Assessing and forecasting water quality in the Danube River by using neural network approaches

Puiu-Lucian Georgescu; Simona Moldovanu; Catalina Iticescu; Madalina Calmuc; Valentina Calmuc; Catalina Topa; Luminita Moraru

doi:10.1016/j.scitotenv.2023.162998

Assessing and forecasting water quality in the Danube River by using neural network approaches

Sci Total Environ. 2023 Jun 25:879:162998. doi: 10.1016/j.scitotenv.2023.162998. Epub 2023 Mar 24.

Authors

Puiu-Lucian Georgescu¹, Simona Moldovanu², Catalina Iticescu¹, Madalina Calmuc¹, Valentina Calmuc¹, Catalina Topa¹, Luminita Moraru³

Affiliations

¹ Faculty of Sciences and Environment, Department of Chemistry, Physics and Environment, "Dunarea de Jos" University of Galati, 47 Domneasca Street, 800008, Romania; REXDAN Research Infrastructure, "Dunarea de Jos" University of Galati, 98 George Cosbuc Street, 800385 Galati, Romania.
² Department of Computer Science and Information Technology, Faculty of Automation, Computers, Electrical Engineering and Electronics, "Dunarea de Jos" University of Galati, 47 Domneasca Street, 800008 Galati, Romania; The Modelling & Simulation Laboratory SMlab, "Dunarea de Jos" University of Galati, 47 Domneasca Street, 800008 Galati, Romania.
³ Faculty of Sciences and Environment, Department of Chemistry, Physics and Environment, "Dunarea de Jos" University of Galati, 47 Domneasca Street, 800008, Romania; The Modelling & Simulation Laboratory SMlab, "Dunarea de Jos" University of Galati, 47 Domneasca Street, 800008 Galati, Romania. Electronic address: luminita.moraru@ugal.ro.

PMID: 36966845
DOI: 10.1016/j.scitotenv.2023.162998

Abstract

The health and quality of the Danube River ecosystems is strongly affected by the nutrients loads (N and P), degree of contamination with hazardous substances or with oxygen depleting substances, microbiological contamination and changes in river flow patterns and sediment transport regimes. Water quality index (WQI) is an important dynamic attribute in the characterization of the Danube River ecosystems health and quality. The WQ index scores do not reflect the actual condition of water quality. We proposed a new forecast scheme for water quality based on the following qualitative classes very good (0-25), good (26-50), poor (51-75), very poor (76-100) and extremely polluted/non-potable (>100). Water quality forecasting by using Artificial Intelligence (AI) is a meaningful method of protecting public health because of its possibility to provide early warning regarding harmful water pollutants. The main objective of the present study is to forecast the WQI time series data based on water physical, chemical and flow status parameters and associated WQ index scores. The Cascade-forward network (CFN) models, along with the Radial Basis Function Network (RBF) as a benchmark model, were developed using data from 2011 to 2017 and WQI forecasts were produced for the period 2018-2019 at all sites. The nineteen input water quality features represent the initial dataset. Moreover, the Random Forest (RF) algorithm refines the initial dataset by selecting eight features considered the most relevant. Both datasets are employed for constructing the predictive models. According to the results of appraisal, the CFN models produced better outcomes (MSE = 0.083/0,319 and R-value 0.940/0.911 in quarter I/quarter IV) than the RBF models. In addition, results show that both the CFN and RBF models could be effective for predicting time series data for water quality when the eight most relevant features are used as input variables. Also, the CFNs provide the most accurate short-term forecasting curves which reproduce the WQI for the first and fourth quarters (the cold season). The second and third quarters presented a slightly lower accuracy. The reported results clearly demonstrate that CFNs successfully forecast the short-term WQI as they may learn historic patterns and determine the nonlinear relationships between the input and output variables.

Keywords: Danube River; Neural network model; Spatial-temporal analysis; WQI forecast; Water quality.