Influence of the Three Gorges Dam on Total Suspended Matters in the Yangtze Estuary and Its Adjacent Coastal Waters: Observations from MODIS

Lian Feng, Chuanmin Hu, Xiaoling Chen, Qingjun Song

Research output: Contribution to journalArticlepeer-review

Abstract

<p> <p id="x-x-sp0005"> Several studies showed the linkage of the Three Gorges Dam to the downstream coastal ecosystem in the East China Sea, yet its potential influence on the total suspended matters (TSM) in the Yangtze <a title="Learn more about Estuary from ScienceDirect's AI-generated Topic Pages"> Estuary </a> and its adjacent coastal waters has not been reported, possibly due to technical difficulties in obtaining statistically meaningful results. Here, a new <a title="Learn more about Remote Sensing from ScienceDirect's AI-generated Topic Pages"> remote sensing </a> algorithm was established to estimate TSM from <a title="Learn more about MODIS from ScienceDirect's AI-generated Topic Pages"> MODIS </a> observations over the Yangtze Estuary and its adjacent coastal waters. The algorithm was based on a piecewise regression between TSM and <a title="Learn more about Surface Reflectance from ScienceDirect's AI-generated Topic Pages"> surface reflectance </a> at 645 and 869 nm, leading to RMS uncertainties of only 20&ndash;30% for TSM between 2 mg L <sup> &minus; 1 </sup> and 1762 mg L <sup> &minus; 1 </sup> . The algorithm was applied to MODIS data to derive TSM distribution maps from 2000 to 2010 at 250 m resolution, which revealed significant spatial and temporal (seasonal and inter-annual) variability. Mean TSM in the Yangtze Estuary increased from 44.4 &plusmn; 34.1 mg L <sup> &minus; 1 </sup> in May to 96.0 &plusmn; 58.0 mg L <sup> &minus; 1 </sup> in October, while much higher TSM was found in the nearby Hangzhou Bay (between 100.3 &plusmn; 51.6 mg L <sup> &minus; 1 </sup> in August and 290.2 &plusmn; 120.0 mg L <sup> &minus; 1 </sup> in February). Two regions showed significantly out-of-phase <a title="Learn more about Seasonality from ScienceDirect's AI-generated Topic Pages"> seasonality </a> : region A1 in the Yangtze Estuary driven by sediment discharge from the Yangtze River and region A2 in offshore waters and part of Hangzhou Bay driven by winds. The annual mean TSM in region A1 showed significantly decreasing trend in the 11-year period (&minus; 2.8 mg L <sup> &minus; 1 </sup> /yr), which appeared to be caused by the construction of the TGD. The study also has established a TSM environmental data record (EDR) to assess future TSM in the ecologically and economically important Yangtze Estuary and Hangzhou Bay. </p></p>
Original languageAmerican English
JournalRemote Sensing of Environment
Volume140
DOIs
StatePublished - Jan 1 2014

Keywords

  • Yangtze Estuary
  • Hangzhou Bay
  • TSM
  • MODIS
  • Turbidity
  • Three Gorges Dam
  • Yangtze River
  • Environmental data record

Disciplines

  • Life Sciences

Cite this