Variations in waste load allocations through sensitivity analysis of the QUAL-II water quality model on the South River, Virginia

Abstract

Sensitivity analysis was performed on the QUAL-II water quality model. The reaeration rate, the ammonia nitrogen oxidation rate, and the carbonaceous deoxygenation coefficient were found to be highly sensitive in the model. Only moderate sensitivity was found with the areal flow contribution, the oxidation rate of nitrite nitrogen, and the organic nitrogen reaction rate. Through the ranges tested, the combined effect of the BOD settling rate and the benthos source rate were found to be insensitive. Based on the projected variations within the most sensitive variables, resultant waste load allocations were found to be too variable for adequate application towards treatment requirements. It is also postulated that due to the complexity of the dissolved oxygen balance within the South River, Virginia, that a revised algal subroutine must be incorporated in the model's application to that system.