| The topics on the coupling phenomenon in watershed space,the coupling characteristics and laws,and the degree of coupling are important in land system science and telecoupling theory.In order to reveal the complex interactions between systems,this dissertation proposes a watershed spatial coupling theory framework to reveal the spatial coupling phenomena of watersheds in the context of regionalization of land use so as to expand the direction of scientific research on land system and strengthen sustainable land management.Meanwhile,the Yellow River Watersheds is an important ecological security barrier in China and an important area for human activities and economic development.Taking the Yellow River Watersheds as an example to study watershed spatial coupling can provide a theoretical basis for the ecological protection of the Yellow River and provide a basis for the implementation of high-quality development planning in the Yellow River Watersheds.The research aims of this dissertation is to clarify the universality of spatial coupling of river basin,explain the process and mechanism of coupling,quantify the coupling degree,apply the theory of spatial coupling of river basin to ecological flow estimation,land spatial planning and ecological compensation of river basin,and apply it to the Yellow River basin in the whole process.For this reason,firstly,statistical analysis method and literature research method are used to analyze the spatial correlation commonly existing in watershed space;Then,by analyzing the water quantity coupling mechanism and water quality coupling mechanism,the mathematical modeling method is used to build the water quantity coupling model and water quality coupling model of the basin,and the essence of the complex correlation within the basin space is described;Next,the concept and definition of spatial coupling degree of the river basin are put forward by using the logical reasoning method,and the water quality coupling model and water volume coupling model are established by using the mathematical modeling method,and then the spatial coupling measurement model of the river basin is established.Then,the results of the spatial coupling degree of the Yellow River basin are verified by an example;Finally,according to the spatial coupling theory,the mathematical modeling method is used to build the ecological flow estimation model based on the spatial coupling theory and carry out empirical research,and analyze the practical use of the theory in land spatial planning and ecological compensation.The conclusions of the dissertation are as follows:(1)The land spatial units of the Yellow River Basin are related.The evaluation results of correlation degree show that the mean value of land spatial correlation degree of each province over the years is 0.7265-0.8388,indicating that there is an obvious internal correlation between various subsystems of land space in the basin.This relationship is based on the direct relationship between the frequent human activities in the upstream and downstream and the indirect relationship between the ecological corridor with rivers as the main link.There are complex system interactions across space,time and organizational levels between subsystems of different river sections,which become the basis of mutual feedback between systems.At the same time,there are still many problems in the formulation and management of ecological protection,water resources utilization,land space planning and other policies in the Yellow River basin,so it is necessary to explore the theory of basin space coupling.(2)The intrinsic mechanism of watersheds spatial coupling is based on the composition of quantitative and qualitative changes in water resources,which are the key to the internal coupling of ecological space and ecological-human social space coupling in the watersheds,respectively.Natural factors such as rainfall,substratum vegetation type conditions,river morphology type,and factors such as river construction and human production and domestic water abstraction lead to quantitative changes in water resources,while the self-purification process of water bodies,pollutant deposition and pollutant transport transfer patterns influence the qualitative changes of water resources.The establishment and application of the water quantity spatial transfer model shows that the water quantity transfer within the Yellow River Watersheds is relatively balanced,with Gansu and Qinghai jointly transferring 2.354 billion cubic metres of water surplus to Ningxia(of which Qinghai recharges 52 million cubic metres and Gansu recharges 2.003 billion cubic metres)and continuing to transfer299 million cubic metres of water surplus to Inner Mongolia.Shaanxi transferred 243 million cubic metres of surplus water to downstream Shaanxi,and the surplus water from Henan and Shandong flowed into the Bohai Sea.The establishment and application of the water pollutant migration model shows that at the same time the pollutant concentration shows an exponential function decreasing with distance with a base of e.The pollutant from the upstream region has the greatest level of influence on the local region,and there is an influence not only on the region,but also on the water quality of the adjacent region,and even the water quality of the subsequent region.(3)Based on the derivation of the water quantity coupling model and the water quality coupling model,the spatial coupling metric model of the watershed is established.The results of the derivation of the spatial coupling metric model show that the spatial coupling between two sections is only related to the water quality and water quantity of the upstream section and the water quality and water quantity of the confluence,and has nothing to do with the situation of the downstream itself,and also has nothing to do with the quantity of water and other material quality of the downstream outflow.The application of the spatial coupling metric model in the Yellow River Watersheds shows that the spatial coupling degree of the watersheds is inversely proportional to the distance between river crossings,and the water quality coupling degree and water quantity coupling degree are related to the distance between river crossings as a power exponential function.For example,the spatial coupling between Xiaolangdi and Gaocun,Aishan and Lijin is 0.7565,0.6439 and 0.5622 respectively,but the spatial coupling between Lanzhou and Gaocun,Aishan and Lijin is 0.3131,0.2944 and 0.2769 respectively,a phenomenon mainly related to the This phenomenon is mainly related to the distant geographical location between the upstream cross sections.The spatial coupling measure of the watersheds can visualise the relative changes in water quality or quantity between river cross-sections in the complex ecological process of river flow,and the extent to which the downstream cross-sections are influenced by the upstream cross-sections.(4)The ecological flow estimation model based on the spatial coupling theory of the river watersheds considers the dynamic,territorial and open nature of ecological flow estimation,and considers the incremental influence of the upstream on the ecological flow in the region,as well as the amount of influence of the region on the downstream ecological flow,which is more in line with the definition of ecological flow in the Brisbane annual meeting.The application in the Yellow River Watersheds shows that the ecological flow estimation results based on the spatial coupling theory of the watersheds do not have a large offset compared with the calculation results of the hydrological method,and the offset is within 20% for most sections,especially the ecological flow of the middle and lower reaches sections are closer between the two methods.The comparison between other studies and the results of this dissertation also shows that the change trend of ecological flow results is basically the same compared with other studies,which proves that the ecological flow estimation model based on the spatial coupling theory has high reliability and reasonableness.The application of the theory in territorial spatial planning and watershed ecological compensation also shows that the theory of watershed spatial coupling has strong practical significance. |
PDF Full Text Request