Published September 25, 2014
BY ERICA GIES
The old business dogma, “if you can’t measure it, you can’t manage it,” holds especially true with water usage, but in many places around the world, the amount of water diverted from rivers or pumped from the ground to water crops is not measured. For example, groundwater in California was totally unregulated until this month.
That’s a political problem, not a technical one, said Peter Gleick, cofounder of the Pacific Institute, an independent research organization focused on water issues. Water flow meters to measure water use are not new, nor expensive. It’s simply that in many places groundwater is considered a property right, so farmers have seen no need measure or justify its use. But as drought and overpumping are dropping water tables, some are beginning to recognize that it will benefit them to ensure that they use this resource sustainably.
Milwaukee, Wisc.-based WellIntel uses sound sensors to detect water level in a well without touching the water or opening the well. It transmits that data to its private website, where well owners can see their water level at the present moment, when pumping, after rainfall, and over time to better understand whether they are overdrafting their well. In response to farmers’ sensitivities to measurement, the website specifically touts farmers’ right to not share amount of water used with anyone.
The first place to save is in conveyance: as much as 60 percent of the water withdrawn for irrigation is lost through leaks in canals, spillage, and evaporation, according to the United Nations’ Food and Agriculture Organization.
Another part of the problem is flood irrigation — the most common method of field irrigation globally. About half the water isn’t absorbed by crops, according to the U.S. Geological Survey. Instead it runs off, taking with it fertilizers, pesticides, and topsoil that pollute water bodies around the world and cause dead zones, areas where too much fertilizer causes algae to bloom, which is turn sucks oxygen out of the water, killing other life.
Flood irrigation is commonplace because it’s cheap. Some farmers have made the shift to underground irrigation or precision micro-sprinkler and drip irrigation systems, which deposit tiny amounts of water directly above the root zone. These systems are much more efficient and deliver significant benefits. Farmers can earn more money by planting more acreage since they’re using less water, or they can enjoy greater job security by not relying on as much water.
But the capital cost for a drip system is significant, about US$500 to $1000 per acre, according to the FAO. And even though these systems see a return within a few years, thanks to better water-use efficiency and lower irrigation energy bills, many farmers don’t have the cash — or credit access — to install them. However, a new low-tech solution also targets the root zone and can work with or without drip irrigation — with a much smaller price tag.