Hydropower is coming to the Triangle. The Raleigh News & Observer is reporting that Jordan and Falls Lakes, the area’s primary sources of drinking water, are going to be retrofitted for hydroelectric power generation. They should generate enough power for 1,700 and 1,200 homes, respectively. The two projects will contribute to the 12.5% renewable power generation mandate for the year 2021.
Tags: civil engineering, dam, hydropower, Raleigh News & Observer
The Philadelphia Inquirer is reporting that their fair city is implementing a novel strategy to reduce their problems with combined sewer overflows. Instead of making the pipes and wastewater plants larger to handle the stormwater runoff, they are retrofitting Low Impact Development (LID) practices to reduce the runoff in developed areas. There are to be widespread installations of bioretention facilities, permeable pavement, green roofs, and other technologies. The plan will cost $1.6 billion, but it should end up saving money in the end.
Tags: civil engineering, LID, Low Impact Development, Philadelphia Inquirer, stormwater
“Meandering rivers are common on Earth and other planetary surfaces, yet the conditions necessary to maintain meandering channels are unclear. As a consequence, self – maintaining meandering channels with cutoffs have not been reproduced in the laboratory…” until now. Science Friday, a radio show on NPR, has just posted the following video of the first such model, which has been developed by UC Berkeley researchers.
“Experimental channels <like the one in the video above> are needed to explore mechanisms controlling migration rate, sinuosity, floodplain formation, and planform morphodynamics and to test theories for wavelength and bend propagation. Here we report an experiment in which meandering with near-constant width was maintained during repeated cutoff and regeneration of meander bends. We found that elevated bank strength (provided by alfalfa sprouts) relative to the cohesionless bed material and the blocking of troughs (chutes) in the lee of point bars via suspended sediment deposition were the necessary ingredients to successful meandering. Varying flood discharge was not necessary. Scaling analysis shows that the experimental meander migration was fast compared to most natural channels. This high migration rate caused nearly all of the bedload sediment to exchange laterally, such that bar growth was primarily dependent on bank sediment supplied from upstream lateral migration. The high migration rate may have contributed to the relatively low sinuosity of 1.19, and this suggests that to obtain much higher sinuosity experiments at this scale may have to be conducted for several years. Although patience is required to evolve them, these experimental channels offer the opportunity to explore several fundamental issues about river morphodynamics. Our results also suggest that sand supply may be an essential control in restoring self-maintaining, actively shifting gravel-bedded meanders.”
For the complete research article, see the Proceedings of the National Academy of Sciences.
Tags: civil engineering, fluvial geomorphology, geology, hydraulics, National Academy of Science, NPR, Science Friday, stream restoration, UC Berkeley, water
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