Our Water Problems Are a Crisis of Management

By Frank R. Rijsberman, Boston Review. Posted January 21, 2009.

For drinking purposes, the 60 percent of rainfall that becomes soil moisture is indeed lost. But for plants, and for our food, soil moisture is crucial and needs to be taken into account -- it is renewable. In an effort to refocus the attention of water managers on the 60 percent of rainfall that is not usually counted in assessing water scarcity, Falkenmark distinguishes blue water from green water. Blue water comprises the traditional renewable water resources, while green water is soil moisture. Her efforts are gaining ground as experts increasingly see the key to solving the water crisis in tapping the productivity of the green water, not just the blue.

Paying attention to all the blue water is also essential. While groundwater is included in all definitions of water resources, it is often ignored in practical water management. Groundwater is bypassed in part because it is hard to find in all but the simplest geologies, such as homogenous deep sand layers, and in part because it is difficult to quantify. Large-scale public water projects, from Roman aqueducts to the great irrigation systems in India and China, have traditionally focused on the water in rivers. Groundwater was traditionally accessed by digging wells that provided people with small amounts of clean and reliable drinking water.

The development of small and affordable diesel and electric pumps in the 1960s initiated a revolution in groundwater use for irrigation. In just a few decades, groundwater irrigation in India has surpassed the use of river or surface water. Some 20 million boreholes, equipped with diesel or electric pumps and supported privately by farmers, have overtaken public canal irrigation systems in their impact on agricultural production. These humble devices have contributed to enormous economic growth in the Indian countryside, but they have also led to over-pumping and lowering of the groundwater tables. Farmers in Gujarat, who used oxen to pump water from wells at depths of less than ten meters in the 1970s, have engaged in a race to the bottom. They have invested in successively deeper boreholes and larger and larger pumps. Their wells now have to reach 200 meters deep and their pumps are massive fifty-five horsepower machines. Eventually the aquifers are tapped out and the wells run dry. Similar issues are affecting groundwater use in other parts of the world. Groundwater depletion is reducing supplies both for irrigation and drinking water, as well as industry in cities like Bangkok.

In addition to green as well as blue water, and ground as well as surface, hydrologists need to consider the quality of available water. Cities discharge large amounts of organic material and human waste into the surrounding streams and rivers, making them bacteriologically unsafe to drink. Time and oxygen tend to reduce these problems. But ever-larger cities overwhelm this self-cleaning capacity of rivers, leading to lower and lower oxygen levels until the rivers become black, anaerobic, and practically devoid of life, as is now true of rivers near many Chinese cities.

Industry discharges chemical waste such as heavy metals or solvents that pose a different set of challenges for downstream users. These pollutants are generally "conservative": they are not biodegradable and, at best, settle into the sediments on the riverbeds. Agriculture that uses chemicals, particularly pesticides and herbicides, but also excess fertilizer, provides yet another load of pollutants into surface and groundwater water. These are often persistent organic chemicals which build up in the tissues of the animals that drink the water or the larger predators that, in turn, feed on them. Because of current levels of population and economic activity, hardly a stream on the planet is now untouched by pollution. In fact, the concerns of water managers in many cities today focus on a class of pollutants most water engineers had not heard of fifteen years ago: endocrine disruptors, which form when prescription drugs pass through patient's bodies.

The water cycle is a complex system that we must understand well in order to find sustainable solutions to the crisis. The traditional supply-side approach to water management emphasizes engineering the development of enough "new" water resources -- displacing the current use of ecosystems of the same water -- to satisfy growing human demands in agriculture, homes, or industry. This water is made available to users at subsidized prices that tend not to reflect the cost of providing the water, let alone the scarcity value of the resource. This approach makes sense only if there is abundant water available in the system and the value of the current use is much lower than the value of the use for which the water will be "developed."

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Frank R. Rijsberman is Program Director at Google.org, the philanthropic arm of Google Inc. He was previously Director General of the International Water Management Institute.

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