This study aimed to develop a reliable turbidity model to assess reservoir turbidity based on Landsat-8 satellite imagery. Models were established by multiple linear regression (MLR) and gene-expression programming (GEP) algorithms. Totally 55 and 18 measured turbidity data from Tseng-Wen and Nan-Hwa reservoir paired and screened with satellite imagery. Finally, MLR and GEP were applied to simulated 13 turbid water data for critical turbidity assessment. The coefficient of determination (R 2 ), root mean squared error (RMSE), and relative RMSE (R-RMSE) calculated for model performance evaluation. The result show that, in model development, MLR and GEP shows a similar consequent. However, in model testing, the R 2 , RMSE, and R-RMSE of MLR and GEP are 0.7277 and 0.8278, 0.7248 NTU and 0.5815 NTU, 22.26% and 17.86%, respectively. Accuracy assessment result shows that GEP is more reasonable than MLR, even in critical turbidity situation, GEP is more convincible. In the model performance evaluation, MLR and GEP are normal and good level, in critical turbidity condition, GEP even belongs to outstanding level. These results exhibit GEP denotes rationality and with relatively good applicability for turbidity simulation. From this study, one can conclude that GEP is suitable for turbidity modeling and is accurate enough for reservoir turbidity estimation. artificial neural networks, supper vector machine (SVM), random forest (RF), partial least squares (PLS), and principal components regression (PCR) . However, the empirical relation and observation method used to test different data with various temporal and spatial backgrounds or different measuring instruments, the results of reservoir turbidity estimation are considerably different from those of the original research area [35]. The accuracy of the simulated turbidity by the empirical equation is also influenced by the algorithms. Chang et al., using the high-resolution spectral image obtained from Formosat-2 satellite imagery have a resolution of 8 m and the SSC data of 53 mud samples, the empirical relation that is established using the stepwise regression method exhibit the R 2 of 0.84 and the relative-RMSE (R-RMSE) of 31%, however, in the case of data validation and testing, R-RMSE improved to 43%, indicating that the empirical relation between the remote sensing imagery and the water quality observations exhibited a considerable degree of error. Therefore, the rationality and applicability of the integrated assessment for relevant research related to the water quality estimation of remote sensing imagery can be improved if the simulated turbidity accuracy is improved and the difference is reduced [36]. Based on the large-area and high-repetition remote sensing imagery and the measured turbidity, this study would like to provide a simulation algorithm for the one who cannot obtain an ideal result in typical algorithms for reservoir turbidity estimation.
Materials and MethodsThis study refers to Quang, N. H. et al., adopted the high-resolution multi-spectrum satell...