To sustain a healthy ecosystem, continuous monitoring of the water quality is vital. Ocean colour remote sensing is an important tool to carry out such studies. Thus, chlorophyll-a (Chl-a), chromophoric dissolved organic matter (aCDOM440), turbidity (T) and sea surface temperature (SST), among others, have been considered in the present study to evaluate the water quality of the Cochin Backwaters, a tropical estuary along the southwest coast of India. Landsat 8/OLI data have been used to derive the water quality parameters (WQP), and seasonal averages have been estimated to study the variations occurring in the area during 2014–2018. These were then plotted against the river runoff occurring in the area to find out its impact upon the said parameters. The results showed that the aCDOM440 and Chl-a concentrations were related to the runoff of the area as both the parameters were at their peaks during the southwest monsoon season with values approximately more than 1.6 m−1 and 5.6 mg/m3, respectively. However, in the other seasons, aCDOM440 was not seen to directly correspond with the runoff in the area. Turbidity was observed to be the highest during the spring inter-monsoon season (SIM) with values reaching more than 60 FNU. As far as the surface temperature of the estuary is concerned, it was found to be around ~ 25 °C for most parts of the year, except for the southwest monsoon season when the temperature dropped below 25 °C. Interannual variability of the WQP showed that they were at their highest in 2014 followed by 2016, 2017 and 2018, while the year 2015 had the lowest concentration. The study also brings out the utility of ocean colour remote sensing products as an alternative to study the Indian coastal and estuarine waters.

中文翻译：

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基于卫星的印度西南海岸热带河口水质参数季节性变化研究

为了维持健康的生态系统，持续监测水质至关重要。海洋颜色遥感是开展此类研究的重要工具。因此，本研究考虑了叶绿素 a (Chl-a)、发色溶解有机物 (aCDOM440)、浊度 (T) 和海面温度 (SST) 等来评估科钦回水的水质，印度西南海岸的热带河口。Landsat 8/OLI 数据已用于推导水质参数 (WQP)，并估算了季节性平均值以研究 2014-2018 年期间该地区发生的变化。然后根据该地区发生的河流径流绘制这些图，以找出其对上述参数的影响。结果表明，aCDOM440 和 Chl-a 浓度与该地区的径流有关，因为这两个参数在西南季风季节都处于峰值，值分别超过 1.6 m-1 和 5.6 mg/m3。然而，在其他季节，没有看到 aCDOM440 与该地区的径流直接对应。据观察，春季季风间期 (SIM) 的浊度最高，值达到 60 FNU 以上。就河口地表温度而言，除西南季风季节气温降至25°C以下外，全年大部分时间都在~25°C左右。WQP 的年际变化表明，它们在 2014 年最高，其次是 2016 年、2017 年和 2018 年，而 2015 年浓度最低。