Circle of Blue has just published an in-depth article about the South-to-North Water Diversion Project (SNWT) in China. The SNWT is a $64-billion, 50-year effort to divert water from river basins in southern China to arid regions in the north, where serious water shortages restrict economic growth.
This project is one of the largest water diversion projects ever undertaken in the world. The eastern line diverts water from the Yangtze River into a canal in Jiangdu City, from where it is pumped uphill and through a tunnel under the Yellow River. It then flows downhill to reservoirs near Tianjin. The line is 1,152 km long. By 2013 the eastern line will deliver 14.8 km3 per year. By 2014 the central line, which diverts water from the Danjiangkou Reservoir in the south to Beijing via long-distance channels and is 1,264 km long, is scheduled to deliver 13 km3 per year. A western line is in the planning stages.
20th Century Water Diversion Projects
It's worthwhile comparing this project to some of the other major water diversion projects in the 20th Century.
- Los Angeles Aqueduct (1913) ~260 million m3 per year
- Qaraqum Canal (1988) 13 km3 per year
- South-to-North Eastern (2013) 14.8 km3 per year
- South-to-North Central (2014) 13 km3 per year
The Qaraqum (Karakum) Canal, Karshi Canal, and Bukhara Canal projects, diverted between 20 and 60 km3 from the Amu Darya and Syr Darya rivers to cotton irrigation, instead of to the Aral Sea.
The Qarakum Canal, which is 1,375 km in length, carries 13 km3 of water annually from the Amu-Darya River across the Karakum Desert. Because of the primitive engineering of the canal, roughly 50% of the water is lost enroute. The canal is a major factor in what has has been called the largest environmental disaster of all time. By restricting inflow, the Aral Sea has been reduced to less than 10% of its former extent and what's left of the sea is heavily polluted and has been blamed for serious public health problems. The fishing industry has been destroyed. The shrinking of the sea has also been blamed for local climate change.
Largely as a result of the Aral Sea environmental disaster, plans to divert Siberian river water to Central Asia were stopped by Russian ecologists, although a renewed discussion of the project has appeared recently.
Los Angeles Aqueduct
As another example closer to home, of Los Angeles' water requirements, which amount to about 600,000 acre-feet/yr or 740 million cubic meters/year, 88% comes via aqueducts from the Sierra Nevada watershed (via the Los Angeles Aqueduct); the Colorado River (via the Colorado River Aqueduct) and the Sacramento-San Joaquin Delta (via the State Water Project / California Aqueduct). It is also interesting that in California 19% of the state's power consumption is for water, primarily to pump water from the north to the south.
Historically there have been large fluctuations in water deliveries from the main water sources, the Las Angeles Aqueduct, the Metropolital Water District of Southern California, and local groundwater, due to climate conditions. However, LA is now facing permanent reductions in water deliveries from these sources because of environmental issues. Water deliveries over the LA aqueduct are being reduced, largely due to the reallocation of water for environmental mitigation and enhancement, for example, the State Water Resources Control Board Mono Lake decision, which permanently limits water exports from the Mono Basin, the Owens Lake Dust Mitigation Project, and rewatering of the Lower Owens River.
An environmental crisis in the Delta has led to a Federal Court decision that will result in the Metropolitan Water District receiving up to 30 percent less water from the State Water Project.
The San Fernando Groundwater Basin is contaminated and the City intends to accelerate the cleanup of the basin to fully utilize the City’s groundwater supplies.
Water Diversion in the 21st Century
I expect that with rising population and changing climate we are going to see many more water diversion projects in the 21st Century. How we manage the environmental impact is going to be crucial if these projects are going to provide net social benefits. For example, the South-to-North project seems to be different from major 20th Century water diversion projects in at least two ways.
First of all and probably as a result of examples like the Aral Sea and the LA Aqueduct, there seems to a greater awareness of the importance of environmental issues. Just earlier this week, Chinese Vice Premier Li Keqiang, while chairing a meeting of the South-to-North Water Diversion Project Construction Commission of the State Council, emphasized how important saving and protecting water resources are in desigining and building the project. He further siad that the project is intended to have long term social benefits, to support a resources-efficient and environmentally-friendly society. Further, he said that pollution treatment and environmental protection are crucial to the project. I think this is important because it shows that at the highest level of the Chinese government there is an awareness of the importance of environmental issues in a project of this size.
Convergence enables holistic design
Secondly, the explosion in engineering capability that we are seeing in the last couple of decades is changing how we design and build. As an example, one of the things I have been seeing is many different areas of design and construction is the convergence of engineering design, geospatial data and technology, and 3D visualization technology (originally developed by the gaming industry.) One of the big benefits of convergence is that it helped make it possible to design projects much more holistically than was possible in the past.
The Changjiang Institute of Survey, Planning, Design and Research (CISPDR), which has provided engineering, surveying, planning, design, and construction services on mega-infrastructure projects throughout China and in other countries, is responsible for overseeing surveying and design on the South-to-North central route. For a project of this size there are many design teams and stakeholders and collaboration between surveying, mapping, design and construction teams and a multitude of local and national design institutes, river commissions, and government ministries is critical. What I find most interesting is that CISPDR's approach to survey and design on this mega-project project integrates geospatial, model-based design, and 3D visualization technology to not only help technical teams to collaborate, but also to include non-technical stakeholders in the design process. On past mega-projects with complex landscape geometries, CISPDR engineers using traditional design software had to design slowly, or risk making errors that would have a large ripple effect elsewhere. On the South-to-North project, engineers were able to simulate complex, real-world environments, enabling them to test the feasibility of their designs and to identify and correct potential construction problems earlier in the design process. And most importantly, in the context of the environmental issues associated with mega-water diversion projects, convergence supported CISPDR's practice of sustainable design on the project by enabling the project team and non-technical stakeholders to view the entire project holistically and to economically minimize waste and environmental impact.