Tag Archives: water

groundwater

This paper in Water Resources Research is about global groundwater depletion and pollution, and how groundwater can be managed better.

With rivers in critical regions already exploited to capacity throughout the world and groundwater overdraft as well as large-scale contamination occurring in many areas, we have entered an era in which multiple simultaneous stresses will drive water management. Increasingly, groundwater resources are taking a more prominent role in providing freshwater supplies. We discuss the competing fresh groundwater needs for human consumption, food production, energy, and the environment, as well as physical hazards, and conflicts due to transboundary overexploitation. During the past 50 years, groundwater management modeling has focused on combining simulation with optimization methods to inspect important problems ranging from contaminant remediation to agricultural irrigation management. The compound challenges now faced by water planners require a new generation of aquifer management models that address the broad impacts of global change on aquifer storage and depletion trajectory management, land subsidence, groundwater-dependent ecosystems, seawater intrusion, anthropogenic and geogenic contamination, supply vulnerability, and long-term sustainability. The scope of research efforts is only beginning to address complex interactions using multi-agent system models that are not readily formulated as optimization problems and that consider a suite of human behavioral responses.

They get something important right here, which is that if you are formulating a question in a way that the answer can be “optimized”, you have probably defined the question much too narrowly. Water resources are one part of much larger complex natural and social systems. Modeling and technical analysis is important to pare the universe of all possible decisions down to a smaller set where each possible decision is close to “optimal” or efficient in the technical and economic senses. But then this information needs to be fed into a stakeholder or political process where a much wider range of factors can be considered and decisions made.

I am concerned that the current laser focus on “science, technology, engineering, and math” in education is pushing people too far down the path of expecting clear-cut technocratic answers to questions that have messy political and cultural dimensions in reality. All these subjects are good to study, but they need to pared with solid education in planning processes and tools, and an appreciation of systems in general.

Joe Jenkins

Here’s an interview with Joe Jenkins, author of The Humanure Handbook, a guide to compost toilets. Composting toilets are a potentially very good idea – they could save enormous amounts of water, energy, and money everywhere, address problems caused by aging and inadequate wastewater infrastructure in developed countries, and bring life-saving basic sanitation to billions who don’t have it now.

There are commercial composting toilet systems available – you can see some in Chapter 6 of Jenkins’s book. I don’t know why they have not caught on more widely. Maybe it’s a case like the QWERTY keyboard where the design that caught on is not the best one available, but simply an adequate design that got implemented at scale first, and is now hard to displace. Or maybe the designs are too expensive and/or just not good enough to overcome the incredible power of social taboos about human waste, which are not to be taken lightly. If this is the case, the technology may be stuck in a chicken and egg problem where it is not quite good enough to be adopted on a larger scale, and it is not going to be improved unless and until it is subjected to a larger marketplace. People are not going to take a risk on it as long as they are content with the flush toilet system they already have. That said, it really would not be rocket science to come up with better designs. It would just have to be taken seriously as a research and development project and have some real resources thrown at it, the kind of resources we routinely throw at weapons, chemicals, drugs and electronics.

Let’s assume we get to a better, cheaper composting design that everyone will want in their house – what then? The composting toilets people are using now need a carbon source such as sawdust to balance out the nitrogen in the feces. That is fine on a small scale, but on a large scale we would now need a system to produce and distribute sawdust or something similar to billions of people. That sounds like a sustainability problem. A possible solution there would be to build the carbon source into packaging of consumer products – instead of all the plastic wrap we use now, make consumer packaging out of some sort of carbonaceous waste (corn stalks, switchgrass?). When people unwrap things they would just throw it into the toilet.

The next problem is what to do with the compost. Compost is great stuff that gardeners love. But not everybody is a gardener, and now you have done this on a large scale. You have to collect the stuff and get it to gardens, parks or farm fields where it can be used. So now you are back to a system of trucks or pipes to do this – not much different from what we do now, except you have moved the treatment step from the central wastewater plant to individual homes.

A biogas system is a possible alternative technology. Instead of the aerobic composting system, you would put your bodily waste, carbonaceous packing material, and food waste (the same ingredients from your aerobic system) in a sealed reactor with the right microbes to break it down to methane. The solids remaining should be less than with the aerobic system although you still have to deal with them. You can use the methane for anything you use natural gas for now – heating, hot water, or electricity which you can either use or sell back to the grid. An intriguing possibility is to feed it into a fuel cell rather than burning it. Whereas both aerobic composting and combustion will liberate the carbon from the carbon source back into the atmosphere (if the carbon source is plant-based, it will be the same carbon absorbed from the atmosphere when the plants were grown), an ideal fuel cell (which may not have been invented yet) theoretically will produce only electricity, clean water, and elemental carbon. So in theory, the carbon is sequestered. You still need to pick it up and do something with it. Since I’m daydreaming, we’ll use some kind of biotechnology to turn it into cement.

climate change, water, and corn

Here are a couple stories on U.S. corn yields:

From the “Risky Business Project“:

Shifting agricultural patterns and crop yields, with likely gains for Northern farmers offset by losses in the Midwest and South.

  • As extreme heat spreads across the middle of the country by the end of the century, some states in the Southeast, lower Great Plains, and Midwest risk up to a 50% to 70% loss in average annual crop yields (corn, soy, cotton, and wheat), absent agricultural adaptation.

  • At the same time, warmer temperatures and carbon fertilization may improve agricultural productivity and crop yields in the upper Great Plains and other northern states.

  • Food systems are resilient at a national and global level, and agricultural producers have proven themselves extremely able to adapt to changing climate conditions. These shifts, however, still carry risks for the individual farming communities most vulnerable to projected climatic changes.

From Ceres:

  • 87% of irrigated U.S. corn is grown in regions with high or extremely high water stress, meaning there is limited additional water available for expansion of crop irrigation. The most vulnerable regions are in Nebraska, Kansas, California, Colorado and Texas.
  • 27% of rainfed corn is grown in regions with high or extremely high water stress, meaning that there is limited water available should climate change make irrigation necessary. The most vulnerable regions are in Illinois, Wisconsin and Michigan.
  • Twelve ethanol refineries above the High Plains aquifer – with nearly $1.7 billion in annual corn ethanol production capacity – are sourcing corn in areas experiencing cumulative declines in groundwater levels. Six of these refineries are in regions of extreme water-level decline (between 50-150 feet).

To me, this sounds like a lot of today’s productive farmland may not stay that way due to a combination of higher temperatures and drought. Can we really open up enough farmland and/or increase yields in “Northern States” to make up the difference? I suppose maybe there are areas of Canada that could go from ice-covered to prime farmland, as long as they stay wet enough.