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北京市2012年7月21日遭遇特大暴雨袭击,全市平均日雨量达170 mm,大部分地区20年一遇,房山区超过100年一遇。占全市面积1/3的区域为有记录以来的最大日降雨量。在这次特大暴雨中,山区坡面水土保持措施削减洪峰和减少水土流失作用显著。在受灾最严重的房山区,各种水土保持措施减少径流23%,削减洪峰流量35%。全市各种水土保持措施共减少土壤侵蚀2 392.56万t,与无水土保持措施相比,减少土壤流失49%,其中以生态修复为主的第一道防线占34%;以梯田、水平条及树盘等生态治理为主的第二道防线占15%。
On July 21, 2012, Beijing was hit by a heavy rainstorm. The average daily rainfall of the whole city reached 170 mm. In most areas, it happened in 20 years and in Fangshan District exceeded 100 years. The area occupying 1/3 of the city is the largest daily rainfall ever recorded. In this torrential rain, mountain slope soil and water conservation measures to reduce the peak and reduce soil erosion has a significant effect. In the most affected Fangshan District, various soil and water conservation measures reduce runoff by 23% and reduce peak discharge by 35%. The city’s soil and water conservation measures to reduce a total of 23.5656 million tons of soil erosion, and soil conservation measures to reduce soil erosion 49%, of which the first line of ecological restoration accounted for 34%; with terraces, horizontal and Tree plate and other ecological management of the second line of defense accounted for 15%.