Research On The Water Depth Retrieval Of Dali Lake Based On 3S Technology

Bathymetric mapping is one of the most important works in Lake survey.It is very important to understand the change of water depth in water resources utilization,flood,disaster prevention and control.At present,the traditional bathymetry method is still be used for the determination of the water depth in Da Li Lake.There is no report on the application of remote sensing technology of large scale synchronous sounding.For the first time,3S technology is used with 3 kinds of remote sensing satellite images of a total of 6 images for the comparative analysis,retrieve the depth of the lake and construction of underwater bottom topography.The conclusions as following:(1)The red wave band is sensitive to the change of the lake water depth in visible lights.OLI data is more suitable band in the remote sensing of the lake water depth retrieval than that of ETM+ data and MS data.The thermal infrared band showed better correlativity between band and water depth in the late autumn and early winter.The reason is related to the heat convection in the upper and lower lake water.(2)Extracting the lake surface by using two separation methods from 5 Landsat satellite images:color synthesis and MNDWI.It was found that the lake area increased in 2013 compared with the year of 2012 and 2014,then it began to decrease to the size ofthe area in the year of 2012 until 2016.The lake area is about 189km2 by the computation.The annual variation of the lake water area is in the range of 1%in 2012 to 2016.(3)152 single factor models and 12 multivariate models were established for comparative screening.The best inversion model in single factor models is the one by way of taking B1*BB10 as the index in 2015 remote sensing image.In multivariate models,the multiple regression model of single band and band combination in 2015 is the best.The accuracy of multi factor regression models is higher than that of single factor regression models.In contrast to the three kinds of data sources,the accuracy degree from large to small is OLI>MS>ETM+.It is shown that the better water depth retrieval is not because of the higher resolving power of the remote sensing image.The appropriate band settings will get better results.(4)Through contrast analysis,the 2015-10-16 multi factor model is selected as the optimal bethymetric model,and computing the water depth of each pixel point in the image by using this model.The contour map with 3D grid and the profile of Dali lake are drawed.The variation of lake bottom topography is analyzed and the storage capacity of Dali lake is estimated as 1.3 billion cubic meters.