Influence of the Three Gorges Dam on total suspended matters in the Yangtze Estuary and its adjacent coastal waters: Observations from MODIS
Influence of the Three Gorges Dam on total suspended matters in the Yangtze Estuary and its adjacent coastal waters: Observations from MODIS
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DOI：
10.1016/j.rse.2013.10.002
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发表时间：
2014-01-01
影响因子：
13.5
通讯作者：
Song, Qingjun
中科院分区：
文献类型：
--
作者：
Feng, Lian;Hu, Chuanmin;Song, Qingjun
已有研究表明三峡大坝对东海下游沿岸生态系统的影响，但三峡大坝对长江口及其邻近沃茨海域总悬浮物（TSM）的潜在影响尚未见报道，这可能是由于获取有统计意义的结果存在技术困难。本文提出了一种利用长江口及其邻近沃茨海域的MODIS遥感数据估算TSM的新算法。该算法是基于TSM和表面反射率在645和869 nm之间的分段回归，导致2 mg L-1和1762 mg L-1之间的TSM的RMS不确定性仅为20-30%。该算法被应用到中分辨率成像光谱仪数据，以获得TSM分布图，从2000年至2010年在250米的分辨率，揭示了显着的空间和时间（季节和年际）的变化。长江口的平均TSM从5月的44.4 +/- 34.1 mg L-1增加到10月的96.0 +/- 58.0 mg L-1，而附近的杭州湾的TSM要高得多（8月为1003 +/- 51.6 mg L-1，2月为290.2 +/- 120.0 mg L-1）。两个区域表现出明显的反相季节性：A1区域位于长江口，受长江输沙的驱动; A2区域位于杭州湾近岸沃茨和部分海域，受风的驱动。A1区的年平均TSM在11年期间呈显著下降趋势（-2.8 mgL（-1）/yr），这可能是TGD建设的结果。本研究还建立了一个TSM环境数据记录（EDR），以评估具有重要生态和经济意义的长江口和杭州湾未来的TSM。(C)2013 Elsevier Inc. All rights reserved.
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 Estuary and its adjacent coastal waters has not been reported, possibly due to technical difficulties in obtaining statistically meaningful results. Here, a new remote sensing algorithm was established to estimate TSM from MODIS observations over the Yangtze Estuary and its adjacent coastal waters. The algorithm was based on a piecewise regression between TSM and surface reflectance at 645 and 869 nm, leading to RMS uncertainties of only 20-30% for TSM between 2 mg L-1 and 1762 mg L-1. 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 +/- 34.1 mg L-1 in May to 96.0 +/- 58.0 mg L-1 in October, while much higher TSM was found in the nearby Hangzhou Bay (between 1003 +/- 51.6 mg L-1 in August and 290.2 +/- 120.0 mg L-1 in February). Two regions showed significantly out-of-phase seasonality: 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 (-2.8 mgL(-1)/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. (C) 2013 Elsevier Inc. All rights reserved.