Sensitivity analysis applied to a water quality model for dissolved oxygen. Application to an irrigation channel in Valencian Community, Spain
This paper presents the sensitivity analysis developed with a mathematical model for Dissolved Oxygen over an irrigation channel in Valencia Community, Spain. This channel transports water from agricultural irrigation, wastewater and industrial discharges, and the processes of dispersion, transport and interaction between the water constituents have been studied.
The Dissolved Oxygen (DO) model, developed in finite differences, integrates the Nitrogen cycle and the BOD study within the DO equations. As a result, we can evaluate the concentration of every constitutent in the system. We can make also an estimation of the influence of each parameter in the comparison between the data given by the model and the collected data in the real channel. The results have been contrasted with other mathematical surface water model such as QUAL2E.
The results have been calibrated with data collected in the channel during a measurement campaign, and in the process of calibration, the sensitivity analysis has been used as a tool for optimising this verification process. The study has pointed out the more influencing parameters in the concentrations over the whole system, and the optimum methodology for calibrating the model, which can be used also in unsteady state pollution situations and in branched systems. As a conclusion we show the results of the sensitivity analysis comparing the more important factors influencing the concentration of DO, BOD, Organic Nitrogen, Nitrite and Nitrate and the calibration methodology for this case.