By Megan Cassidy
Scientists are telling us that Australia is most likely going to be much drier as climate change takes hold, and the rain storms more fierce and intense.
With all of us growing more gardens and food at home during the pandemic, it is important that we put in place strategies to make the most of any rain that does fall, thus reducing our need to use mains water to keep our gardens going.
Winter is the perfect time to start a project like this, so you can be ready for summer. Plus, watering with a hose can take a lot of time and money, both of which are things you can reduce if you think a little differently about water and rain.
One of the big issues with our masses of roads, footpaths, concrete and fake grass yards, is that the rain that falls cannot soak into the soil. Instead it runs off, moving fast over these smooth surfaces and thus can be more damaging when it overwhelms the existing drainage systems.
More importantly, instead of adding to our ‘bank’ of water in the water table, we lose it, and it is usually now contaminated runoff that sweeps chemicals and oils into our waterways. This is the water that our trees depend on during warmer weather to keep them going, and we are missing out on the opportunity to capture it.
Now, drainage is important to make sure that we don’t have flooding in our communities, but there is a place for us to re-think how we see the rain that falls on our properties as a something valuable, that we should make the most of, not as a problem to be directed out to sea. If you have any garden on your property, capture as much rain as you can so that you spend less time watering, as well as save yourself some money!
Water tanks are one way to capture water, but there is another lower-tech and lower-cost way that you can consider doing too – redirecting your downpipes to flow onto your garden before they go down the drain. This way, you slow the water down, give it a chance to soak into your garden, stop it getting contaminated, and ‘bank’ it for the future, in the soil.
This is one of our downpipes that we have directed into a rain garden by placing a sloped rock under the pipe exit, so that it goes away from the house. This flows into a deep, wide trench/path that slopes down slightly towards the driveway, which also has a slope that takes the water out to the stormwater drain on the road. It’s not often that it overflows to the driveway though, as there is plenty of soil and some growing plants to suck up the water.
Here you can see a dwarf mulberry, lavender, kiwiberry, azalea, and off screen there are raspberries, mint, a cape gooseberry, avocado and several flowering bushes/plants. There’s also a native grass that don’t mind inundation near the exit. If you don’t want food plants, native plants offer lots of options to fill up the space. This is all in a space of 4m2, so you don’t need much room to have an impact.
One note is to make sure you choose plants that are suitable for the conditions – is it sunny or shaded, windy or protected, throughout the whole year? Will they mind being inundated with water? Don’t plant things that are sure to disappoint you, because that’s a waste of energy and money. Our plants are mounded up so they don’t sit in a puddle, but still get the benefits.
There are issues that need to be addressed in the design of it, like making sure that the water does not flow back under your house, that you don’t pile dirt up against weatherboards or above the ventilation holes in the bricks, and that excess water has a way to escape to a drain if the downpour is too heavy. But if you address these, it is a great way of slowing the water down in your landscape, and increasing the water content and resilience of your soil. This will stand you in good stead for the hotter months.
It is also essential that you couple this with some soil improvement, best done with compost so that you increase the water holding capacity as much as possible, especially if you have clay-heavy or sandy soils. If your soil can’t absorb the water it will still just run off and create mud gardens! Nobody wants one of those (except pigs and ducks perhaps!). The added bonus of soil improvement will be happier, healthier plants as well, and therefore more success in your garden overall.
The key here is to design it well. See if your local environmental or sustainability group has any members that can help, read up on rain gardens online, visit your local plant nursery, and/or engage a professional.
So next time it rains, take a walk around your property, and notice if there is any strong flows of water that you can slow down with trenches or swales, so that they can collect the water and allow it to soak into your soil. Or is there a drainpipe that could be redirected out onto the garden so that it can benefit from any rain that does fall?
Once you have put in the rain garden, make sure you go out when it rains to check whether it is having the desired effect, or if the trench need to be adjusted, or the soil improved further.