Wind Proof Performance of Shanghai Coastal Shelterbelts Tested by Wind Tunnel Experiments

Taking the coastal plantations of Shanghai as study object,the wind proof performance of the different structured shelterbelts of Cunninghamia lanceolata pure stands,Populus spp.pure stands and the mixed stands composed of Cunninghamia lanceolata and Populus spp.was tested by combining the field monitoring with wind tunnel simulation.The results showed that the vertical distribution of the wind velocity on the lee side of the 3 types of shelterbelts was similar.The wind profile was declined within 0.9 H-2.0 H distance,whereas the wind profile tended to be vertical within 2.0 H-4.0 H distance.The wind profile close to the ground surface was almost horizontal.The horizontal distribution of the wind velocity on the lee side of the 3 types of shelterbelts was also similar.A large proportion of the wind air flow changed its original route when it was blocked by the shelterbelts and then flew over the plantations,and the little proportion of the air flow penetrated the shelterbelts and its flow speed was consequently reduced.When the density of the shelterbelts was 40%,the effective protection distance within which the wind speed could be reduced by 30% would be significantly increased along with the increment of the sine value of the angle between the wind direction and the shelterbelts.