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Prediction of daily chlorophyll a concentration in rivers by water quality parameters using an efficient data driven model: online sequential extreme learning machine

Alizamir Meysam, Heddam Salim, Kim Sungwon, Gorgij Alireza Docheshmeh, Li Peiyue, Ahmed Kaywan Othman, Singh Vijay P.

Acta Geophysica

2021

Vol. 69, no. 6

2339--2361

One of the main concerns of environmental and ecological managers for rivers, lakes, reservoirs, and marine ecosystems is developing a reliable and efficient predictive model for chlorophyll a concentration. In this study, the online sequential extreme learning machine, M5 Prime tree, multilayer perceptron artificial neural network, response surface methodology, and multivariate adaptive regression spline models were investigated for daily chlorophyll a concentration prediction by assessing the relations between Chl-a and several water quality parameters, including water temperature, pH, specific conductance, and turbidity. Different scenarios based on TE, pH, SC, and TU were defined. Also, this study evaluated the influence of periodicity input as the last scenario to obtain more accurate predictions of Chl-a values. Daily data measured for 2009–2019 from USGS no. 14207200 and USGS no. 14211720 stations were used. For assessing the prediction performance of the proposed techniques, three different objective indicators were employed, namely RMSE, R2 , and NSE. Moreover, the Taylor diagram was employed for evaluating the accuracy and generalization capability of the applied models for the prediction of Chl-a. Results indicated that OS-ELM with input parameters of TE, pH, SC, TU, Y (year), M (month), and D (day) showed higher accuracy in predicting Chl-a with RMSE of 3.151, NSE of 0.798, and R of 0.894 for USGS no. 14207200 and with RMSE of 0.907, NSE of 0.820, and R of 0.912 for USGS no. 14211720 than the other models, respectively. Additionally, MLPNN ranked as the second best method for the estimation of Chl-a values at both stations. As an interesting point, it was quite evident that adding periodicity as an input parameter could significantly enhance the performance of all models in predicting the daily Chl-a concentration at both stations. Results proved that OS-ELM models can be a reliable tool for the prediction of the Chl-a values in aquatic environments, benefiting ecological and environmental management, and algal bloom control.

Novel hybrid approaches based on evolutionary strategy for streamfow forecasting in the Chellif River, Algeria

Zakhrouf Mousaab, Bouchelkia Hamid, Stamboul Madani, Kim Sungwon

Acta Geophysica

2020

Vol. 68, no. 1

167--180

In this study, the feedforward neural networks (FFNNs) were proposed to forecast the multi-day-ahead streamfow. The parameters of FFNNs model were optimized utilizing genetic algorithm (GA). Moreover, discrete wavelet transform was utilized to enhance the accuracy of FFNNs model’s forecasting. Therefore, the wavelet-based feedforward neural networks (WFFNNs-GA) model was developed for the multi-day-ahead streamfow forecasting based on three evolutionary strategies [i.e., multi-input multi-output (MIMO), multi-input single-output (MISO), and multi-input several multi-output (MISMO)]. In addition, the developed models were evaluated utilizing fve diferent statistical indices including root mean squared error, signal-to-noise ratio, correlation coefcient, Nash–Sutclife efciency, and peak fow criteria. Results provided that the statistical values of WFFNNs-GA model based on MISMO evolutionary strategy were superior to those of WFFNNs-GA model based on MISO and MIMO evolutionary strategies for the multi-day-ahead streamfow forecasting. Results indicated that the performance of WFFNNs-GA model based on MISMO evolutionary strategy provided the best accuracy. Results also explained that the hybrid model suggested better performance compared with stand-alone model based on the corresponding evolutionary strategies. Therefore, the hybrid model can be an efcient and robust implement to forecast the multi-day-ahead streamfow in the Chellif River, Algeria.