A Study On Urban Ecological Networks And Ventilation Corridors Based On GIS

With the deepening of urbanization,urban ecological environment has become increasingly harsh,such as urban green space dwindling,water contamination and a sharp decline in air quality.Urban planning is starting only from the considerations of increasing large landscape area,rarely from the considerations of ecological networks and corridors and or other urban ventilation systems perspective,leading to a serious landscape fragmentation,bad connectivity between patches and urban poor permeability,which become a serious threat to urban ecology.On the basis of a comprehensive analysis of relevant research at home and abroad,we take Tianjin as research subject,and divide the urban land into woodland,water,farmland / garden,built-up areas,and then we calculate landscape index of Tianjin in the landscape level and the patch type level with the land classification map.At the same time,we choose Sofia.as the comparison sample,whose latitude and the natural environment is very similar to Tianjin and ecological environment is good.The results show that Tianjin farmland / garden patches has more obvious advantages in resources,but patches of woodland and water have more serious fragmentation and poor connectivity between the plaques.To improve the eco-system in Tianjin,we choose woodland and water source as ecology to construct urban ecology network constructed of Tianjin from the model based on the minimum cost.And then we optimize the ecological network based on network model we have built,obtained three different Ecological network structure.Finally,We find the basic framework of Tianjin ecosystem from the three different Ecological network structure,and propose construction of the corridor,increasing the source point,foot stone and other technical means to improve the ecosystem of Tianjin.The Least-Cost Distance Model is used to build a conceptual model of urban ventilation corridors in our study.we propose the city drag coefficient formula,and the approach of the establishment of the urban ventilation corridors based on The Least-Cost Distance Model.Then we take a certain cell for example,and compare the result of the certain with the results of CFD simulation,finding that the use of The Least-Cost Distance Model in building ventilation corridor has good accuracy,which will improve speed of building the ventilation corridor of the city.