Getting it right: water management and landscape design

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Guest post: Claire Thirlwall is the director of landscape architecture practice Thirlwall Associates. She specialises in river restoration and water management, and also works on more traditional landscape architecture projects. Here, Claire outlines the pitfalls and opportunities presented by water in landscape design and construction schemes.

Water, and more precisely how you manage that water, can be make or break on a construction project. From the water falling on the roof of each building to flood water rising up through the drainage network, dealing with water within your site can be a real challenge.

Get it wrong and you could be facing claims from your client as their prestigious building fills with water every time it rains.

It is worthwhile taking time at the very start of the project to look at all the ways in which water could impact on your scheme. Simple decisions, such as which way large areas of paving will drain or the location of downpipes, can allow you to capitalise on the rainwater falling on your site, avoid damage to wildlife and even help reduce flood risk in your region.

So how can all these issues be covered by such basic choices? Rainwater falling onto a site is often wasted when it could be used to irrigate planting areas or tree pits, as long as there is no risk of contamination. Think of those small, raised areas of bare earth surrounded by high kerbs in supermarket car parks – they make no use of rainwater and create a hostile environment for plants to grow in. Carefully designing the site levels, with planting below the level of paving, allows natural irrigation.

Your aim within a site should be to match, as closely as possible, the way that the area drained before development. With no hard paved areas rain would fall onto the ground and slowly find its way into the groundwater and into local rivers. This would retain natural water levels and in turn support the habitat within the river or stream.

The traditional approach for draining paved areas has been to direct all rainwater into a piped system to remove it from site as quickly as possible. These pipes then either link into the sewerage network or run into the nearest water course. During heavy rainfall these pipe systems can be overwhelmed and cause surface water flooding or create dramatic surges in the flow in rivers.

By using a sustainable drainage approach, as much water as possible is kept out of piped systems and is instead allowed to soak into the ground as part of the water cycle.

We often make the mistake of viewing water in the same way as we view other resources such as energy or materials. However, water is in fact a sustainable resource that we reuse over and over again. When it leaves our site it has an impact, and through careful design we can ensure that that impact is always positive.

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One Response to “Getting it right: water management and landscape design”

  1. ESI.info External Works Blog- Q & A with Stephen Bird. « esidigitalmarketing Says:

    […] Claire Thirlwall, a landscape architect and river restoration specialist, wrote a post on water management and sustainable drainage for us earlier this year. And we’ve currently got posts in the pipeline from the brains behind […]

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