广州城市湿地的景观特点及小气候效应

Landscape characteristics and microclimatic effects of the urban wetlands in Guangzhou city

研究了广州城市湿地景观特点,对广州市5个不同类型湿地周边的气温、相对湿度及风速进行了一年的测定,分析了城市湿地周边的小气候效应。广州市湿地总面积为74373hm2,占国土面积的10%,其中老城区的湿地面积为18400hm2,占老城区国土面积的15.8%。广州市老城区湿地斑块平均密度(以每10000hm2面积内拥有的湿地斑块数计)为2.8块,平均距离为3270m。气温随着与湿地距离的增大逐渐升高,200m观测点的年平均气温比水边高0.8℃。相对湿度的变化与温度的变化相反,随着与湿地距离的增大而降低,200m观测点的年平均相对湿度比水边低2.4%。湿地周围的平均风速(在100m范围内)随与湿地距离的增大而降低。市郊湿地与市区内最高温的湿地比,年平均气温低2.7℃,夏季平均气温低1.1℃,冬季平均气温低4.1℃。气温的日变化呈单峰型,夏季13:00达到最高,冬季15:00达到最高。相对湿度的日变化和气温的日变化相反,早晨最高,13:00—15:00最低。市郊湿地的日平均相对湿度较市区内湿地高,夏季最大差值达7.5%;冬季最大差值达17.4%。风速的日变化冬季基本呈单峰型,1d中以11:00的风速较大。夏季13:00风速有所下降,1d中以15:00-17:00的风速较大。市郊湿地的日平均风速较市区内湿地夏季高30%,冬季高60%。气温和空气相对湿度的季节变化呈单峰型。

The landscape characteristics and microclimatic effects of five urban wetlands in Guangzhou were studied. A total 74 373 hm^2 of wetlands exist in Guangzhou city, which makes up 10% of the total area, among which 18400 hm^2 are in the urban region which accounts for 15.78% of the urban area. The urban region presents an average wetland patch density 2.8× 10^-4 per hm^2 and an average patch distance 3 270 m. Air temperature increases with the distance from the urban wetlands, with an annual average of 0.8 ℃ higher at 200 m from the wetland than at the wetland edge. Air relative humidity decreases with the distance from the wetlands, with an annual average 2.4% lower at 200 m from the wetland than at the wetland edge. Within a range of 100 m, average wind speed decreases with the distance from the wetland. Wetlands in the suburb have lower average air temperatures （2.7℃ in annual average temperature, 1.1 ℃ in summer and 4.1 ℃ in winter）, higher relative humidity （7.5% in summer and 17.4% in winter） and higher average wind speed （by 30% in summer and 60% in winter） than those in the urban area. Daily variation and annual variation of air temperature, and annual variation of relative humidity indicate a single-peak pattern. Wind speed generally has higher values at 11：00 and between 15：00-17：00 during a day and in winter months during a year.