英和和英

出典:『Wikipedia』 (2010/10/19 09:45 UTC 版)

英語による解説

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Flow devices are man-made solutions to beaver-related flooding problems. Traditional solutions have been focused on the trapping and removal of all the beavers in the area. While this is sometimes necessary, it is typically a short-lived solution, as beaver populations have made a remarkable comeback in the United States (after near extirpation in the nineteenth century) and rapidly recolonize suitable habitat. In fact, a 2006 survey found that trapping as a solution to beaver problems had a 79% failure rate within two years due to re-settlement by new beavers. Flow devices are relatively cost-effective, low maintenance solutions that regulate the water level of beaver dams and keep culverts open. A 2006 study by the Virginia Department of Transportation found that for every $1 spent on flow device installation relative to historical preventive maintenance, road repairs and beaver population control activities, $8 was saved for a return on investment of nearly 8:1.