Beyond the Drought: Designing for Water Scarcity

February 19, 2018

 

Water wise species - and most gardeners interpret this label to mean plants that survive on little water - are currently the go-to plants as gardeners respond to a drought that ranges in degree of toughness from harsh to disastrous. But, beyond the drought – what then? Focusing on drought-hardy planting suggests to me a temporary fix, a way to ease a garden through a current crisis. We live, though, in a country of low rainfall and unreliable water supply, where future droughts are a certainty. Designing for water-scarcity then requires more from us than simply a change in plant material and installation of a water tank to collect roof runoff.

For the most part, we have gardened on through recent years, planting the same kind of landscapes as if the world was not changing around us”, wrote horticultural journalist, Thomas Christopher, in a recent blog post on Garden Rant.

 

Decades of American and English-style garden design, plant choice and management has given South African gardeners a legacy of high-input landscapes, leaving us high and dry when this latest severe drought hit. Yet, as the rains arrived in Durban and Gauteng, volumes were heavy and concentrated, causing wide-spread damage as water flowed off hard surfaces rather than soaking into ground prepared to receive it.

So often droughts break with local flooding; how do we grow gardens to cope with these extremes? The same designs can mitigate both drought and high rain events.

It requires a 6-pronged approach:

Up until now, urban planning directs water off-site as a way to keep property and road surfaces clear of water. Now, designs must focus on keeping rain where it falls, slowing it down, spreading it out, giving it time to soak in. To do this, we need to:

 

  1. Shape the ground – to direct water flow

  2. Build living soil – to absorb and hold water and feed plants

  3. Capture rainwater – to keep it where it provides the most benefit

  4. Designate planting hydro-zones – matching a plant’s water needs with soils moisture levels

  5. Choose climate and soil appropriate plants – match plant to place (climate and soil type)

  6. Establish resilient plants

     

     

     

1. SHAPE THE GROUND

 

Meet plant water needs through contouring and drainage. Imagine your property as a mini-watershed. A watershed (or basin) is the area of land that catches precipitation and directs it to drain into a larger body of water, like a wetland, natural lake, stream or river. Topography (physical features and shape of the ground) influences the entire watershed, controlling the direction the water takes and the speed with which it moves across the ground. Plant roots and soil clean the water of contaminants as it filters through the profile to recharge underground water storage.

We can shape our properties to direct water away from areas where we don’t need it to areas where we do need it, and finally to soak into the ground