西安市主城区景观格局演变对地表径流的影响

Impacts of Landscape Pattern Changes on Surface Runoff in Main Urban Area of Xi’an City

[目的]探究景观格局演变和地表径流变化的时空相关性,为有效缓解城市内涝,保障城市生态安全提供理论支撑。[方法]以2000-2019年遥感影像为数据集,提取西安市主城区景观格局空间分布图,结合实际土地利用数据进行修正。利用SCS模型、景观格局指数、ArcGIS和皮尔逊相关性分析方法,研究西安市主城区景观格局动态变化与地表径流变化间的关系。[结果]①2000-2019年研究区景观格局呈现出高连通高聚集,斑块形状规则化,均质稳定化,景观蔓延度下降等的发展趋势。同期,研究区地表径流深度逐年增加,但径流深度增加量随时间动态变化呈下降趋势,其中2000-2005,2005-2010,2010-2015,2015-2019年分别增加了4.99,4.95,3.55和3.33 mm,说明景观格局对地表径流量的滞留作用逐渐增大。②景观格局指数变化率与地表径流量年增长率呈显著相关性。其中建设用地等人工景观指数变化率和地表径流量年增长率呈显著正相关,相反绿地、耕地、水域等自然景观指数变化率与地表径流量年增长率呈负相关关系。③借助城市生态廊道及生态节点构建内涝防治生态系统,并对城市不透水面高度集中的地区进行拆分,增设城市绿色基础设施,构建源头减排的内涝防治景观格局。[结论]景观格局演变对地表径流变化具有显著影响,景观格局优化能有效促进城市良性水循环,减缓内涝的发生。

[Objective]The spatial correlation between the evolution of landscape pattern and surface runoff was explored,in order to propose a landscape pattern optimization strategy that could effectively alleviate urban waterlogging and provide suggestions for urban ecological safety.[Methods]Based on the remote sensing data sets from 2000 to 2019,the spatial distribution map of landscape patterns in the main urban area of Xi’an City was extracted,and validated with actual land use data.The methods of SCS model,landscape pattern index,ArcGIS and Pearson correlation analysis were employed to analyze the landscape pattern changes and its impacts on surface runoff.[Results]①From 2000 to 2019,the landscape pattern showed a developing trend of high connectivity and high aggregation,regular patch shape,homogenization and stabilization,and the patch spread decreased.At the same period,the surface runoff depth increased year by year,however,the increase of runoff depth showed a downward trend with the time.In 2000-2005,2005-2010,2010-2015,2015-2019,the increment of runoff depth was 4.99,4.95,3.55,and 3.33 mm respectively,indicating that retention effect of landscape pattern on surface runoff increased gradually.②The correlation between the change rate of landscape pattern index and the annual growth rate of surface runoff was significant,and the artificial landscape index such as urban construction land had a significant positive correlation with the annual growth rate of surface runoff.On the contrary,there was a negative correlation of the annual growth rate of surface runoff and the change rate of natural landscape index such as cultivated land and water area.③With the help of urban ecological corridors and ecological nodes,the waterlogging prevention and control ecosystem was constructed,and the areas with high concentration of urban impervious surface were split,the urban green infrastructure was added,and the waterlogging prevention and control landscape pattern of source emission reduction was constructed.[Conclusion]Landscape pattern changes had a significant impact on the change of surface runoff,and the optimization of landscape pattern can effectively promote the urban benign water cycle and slow down the occurrence of waterlogging.