Spatiotemporal Variation of Turbidity Based on Landsat 8 OLI in Cam Ranh Bay and Thuy Trieu Lagoon, Vietnam
Spatiotemporal Variation of Turbidity Based on Landsat 8 OLI in Cam Ranh Bay and Thuy Trieu Lagoon, Vietnam
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DOI：
10.3390/w9080570
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发表时间：
2017-08
期刊：
影响因子：
3.4
通讯作者：
N. Quang;J. Sasaki;Hiroto Higa;N. V. Huan
中科院分区：
文献类型：
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作者：
N. Quang;J. Sasaki;Hiroto Higa;N. V. Huan
近年来，金兰湾和翠礁湖的海草床从800公顷减少到550公顷，导致鱼类捕捞数量没有明显减少。这种现象是由于水环境退化的影响。浊度是直接关系到水下光穿透的重要水质参数之一，影响着初级生产力。本研究旨在利用遥感数据研究水域浊度的时空变化及其主要影响因素。基于原位测量值与Landsat 8 OLI红色波段的相关性，建立了一种浊度反演算法，R2 = 0.84 （p < 0.05）。采用模拟近岸波浪（SWAN）模型对影响浅水浊度的主要因素床层剪切应力进行了计算。此外，还分析了浊度与降雨、风引起的河床剪应力之间的关系。结果表明：(1)干季海湾中部浊度低，沿岸浅水浊度高；无雨期河床沉积物的再悬浮是控制浊度的主要因素。(2)在雨季或旱季降雨后短时间内，由于大量径流进入研究区，浊度较高。
In recent years, seagrass beds in Cam Ranh Bay and Thuy Trieu Lagoon have declined from 800 to 550 hectares, resulting insignificantly reducing the number of fish catch. This phenomenon is due to the effect of the degradation of water environment. Turbidity is one of the most important water quality parameters directly related to underwater light penetration which affects the primary productivity. This study aims to investigate spatiotemporal variation of turbidity in the waters with major factors affecting its patterns using remote sensing data. An algorithm for turbidity retrieval was developed based on the correlation between in situ measurements and a red band of Landsat 8 OLI with R2 = 0.84 (p < 0.05). Simulating WAves Nearshore (SWAN) model was used to compute bed shear stress, a major factor affecting turbidity in shallow waters. In addition, the relationships between turbidity and rainfall, and bed shear stress induced by wind were analyzed. It was found that: (1) In the dry season, turbidity was low at the middle of the bay while it was high in shallow waters nearby coastlines. Resuspension of bed sediment was a major factor controlling turbidity during time with no rainfall. (2) In the rainy season or for a short time after rainfall in the dry season, turbidity was high due to a large amount of runoff entering into the study area.