Rearch Of Spatio-temporal Variation Of Vegetation Ecological Water Use And Ecological Vulnerability Evaluation Based On Multi-source Remote Sensing Data In Haihe River Basin

The coordination of water resource utilization and the ecological environment is the core of achieving sustainable development of the Haihe River Basin.This study analyzed the characteristics of the meteorological,hydrological,soil,water resources use and the change of land-use patterns of the Haihe River Basin from a long-term perspective,with the aim of exploring issues such as excessive use of water resources and vulnerability of ecosystems in the area.Based on the coupled model of remote sensing and ecological hydrology,the water consumption model of the ecological system and the assessment model of ecological vulnerability were optimized.The input parameters of the ecological water use model and ecological vulnerability assessment model were obtained based on the existing multi-source remote sensing data products and related auxiliary data,and then the effects of different types of land use patterns on water consumption were analyzed.The ecological vulnerability assessment method under the water resources limitation of the Haihe River Basin was studied to identify the characteristics of ecologically fragile area changes in terms of time,and the relationship between vegetation water use and ecological fragility was discussed.The main achievements of this study are as follows:(1)The regular pattern of land-use change in the Haihe River Basin was analyzed.The results show that the most obvious change among land use types in the Haihe River Basin is cultivated land,followed by grasslands,wetlands and others.Specifically,the area of cultivated land accounted for 46%,42%,and 35% in 2005,2010,and 2015,respectively.The reduced cultivated land area is mainly converted into forest land and artificial surface.In addition,the types of grasslands,wetlands and other ecosystems have also changed significantly.(2)The watershed vegetation ecological water use model and ecological vulnerability assessment model were constructed and optimized based on remote sensing data products and related auxiliary data,aiming to simulate the vegetation water use and assess ecological vulnerability in the Haihe River Basin from a long-term perspective.(3)The remote sensing and non-remote sensing data were optimized to meet the input requirements of ecological water use and ecological vulnerability assessment models.In response to the needs of ecological water use models and ecological vulnerability assessment models,remote sensing data such as MODIS and TRMM and other auxiliary data were selected and optimized,and spatial data sets in terms of the time were obtained.(4)According to the time series,the situation of vegetation water use in the Haihe River Basin was simulated,and the temporal and spatial changes of vegetation ecological water use in the watershed were revealed.The results show that the overall ecological water consumption of the Haihe River Basin continues to increase,especially in urban areas.Changes in temperature and precipitation have an impact on the continued growth of vegetation water use,but it is not the most important.Conversely,changes in land use types are the main cause of the spatial and temporal differences in vegetation water consumption,with the most obvious in terms of arable land water consumption.In addition,on the monthly scale,there is a positive correlation between precipitation and vegetation coverage and vegetation water use,but their correlation trends are different.Specifically,there is a highly linear positive correlation between vegetation coverage and changes in vegetation water use(the experimental data fitting formula is y=0.3115 x + 0.919,R2= 0.9677).However,the positive correlation between precipitation and vegetation ecological water consumption is closer to the exponential relationship(y=2.0141e0.0193 x,R2= 0.6949).(5)An ecological vulnerability assessment model of the Haihe River Basin was established,and an assessment of the ecological vulnerability of the basin was carried out.The results show that the overall ecological vulnerability of the Haihe River Basin is gradually increasing from southeast to northwest,which means that the ecological vulnerability level of the mountainous area in the northwest is higher than that in the plains and coastal areas in the southeast.Specifically,in 2005,the total proportion of weak and mid-week vulnerability was about 52%,while the total proportion of moderate,mid-strong,and strong vulnerability was about 48%.Subsequently,in 2010,the level of ecological vulnerability increased slightly in the entire basin,of which medium,medium and strong vulnerability accounted for about 51%,with a 3% increase.Furthermore,in 2015,the ecological environment has improved significantly,and the corresponding vulnerability levels have declined significantly overall.The total proportion of moderate,mid-strong,and strong vulnerability is about 40%.(6)The effect of vegetation water use on the ecological vulnerability of the Haihe River Basin was discussed.The vegetation water use and ecological fragility of the Haihe River Basin are negatively correlated as a whole,considering that 86% of the total area of the basin is negatively correlated.The introduction of vegetation water use has increased the overall level of ecological vulnerability assessment results slightly,especially the increase in the medium level: in 2005,the medium vulnerability increased by 2%,the strong vulnerability increased by about 1%;in 2010,the medium vulnerability increased by 4%,the strong vulnerability increased by about 1%;in 2015,the medium vulnerability increased by 2%.There are 71 pictures,25 tables,and 160 references included in this thesis.