Earth & Sky

A pressing global issue is water to grow food

Frank Rijsberman says simple technologies can help.

Frank Rijsberman is Director General of the International Water Management Institute, located in Sri Lanka, a nonprofit scientific research organization focusing on the sustainable use of water and land resources in agriculture and on the water needs of developing countries. The IWMI has just released a new report, called Beyond More Crop Per Drop, available at their website.

Dr. Rijsberman spoke with Earth & Sky’s Jorge Salazar about meeting the water needs of the world’s population and innovative ways to get the most out of water in growing food.

Salazar: Thanks for speaking with me today. Can you tell us about the role of fresh water in the world today?

Rijsberman: Some 20% of the world’s population, 1.2 billion people, does not have access to safe and reliable drinking water. And that is a major concern, particularly for people’s health.

People die every day from diarrhea. Particularly children die. And that is a major, pressing concern.

Now, at the same time, what many people don’t realize is that we need much more water to grow food. While people need at least something like 20 liters of water per day for their drinking and washing and cooking, and so on, and the U.N. generally recommends something like 50 liters per day, that is still a very small amount compared to what we need to grow our food. We estimate that on average, depending on diet, people need 70 times as much water to grow food than to drink. Many people fear that water scarcity is not going to allow us to grow enough food to for the growing world population.

Salazar: Would you describe what the goals are, and what the situation is like, as far as people’s needs for water?

Rijsberman: The Millennium Development goals are the key goals for sustainable development. They were adopted by the Millennium Summit in the year 2000, which brought most of the world’s leaders together. These leaders adopted a series of targets to reduce hunger, to reduce poverty, and so on. And the key one for water was to halve the number of people who do not have access to safe and affordable water supply and sanitation by the year 2015.

Much of the world’s development effort is geared towards reducing the number of people who don’t have access to safe and affordable water supply. But water is also a key constraint, if you will, for many of the other Millennium Development Goals. To be able to meet the Millennium Development Goals in poverty and hunger, a lot of water is required to grow food. As I said, we need as much as 70 times more water to grow food than for drinking, washing, bathing, and other domestic use. In essence, it takes several thousand liters of water to produce a single kilo of rice or grain, like wheat, that we use for bread. If you eat meat, particularly if that meat is corn–fed as it is in the United States, the bottom line is that just in the production of a hamburger, you need some 15,000 liters of water.

That is the basis for worrying about water scarcity in the world: the enormous amount of water that we need for food production. But we do have ideas about what we can do about this. In fact, in the 1970s, there was a lot of investment in water by the World Bank and national governments for large–scale irrigation systems. In Asia, many of those have worked. We had a green revolution there. Now, in India, China, and Viet Nam do indeed produce enough food to feed their populations. But in Africa, that’s not yet the case. So we have ideas. That’s what we bring to the table when we meet on these subjects. What we should do, where we should invest in Africa, for example, to realize our Millennium Development Goals on water?

In particular, what we are saying is that we have new ways of providing people with small scale micro–irrigation, small pumps that were not available 30 years ago, small diesel and electric pumps, or even foot pumps, so–called treadle pumps that provide enough water so that a family can grow their own food on a small, even backyard garden. They can also grow enough vegetables, for instance, to bring to the market and have some income.

Salazar: So, we’re not just talking about constructing more large–scale projects, such as dams, for meeting the world’s water needs?

Rijsberman: We’ll definitely need some more large–scale dams in some places like Africa. That’s because the total amount of water infrastructure that is currently available to people in Africa is absolutely minute compared to what is available in, say, the U.S. or Australia. In the U.S., there are more than 5,000 cubic meters of water storage for every inhabitant, for every citizen. In contrast, in a place like Ethiopia, there are less than 50 cubic meters of water storage. So, they are incredibly behind in almost every form of water infrastructure in Africa. And it will need a lot of large–scale investment by government as well.

But I guess the new thing that we are bringing to the table is that we involve people. There are many things that you can do at a much smaller scale, through investments by farmers themselves and through community action. And while, say, 20–30 years ago, almost the only model that governments invested in were these large–scale dams – still necessary in some places – we now know that it’s perfectly possible for communities to build their own small–scale water harvesting dams, for instance, or to have diesel and electric pumps. We’re talking about 1/2 horse power, pumps so small that you can actually carry them around. You can share them with your neighbors.

At the lowest level, when people are basically unemployed and have quite a bit of excess labor, we have treadle pumps, which you step on and they work like a bicycle. It gives you enough water to irrigate a large garden, or a small farm where you’d grow vegetables. It means that we can involve farmers much more directly, for an investment of something like $100, a family can have something like $100–$200 of annual additional income. And it’s a very good way of involving women, who are often not very involved in these official projects, but who are very important decision makers on these farms. The treadle pumps give women an opportunity to grow food, vegetables for the market under their own control.

Salazar: Would you talk a little about green and blue water, what are they?

Rijsberman: Normally, if you are a city water manager, and you are trying to find water to pipe into people’s homes, then people look at something which experts call renewable water resources. That’s really that share, that percentage of rainwater that falls onto the land and then runs off, that runs off into rivers. Of 100% of rainfall, maybe 70–80% will normally infiltrate into the soil, but 20–30% will runoff, will become water that goes into a small stream and will eventually find its way into a river. In addition, some goes into groundwater. All of that together we call renewable water resources. That’s the amount of water that people can pipe, can pump, can send to a city. That’s what we sometimes call “blue water.”

But another rather large area, in fact 60% of total rainfall, just gets into the soil. It’s what we call “green water.” Like water going into a sponge, it becomes soil moisture. And from there, it’s taken up by the roots of plants, which plants use to grow, or it’s evaporated back into the atmosphere.

For a city water manager, water that goes into the soil is not very interesting. You can’t really pump it out or do anything with it. But for a plant, it’s super important. That’s the water that the plant lives and grows on. For agriculture, for food, for farmers, the “green water – the 60% of total rainfall – is very important.

So we’re trying to get people, including water managers, to focus on the full water cycle and take full advantage of both the green and the blue water. And if we manage that together, we see a lot of scope for increasing opportunities for people to grow food better and increase their livelihoods.

Salazar: Thank you for speaking with me today. Is there anything else you’d like to share with the public at this time?

Rijsberman: To work toward solving the problem of water, per person the investments can be quite small. I’m talking again here about small–scale water harvesting dams, or diesel and electric pumps, or even treadle pumps. Of course, if you then see how many people are in need, then yes, we’re talking about quite a few billions of dollars. And that sounds like a lot.

But if you compare that to other large–scale investments – roads, schools or other major public investments – then you see that the amount of money required for providing people with enough water is actually quite limited. We reckon that for less than a couple of hundred dollars per person, you can hook people up to a decent, improved water supply. That is, for 100 million people, then you can see that that would be on the order of magnitude of 10–20 billion dollars. That’s a lot of money for an individual, but not very much money for a number of governments combined. So the numbers are actually not that scary.

We will need investments in water for livelihoods, water for food and agriculture to help something like 800 million poor people in Africa and South Asia escape from poverty. That requires a lot more water than for drinking. But it’s available if we manage our resources well, and we do have fairly simple technologies at our disposal that can help people step up.