Remote Sensing Study On Landscape Ecological Pattern Changes In Shanghai Waters On The North Shore Of Hangzhou Bay And Its Ecological Vulnerability Risk Assessment

The coastal zone is an interactive zone of sea-land interaction,and it is also the zone where human activities are most active and concentrated.Waters are an indispensable material condition for human survival and play an irreplaceable role in the process of social development.The coastal waters usually include rivers,lakes,seas,reservoirs and ponds.While economic activities are advancing rapidly to the coastal zone,the sustainable use of the coastal zone becomes particularly important.The current discussion on the ecology of the coastal zone has been deeply valued by scholars and experts at home and abroad.Examining the comprehensive human activities and geo-ecological processes from the perspective of the evolution of coastal waters can reveal the response characteristics of the spatial form of waters to natural and human factors.The economic development of the Shanghai section on the northern shore of Hangzhou Bay is an important part of the "Yangtze River Delta" economic belt.With the economic development and human activities on the coast of Hangzhou Bay and its adjacent areas,the landscape pattern and ecology of the waters on the northern section of Hangzhou Bay Bound to change.Landscape spatial pattern and ecological process have always been hot topics in landscape ecology research,and have applications in many fields such as urban and rural landscapes,water landscapes and biodiversity.With the rapid urbanization of China's coastal areas,the number and shape of patches in the water environment continue to change spatially,causing the water environmental carrying capacity to change continuously.Therefore,studying the law and mechanism of the spatial and temporal evolution of water quantity and form is one of the issues that need to be solved urgently at present.The ecological vulnerability of landscape reflects the sensitivity of the landscape pattern to the influence of external disturbances and the lack of adaptability to change the properties of the landscape system structure,function and characteristics.Landscape vulnerability is generally used to measure.Changes in the landscape ecological pattern and ecological risk assessment in the waters of the Shanghai section on the north bank of Hangzhou Bay,which are highly utilized by human activities,are conducive to the sustainable development of the coastal ecological environment in the region.Based on Landsat satellite data,this paper constructs the northern shore of Hangzhou Bay according to the rule of combining Normalized Difference Vegetation Index(NDVI),near infrared reflectance and Normalized Difference Water Index(NDWI)Water extraction model of decision tree in Shanghai waters.The results show that:(1)From 2011 to 2018,The largest change in landscape feature characteristics was the patch fractal dimension(Fract),which increased from 2.0369 to 3.4762,followed by patch density(PD)and patch number(NP),and patch density(PD)from 8.7486 / Km The number of plaques(NP)increased from 12,156 to 15,125.(2)From 2011 to 2018,the largest change in water landscape heterogeneity index is the uniformity index(EI),which increased from 37.98% in 2011 to 45.69%,with a total increase of 7.71%.The change of landscape index data shows that the patch distribution in this area tends to be complicated and the landscape aggregation tends to be scattered.Based on a total of 14 indicators of landscape element characteristics and landscape heterogeneity characteristics,the changes in the landscape ecological pattern of the waters in the Shanghai section of the northern shore of Hangzhou Bay in 2011,2014,2017,and 2018 were analyzed.Based on GF-1 remote sensing data,the landscape vulnerability index and landscape artificial interference intensity index of the Shanghai section of the northern bank of Hangzhou Bay were calculated,and their spatiotemporal changes and their response to human activities were analyzed.Areas of various landscape vulnerability levels in the Shanghai section of the northern shore of Hangzhou Bay in 2022.Research indicates:(1)From 2013 to 2016,the lower fragile areas were the dominant fragile area types.From 2016 to 2018,the low fragile areas became the dominant fragile types.The area occupied by higher and higher vulnerability areas is increasing year by year.The fragile areas in 2018-2019 changed from the previous Phases are slow.Highlevel fragile areas continue to spread,mainly from cities to suburbs,inland to coastal areas,and land to ports.(2)The landscape changes in the study area responded significantly to human activities,and there was a significant positive correlation between landscape vulnerability and the intensity of landscape artificial disturbance.(3)The results of predicting the graded areas of various landscape fragile areas in 2022 based on the Kalman filter method show that the areas of low-fragility-grade areas and higher-fragility-grade areas have increased from the previous moment,and The area of the medium-fragility-grade area has increased from the previous moment,and the area of the high-fragility-grade area has increased from 2018 and decreased from 2019.