湿地对福州市热岛效应影响遥感分析

The impact of wetland on heat island effect using remote sensing technology in Fuzhou

以4期Landsat TM/OLI影像为基础,利用大气校正后的单窗算法对福州市地表温度进行反演并验证。进而利用ArcGIS的空间分析工具和土地利用/覆被类型数据,进行湿地对福州市热岛效应影响分析。结果显示:(1)通过地表温度实测数据对地表温度反演结果进行验证,二者之间R;值为0.9475,满足研究需要;(2)各土地利用/覆被类型中建设用地和道路的温度最高,成为城市热岛的主要热源。建设用地在所有地物中所占比例由1985年的10.6%增大到2015年的23.4%,其城市热岛贡献指数(UHI)由1985年的24%上升到93%;(3)湿地的冷岛效应对周围地物的高温环境具有一定的缓解作用,但是针对不同地物类型其影响范围并不相同;(4)1985—2015年湿地面积不断减少,冷岛效应正在逐渐减弱。湿地对周边地物地表温度的影响距离400 m减小到360 m,影响面积也由352 km^(2)减小到320 km^(2),影响范围下降的平均速度为0.94 km^(2)·a^(-1)。

Background,aim,and scope With rapid urbanization and industry development,urban heat island effect is becoming more and more prominent.Recently,Fuzhou,largest city in Southeast China,has continued to expand due to the continuous economic development,making urban heat island effect increasing.Wetland has a certain cooling effect on surrounding area.Quantitative analysis of the impact of the wetland factors on urban heat island is critical for further study.On urban heat island mitigation,useful recommendations for policy and practice can be formulated based on the Quantitative analysis.Materials and methods Based on Landsat series images,the single window algorithm with atmospheric correction was used to estimate land surface temperature(LST)of Fuzhou.Furthermore,the spatial analysis tool of ArcGIS and land use type data were used to study the wetland impact on the heat island effect in Fuzhou.Results The results showed:(1)The area proportion of construction land in all land use types increased from 10.6%in 1985 to 23.4%in 2015.At the same time,the urban heat island contribution index(UHI)for construction land rose from 24%to 93%.(2)The impact distance of wetlands on construction land is 270—510 m,while 210—480 m on road.(3)The cooling effect of wetland on neighbor area diminished with wetland area decreasing during the period of 1985—2015.The influence distance of wetland on the LST of surrounding area decreased from 400 m to 360 m.Meanwhile,the affected area reduces from 352 km^(2)to 320 km^(2).The average decreased speed of impact area was 0.94 km^(2)·a^(-1).Discussion The wetland has a certain cooling effect on surrounding environment,and the results support this effect diminishes with loss of wetland area.And,compared with this study,the present study focused on how wetlands affect the surrounding LST distribution characteristics only and ignored how wetlands structure influences surrounding areas.Our further study will concentrate on the impact of wetland area and shape on urban heat island intensity.This study provides added depth in our understanding of the impact of wetland cooling effect on surrounding environment.Conclusions Construction land and road have the highest temperature,which contribute urban heat island intensity most in Fuzhou.The area influenced by wetlands decreased,indicating a weakened trend of wetland cooling effect in Fuzhou City.Recommendations and perspectives Therefore,protecting existing wetlands from damage,and reinforce the management of wetland will help to reduce the urban heat island effect in Fuzhou.