IELTS Academic Reading passage: Urbanisation and Water Scarcity

Urbanisation and Water Scarcity

Urbanisation, the movement of populations from rural areas to cities, is one of the defining demographic trends of the 21st century. According to the United Nations, more than 55% of the world's population currently lives in urban areas, a figure projected to rise to 68% by 2050. As cities expand rapidly, particularly in developing nations across Sub-Saharan Africa and South and Southeast Asia, the strain on municipal water supplies has become increasingly critical.

Water scarcity, defined as an insufficient supply of clean water relative to demand, affects more than 2 billion people globally. In many rapidly growing cities, ageing infrastructure, population growth, and the effects of climate change are converging to create what experts describe as a "perfect storm" for water security. Cities such as Cape Town in South Africa, Chennai in India, and Lima in Peru have all experienced severe water crises in recent years, forcing emergency rationing measures and prompting long-term investments in water management.

The agricultural sector remains by far the largest consumer of freshwater globally, accounting for approximately 70% of all water withdrawals. Urban growth compounds this challenge in two ways: as cities expand onto fertile agricultural land, farmland is lost, requiring the remaining land to be irrigated more intensively. Simultaneously, rising urban populations demand greater quantities of food, increasing the agricultural water footprint.

Groundwater, water stored in underground aquifers, is an increasingly critical source of freshwater for urban populations worldwide. However, groundwater is being extracted faster than it can be replenished by rainfall in many regions, a process known as aquifer depletion. Once depleted, some aquifers may take thousands of years to recover, making groundwater loss effectively irreversible in human timescales.

Several innovative approaches are being explored to address urban water scarcity. Rainwater harvesting systems collect and store precipitation for later use in irrigation or toilet flushing, reducing demand on municipal supplies. Wastewater recycling, treating sewage and industrial effluent to a standard suitable for reuse, is gaining acceptance in water-stressed regions. Singapore, which has almost no natural freshwater sources, has developed a world-leading water recycling programme that now supplies approximately 40% of the city-state's water needs.

Desalination, the process of removing salt from seawater to produce fresh water, offers another potential solution, though it is energy-intensive and has historically been costly. Advances in membrane technology have reduced desalination costs significantly in recent years, making it more viable as a component of diversified water supply strategies.