垂直投影面积
垂直投影面积-
建城区绿化覆盖面积是指城市绿化种植中的乔木、灌木、草坪等所有植被的垂直投影面积及水面之和，其中建成区范围内的耕地不统计在内。
Green coverage is the area of all growing planting projection , including tree , shrub and grass .
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通过试验发现就环状橡胶圈（模拟废旧轮胎）这种柔性加糙体，垂直水流方向的投影面积是影响槽底糙率、水深和流速的主要因素。
By the testing we found the flexible artificial roughness rubber turns which simulated the wasted tires were the main factor which affect the roughness of the bottom which directed to vertical flow .