Changes of Water Turbidity in Liangzi Lake Based on Multi-temporal Remote Sensing

Water turbidity is a crucial indicator of aquatic environment as it directly reflects water quality. Taking Liangzi Lake as the research object, this paper utilized Aqua MODIS remote sensing data from 2003 to 2021 on the Google Earth Engine (GEE) remote sensing cloud computing platform to invert the water turbidity of the Liangzi lake and analyze its spatiotemporal variation characteristics. Results indicate the following: (1) Liangzi Lake features higher water turbidity in winter and spring than in summer and autumn, with turbidity exceeding 30 NTU in winter and spring and below 20 NTU in summer and autumn.(2) The water turbidity of Liangzi Lake has gradually decreased in recent years. Before 2011, the average water turbidity was approximately 30 NTU, with significant spatial variation. Areas close to land had a higher turbidity of about 50 NTU compared to the average. After 2011, the average water turbidity gradually decreased to about 25 NTU, with areas close to land experiencing a notable decrease to approximately 30 NTU. (3) The water turbidity of Liangzi Lake is correlated with land cover types within the Liangzi Lake Protected Area, with the green area having the greatest impact with a correlation coefficient of -0.63. Larger green areas correspond to lower turbidity. Over the past ten years, the overall water turbidity of Liangzi Lake has decreased from 30 NTU to 25 NTU, a reduction of 16.67%, indicating significant achievements in the management and improvement of Liangzi Lake.