Shortage and Stress, Trends and Scenarios in the 21st century
Water scarcity can be defined as the point at which the cumulative impact of all users impinges on the supply or quality of water under prevailing institutional arrangements to the extent that the demand by all sectors, including the environment, cannot be satisfied fully. Water scarcity is a relative concept and can occur at any level of supply or demand. Scarcity may be a social construct (a product of affluence, expectations and customary behaviour) or the consequence of altered supply patterns – for example, stemming from climate change.
Water stress versus water scarcity
Hydrologists typically evaluate scarcity by looking at the population-water equation. An area is experiencing water stress when annual water supplies drop below 1,700 m3 per person. When annual water supplies drop below 1,000 m3 per person, the population faces water scarcity, and below 500 cubic metres “absolute scarcity”.
The overutilisation of freshwater resources very much threatens food security and the general wellbeing of humankind around the globe. The maximum global potential for consumptive freshwater use (i.e., freshwater planetary boundary) is approaching rapidly, irrespective of the estimate used. Due to swelling population pressure, fluctuating water consumption behaviour, and climate change, the challenge of keeping water consumption at sustainable levels is projected to become even more grim in the near future.
Findings have shown a nearly 16-time increase in population under water scarcity since the 1900s although total population increased only 4-fold over the same time period.
Trends in per capita water consumption also vary significantly within regions. A glaring example of this is North America, where the west coast experienced a decreasing trend, while on the contrary east coast experienced an increasing trend.Of the world population, 46%, 25% and 29% respectively live in regions where per capita consumption increased, decreased, or showed no statistically substantial trend with passage of time. The total water consumption experienced an increasing trend in all regions due to increased population except in Eastern Europe and Central Asia, where the total consumption decreased slightly (~7%) since the collapse of the Soviet Russia in 1990. Growth was greatest in Australia-Pacific (30-fold increase) followed by Central America, Southern Africa, and Southeast Asia (approximately eight-fold).
In a number of regions, water consumption increased 3-4 fold, with the lowest increase in Northern Africa with about a three-fold increase. Globally, irrigation and associated practices emerged as the largest water consumer over the with a share ranging over time between 90-94% of global water consumption, with shares spanning in South Asia from 96–98% due to extensive rice cultivation, while shares of Middle East were 97-99% due to arid conditions. Interestingly, in Western Europe was seen the lowest (62-74%) share due to less use of irrigative practices. Altogether, the second largest sector until the 1990s was domestic water consumption. However, this was surpassed by industrial water consumption in 2000s (domestic 3.7%, industrial 4.3%).
A second notable global trend is the emergence of water consumption due to thermal electricity production (~1% share). In the 2000s, roughly half of the people under water scarcity suffered either moderate water shortage or moderate water stress, while the other half lived in areas facing both water stress and water shortage. Of these, 1.1 billion people (17% of global population) lived in areas facing both high-water shortage and high-water stress.
According to the World Bank estimates, water scarcity, exacerbated by climate change, could cost some regions up to 6% of their GDP, spur migration, and spark conflict. The combined effects of growing populations, rising incomes, and expanding cities will see demand for water rising exponentially, while supply becomes more erratic and uncertain.
Lest action is taken soon, water will become scarce in regions where it is currently abundant – such as in Central Africa and East Asia – and scarcity will greatly worsen in regions where water is already in short supply – such as the Middle East and the Sahel in Africa. These regions could see their growth rates decline by as much as 6% of GDP by 2050 due to water-related impacts on agriculture, health, and incomes.
Water insecurity could multiply the risk of conflict. Food price spikes caused by droughts can inflame latent conflicts and drive migration. Where economic growth is impacted by rainfall, episodes of droughts and floods have generated waves of migration plus transmigration and increased violence within countries.
The negative impacts of climate change on water could be neutralised with better policy decisions, with some regions standing to improve their growth rates by up to 6% with better water resource management. Improved water regulation pays high economic dividends. When governments respond to water shortages by boosting efficiency and allocating even 25% of water to more highly-valued uses, such as more efficient agricultural practices, losses can be addressed in a positive way and for some regions may even vanish.
Dr Sajood Maqbool Bhat works at Dept of Chemistry, Govt SGS Autonomous PG College, Sidhi Madhya Pradesh. Dr Rayees Ahmad Bhat works at Dept of Chemistry, Baba Sahib Bhim Rao Ambedkar University, Lucknow, Uttar Pradesh.