Estimation of reservoir bio-optical water quality parameters using smartphone sensor Apps and landsat ETM+: Review and comparative experimental results

Abstract

This study presents a comparative evaluation of three real-time imaging-based approaches for the prediction of optically active water constituents as chlorophyll- a (Chl- a ), turbidity, suspended particulate matter (SPM), and reservoir water colour. The imaging models comprise of Landsat ETM+-visible and NIR (VNIR) data and EyeOnWater and HydroColor Smartphone sensor apps. To estimate the selected water quality parameters (WQP) from Landsat ETM+-VNIR, predictive models based on empirical relationships were developed. From the in situ measurements and the Landsat regression models, the results from the remote re fl ectances of ETM+ green, blue, and NIR independently yielded the best fi ts for the respective predictions of Chl- a , turbidity, and SPM. The concentration of Chl- a was derived from the Landsat ETM+ and HydroColor with respective Pearson correlation coe ffi cients r of 0.8977 and 0.8310. The degree of turbidity was determined from Landsat, EyeOnWater, and HydroColor with respective r values of 0.9628, 0.819, and 0.8405. From the same models, the retrieved SPM was regressed with the laboratory measurements with r value results of 0.6808, 0.7315, and 0.8637, respectively, from Landsat ETM+, EyeOnWater, and HydroColor. The empirical study results showed that the imaging models can be e ff ectively applied in the estimation of the physical WQP.