Water clarity is the most common indicator of water quality. The purpose of the study was to develop an instrument which can automatically measure water clarity in place of manual measurement by Secchi disk. The instrument is suspended by buoys at the water surface and uses solar energy to measure the light intensity of LED bulbs after passing through a water column; the result is then converted to Secchi depth by using a regression function. Measurement data are stored in a cloud server so that mobile users can access via an Internet connection. Three experiments were conducted to examine the instrument performance: (i) to ensure light intensity of the LED bulbs is strong enough to pass through the water column; (ii) to determine the regression relationship between the measured light intensity of the instrument and Secchi depth; and (iii) to evaluate the coefficient of variation (CV) of the measured water clarity when using our instrument and a conventional Secchi disk. Experiment results show that the measured values of light intensity are stable with the average CV = 5.25%. Moreover, although there are slight differences between the Secchi depth measured by our instrument and those measured by Secchi disk, the measurements by our instrument can efficiently replace the measurements by conventional Secchi disk, which can be affected by weather conditions as well as by human subjectivity.

中文翻译：

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基于太阳能的基于IoT的水透明度自动测量仪的开发。

水的透明度是水质的最常见指标。研究的目的是开发一种仪器，该仪器可以自动测量水的透明度，而不是通过Secchi磁盘进行手动测量。该仪器被浮标悬挂在水面上，并利用太阳能测量穿过水柱后的LED灯泡的光强度。然后使用回归函数将结果转换为Secchi深度。测量数据存储在云服务器中，以便移动用户可以通过Internet连接进行访问。进行了三个实验以检查仪器的性能：（i）确保LED灯泡的光强度足以穿过水柱；（ii）确定所测量的仪器的光强度与塞基深度之间的回归关系；（iii）使用我们的仪器和传统的Secchi圆盘评估所测得的水澄清度的变异系数（CV）。实验结果表明，光强度的测量值是稳定的，平均CV = 5.25％。此外，尽管我们的仪器测量的Secchi深度与Secchi磁盘测量的深度之间存在细微差异，但我们的仪器测量可以有效替代传统Secchi磁盘的测量，因为传统的Secchi磁盘可能会受到天气条件以及人类主观性的影响。