Analysis Of Urban Land Use Change And Its Impact On Surface Rainfall Runoff Based On Geographical Conditions Data

With the rapid development of society and economy,the acceleration of urbanization,and the improvement of people's production and living standards,urban problems such as heat island effect,environmental pollution,and urban waterlogging have become increasingly prominent.Among them,compared with other disasters,urban waterlogging occurs more frequently and affects a wide range,posing a threat to the safety of people's lives and property.In the process of urbanization,the types of land use affected by human activities are constantly changing,and the underlying surface of the city changes accordingly,which leads to changes in processes such as regional evaporation,runoff infiltration,and vegetation interception in the hydrological cycle,which further affects urban surface runoff.and its cycle with groundwater.Therefore,studying the impact of land use changes in the process of urbanization on changes in surface rainfall and runoff is of great significance to effectively alleviate urban problems and promote healthy and high-quality urban development.This paper takes the central urban area of Jinan as the research area.Based on the three-phase geographic and national conditions data in 2015,2018 and 2020,the land use types in the central urban area of Jinan are integrated into impervious surface,unused land,forest land,grassland,farmland,There are six types of water areas,and quantitative analysis of the spatial and temporal characteristics of land use,such as spatial distribution,structural composition,and transfer changes of land use in the central urban area of Jinan,is carried out through index methods such as the change dynamics of a single land use type and the land use transition matrix.Second,based on high-resolution land use Using data,soil type data,and rainfall data in the study area,the SCS(Soil Conservation Service)hydrological model was selected to simulate and calculate the surface rainfall and runoff in three phases,and at the same time to explore its variation characteristics;The coefficients were used to analyze the correlation between land use types and surface rainfall and runoff,and changes in land use types and surface rainfall and runoff in the central urban area of Jinan,revealing the impact of urbanization on urban waterlogging,in order to provide a scientific basis for future urban development and planning in the study area.conclusion as below:(1)Land use changes in the central urban area of Jinan in 2015,2018 and 2020.From a spatial point of view,the spatial distribution of farmland in the western and northeastern regions of the study area has decreased significantly;the unused land in the central and eastern regions has increased significantly,and the impervious surface has It is more concentrated in the center of the study area.Combined with the statistical analysis of the area,farmland and unused land are the land types with the largest area reduction and increase respectively among the land use types.Most of the unused land is demolition,to-be-built,or under-construction land.Therefore,the spatial change is an external sign of the east and west expansion of urban development.In terms of the composition and transfer of land use types,there is a large area of mutual conversion between unused land and impervious surface,and a large area of mutual conversion between forest and grass.Impervious surface,unused land,and reduced farmland are mainly converted to forest land.(2)When the soil type,soil moisture and rainfall conditions remain unchanged,the surface rainfall runoff in the central urban area of Jinan from 2015 to 2020 showed an overall increasing trend,and the spatial distribution and impermeability of areas with increased runoff increased.The expansion trends of surface and unused land are close to the same,showing obvious changes in the eastern part of the study area,and the Pearson correlation coefficient shows that impervious surface,unused land area and surface rainfall runoff are significantly positively correlated There was a significant negative correlation between the area of grassland and forest land and the surface rainfall and runoff,while the correlation between the area of water and farmland and the surface rainfall and runoff was not significant.(3)Based on the geographic detector and the Pearson correlation coefficient,the land use changes with the strongest and most significant explanatory power for the change of surface rainfall and runoff were detected as the difference between the four land use types of impervious surface,unused land,grassland and forest land.Mutual conversion;among them,the conversion of grassland to impervious surface,forest land to grassland,impervious surface to grassland,unused land to grassland is highly correlated with the change of surface rainfall and runoff.