Thursday, February 11, 2010

Irrigation and Sustainability in Water Use

"Development that meets the needs of the present without compromising the ability of future generations to meet their own need is sustainable." (World Commission of Environment and Development, 1987)

Irrigation has the potential to increase farm yields dramatically. Irrigated land is far more productive than the same lands fed only by rainfall. However, irrigation can also impact the condition of natural resources (riparian zones, wetlands, etc), while impacting the balance of surface and ground water. Not all irrigation is bad nor is it good. Irrigation like all agricultural practices must be preformed sustainability and often it is not.

In 1996 it was estimated that developed countries, irrigate on average 10% of their agricultural area, and countries in development irrigated 23% of their agricultural land, and that combined they irrigated 18% of the total agricultural area. Chronic water scarcity is away of life in large parts of Africa and the Middle East, the northern part of China, parts of India and Mexico, the western part of the USA, north-east Brazil, and in the former Soviet Union and the Central Asian republics. China, India, the United States and Pakistan have the largest quantity of land in irrigation; however, the United States with the largest total area of cultivated land has only about 9-10% of that land in irrigation. (FAO AGROSTAT Database 1998)

In 1900 the world’s population was 1.6 billion; by 1950 it had increased to 2.5 billion and 6.1 billion by the year 2000. Despite a general decline in human fertility rates world wide, world population is still growing. It is projected that world population will reach more than 7.5 billion by 2050. This alone will increase demand for food and place enormous pressure on the environment. The increased need for water to support the growing population is becoming urgent, and environmental degradation related to water usage is serious.

Fresh water (not locked in ice caps) represents less than 2% of all water on earth. Agriculture is the major user of freshwater, with a world’s average of 71% of the water use. In agriculture water is used for irrigation, and small quantities for watering animals. There are large regional variations in water use. In Africa 88% of fresh water is used for agriculture and less than 50% in Europe. The USGS estimates that 40% of fresh water in the United States is used for irrigation. There are huge variations in water use across the country. In California it is estimated that 80% of fresh water is used for irrigation that is approximately 30,700 million gallons a day for irrigation. In Virginia, in the far wetter southeast, agriculture uses only 1.5% of the annual fresh water used annually, which translates to 21 million gallon a day for irrigation. The differences between the states is the climate, California is semi arid and requires irrigation on almost all crop land, but can produce several crops a year. It rains in Virginia, but the growing season is confined to the warmer half of the year.

What the above data tells us is that California needs to get more agricultural value out of their water usage. They are producing more than three time the revenue per agricultural acre but it is requiring 123 times the water for each dollar of revenue. California is mining their water. They are using more water than is renewably available. Water is a resource that needs to be valued. The nominal price of water in California does not reflect its value and scarcity, nor does it reflect the amortized cost for mining this resource. They are misallocating this resource. The price of the food produced does not reflect to costs to produce it.

The large and growing proportion of the population living in urban areas will put considerable pressure for continued transfers of water out of agriculture to supply growing urban centers in California and the rest of the world. Other competing uses include hydroelectricity, protection of aquatic ecosystems (e.g., restoration of Delta estuary), and recreation will put severe pressure on fresh water supplies. It is important that our farming practices as well as all of man’s activities have the smallest impact on the natural balance; we can only do this by valuing and allocating our resources appropriately.

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