What happens when a high-rainfall language is implanted on a low-rainfall environment? Are urban density and suburban street design adequate enough to deal with the heavy rains which fall in a city like Adelaide? And how can the reality of stemming the flow and movement of ambient water, which can be captured when it rains, be transferred metaphorically to helping us better understand how we exist as water-dependent creatures in metropolitan areas?
WSUD—water-sensitive urban design—has been around for a while. It is the concept and the outcome, which has brought about, among other things, rain gardens on the side of roads in many council areas. These slow and filter water, create a cooling effect with vegetation and increase ambient moisture, and beautify roads. A side effect is a reduction in the number of car parking spaces, a soft raspberry to urban motorists. Still, WSUD is more than rain gardens, with their specific filtrates and overflows. Perhaps my favourite is what we call ‘thirsty pavers’, slight gaps which allow water to filter through special layers underneath and direct water to nearby vegetation, often in car parks. These little islands provide an oasis that keep our cars and folks cool. Ideally, of course, car parks shouldn’t take up this land at all.
Rain naturally hits the ground and seeps down into the earth and into ground water. This is the natural way, a recharge process which can take many years to then discharge into aquifers, mound springs, and rivers. When it rains a lot and the earth is saturated, water sheets and moves downhill to valleys. This flow would normally and naturally be slowed by vegetation and ground cover. Creeks are formed which feed into larger rivers and open into the ocean. Given the inconsistent but reliable flooding that occurs, riverine areas naturally expand and contract over many years, sometimes dry, sometimes flowing, with wet areas interspersed, occasionally. The vegetation around creates a buffer. The flooding of riparian zones is critical for promoting diversity, new life, and the flushing out of stagnant water. In dry parts of the world, this is the way it should be.
Like many natural systems in human settlement history, western interlopers implant their ideas of how things should be, often realising in time that their worldviews are not best suited to the environment in which they are implanted. Indeed, environments were typically managed more carefully by indigenous people, here for thousands of years, coping fine without surfaces like bitumen. In a short space of time, colonisers created hard surfaces, secured channels to define water boundaries for all times of year, built engineered structures like roads to allow passage over rivers, covered rivulets up, and dammed watercourses to ensure perpetual lake and waterfront views. Residents and tourists desire pedestrian access around lakes and buildings with the best outlooks at prime cost, often displacing habitat for native animals and taking up the natural buffer for storms and flood events. WSUD is an example of how we might bring back old ideas to adapt to extremely altered and even destroyed landscapes and ecologies.
In the suburbs around these watercourses, water runs into storm water drains and sometimes tumbles around in gross pollutant traps where most of the big stuff like rubbish and plant debris is filtered out. These need regular cleaning, especially after storms, to keep them operational. Some of the water goes straight into creeks, carrying oils and other pollutants from roads. The erosion of riverbeds is common when water flow is heavy. Before European colonisation in Australia, most of the rainfall seeped into the ground in situ, with only a small amount replenishing creeks. Now, much less water permeates through our soils, and the majority hits footpaths, roofs, driveways, car parks, into storm water drains, and eventually into creeks, taking chemicals and pollutants with it. There is not enough water in urban areas restocking aquifers and supplying ambient water to remnant urban vegetation.
This phenomenon impacts many parts of the world, not just Adelaide. Humans have drastically impacted the flow of water and direct it to where they want it. We largely let water run out into the ocean, without too much care for what inputs are added along the way. Domestic gardening and the landscaping of public spaces have often been part of residents’ and a local government’s role in maintaining some sense of natural beauty in the streetscape. Event, sport, and recreation places are now seen as locations of the greatest opportunity to improve permeability in the landscape and harness this resource of water. WSUD helps to capture more water where it lands, and to filter and clean more of it before it enters our riverine systems. Water slowed down and made more usable and versatile is repackaged and usable in a fit-for-purpose way. This process incidentally helps cool our suburbs, which mitigates the urban heat island effect.
Unfortunately, that’s not what often happens. Different levels of government decide on different elements of planning, design principles, and budgets. Bureaucracies try to regulate what people do on their own land, which is near impossible. What you do on your land affects the commons: the streets where kids walk home from school, the footpaths where people stroll with their dogs, the heavy runoff when it rains, where bird populations exist, and how hot or cool it is in your area in a heatwave. The adage do it once, do it properly is ideal in urban design. We shouldn’t have to ‘retrofit suburbia.’