29 | July | 2019 | Kevin's Walk on the Wild Side

Inland towns need far more water storage.
Flickr/Mertie, CC BY-SA

Michael Roderick, Australian National University

The federal parliament has voted to funnel A$200 million to drought-stricken areas. What exactly this money will be spent on is still under consideration, but the majority will go to rural, inland communities.

But once there, what can the money usefully be spent on? Especially if there’s been a permanent decline in rainfall, as seen in Perth. How can we help inland communities?

Let’s look at the small inland town of Guyra, NSW, which is close to running dry. Unlike our coastal cities, Guyra cannot simply build a billion-dollar desalination plant to supply its water. Towns like Guyra must look elsewhere for its solutions.

Running dry isn’t just about rainfall

“Running dry” means there is no water when the tap is turned on. It seems to make sense to blame the drought for Guyra’s lack of water. But the available water supply is not only determined by rainfall. It also depends on amount of water flowing into water storage (called streamflow), and the capacity and security of that storage.

While Perth has had a distinct downturn in its rainfall since the 1970s and has built desalination plants to respond to this challenge, no such downturn is evident at Guyra. Indeed, to date, the driest consecutive two years on record for Guyra were 100 years ago (1918 and 1919).

Long-term rainfall records for Perth (left) and Guyra (right). Dashed red line shows the trend and the full yellow line shows 600 mm annual rainfall.
Bureau of Meteorology

Despite the differences, there are some similarities between Perth and Guyra. As a rule of thumb, in Australia, significant streamflow into water storages does not occur until annual rainfall reaches around 600mm. This occurs as streamflow is generally supplied from “wet patches” when water can no longer soak into the soil. Thus, if annual rainfall is around 600mm or below, we generally anticipate very little streamflow.

While Guyra has seen some rain in 2019, it is not enough to prompt this crucial flow of water into the local water storage. The same is true for Perth, with annual rainfall in the past few decades now hovering close to the 600mm threshold.

Importantly, rainfall and streamflow do not have a linear relationship. Annual rainfall in Perth has declined by around 20%, but Perth’s streamflow has fallen by more than 90%.

With little streamflow filling its dams, Perth had little choice but to find other ways of increasing its water supply. They built desalination plants to make up the difference.

Let’s return to Guyra in NSW and the current drought. The rainfall records do not indicate there is a long-term downward trend in rainfall. But even without a rainfall trend, there are still dry years when there is little streamflow. Indeed, in Guyra, the rainfall record shows that, on average, the rainfall will be 600mm or less roughly one year out of every ten years.

Build more storage

So how do the residents of Guyra ensure a reliable water supply, given that they cannot build themselves a desalination plant?

Well, in this case, you can simply get water from somewhere else if it is available. A pipeline is currently under construction to supply Guyra from the nearby Malpas Dam, and is expected to be in operation very soon.

But that’s not always an option. A made-in-Guyra water solution means one thing: expanding storage capacity.

Guyra can generally store around 8 months of their normal water demand (although of course demand varies with the seasons, droughts, water restrictions and price per litre).

To give a point of comparison, Sydney can store up to five years of its normal water demand, and has a desalination plant besides. Despite these advantages, Sydney residents are now under stage one water restrictions which happens when its storages are only 50% full. Yet, even when Sydney’s glass is only half-full, that city still has at least another two years of water left to meet the expected water demand even without using desalination.

By comparison, when water storages in Guyra are 50% full, they have less than six months normal water supply.

It is astonishingly difficult to find accurate data on small-town water supplies but in my experience Guyra is not unique among rural towns. There is a big divide between the water security of those living in Australia’s big cities compared to smaller inland towns. Many rural communities simply do not have sufficient water storage to withstand multi-year droughts, and in some cases, cannot even withstand one year of drought.

Nature, drought and climate change cannot be blamed for all of our water problems. In rural inland towns, inadequate planning and funding for household water can sometimes be the real culprit. Whether Australians live in rural communities or big cities, they should be treated fairly in terms of both the availability and the quality of the water they use.

Michael Roderick, Professor, Research School of Earth Sciences and Chief Investigator in the ARC Centre of Excellence for Climate Extremes, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Adam Cross, Curtin University

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On a warm evening in early 1802, Robert Brown sat aboard the HMS Investigator describing several plant specimens collected that day. Brown was the botanist on Captain Matthew Flinders’ expedition, and they had been anchored in King George Sound for nearly a month documenting the remarkable flora of the area.

He keenly awaited the return of their gardener, Peter Good, who had left earlier in search of a curious “pitcher plant” discovered the previous morning by botanical artist Ferdinand Bauer and landscape artist William Westall.

Unbeknownst to him, in minutes he would be gazing upon a uniquely wondrous plant: Cephalotus follicularis, the Albany pitcher plant.

Named after the southwestern Australian port city around which it occurs, the Albany pitcher plant stands out as an oddity even by the standards of carnivorous plants. The species is instantly recognisable, as it produces distinctive insect-trapping pitcher leaves that sit on the ground almost expectantly waiting for prey.

The toothed mouth and overarching lid of these pitchers look superficially similar to those of the tropical pitcher plants (Nepenthes) and North American pitcher plants (Sarracenia). However, these plants are not related; this similarity is a remarkable example of convergent evolution. The Albany pitcher plant is unique.

C. follicularis is the only species in the genus Cephalotus, which is the only genus within the family Cephalotaceae. Its nearest living relatives are rainforest trees from tropical South America, from which it is separated by some 50 million years. Indeed, it is the only carnivorous plant among the 70,000 species, a quarter of all flowering plants, that make up one of the largest evolutionary plant groups, the rosid clade.

The Albany pitcher plant is more closely related to cabbages, roses and pumpkins than it is to other pitcher plants.

The Albany pitcher plant only grows in a very small area of Western Australia, and is thought to be an ancient Gondwanan relict from a period when this region was almost tropical. It grows in nutrient-poor soils of coastal swamps and lowlands, where it survives by luring insects into its traps to be digested in a pool of enzymes at the base of each pitcher. Each pitcher bears a lid to prevent rain from diluting the pool of enzymes, with translucent windows to disorient trapped prey and prevent escape.

Interestingly, one species of insect not only survives inside the fluid of the pitchers, but relies on it for survival. The wingless stilt fly Badisis ambulans lays its eggs in the pitchers, and the larvae develop in the pool of pitcher fluid, feeding on captured prey.

The wingless stilt fly lives inside the Albany pitcher plant.
Tony D/Wikimedia, CC BY

These stilt flies live only in the dense vegetation of the swamps inhabited by the Albany pitcher plant. They look more like an ant than a fly, which is probably a deliberate mimicry of the ant Iridomyrmex conifer, the primary prey of the pitcher plant. It is likely that these three species – plant, fly and ant – have co-evolved together over millions of years.

The Albany pitcher plant was probably widespread in the southwest corner of WA before European settlement, and almost 150 populations have been recorded throughout this region. However, the species has declined dramatically over the past century as extensive land has been cleared throughout the southwest for agriculture and urban development.

The Albany pitcher plant now occurs only as small, isolated populations in remnant habitat patches. It is thought that less than 3,000 hectares of habitat suitable for the species now remains in the greater Albany region. Recent survey efforts suggest that fewer than 20 populations of the Albany pitcher plant still exist, and fewer than 5,000 plants remain.

Despite the perilous state of the Albany pitcher plant, it still has no formal conservation status. Indeed, swamps containing the species have been bulldozed for housing development in the past 12 months. But habitat loss and changes to bushfire frequency and water flow are not the only threats to this amazing species. Current projections of a drying climate in the southwest of Western Australia may see the species pushed towards extinction in the coming decades.

Incredibly, the Albany pitcher plant is also at risk from poaching. The species is prized for its horticultural novelty, and unscrupulous individuals dig up plants from the wild either to grow or sell. At one accessible location where the species was known to grow in abundance, every single plant within reach has been removed. At other sites, entire populations have been dug up.

Without improved conservation measures, and tough penalties for removing this incredible species from its natural habitat, the Albany pitcher plant and its complex web of insect relationships face a potentially dire future.