Study On Assessment And Optimization Suggestions Of Water Adaptable Landscape Pattern Of Urban Fluvial Island Based On The Coordination Model Of Composite System

As a part of urban land,the urban fluvial island is superior in natural conditions and rich in history and culture.It is not only an important part of the urban waterfront landscape,but also one of the few habitats in the river-ecosystem.As the process of urbanization,it is facing a variety of disturbances,such as natural disasters,excessive expansion of land use,and increased population density,which have brought about a series of water security and water ecology issues.The urban fluvial island landscape system is the combination of natural system and social system,While protecting and using the island,mankind has gradually formed a landscape pattern that adapts to flood disasters and the natural environment.Optimizing the water adaptable landscape pattern can help island improve its ability to resist interference,protect ecological resources,make rational use of land,and guide the sustainable development of the urban fluvial island.First of all,this paper analyzes the composition of the urban adaptive landscape system of the urban fluvial island based on system theory,coordination theory of composite system,layers model and other related theories,builds a composite system coordination degree model of the occupation-networks-base layers,analyzes the operation of the composite system The internal laws and internal contradictions of the system take the inter-layers coordinate degree and synthetic coordinate degree of the composite system as the criteria for evaluating the water adaptive landscape pattern.Secondly,the land use,space pressure,embankment system,transportation networks.Water and green space are used as element layers,and relevant indicators are selected to construct an indicator system for evaluating the water adaptable landscape pattern of the urban fluvial island based on a coordination degree model of the composite system.An evaluation model is constructed using the minimum distance method and weighted by entropy weight method;again,This paper takes urban fluvial island as the research object,and establishes the target value in combination with the specific development of islands,calculates the inter-layers coordinate degree and comprehensive coordinate degree of the composite system,and divides the evaluation results into different levels.The changetrend of the occupation-networks-base layers composite system is analyzed from the time dimension,and the characteristics of the water adaptive landscape pattern are explained.The main reasons for the change of the water adaptive landscape pattern are compared through the comparison between the inter-layers and the synthetic coordinate degree.Finally,from the perspective of improving the coordinated development of the occupied layer-network layer-base layer,an optimization suggestions for the water adaptive landscape pattern of urban fluvial island is proposed.The main research conclusions of this article are as follows:(1)The synthetic coordinate degree of the composite system increased in 2003-2018,showing the lowest in 2008 and the highest in 2013.For the inter-layers coordinate degree,in 2003,the networks layer-base layer> occupation layer-networks layer> occupation layer-base layer;after 2003,the networks layer-base layer> occupation layer-base layer>occupation layer-networks layer.(2)The evaluation results show that from 2003 to 2008,the occupation layer-base layer,network layer-base layer decreased in the area of cultivated land was higher,and the patch area of river shoal and water suddenly decreased.The sharp decrease between the occuption layer and the networks layer indicates that the local road networks density is too large and does not match the base layer.From 2008 to 2013,the increased coordination between the networks layer-base layer and the occupation layer-base layer was mainly due to changes in the base layer,indicating that land expansion and infrastructure growth did not cause a potential threat to the natural basement.At the same time,with the development of the road networks,the waterfront accessibility of the main roads has increased,and local spaces can be integrated into the overall space.From 2013 to 2018,the area of Yuliang Island's water and green patches increased,and the patch cohesion index increased,but there is still a large area of cultivated land on the north side of the island,resulting in a reduction in the coordination between the occupation layer and the base layer.The decrease between the occupation layer and the networks layer is reflected in the low degree of integration and intelligence of the road due to the disorder of the road networks.(3)The optimization strategies construction of urban fluvial island water adaptable landscape pattern can be started from three uncoordinated development types: occupationlayer-networks layer lag type,networks layer-base layer lag type,occupation layer-base layer lag type:controlling capacity,building sponge storage facilities;optimizing road networks,and improving waterfront accessibility;Intensive use of land to improve blue-green space connectivity.