Water scarcity likely to worsen as world population grows

In a study prepared for World Water Day on March 22, the Worldwatch Institute released a study that indicates the world’s water supply will continue to become scarcer in the years to come.

At the global level, 70 percent of water withdrawals are for the agricultural sector, 11 percent are to meet municipal needs and 19 percent are for industrial needs, according to figures from Worldwatch.

World population is expected to grow from the current 7 billion to 9.1 billion by 2050, which will put a strain on water resources to meet the increased demands for food, energy and industrial use. And figures from the United Nations Food and Agriculture Organization and UN Water, the global use of water has been growing at more than twice the rate of population increase in the last century.

At this time some 1.2 billion people – almost a fifth of the world population – live in areas of physical water scarcity, while another 1.6 billion face what can be called economic water shortage. Predictions from Worldwatch indicate that by 2025 1.8 billion people will live in countries or regions with absolute water scarcity, with almost half of the world living in conditions of water stress.

According to UN Water, each person in North America and Europe (excluding former Soviet Union countries) consumes at least 3 cubic meters per day of virtual water in imported food, compared with 1.4 cubic meters per day in Asia and 1.1 cubic meters per day in Africa.

Climate change is also expected to impact the global water resources, the study noted. Reductions in river runoff and aquifer recharge are expected in the Mediterranean basin and in the semiarid areas of the Americas, Australia and southern Africa. And rising temperatures will translate into increased crop water demand everywhere.

The Worldwatch study said to combat the effects of the growing problem of water scarcity, efforts must be made to follow an integrated water resource management approach on a global scale.

“This involves water management that recognizes the holistic nature of the water cycle and the importance of managing trade-offs within it, that emphasizes the importance of effective institutions, and that is inherently adaptive,” the report said.

In at least the near future, North Dakota’s outlook for water supplies is a little more optimistic, according to NDSU Extension ag engineer Tom Scherer, who specializes in water quality and irrigation.

In long range models put together by the North Dakota State Water Commission, they predict that the state will become a net gainer in terms of water supplies. This is a result of the abnormally wet cycle the state and region has experienced starting back in 1993 and is based on tracking aquifer water levels for the past 40 to 50 years.

“Ground water sources have become the major supplier for irrigation in the state,” Scherer said. “If you look at total water use in the state, irrigation accounts for only about 16 percent of the total water use, based on Water Commission reports. But, if you look at total ground water use, it accounts for about 50 percent.”

Irrigation in this region, Scherer noted, is mainly confined to the soils that do not have the water holding capacity to carry them through the dry period of July and August. This usually is the case in areas where the soil isn’t very deep or if they have a sandy soil texture. And of course there also must be a source of good quality water present in order to have irrigation.

Mainly due to this need for a good quality ground water supply, irrigation is usually found in the eastern and central regions of North Dakota, with hardly any irrigation systems found in the southwestern portion of the state, where aquifers are scarce, Scherer said.

The Water Commission maintains test wells in all of the significant aquifers, that allows them to track water levels over a period of time.

“Since 1993 all of those aquifer levels that were trending downward in the droughts of the late ’80s and now at the same level or even higher than they were in at the time of major irrigation development in the state,” Scherer said.

For several years those growers with irrigation systems have been practicing ways to lessen the amount of water they apply. The impetus behind this, however, hasn’t been so much from the angle of saving water, as Worldwatch is advocating, but rather cutting costs associated with pumping the water.

The cost of their water is the pumping costs, Scherer noted, and it’s not an insignificant cost. In a dry year, producers can rack up costs between $25 to $40 an acre of pumping costs with an electrical system. Pumps powered by diesel will cost considerably more, with those expenses ranging between $60 to $80 per acre.

With crops such as potatoes, growers probably aren’t going to worry too much about pumping costs, since it’s a minor part of their operation and they need the water to get a high quality product. But it can be a big concern for some of the lesser value crops grown in the region.

“North Dakota was probably the first state in the nation to put together an Extension bulletin together on a ‘checkbook method of irrigation scheduling,’ which is a soil-water method. It was a simple form that farmers could use. That was developed in 1977,” Scherer said.

Later on in the ’80s computer programs were developed and in 1999 North Dakota and Minnesota Extension Services worked together to develop a computerized irrigation scheduling program that could be used in both states. Eventually the software for that program became obsolete, so a couple of years ago an Excel-based scheduler was developed where the operator inputs information on their particular field and uses that as a guide as to when critical periods are being reached.

In 2008, Scherer developed a web-based irrigation scheduler that uses information from the North Dakota Ag Weather Network (NDAWN) stations. That program is part of the NDAWN website, where it’s listed as “irrigation scheduler” on the applications menu.

This allows the producer to select their field from a geographic information systems (GIS) map of the state. By making that selection, it will extract the soil information right out of the NRCS’s web soil survey data base.

Using the checkbook method, the grower can then set up an irrigation schedule using the most predominant soil type in the field and information from the nearest three NDAWN stations can also be incorporated into the schedule.

Another program available on the NDAWN site calculates crop water use based on the conditions at the selected NDAWN station, which can also be useful in setting up an irrigation schedule.

Remote sensing of the plants has been studied as a means of scheduling irrigation events, according to Scherer, but it’s usually by the time the plants signal there is a need for water. Even if water was applied soon after some yield loss has probably occurred from moisture stress.

Instead, there is a move now to use information from soil moisture sensors that are distributed across the field and can communicate the soil moisture status across the field.

2 Comments on "Water scarcity likely to worsen as world population grows"

BillT on Wed, 17th Apr 2013 1:14 am 



Ah yes, water, the necessity of life.

The stress will come long before 2050 in the Us. Vegas and those other desert cities will be hurting first as the farmers take all of their water to grow food in the Midwest desert. The water still flowing on the surface will be a chemical and bacterial soup unfit for consumption by any living thing. Well water that is still drinkable will become more and more rare as fraking and other processes invade the ground water. On and on we go, fouling our own nests.

J-Gav on Wed, 17th Apr 2013 8:53 am 



More people = less water per person … How could it be otherwise?