Remote Estimation of Water Clarity and Suspended Particulate Matter in Qinghai Lake from 2001 to 2020 Using MODIS Images

Climate change and human activities have been heavily affecting oceanic inland waters, it is critical to a comprehensive understanding of the aquatic optical properties lakes. Since many key watercolor parameters Qinghai Lake are not yet available, this paper aims study spatial temporal variations water clarity (i.e., Secchi-disk depth, ZSD) suspended particulate matter concentration (CSPM) in from 2001 2020 using MODIS images. First, four atmospheric correction models, including NIR–SWIR, MUMM, POLYMER, C2RCC were tested. The NIR–SWIR with decent accuracy all bands was chosen for experiment. Then, existing models ZSD six CSPM evaluated. Two semi-analytical proposed by Lee (2015) Jiang (2021) selected (R2 = 0.74) 0.73), respectively. Finally, distribution variation derived over past 20 years. Overall, quite clear: monthly mean 5.34 ± 1.33 m, 2.05 1.22 mg/L. Further analytical results reveal that highly correlated, relationship can be formulated ZSD=8.072e−0.212CSPM 0.65). Moreover, turbid mainly exists along edge Lake, especially on northwestern northeastern shores. lakeshore exhibits some irregularity, while main area lake experiences mild quality deterioration. Statistically, 81.67% total dominated constantly increased CSPM, decreased occupies 4.56%. There has distinct seasonal deterioration non-frozen period (from May October). broadly deteriorated 2008. year 2008 witnessed sudden improvement, after that, experienced an extremely inconspicuous degradation. This fill gap regarding long-time monitoring expected provide scientific reference protection management lake.