Optimal development of calibration equations for paired catchment projects

Abstract

Data from two Australian paired-catchment projects were used to assess the effect of length of the calibration period on the quality of calibration achieved. The data were divided into a "calibration" and a "verification" set. The Nash-Sutcliffe (N-S) coefficient of efficiency was used to assess the quality of prediction of the verification set as a function of the length of the calibration set. The results showed a rapid initial increase in quality of calibration with increasing calibration length. This then "plateaued". With simple linear regression models, reasonable calibration (N-S > 0.7) was achieved in 60 days and good calibration (N-S > 0.8) in 100 days. More complex models achieved ..