 Micro Drainage Ltd looks at the importance of making space for water
We have been made painfully aware of the consequences of interfering with natural processes.
The list of flooding events and the towns and cities affected are too numerous to list and it does not adequately express the deep distress caused to the victims of flood events.
The EU Floods Directive puts this phenomenon into context as a global issue, something we have learnt from our customers in the Far East and America. In the UK we have just completed a consultation period on the Flood and Water Management Bill and legislation will be in place shortly.
This article is written to share recent flooding experiences and how implementation of PPS25 compliments the way forward for new developments, providing we make space for the water and have early dialogue with the stakeholders to facilitate.
Summer 2007 floods
We have quite rightly been focused on identifying flood zones around our rivers and coastlines to ensure we locate new developments away from areas of highest fluvial risk. However, the summer 2007 floods in many areas were caused by pluvial flooding as rural areas became totally saturated and sheet runoff flowed through urbanised areas with dire consequences to transport links as well as households, businesses, schools, in fact the whole social fabric surrounding the areas affected.
These events were very extreme, beyond the 200 year Return Period in many cases, so surface water flooding was inevitable. We and future generations will need to live with, and better manage, these risks.
Defra is funding six pilot studies, in which Surface Water Management Plans are being produced across the country as a way of improving coordination of activities between stakeholders involved in surface water drainage. The results of the studies will help us to prepare local Surface Water Management Plans that will establish a partnership to identify the risks, review the options and implement strategies.
‘Blue corridors’
There are a number of good examples where new developments have already been designed to include ‘green or blue corridors’, where the existing overland flood flow routes have been identified at the outset. The concept of embracing the opportunity to construct a water friendly development that not only acknowledges but respects the pre-existing condition brings added environmental and aesthetic benefits.
A digital terrain model can be deluged and the ‘blue corridors’ identified, to assess the existing overland flood flow routes.
The development itself can then be located away from the high risk areas, effectively identifying and avoiding the fluvial as well as the pluvial hazard zones.
This approach may require larger open areas and this may conflict with other planning requirements such as PPS3, but more open space will help to provide biodiversity and more amenity value. Combined with less flood risk this would better satisfy ‘long term’ sustainability. The balance between satisfying the space required against high density planning requirements will need to be addressed and hopefully everybody has contributed their views on this within their feedback on the draft Flood and Water Management Bill.
The Upton development near Northampton features in CIRIA report C635 and provides a robust, long term sustainable drainage solution comprising of pipes, ponds, swales and wetlands. Amenity and biodiversity have also been satisfied, as well as managing both the quantity and quality of surface water runoff.
In the near future the issues of adoption and maintenance of Sustainable Drainage Systems and Surface Water Management will be addressed and we can really start to make a difference that will help to provide betterment and relief for existing as well as future generations.
Could we really see the return of the Municipal Engineer, with Local Responsibility, accountable to Local Communities? Importantly the Pitt Review recognised that it’s what we need and the government has included it in the draft Bill. The question is will the funding be there to enable effective implementation?
For more information
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