When the well runs dry: preserving water sources on earth

As global warming dries up rivers and lakes, innovative solutions are being rolled out to preserve and sustain global water supplies

In Kitui County, in Kenya, water was a source of anxiety for decades. In a 1950 volume of Geographic Review, Edwin Munger described the district as: “hills of gneiss and schist rise above a dry, rolling eastward-sloping plain of red soil covered with thornbush except where scattered native shambas dot the countryside…water is the principal determinant of land use…its yearly presence or absence means prosperity or possible starvation.”

The district’s residents struggled to survive in this parched climate. With erratic rainfall and seasonal rivers quick to dry up, the area is among the poorest in Kenya, with over 56 per cent of the population living in poverty. It is in areas such as these that novel technologies to provide freshwater are so absolutely vital. 

Sand dams are created by building a wall across a riverbed. The wall slows down flash floods or brief water flow and allows coarser sediment to accrue behind the wall. This sedimentation creates a shallow artificial aquifer that is replenished by stream flow. The Kitui District, with its impermeable bedrock and low groundwater salinity, proved an ideal location for the creation of these dams, of which 400 have been built by locals in the area since 1995. Each provide 2,000m3 of water storage, allowing residents greater food and water security during droughts, and less travel time to obtain water.

Fresh water is a finite resource that is constantly becoming scarce as urbanisation increases. According to National Geographic, each American uses 2,000 galleons of water a day, mainly on food production. More than 70% of the Earth’s surface consists of oceans and seas but less than 3% is fresh water and more than two-thirds of that is locked in frozen icecaps and therefore largely inaccessible to current technology.

Jebel Ali Port
Jebel Ali Port. The plant produces 564 million gallons of water a day from the sea

Of all the freshwater we use 70% of our water is for agriculture, 22% for industry and 8% is used in homes for domestic use. And although constantly recycled, the planet’s inhabitants are using up its freshwater supply quicker than it can be replenished. And as global warming dries up rivers and lakes, demand is showing no signs of waning.

“Rising pressure on resources calls for new production and consumption models. We need to better understand the connections between water and energy, because choices made in one area impact – positively or negatively – the other,” said Irina Bokova, Director-General of UNESCO, in the United Nations World Water Development Report in 2014.

“Every production model in energy has consequences on the quantity and quality of available water. In the past, these resources were managed by competition. In the future, we must choose cooperation, and make choices to craft just compromises for all.”

Today, scientists and engineers are engaged in a wide variety of plans and research to maintain, preserve and expand our access to this precious resource. These include pollution control, human impact studies and urban aquaculture, as well as scientific advancements such as instrumentation and sensor development, automation of molecular methods and chemical and biological studies of aqueous environments.

In Southeast Asia, which produces the majority of the world’s rice harvest, but which also suffers from intense flooding, scientists are looking at using Managed Aquifer Recharge (MAR) technology whereby floodwater is captured and stored in natural underground reservoirs and brought out for farming in dry periods.

Another area that suffers from excess water, though in a wholly different setting, is Philadelphia. The American city developed a unique effort to address the city's storm-water runoff problem, which would improve streets, benefit the community, and create jobs. Rather than simply digging new tunnels and storage tanks to hold runoff, The Philadelphia Water Department (PWD) has opted for green infrastructure solutions, relying on a combination of solutions including green roofs, porous paving, storm-water planters, rain gardens, and rain barrels.

We need to better understand the connections between water and energy, because choices made in one area impact – positively or negatively – the other

Irina Bokova, Director-General of UNESCO

Using the seas to access freshwater has also experienced a surge of novel technologies. Desalination of seawater accounts for a worldwide water production of 5000 million m3/year, and a hotspot of intense desalination activity has always been the Arabian Gulf. The Jebel Ali plant in the United Arab Emirates produces 564 million gallons of water a day from the sea, and experience in the Gulf States demonstrates that desalination technology has developed to a level where it can serve as a reliable source of water at a price comparable to water from conventional sources.

Using desalination technology in an environmentally conscious manner is still a work in progress. Science Daily has pointed to a team of researchers from Humboldt State University and the University of Southern California who have developed a process which they claim uses 30 percent less energy than traditional desalination methods. In Reverse Osmosis-Pressure Retarded Osmosis (RO-PRO), freshwater and seawater are combined in a pressurized chamber, creating water pressure that spins a turbine.

Whether it be by desalination, irrigation, or even education, the efforts to address water security are being complimented by the raft of new technologies coming to market. And as rapid urbanisation and population growth take hold, the race to freshwater must be faster than ever before.