Unveiling the outcome of multispectral indices in evaluating total suspended solid of water quality

Abstract

Constant monitoring of TSS in water body remains essential to avoid excessive suspended sediment that can damage water quality. This study examines TSS as a visible indicator of water quality parameter in Hartbeespoort Dam located in the Northwest of South Africa. The study employed multi-spectral spatial bands of Landsat 8–9 (OLI & TIR) and MSI of Sentinel-2A and 2B. Band combination indices such as NDSSI, WRSI was utilized respectively using Landsat 8–9 and MSI Sentinel 2. Nechad TSS algorithm and Automated Water Extraction Index (AWEI) was also utilized with green band and red band of Landsat 8–9 and Sentinel 2 to further understand the concentration of suspended solid. The values derived was correlated with real time in-situ data measurement. NDSSI mapping of TSS showed high values range of 0.895 (suspended solid) while WRSI in Sentinel 2 spatial band showed highest value of 0.551 (suspended solid). The regression analysis utilizes Linear, Exponential and polynomial equation to validate with the in-suit data measurement. The result revealed a strong correlation such as (NDSSI and in-suit =(R2 = 0.54) in polynomial equation, WRSI and in-suit = (R2 = 0.71) in exponential regression, Nechad algorithm and in-suit = (R2 = 0.54) in polynomial regression and AWEI with in-suit = (R2 = 0.71) in exponential regression. The value derived from Nechad TSS algorithm and AWEI confirmed the capacity of NDSSI indices in Landsat 8–9 and WRSI in Sentinel 2 remote sensor.