Analysis Of Water Storage In Typical Area And Variation Of Sediments In The East China Sea Based On GRACE

In this thesis,we used GRACE(Gravity Recovery and Climate Experiment)data combined with hydrological model data,precipitation data,satellite altimeter data and GIA model,to study the variation of water storage in The North China,Three Gorges and Sanjiangyuan regions,and the inversion of sediment variation in the East China Sea.The main contents and conclusions of the paper are as follows:(1)The basic theory and method of inversion of time-variable gravitational field using GRACE data are analyzed in detail,and the commonly used filter methods in data post-processing are described.Combining with simulate observation data,the filtering effect of different filter methods on noise removal and the amplitude attenuation,confusion caused by the signal in the filter process are analyzed.Experimental results indicated that the combined filter and smoothing prior information filter have more advantages.(2)A scale factor calculation method that consider seasonal influence was proposed to quantitatively estimate the terrestrial water and groundwater in The North China Plain from 2003 to 2014 was-2.0±0.6mm/year and-4.8±0.7 mm/year,respectively.By analyzing the cross-wavelet spectral of the groundwater and GPCC,we find groundwater variation had a phase delay of 2.6 months for precipitation before 2008;and the phase delay increased to 4.6 months due to aggravation of groundwater overexploitation after 2008.(3)Through the calculation and analysis of the simulation data,it was indicated that the magnitude of leakage error correction by the forward modeling is about 1 cm,and the annihilated signal can be recovered effectively.The annual amplitude of the variation of terrestrial water storage in the Three Gorges Reservoir area was 70±24mm and 72±27mm before and after the forward modeling correction,respectly.The equivalent water height changes caused by the three impoundments in the reservoir area after correction were 60.2mm,28.3mm and 20.5mm respectively,which have good consistency with the observed data of water]evel.From the perspective of spatial distribution,the water storage signal after correction obviously converged to the Three Gorges reservoir area.(4)The EOF method was used to decompose terrestrial water reserves and hydrology model in Three River Area and its surrounding areas.The results showed that the GRACE and hydrologymodel had the best match on EOF1,and showing obvious seasonal variation characteristics.However,in the spatial model,the variation of the water reserve inversion signal from GRACE was obviously stronger than the hydrology signal,especially in the northern part of India.(5)Perfected the theoretical method of using GRACE to invert sediments,the inversion of sediments has included sea surface high-variation corrections,correction of leakage errors,and GIA corrections.The average rate of variation of sediments at the estuary of the East China Sea after correction was 1.17×109 ton/year,which is closer to the measured data(0.9-1.0×109 ton/year)than the existing research.The sedimentary rate at the estuary is large,and the sedimentary rate is small where far from the estuary;the annual characteristics of the sediment changes are mainly related to the ocean circulation pattern related to the sediment dispersion path in the East China Sea;When using data of more than 5 years and the study area is less affected by the leakage of land hydrological signals,the inversion results of sediments are more reliable.