The vegetative canopy captures some of the rainfall and protects the soil surface from erosion.
Water then drips to the ground surface. The organic humus layer on the soil surface absorbs some of the water and, again, protects the soil surface.
Once this organic layer is saturated, then water percolates into the soil profile.
When the soil is saturated, the water then enters the streams, lakes, the water table.
Each step of this process slows and filters the water.
How it often happens in modified urban environments:
Rainfall hits lots of ‘hard’ surfaces like concrete, asphalt, roofing. There is reduced vegetative cover and little humus layer. Soils are often modified and compacted. There is little opportunity for the water to be absorbed
The waters journey to our streams and harbours is rapid. Streams overflow and water velocity can be high. Erosion of stream banks can occur carrying sediment with it.
There are fewer natural filters in the system and pollutants are collected from hard surfaces and discharged into our waterways.
As we keep intensifying our cities, more surfaces are covered and the problems magnify.
More trees, more planted areas, living soils, slowing water with detention tanks, stormwater swales, rain gardens and permeable paving.
Permeable paving allows water to percolate through the paved surface and the underlying basecourse. This slows and filters water before it enters the soil and stormwater systems. There are many forms of permeable paving – loose gravel, turf-blocks, plastic geo-grids, reinforced grass surfaces, porous concrete and resin bound aggregates.
Second Nature has experience with all these permeable paving systems and are Auckland’s only licensed installer of StoneSet. This product is a porous resin bound aggregate system that is primarily designed to be laid over a permeable basecourse but can also be used as a decorative surface topping. StoneSet is an internationally proven system. Check out this amazing product www.stonesetnz.co.nz