In the Bay Area we have the so-called Mediterranean climate, with cool rainy winters and warm dry summers. Rarely does measurable rain fall between May and September, five dry months.
If this rainfall pattern continues, we will always have a water shortage as long as our population continues to increase. We are always at risk for drought.
Because it arrives in our houses clean and drinkable at the turn of a tap, we take water for granted. In countries where water has always been scarce, it is revered. Such an attitude helps to conserve water, says Francesca de Chatel in her book, Water Sheikhs and Dam Builders (Transaction Publishers, 2007).
In the wet West, water has to be sanctified by priests before it is considered worth respecting. Beneath California’s Central Valley lies an immense aquifer. During the Gold Rush, hydraulic mining was used to dislodge gold-bearing ore. Canals were dug to carry water to where it was needed to wash gold particles. This is the genesis of the Central Valley’s irrigation system.
When mechanical pumps are deployed to take water from aquifers for irrigation, the danger is that the strength of the pumps will deplete the aquifer beyond its capacity to recharge its water supply. This is now happening in the Central Valley, our bread basket.
It is therefore important to recognize that there are limits to our water supply. There are limits to technology. Mankind can not control and dominate nature even by technology because human imagination is limited. We can not foresee the consequences of many expensive, highly-industrialized schemes. The Aswan Dam in Egypt is a case in point. Before the dam was built, as every schoolchild knows, the Nile flooded annually, spreading the lands on either side with nutritious silt. According to Chatel, Egypt now has to buy fertilizers, which pollute the ground water. Nile silt, which now has nowhere to go, is gradually filling Lake Nasser, which lies behind the dam. When Lake Nasser has filled with silt, there will be no water in the lake. There are many stories like this in industrially-underwritten regions—grandiose, expensive, and short-sighted.
Chatel believes that conservation has a better chance of solving water-shortage problems than have technology, money and dreams. It is a solution less flashy, less popular with politicians. It sounds tedious, because we do not respect water.
We gardeners can do our bit, by conserving every drop of water we receive so easily, making sure it goes just where our plants need it, at the roots, and in the right amount, neither too much nor too little. Plant roots need air as well as water. Only bog plants like their roots permanently saturated. Robert Rubik (Drip Irrigation, Metamorphic Press, 1992) thinks that roots longer than two feet are probably produced for stability. It is short roots closer to the surface that convey nutrients to the plant.
Methods of irrigating East Bay gardens include sprinkler systems, soaker hoses, and regular hoses. The most economical and reliable is the humble, hand-held hose. All mechanical systems are expensive to install and maintain. Even soaker hoses clog and become useless after a year or two. Drip irrigation is less wasteful than sprinklers, which spray leaves and create puddles. Most plants dislike wet leaves. Wet leaves in hot sun can burn, and attract virus diseases or mildew. However, even drip systems can not discern the water requirements of individual plants. It is another obligate watering system. If water is applied too fast and for too long, the plant can not absorb it, another source of waste. Rubik advocates frequent, shallow watering. Again, this depends on the location of the garden and the plants that grow in it. Hand watering gives the gardener a chance to observe what each plant needs and when to water it. Daily watering is hardly necessary this side of the East Bay hills.
Chatel’s book is more than a cautionary tale, it is frightening. Imagine atomic-bombing the Congo River to divert it to the Sahara, so that a desert might bloom! Never mind the disruption to thousands of humans, the destruction of acres of tropical rain-forest, the cost. Clearly, this scheme was beyond the capacity of its instigator to imagine the consequences. Desalination has its limits too, she says. It takes huge amounts of energy to remove salt from oceans, and the residue adversely affects its origin.
Closer to home, recently I watched a television interview of a Central Valley farmer. He was angry, because his crop of wheat had died. Wheat is a water-demanding cereal. There are drought-tolerant grains that make delicious breads. There seems to be a connection between political decisions at the highest level in the form of farm subsidies—water as well as crops—and what we see in our shops to eat, vast amounts of wheat-only products in bakeries, for example. In between, there is waste: water carelessly used because it is cheap, acreage with no mulch in sight. Mulch is a great way to prevent surface water loss from evaporation, just as great for farms as for small back yards.
In her last chapter, Chatel’s comments seemed to me to apply as much to the Bay Area as anywhere else where no measurable rainfall is part of the climate pattern. “It is as though water is so fundamental to our lives, that we cannot imagine it running out.” Even where it is scarce on a daily basis, few people feel it is their responsibility to resolve the problem. Could our water supply vanish so radically? Absolutely. When demand exceeds supply, where will the extra water come from?