Integrated versus isolated scenario for prediction dissolved oxygen at progression of water quality monitoring stations

A. Najah, A. El-Shafie, Othman A. Karim, Othman Jaafar

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

This study examined the potential of Multi-layer Perceptron Neural Network (MLP-NN) in predicting dissolved oxygen (DO) at Johor River Basin. The river water quality parameters were monitored regularly each month at four different stations by the Department of Environment (DOE) over a period of ten years, i.e. from 1998 to 2007. The following five water quality parameters were selected for the proposed MLP-NN modelling, namely; temperature (Temp), water pH, electrical conductivity (COND), nitrate (NO3) and ammonical nitrogen (NH3-NL). In this study, two scenarios were introduced; the first scenario (Scenario 1) was to establish the prediction model for DO at each station based on five input parameters, while the second scenario (Scenario 2) was to establish the prediction model for DO based on the five input parameters and DO predicted at previous station (upstream). The model needs to verify when output results and the observed values are close enough to satisfy the verification criteria. Therefore, in order to investigate the efficiency of the proposed model, the verification of MLP-NN based on collection of field data within duration 2009-2010 is presented. To evaluate the effect of input parameters on the model, the sensitivity analysis was adopted. It was found that the most effective inputs were oxygen-containing (NO3) and oxygen demand (NH3-NL). On the other hand, Temp and pH were found to be the least effective parameters, whereas COND contributed the lowest to the proposed model. In addition, 17 neurons were selected as the best number of neurons in the hidden layer for the MLP-NN architecture. To evaluate the performance of the proposed model, three statistical indexes were used, namely; Coefficient of Efficiency (CE), Mean Square Error (MSE) and Coefficient of Correlation (CC). A relatively low correlation between the observed and predicted values in the testing data set was obtained in Scenario 1. In contrast, high coefficients of correlation were obtained between the observed and predicted values for the test sets of 0.98, 0.96 and 0.97 for all stations after adopting Scenario 2. It appeared that the results for Scenario 2 were more adequate than Scenario 1, with a significant improvement for all stations ranging from 4 % to 8 %.

Original languageEnglish
Pages (from-to)2693-2708
Number of pages16
JournalHydrology and Earth System Sciences
Volume15
Issue number8
DOIs
Publication statusPublished - 2011

Fingerprint

dissolved oxygen
water quality
prediction
oxygen
monitoring station
electrical conductivity
sensitivity analysis
river water
parameter
water temperature
conductivity
river basin
station
nitrate
nitrogen
modeling
temperature

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Water Science and Technology

Cite this

Integrated versus isolated scenario for prediction dissolved oxygen at progression of water quality monitoring stations. / Najah, A.; El-Shafie, A.; A. Karim, Othman; Jaafar, Othman.

In: Hydrology and Earth System Sciences, Vol. 15, No. 8, 2011, p. 2693-2708.

Research output: Contribution to journalArticle

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