High-resolution modeling of urban water and carbon fluxes in the main urban area of Beijing,China
Urbanization alters hydrological and ecological processes,such as regional water-heat balance,by af-fecting surface evapotranspiration(ET)processes,which in turn changes the structure and function of terrestrial e-cosystems.To scientifically assess the urban water-carbon process,this study estimated the monthly vegetation in-dex at 10 mx 10 m spatial resolution in the main urban area of Beijing from 2016 to 2021 based on the vegetation in-formation from Sentinel-2 data,and further combined with the PT-JPLim model,the InVEST(Integrated Valua-tion of Ecosystem Services and Tradeoffs),and the analytical WUE(Water Use Efficiency)model to simulate the monthly ET,ET partitioning(transpiration E,,soil evaporationEb,interception evaporation Ei,and impervious surface evaporation Eu),gross primary productivity(GPP),carbon storage,and ecosystem WUE for the main ur-ban area of Beijing at a spatial resolution of 10 m×10 m.Larger values of vegetation index were concentrated in the western mountainous areas,and the park areas of Beijing also presented larger NDVI(Normalized Differnce Vegeta-tion Index)with a maximum value of 0.65.The annual mean ET in the main urban area of Beijing is 497 mm,with the highest ET in the western mountainous area,exceeding 1000 mm.ET increases with the increase of LAI(Leaf Area Index)and EVI(Enhanced Vegetation Index).Increases in NDVI,LAI,and EVI were observed at a rate of 0.0048,0.016 m2·m-2,and 0.0047 per year,respectively,from 2016 to 2021.The regional average E,was 141.51 mm,Ei was 50.77 mm,and Eb was 272 mm.Eu was distributed only on impervious surfaces of building sites,and Eu/ET on impervious surfaces was 18.2％.The areas with higher carbon storage were mainly distributed in the western mountains,which had relatively high elevation,high vegetation cover,and high values of total car-bon storage density exceeding 5 t/hm2.The mean value of GPP in the study area was 2.7 g·m-2·d-1,and the annual mean WUE was 0.63 g·mm-1.There was a significant negative correlation between WUE and Et/ET(R=-0.44,p＜0.001),and WUE tended to increase significantly with increasing GPP.The refined urban water and carbon simulation can provide a theoretical basis for the construction and evaluation of sponge cities,and the simu-lation of urban water and carbon fluxes is of great significance for the achievement of the carbon peaking and carbon neutrality goals.
urbanizationecosystemsevapotranspirationBeijingwater use efficiency
万方数据
维普
