Abstract
Three models were compared on simulating NO3--N stream water solute concentration and estimating annual NO3--N load from a forested watershed. These models are (1) tank-model C-Q method, (2) tank-model concentration coefficient method, and (3) solute runoff tank-model. The models based on the same rainfall runoff tank-model developed by authors, have different methods for calculating stream-water NO3--N concentration.
As a result of applying each model to the data observed in the experimental forested watershed, solute runoff tank-model was most excellent in the reproducibility of the seasonal variation of stream water solute concentration. However, the remarkable difference in calculation result of annual runoff load in each model did not appear. It was cleared that the accuracy of rainfall runoff model is the most important in calculation of runoff load from a forested watershed.
