Water — the force that sorts the country

Water arrives with a bad reputation, and it half deserves it. It is the thief of the sand country: the agent that trickles down through the dunes, picks the pocket of every grain — its iron, its colour, its phosphorus — and makes off with the lot, leaving the bleached poverty the wallum is built on. But larceny is only one line on a very long résumé. Water is also the great connector, the medium the whole reef-to-range gradient is dissolved in and shunted about, and it sorts the same rainfall into separate worlds depending only on the road it takes down.

Watch where it goes. On the basalt range it soaks into deep clay that holds it like a sponge and releases it slowly, which is why the hinterland stays green through the dry. On the thin foothills it runs off fast and the country hardens between rains. On the coastal sand it sinks straight down and vanishes into the body of the dune, where it may wander underground for years before it troubles a stream. Learn where the water goes, and you have already read what is allowed to live there.

The sand hides the strangest of these waters. Stand on a dazzling dune in a drought and you are standing on the lid of an enormous freshwater store — a lens held in the sand, floating on the saltwater below, so slow that a raindrop may take decades to work through it. That hidden sponge is why the heath never quite dies, and it makes the region’s two kinds of lake: a window lake, which is simply the water table showing through where the land dips into it, and a perched lake, stranger and lovelier, cupped high in the dunes on a seal of coffee rock and filled by nothing but rain. And where the litter steeps in that slow water it turns it tea-dark and sour — blackwater, clean as anything and acid as orange juice, hostile enough to shelter a handful of frogs found nowhere else.

Down on the flats, water works by pulse rather than by trickle. The rivers here are short and steep and flood hard, and the flood, for anyone not living on it, is not the disaster it looks — it is the floodplain’s renewal, spreading nutrient across the flat, refilling the swamps, and telling the fish and waterbirds it is time to breed. Then, at the very bottom, the fresh water hands itself to the sea, turns brackish and then salt, and the sorting carries on by saltiness instead of by nutrient, right out into the estuary. The rain that fell on the whole coast is one rain. What breaks it into all these worlds is never the rain. It is the route.