Agriculture, food and water - FAO.org

44 CHAPTER 6 Agricultural water use, environment and health
Water pollution, habitat degradation and massive water withdrawals can deprive fishing
communities of their livelihood and push them into food insecurity. The resulting environmental
impacts affecting fishery resources in inland waters can be devastating. Even in estuarine and
coastal zones at the lower end of river basins, fishery resources are impacted by pollution, habitat
degradation and upstream water withdrawal and use. It is increasingly recognized that agriculture
also has positive externalities, including environmental services and products. The multifunctional
nature of agriculture is increasingly acknowledged and encouraged, so that farmers are seen not
only as commodity-producers but also appreciated as self-employed citizens, stewards of the
landscape and stakeholders in vibrant communities. Trade-offs between food security and the
environment can be further reduced through already available or emerging technologies and
land-management practices. By using more sustainable production methods, the negative impacts
of agriculture on the environment can be attenuated. Agriculture can play an important role in
reversing negative impacts by, for example, environmentally sound water use, biological treatment
of waste, enhancing the infiltration of water to reduce flood runoff, preserving agricultural and
natural biodiversity, and storing carbon in soils.
Water-quality deterioration
With rising demands for water, quality concerns over water have risen rapidly. Pollutant loads
have increased enormously, and at the same time the amounts of water available for dilution
are decreasing. The situation is particularly alarming in developing nations while, in developed
countries, the enforcement of water quality measures has resulted in improved water-quality
conditions for most rivers. Water quality poses a serious threat to the sustainability and the safety
of food produced by intensive farming systems upon which global food security has become
increasingly dependent. Security and stability in food supplies in this century will be closely
linked to success in water quality control. Organic matter, if free of pathogens, can actually be
beneficial to irrigated agriculture (see Box 7), but water contamination with hazardous chemicals
makes it unusable for food production.
It is estimated that poor drainage and irrigation practices have led to waterlogging and salinization
of about 10 percent of the world’s irrigated lands, thereby reducing productivity. In particular,
mobilization of resident salts is a widely-occurring phenomenon in irrigated river basins in arid
regions. Waterlogging and salinization in large-scale irrigation projects are often the result of
unavailable drainage infrastructure that was not included in the engineering design to make
projects look economically more attractive. These problems are generally associated with
large-scale irrigation development under arid and semi-arid conditions, as in the Indus, the
Tigris-Euphrates and the Nile river basins. The solutions to these problems are known but their
implementation is costly.