Suspended sediment monitoring and assessment for Yellow River estuary from Landsat TM and ETM + imagery

We present results of the quantitative monitoring and assessment of suspended sediment in Yellow River estuary from the imagery of TM and ETM + (TM/ETM +) aboard Landsat satellites. The estuary is one of the worldʹs most turbid areas with high concentration of suspended sediment (SSC). As a result, an atmospheric correction algorithm is required for TM/ETM + when applied to monitor SSC in the estuary. Remote sensing reflectance (Rrs) at TM/ETM + bands is retrieved using the air molecule and aerosol scattering information provided by MODIS aboard Terra satellite, which has highly improved radiometric calibration, sensitivity, and spectral bands designed for estimating aerosol radiance. Rrs at the red band is used for retrieving SSC by means of the model developed from in-situ data. TM/ETM + measured water color products (Rrs and SSC) are cross validated with MODIS measurements, which are validated by contemporaneous in-situ data. The cross validation shows that, with the proper atmospheric correction algorithm and retrieval model, TM/ETM + data can be used to quantify the SSC in Yellow River estuary. nnual and seasonal variations, as well as spatial distribution, of SSC in Yellow River estuary are studied and assessed using TM/ETM + measurements from 2000 to 2010. Results show that the SSC is generally increasing from 2000 to the maximum in 2003 and then decreasing and is highly correlated with the annual total sediment discharge from Yellow River. The correlation is not so high for the SSC in Bohai and Laizhou bays. In addition, the SSC in the estuary is generally increasing from June to the maximum in Nov. and then decreasing to the minimum in April. The seasonal variation pattern results from Yellow River sediment discharge, which is higher in June–Nov., corresponding to the flood season than in other months. The SSC in Laizhou and Bohai bays generally follow the same seasonal variation pattern that is higher in Nov.–Apr. than in other months. The higher SSC mainly results from the wind-driven resuspension of bottom sediment.