Reservoir water-quality simulation using simplified mathematical models (case study: Seymareh Reservoir)

In this research, the performance of simple mathematical models was evaluated for predicting total dissolved solids (TDS), biochemical oxygen demand (BOD) and nitrate (NO3-) in a case study, the Seymareh Reservoir located in the south-west of Iran. The accuracy of the mathematical models was compared with a two-dimensional model, called CE-Qual-W2, and real observations. The models were considered as two different input-data scenarios and one scenario for applied mathematical equations (completely mixed reactor). The modelling period was from October 2012 to September 2013. The results of the simple mathematical models show an acceptable performance with the mean relative error (MRE) of 10.8-73.8 compared with the complex CE-Qual-W2 model, whereas they require fewer input data and take less time to execute. To verify the accuracy of the equations, the results were also compared with the sampling data from the reservoir. The best performance of the proposed mathematical models showed a MRE of similar to 10.8%, 31.5% and 16.5% for TDS, BOD and NO3- respectively. These findings suggest using such simple models for screening/feasibility studies and also to model water quality in several dams across the basin to save time and cost.