Modeling and sensitivity analysis of water quality in Meymeh reservoir using CE-QUAL-W2 Software

Water quality of lakes and reservoirs is affected by many factors. Precipitation, inflow and outflow, inlet water quality and water abstraction level are the most important ones. Informing about the magnitude of the factors can help us to choose the best abstraction level and water quality management in different periods of a year, efficiently.

In this study, water quality of the Meymeh reservoir, an under-construction dam, was evaluated by modeling of TDS using the 2-dimensional CE-QUAL-W2 software with available data, for a 5-year period.

The modeling results show that the amount of outflow TDS in all five years has exceeded the FAO permissible level for irrigation. Also, in order to evaluate the impacts of several factors on outflow TDS and choose the suitable solution to improve the quality of water, a sensitively analysis was performed. Discussion and Counclution: The results of the sensitivity analysis showed that the quality of inflow water is the most effective factor on the outflow water quality, so that a 20% change in inflow TDS causes 18-20% change in outflow TDS and the other factors such as temperature, initial values of TDS in reservoir, wind sheltering coefficients (WSC), eddy viscosity and the diffusivity coefficient (AX, DX) do not have significant impacts.