| Surface water resources are of great significance to the water cycle,energy cycle and ecosystem,and the expansion and contraction of water bodies is an important indicator of environmental change.An accurate grasp of the spatial and temporal characteristics of surface water resources is of great scientific significance and application value for protecting regional water resources security and water ecological balance,and promoting healthy and sustainable regional economic development.Modern remote sensing technology provides a valuable source of information for water resources management and monitoring.The growing demand for geographic information on various spatial issues has fostered the development of new methods to extract and analyse data more effectively and efficiently.This paper uses Landsat satellite data from 1986 to 2020 as the object of study for the extraction of spatial and temporal characteristics of surface water resources.The MNDWI model,which is more effective for the extraction of the study area,is selected through a comparative analysis of existing methods,and on this basis the method is improved to solve the problem of difficult extraction of some small rivers and semi-dry rivers.This paper proposes an improved MNDWI water body index model by combining the building index model and the vegetation index model,which improves the extraction accuracy of surface water bodies more obviously.The improved method is applied to the extraction of surface water resources in the study area to achieve the analysis of the spatial and temporal variation characteristics of surface water resources in the study area,and relevant suggestions are put forward for the protection of surface water resources in Shandong Province.The main research contents and conclusions of this paper are as follows:(1)Research on the extraction method of surface water resources in Shandong Province based on Landsat dataIn view of the poor results of the previous surface water extraction process,this paper combines the building index model and vegetation index model,and proposes an improved index model for surface water body extraction.Based on this model,the extraction of surface water resources is carried out in Shandong Province as the study area.The manual visual interpretation of the contrasted high-resolution remote sensing images of the Yellow River basin within the study area was used as the validation standard sample,and the extraction results were verified with four kinds of accuracy: accuracy evaluation,kappa coefficient accuracy,overall accuracy and user accuracy verification.The experimental results show that the extraction results based on the index model of this paper are 21.5%,1.68%,15.75% and 15.75% better than the JRC water body dataset(global surface water dataset)in terms of accuracy evaluation,Kappa coefficient accuracy,overall accuracy and user accuracy,respectively.The results show that the method has achieved an improvement in extraction accuracy.(2)Analysis of the spatial and temporal variability of surface water resources in Shandong Province from 1986 to 2020The analysis of the spatial and temporal variation of surface water resources in the study area reveals that the spatial and temporal distribution of surface water resources in the study area is uneven,with a distribution characteristic of "dense in the south and sparse in the north".From 1986 to 2020,the area of surface water resources has changed significantly: the overall trend of change in the area of dry season water and wet season water is basically the same,both show an increase and then a decrease;from the comparison of the beginning and end of the study period,the area of wet season water shows an increase,the area of dry season water shows a decrease,and the overall area of surface water shows a decrease,and it is expected that this trend will be maintained in the future.The trend of changes in surface water under different altitude classifications varies,with surface water area increasing under the low altitude classification,surface water area under the middle altitude classification showing a general trend of decrease,and surface water area under the high altitude classification remaining relatively stable.(3)Assessment of the correlation between the influencing factors of surface water changes in Shandong Province from 1986 to 2020 In this paper,the driving factors of surface water area change in Shandong Province are discussed from both natural and social aspects.Temperature and precipitation are selected as natural factors;four influencing factors,namely population,GDP,arable land area and water consumption,are selected as social factors.Factor analysis was used to analyse the above factors and found that the dominant factors included temperature,GDP and population.Pearson correlation analysis was used to analyse the correlation between the influencing factors and surface water area.The factor that correlated more with the change in water area in the rainy season was rainfall,and the factor that correlated more with the change in water area in the dry season included arable land area,indicating that the combined effect of the two was the key factor that led to the change in surface water area in the study area.Finally,based on water system zoning,change characteristics and actual provincial conditions,feasible measures for disaster prevention and control are provided for the study area.In response to the characteristics and actual conditions of different cities and regions,locally appropriate emergency management measures for flood and drought control are proposed,while a management scheme for graded zoning management is proposed for the provincial conditions of Shandong Province,providing strong guidance and reference implications for disaster prevention and control,ecological environmental protection and sustainable development in the region. |
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