Water use has been growing globally at more than twice the rate of population increase in the last century, and an increasing number of regions are reaching the limit at which water services can be sustainably delivered. Essentially, demographic growth and economic development are putting unprecedented pressure on renewable, but finite water resources, especially in arid regions.
By 2025, 1800 million people are expected to be living in countries or regions with “absolute” water scarcity (<500 m3 per year per capita), and two-thirds of the world population could be under “stress” conditions (between 500 and 1000 m3 per year per capita). The situation will be exacerbated as rapidly growing urban areas place heavy pressure on neighbouring water resources. Moreover, environmental services and ecosystem functions cannot be treated any longer as the residuals of all water users. In the future, climate change and bio-energy demands are expected to amplify the already complex relationship between world development and water demand.
The last 50 years have seen remarkable developments in water resources and in agriculture. Massive developments in hydraulic infrastructure have put water at the service of people. While the world population grew from 2.5 billion in 1950 to 6.5 billion today, the irrigated area doubled and water withdrawals tripled.
Agricultural productivity grew thanks to new crop varieties and fertilizers, fueled by additional irrigation water. World food production outstripped population growth. And the greater use of water for irrigated agriculture benefited farmers and poor people—propelling economies, improving livelihoods, and fighting hunger.
But in 2003, 850 million people in the world were food insecure, 60% of them living in South Asia and Sub-Saharan Africa, and 70% of the poor live in rural areas. In Sub-Saharan Africa the number of food-insecure people rose from 125 million in 1980 to 200 million in 2000.
The fight to greatly reduce food insecurity and poverty continues at the forefront of mankind’s priorities. Irrigated agriculture is to play an important role in achieving this goal by securing innovative approaches that lead to higher productivity per unit of water, unit of labour, unit of investment or combinations thereof. This can only be accomplished through appropriate reaction and adjustments to emerging worldwide political and development realities concerning the sustainability and increasing competition for the water resource.
There are many solutions to address water scarcity for food and agriculture. Technologies and management approaches that raise the efficiency of farming systems and the productivity of water use in agriculture, including aquaculture and livestock sectors must be combined with recycling and reuse of water and drainage. This has to be achieved amid increasing competition for water among domestic, industrial, energy and agricultural uses.
Considerable reduction of food loss and waste can also be obtained in the supply chain in storage, transportation, food processing, wholesale and retail. Behavioural changes, especially in diets and consumption patterns also influence water demand in agriculture.
Policies and strategies are needed at all levels from local sustainable agriculture plans to regional, national and global programmes.