| Water has given the Yellow River Delta its birth,its reputation and its prosperity,but is currently in the trap of being"subject to water".Surface water is the primary storage unit of water resources in the Yellow River Delta,the main source of available water resources for human beings,the basic element of regional natural environment,and the component of the structure and function of the ecological environment system.Therefore,it is of great theoretical and practical value to pay attention to the evolution of surface water and the effect of the ecological environment in the Yellow River Delta.Many scholars have carried out the multiple time-span evolutionary research on surface water in different regions,which have deepened people’s understanding of the evolutionary characteristics and driving conditions of surface water.However,existing research either pays little attention to the ecological environmental effect of water evolution,or the analysis of the driving force of surface water evolution remains in the semi-qualitative and semi-quantitative stages.In addition,due to the significant regional differences in the evolution of surface water and ecological environment effects,the research content and emphasis of surface water are different.Therefore,this paper takes the new geographical unit,the Yellow River Delta,as the research area and the surface water as the research object.The research content and goal are to reveal the evolution law of the surface water,analyze the driving force of the evolution of the surface water and the ecological effect of the evolution of the water.The research results can deepen people’s understanding of the evolution process of the surface water in the Yellow River Delta,enrich the theoretical research on the evolution of the surface water and provide scientific reference to the water resource management and water layout in the Delta.The paper is divided into seven chapters.The first chapter is the introduction,which mainly including the research background,research significance,research progress,research content,technical route,paper characteristics and so on.In the part of research progress,it summarizes the advantages and disadvantages of previous studies from four aspects:water extraction,water evolution,water evolution driving analysis and water evolution ecological environment effect.The second chapter is about the study area and main research methods.The study area introduces the boundary and scope,the natural environment and social and economic conditions of the Yellow River Delta.And the data processing introduces the format and source of the data required for this study,and focuses on the extraction process of surface water and land use/vegetation cover data in the Yellow River Delta,the main research methods are introduced According to the research content.The third chapter is the evolutionary characteristic of the surface water in the Yellow River Delta,which analyzes the change law of the water in the Yellow River Delta from several angles,such as time series,watershed distribution and land-based transformation.Chapter four analyzes the dynamic evolution driving force of surface water in the Yellow River delta.In this part,the driving force of the dynamic evolution of a surface water is analyzed from the two evolutionary directions of area increase and the area decrease according to different water types by using the track analysis method and geographical detector model.The fifth chapter is the study of landscape pattern effect of surface water evolution,and this chapter constructs the surface water network of the Yellow River Delta,so as to extract the network structure characteristic index and explore the influence of surface water evolution on the landscape pattern of the Yellow River Delta from the overall level and type level.Chapter six is the effect study of the service function of the surface water ecosystem in the Yellow River Delta,which mainly estimates the value of the service function of the surface water in the Yellow River Delta and analyzes its evolutionary trend.The seven chapter gets conclusion and prospect,summarizes the main conclusions,objectively analyzes the shortcomings,and further discusses the possible deepening of this research.The main results are as following:(1)The area and length of the surface water in the Yellow River Delta showed an increasing trend,with an increase of 1121.2 km~2 in the surface water,of which 959.6km~2 in the salt field aquaculture pool was the most variable surface water from 1986to 2016.The length of linear water has increased by 9530 km,among which the length of the ditch has increased by 9525.8 km,which is the largest increase of linear water.The composition of the surface water is progressively dominated by the river and the salt field aquaculture pool,and then transformed into the salt field aquaculture pool.And the number of water in different basins has different evolutionary characteristics,with the area of surface water in the Yellow River Mainstream District increased by 391.9 km~2 and the linear water by 2989 km from 1986 to 2016.The surface water of the Xiaoqinghe District increased by 340.5 km~2,while the linear water increased by 3119.4 km.The surface water of the Tuhai-Majia River District increased by 388.9 km~2,while the linear water increased by 3416 km.The composition of surface water in separate basins shows an evolutionary trend from the imbalance to the balanced distribution,and the distribution of surface water in the three districts tends to be average.The transfer and exchange of surface water have a certain regularity.Rivers are mainly converted into arable land and beaches,while the exchange and transfer of pits has a certain stage-unused land and cultivated land before 1998 is the main sources of increase dwelling area,while marshes,reservoirs and unused land are the main destinations for the reduction.(2)Limited by the starting year of social and economic data statistics,the evolution driven analysis of surface water began in 1992,with 2004 as the intermediate node,and was carried out in time periods.The results show that(1)the increase of effective irrigation area and the increase of GDP development in1992-2004 are the main drivers of the decrease of the river area.The growth of river area is most affected by GDP growth and effective irrigation area growth,and the increase in population and primary industrial output value in 2004-2016 are the main factors influencing the decrease of the river area.The growth of irrigable area and the improvement to social economic development are the leading factors for the increase of river area during this period.(2)The increase in the output value of the secondary industry from 1992 to 2004 is the main factor influencing the increase in reservoir area,and the increase of effective irrigation area from 2004 to 2016 is the main driver of the increase of reservoir area.(3)The increase in the output value of secondary industry and the output value of primary industry in 1992-2004 was the main factor influencing the decrease of the area of the pit pond,while the increase of population was the main factor influencing the increase of the area of the pit pond during the period.The increase in GDP,the expansion of effective irrigation area and the increase of population in 2004-2016 are the principal factors influencing the decrease of the area of the pits.(4)The increase in the output value of the secondary and primary industries from 1992 to 2004 was the main factor that caused the growth of the area of the salt field aquaculture pond.The increase of irrigable area in 2004-2016was the main influencing factor of the decrease of salt field aquaculture pond,and the increase of irrigable area and GDP were the indicative factors for the decrease of the area of the salt field culture ponds;(5)GDP growth,the expansion of effective irrigation area and the increase of primary industry output value in 1992-2004 are the main factors influencing the growth of ditches,and the growth of GDP and effective irrigation area in 2004-2016 are the main factors of the growth of ditches.(3)From the perspective of the overall landscape pattern,the surface water showed a significant physical segmentation effect on the overall landscape pattern of the Yellow River Delta in 1986 and 2016,that is,the evolution of the surface water increased the patch density and fragmentation degree of the Yellow River Delta landscape.From the perspective of the effect of the evolution of surface water network pattern on the evolution of the overall landscape pattern in the Yellow River Delta from 1986 to 2016,it shows a comprehensive effect of spatial agglomeration effect and physical segmentation effect.While promoting the increase of the density of plaques in the research area,the surface water also reduces the complexity of the landscape and enhances the advantage of the overall landscape and the polymerization of the plaques.From the level of landscape pattern,the evolution of surface water in the Yellow River Delta shows the combined effect of spatial aggregation and physical division of cultivated land,the combined effect of environmental constraint and physical division on marshes and unused land,and the combined effect of spatial environment constraint,physical fragmentation and spatial attraction.(4)The core service functions of the surface water ecosystem in the Yellow River delta include water resources supply,material production,flood storage and water diversion,leisure tourism,habitat maintenance,water quality purification and sedimentation.From 1986 to 2016,the supply value of water resources increased by3.216 billion yuan,and the supply structure was converted from a river supply to a reservoir.The value of material production,flood regulation and storage,leisure tourism,habitat maintenance and pollution purification increased from 633 million yuan,77 million yuan,0 million yuan,87 million yuan and 39 million yuan to 6.85billion yuan,126 million yuan,6.947 billion yuan,489 million yuan and 67 million yuan,respectively.The value of deposition land formation decreased significantly,from 1.905 billion yuan to 361 million yuan.The absolute value of surface water services in the Yellow River delta has increased by 15.315 billion yuan in the past 30years.The core service function of water has changed significantly,and in 1986 the core service function of surface water in the Yellow River Delta was the supply of water resources,land deposition and material production,but by 2016 it was transformed into aesthetic function,material production and water resource supply.The value of pollution purification and flood storage in surface water has increased,but its proportion in the total value of service has declined from 0.73%and 1.44%to0.61%and 0.32%,and the function of pollution purification and flood regulation and storage of surface water has gradually weakened and marginalized. |
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