t those Victorian forefathers the chaps who founded the City & Guilds?