| Eco-water or eco-water layer refers to the water body which is closely related to the aboveground vegetation.It plays a significant role in regulating water cycle.Besides,it guarantees the healthy growth of vegetation.By studying the status and distribution of eco-water,the growing conditions of vegetation can be learned,and the theoretical basis for ecological environment protection and ecological rehabilitation can be provided.Different from other resources,eco-water resources are dynamic,and hard to be extracted and qualified by conventional methods,nor can they be directly interpreted from remote sensing images.Quantitative remote sensing technology can be used to establish eco-water retrieval model,which can study eco-water quantitatively.This paper is based on the National Natural Science Foundation Remote Sensing Dynamic Monitoring Method for Eco-water(Layer)and Water Stress Condition of Vegetation in Western Sichuan Plateau(41671432).Taking Maoxian County of Western Sichuan Plateau as the study area,three phases of Landsat remote sensing images in November of 2006,2008 and 2016 were selected to carry out the retrieval study on eco-water content of vegetation canopy.The vegetation damage in 2008 after the earthquake and the vegetation restoration in 2016 were analysed.In this paper,aboveground vegetation distribution and vegetation indexes were extracted from these remote sensing images.With the measured vegetation water content,the retrieval model of canopy eco-water content was established and verified.The model was used to perform quantitative retrieval and dynamic monitoring of canopy eco-water content based on these images.The main achievements of this paper are as follows:(1)By extracting the information of aboveground vegetation classification,the vegetation distribution map of the same month in 2006,2008 and 2016 was obtained,and the vegetation distribution area in different periods was statistically analysed.The major vegetation type of Maoxian County is coniferous forest.In 2006,the proportion of forest land was 52.24%.After the earthquake in 2008,vegetation was damaged and the proportion of forest land decreased to 41.97%.The post-disaster reconstruction of the ecological environment was carried out after the earthquake,and the proportion of vegetation was increased to 55.97% by 2016.(2)The empirical regression models between different vegetation indexes and the measured canopy eco-water content were constructed,and the correlation coefficients of each model were compared and analysed.It was concluded that the logarithmic regression model based on RVI vegetation index had a stronger correlation than others.Through fitting analysis,the model is verified to be appropriate.(3)Using the constructed retrieval model of canopy eco-water content,the distribution of canopy eco-water content in different periods was obtained from these three remote sensing images.Through dynamic analysis of canopy eco-water content in Maoxian County,a tendency of decrease was presented from 2006 to 2008.And from 2008 to 2016,the canopy eco-water content is increasing.(4)According to the statistical analysis of the average canopy eco-water content of different vegetation types,the result of sorting vegetation types by theirs average canopy eco-water content from largest to smallest is: mixed forest > broad-leaved forest > coniferous forest > shrub or alpine shrub and meadow.In this paper,quantitative remote sensing method was used to study the canopy eco-water damage and post-earthquake restoration in Maoxian County after the earthquake in 2008,which not only enriches the scientific research on eco-water and quantitative remote sensing,but also has practical guiding significance for the construction and protection of the ecological environment in this area. |
PDF Full Text Request