Formulation of Wavelet Based Multi‐Scale Multi‐Objective Performance Evaluation (WMMPE) Metric for Improved Calibration of Hydrological Models
Velpuri Manikanta, Vamsi Krishna Vema
Abstract
Abstract Estimation of the hydrological model parameters, known as model calibration, is an important step in application of these models for various water resources problems. In the auto‐calibration approach, the match between the simulated and observed variables is assessed using the statistical performance measures, which are used as objective functions. Earlier studies show that the use of traditional single‐objective functions alone cannot capture all the features of the hydrographs, motivating the utilization of multi‐objective calibration. Further, wavelet‐based approaches can capture features that occur at different time scales. In this study, Wavelet Transforms are employed to formulate a Wavelet based Multi‐Scale Multi‐Objective Performance Evaluation (WMMPE) metric that combines multiple standard metrics at multiple time scales. The performance of WMMPE along with other objective functions such as Nash Sutcliffe Efficiency (NSE), Kling Gupta Efficiency (KGE)), Euclidean distance based Multi Objective Calibration Function and wavelet based Multi‐Scale NSE in calibrating two conceptual hydrologic models were tested on 53 watersheds. The performance of the five calibrated models were evaluated for their efficacy in simulating different characteristics of hydrograph such as, low and high flows, water balance components, frequency domain characteristics and average error magnitude. The results show that WMMPE calibrated models are performing well in matching all the flow segments of hydrograph in >22 basins for the two conceptual models. Further, results of the analysis suggested that the presence of outliers have minimum impact on the simulation of WMMPE calibrated models in the validation period.