Water-use efficiency and water scarcity
Water scarcity affects every continent, hindering environmental stewardship and sustainable social progress. Few countries have the means to continually increase their access to safe and clean water supplies, making it essential that they make the best use of the water that they do have through more efficient agricultural practices, water capture and storage, and recycling. In practice, this is largely facilitated by technologies which combine mature infrastructural concepts with innovative nature-based and ICT-enabled solutions, together with smart monitoring.
Though there is sufficient freshwater to serve the global population, it is distributed unevenly. Many countries globally – whether developed or developing, with wet or dry climatic conditions – continue to be exposed to chronic shortages of water.
In the early 2010s, around 1.9 billion people (or 27 per cent of the global population) were estimated to live in potentially severely water-scarce areas, while around 3.6 billion people (almost half the global population) were living in potentially water scarce areas for at least one month a year – a figure projected to increase to 5.7 billion by 2050. A vulnerability that could often be mitigated by the introduction of improved water management systems.
Water scarcity is exacerbated by climate change (for each degree of global warming, 7 per cent of the global population is projected to experience a decrease of 20 per cent or more in renewable water resources), while water supply and demand imbalances are further driven by population growth and human impact on the environment.
An ever-increasing demand
Water demand is growing at more than twice the rate of population increase, with half a billion people now estimated to live in areas where water consumption exceeds the locally renewable water sources by a factor of two.
Driven by the agricultural sector, which accounts for 70% of global water usage (and up to 95% in some of the world’s least developed countries) – future demand for water is only expected to increase, as it responds to rising food demand. Expanding cities, increased usage from manufacturing and for energy production, and climate change will also contribute to an ever-widening gap between water supply and demand. Together, these could result in a global water deficit of 40 per cent by 2030.
The broader socio-economic impact
Besides a negative impact on water security itself, water scarcity has wide-ranging social, economic, political and environmental implications. With half of the global workforce employed in just eight key water and natural resource-dependent industries (agriculture, forestry, fisheries, energy, resource-intensive manufacturing, recycling, building and transport), water scarcity can affect livelihoods, employment prospects and incomes.
Water scarcity also affects food security – potentially triggering displacement or environmental migration, which in turn can trigger political and social instability – and the health of poorer populations, thus making them more vulnerable.
In terms of economic impact, it has been estimated that water-related factors could create as much as a 6% decrease in affected countries’ GDP by 2050. Hence water scarcity not only affects water and food security, public health and people’s livelihoods, but has a sizeable impact on global and regional economic growth and stability.
In essence, water scarcity occurs when societal and environmental requirements exceed either the physical availability of water, or the economic and institutional capacity to harness – and sustain – sufficient water supply. Water-use efficiency improvements are therefore instrumental in addressing the ever-increasing strains on clean water, and in mitigating broader water scarcity-related challenges.
Sustainable solutions for wastewater management
Despite the multiple challenges of water scarcity, a number of innovative, technology-driven solutions are currently being implemented across the globe to ensure more efficient, sustainable use of this increasingly precious resource.
Demand-side efficiency improvements
Since agriculture is responsible for more than two thirds of water withdrawals globally, it’s vital that the sector uses water as efficiently as possible, with larger-scale deployment of more water technologies.
Precision irrigation combines mature technologies (ie irrigation systems) with innovative ICT solutions (such as sensors and GPS), enabled by automation and big data. More specifically, drip irrigation systems help farmers achieve better water-use efficiency (as well as contributing to better nutrient management and increasing crop yields), by transporting water from source through polyethylene tubing, and releasing it directly to plants by emitters, drip lines, sprayers, or sprinklers – using automatically-controlled pumps, valves and backflow preventers.
Additionally, incorporating irrigation controllers (such as micro-sprinklers or rainfall shutoff devices) allows for variable rate irrigation, balancing potentially different irrigation needs of the same field. Materials used for these parts are primarily plastic or brass, with brass components being more resistant to high pressure and direct sunlight. When combined with GPS technology and sensors (such as rain detection and soil moisture sensors, the antennae of which are made of copper, aluminium or stainless steel, alongside a power source which may be a solar panel or a battery), precision irrigation creates better understanding of field conditions, and ultimately better management of water needs (which may differ across different topography, soil texture, and type of crop).
Consumption of clean water in agriculture can be further mitigated by re-using treated wastewater for irrigation. Wastewater treatment is a multistep process occurring within large tanks, channels, chambers, and gasometers fitted with equipment made of concrete, steel, galvanised and stainless steel, and concrete lined ductile iron.
Supply-side efficiency improvements
On an urban design level, sponge cities can help improve water availability (while also minimising urban flooding risk from increased stormwater runoff). The combination of nature-based solutions with grey infrastructure (such as green rooftops and water tanks, permeable pavements, bioswales and rain gardens) helps to collect and retain urban runoff and divert it back to natural storage, for later re-use in irrigation and cleaning.
Unlike large-scale, hard, impervious surfaces (which block the natural flow of water), materials with improved permeation (such pervious concrete, porous asphalt, paving stones, permeable interlocking concrete or clay brick, as well as loose gravel or stone-chippings without any binder) allow precipitation to infiltrate the surface areas in cities. Additionally, they act as layers of filtration, and thereby also contribute to increased water quality, capturing heavy metals and preventing them from being washed down to the soil.
If not newly built from the outset, a lot of the existent infrastructure is currently being retro-fitted with green roofs and permeable pavements in the largest cities globally – most notably in China.
Smart water meters
On the demand side, smart water meters help to accurately track real-time water consumption at the level of households and businesses. Such information, collected through automated and remote reading of sensors and smart water efficient gadgets, enables end-consumers to make informed choices about water consumption, and can ultimately lead to water conservation. Additionally, the use of data from automated meter readings helps more accurate demand prediction, which in turn might inform optimisation of water treatment and pumping schedules.
At the same time, water utilities use smart monitoring infrastructure to improve efficiency of supply and enable easier detection of potential leaks along the water distribution networks. This in turn helps reduce strains on freshwater availability. In developing countries, for instance, preventing current daily rates of water leakages would be enough to serve nearly 200 million people.
Taken together, the potential for integrating the water sector with cloud computing, the Internet of Things (IoT) and big data is gaining in importance. The essential components of smart water meters are sensors (made from steel, brass, aluminium, and magnesium) that convert water flow to an electrical signal, allowing for temperature monitoring, low flow diagnostics and more accurate billing. The sensor, mounted on a printed circuit board, sends a signal to the microcontroller unit. The water flow data is then transmitted to remote information management systems via transmitters in the form of radio waves.
Depending on the design choice, the meter housing may be made of polymer composite, brass or copper alloy, while reflectors and strainers are typically made of stainless steel and composites, respectively. The meter is powered by a battery with lithium thionyl chloride chemistry, as this offers the highest specific energy and energy density of all existing battery chemistries.