夏季城市河流宽度对绿地温湿效益的影响

城市河流是城市生态系统中重要的组成部分,对城市生态环境的改善发挥着重要作用.利用小尺度定量测定的技术方法,分析了北京市三环至五环附近7条不同宽度城市河流对其旁侧绿地温湿效益的影响.结果表明:城市河流宽度是影响绿地温湿效应的重要因素.当河流宽度为8 m时,绿地具有一定的增湿效应,但降温效果不明显；当河流宽度为14～33 m时,绿地降温、增湿效果明显；当河流宽度超过40 m时,绿地降温、增湿效果显著且趋于稳定.7条河流旁侧绿地与各自对照间的温、湿度差异均达到显著水平,且显著发挥温湿效益的河流宽度为44 m.河流旁侧绿地夏季温度(x)、湿度(y)关系的回归方程为y=173.191-3.247x,相对湿度每升高1.0％,温度降低约0.3 ℃.

Effects of urban river width on the temperature and humidity of nearby green belts in summer

As an important part of urban ecosystem, urban river plays a vital role in improving urban ecological environment. By the methods of small scale quantitative measurement, this paper analyzed the effects of seven urban rivers with different widths along the Third to Fifth Ring in Beijing on the air temperature and relative humidity of nearby green belts. The results showed that urban river width was the main factor affecting the temperature and humidity of nearby green belts. When the river had a width of 8 m, it had no effects in decreasing temperature but definite effects in increasing humidity; when the river width was 14-33 m, obvious effects were observed in decreasing temperature and increasing humidity; when the river had a width larger than 40 m, the effects in decreasing temperature and increasing humidity were significant and tended to be stable. There existed significant differences in the temperature and humidity between the green belts near the seven rivers and the corresponding controls. The critical width of urban river for the obvious effects in decreasing temperature and increasing humidity was 44 m. The regression equation of the temperature (x) and humidity (y) for the seven green belts nearby the urban rivers in summer was y = 173.191-3.247x, with the relative humidity increased by 1.0% when the air temperature decreased by about 0.3 degrees C.