Remote Sensing Retrieval of Water Transparency for Pingzhai Reservoir Based on Sentinel-2 Images

Abstract

[Objective] The variation rule of water transparency and the driving factors of its spatial differentiation were analyzed in order to provide a scientific basis for the management of lake reservoirs and the restoration of lake reservoir ecosystems. [Methods] A remote sensing inversion model of water transparency in Pingzhai reservoir was constructed based on sentinel-2 MSI satellite images and quasi-synchronous measured transparency data collected on May 18, August 26, and November 14, 2020. We quantitatively analyzed the drivers affecting spatial differentiation of water transparency using the GeoDetector package in R. [Results] ① The water transparency of Pingzhai reservoir was most sensitive to the B3 band of Sentinel-2 MSI, and the transparency inversion model constructed by using the band combination B3×B4 as the most sensitive factor had high accuracy (R2=0.81, RMSE=0.11 m, MRE=16.91%). ② The water transparency of Pingzhai reservoir showed a spatial distribution trend of high in the central reservoir area, low in the upstream region of each tributary, and low on both sides of the near water body. Water transparency was greatest in November followed by August and then May. [Conclusion] The contents of total suspended solids, chlorophyll a, and total organic carbon were the main factors affecting the spatial differentiation of water transparency in Pingzhai reservoir. Total phosphorus, total nitrogen, water temperature, and wind speed affected the spatial distribution of water transparency by affecting the content of total suspended solids, chlorophyll a, and total organic carbon in the water.

Keywords

• water transparency
• sentinel-2 msi
• remote sensing retrieved
• geodetector
• pingzhai reservoir