CAN SMART LEVEES PROTECT THE SACRAMENTO DELTA?
NEWS
Dikes and levees are used in many areas around the world for flood protection. But in the Sacramento Delta in California, USA, they have an additional use: without the dikes the supply and the quality of the drinking water would be endangered. Current dikes give protection for the 100 year flood. Upgrades are being prepared, but will take many years to complete. Two students of the University of California, Berkeley investigated the possible application of smart sensor systems to prevent catastrophic damages due to unexpected levee failure.
Identify critical areas
Gordon Ng and Kyle Oswalt, recent graduates of the UC Berkeley Civil Engineering program, saw the societal impact of a levee breach in the Delta. Gordon Ng: “The Delta levees are a critical part of California’s economy and infrastructure, but unfortunately, are in extremely poor condition. We have been very lucky that a major disaster has not already occurred in the Delta. Since the state currently lacks the financial resources to undertake large scale improvements over the entire Delta, a monitoring system would allow the state to allocate resources to the most critical areas through better understanding of real-time levee performance.”
Different sensor solutions
Based on the specific levee failure modes in the Delta, Oswalt and Ng selected three promising sensor techniques to evaluate further: piezometers or ‘traditional’ water pressure sensors, MEMS multi-sensor arrays, and Voltmeters detecting water flow through self potential phenomena. These systems were then valued on the total cost, the information quality and yield, accuracy, durability & resilience and finally documentation & precedent. With this data, different sensor systems can be designed for specific locations depending on local needs. As an example a cost-benefit analysis was carried out for Twitchell Island, taking into account benefits such as the value of land and assets and of course, the value of lives saved. Even though the analysis is done on limited data, the calculated ratio of benefits to costs is very high.
Hurdles for adoption
The potential for smart sensor networks in the California Delta seems high. “Levees are a series system”, says Ng. “It doesn’t matter if you have 10 miles of the best levee in the world if a segment somewhere in the middle somehow fails - the end result will be flooding. By monitoring in real-time, we can find those weak links as they develop and repair them before it ever becomes a problem.” But there are also hurdles to large-scale introductions of these systems, as Oswalt explains: “The biggest hurdle to overcome for sensor systems is simply trying to get the word out and make knowledge of them more widespread. Economic barriers are significant as well. There are over 1100 miles of levees in the Delta and effective monitoring of their performance is going to entail a significant number of sensors and data-loggers. In the short term, it could be argued that that money might be better spent reinforcing areas that are already known to be at high risk of failure.”
Societal awareness
The willingness to invest in a monitoring system depends on the societal awareness of the risks. Currently, not many inhabitants realize how essential the dikes are - even for population centers as far away as Southern California. Ng: “Prior to this project I didn’t fully appreciate the magnitude of the need for quality flood control in California. I thought all we had to worry about was earthquakes.” Oswalt adds, “Flood safety and management should be a top priority, especially in places such as the Sacramento Delta where an upgrade in flood management is in dire need.”
Downloads
- Levee Monitoring System - Better Management through Better Information (Article, PDF)
- Poster accompanying the article (PDF)
Part of the information used in this study was provided by the Flood Control 2015 program. Real-time monitoring of dikes using sensor and remote sensing technology is an ongoing research topic in Flood Control 2015. For more information on this research, see our website.
