A Recommended Calibration and Validation Strategy for Hydrologic and Water Quality Models

Abstract

Hydrologic and water quality (H/WQ) models are widely used to support site-specific environmental assessment, design, planning, and decision making. Calibration and validation (C/V) are fundamental processes used to demonstrate that an H/WQ model can produce suitable results in a particular application. However, the lack of comprehensive guidelines has led to the use of ad hoc, inconsistent, and incomplete C/V processes, which have made it difficult to interpret the myriad of published modeling studies, reduced the utility of many modeling applications, and slowed the advancement of H/WQ modeling. The objective of this article is to provide a generalized structure and process to assist modelers in developing a C/V strategy for H/WQ modeling applications. These best practice recommendations were developed based on an expansive review of the modeling literature, including a special collection of articles on H/WQ model calibration, validation, and use, as well as extensive discussion and debate among the authors. The model C/V recommendations include careful consideration, execution, and documentation of the following elements: (1) goals of model use, (2) data and parameters used in C/V, and (3) model C/V processes. Considerations in element 3 include the warm-up period, C/V strategy complexity, C/V process staging, spatiotemporal allocation of C/V comparison data, manual vs. automatic C/V, and additional diagnostics. Notable examples from the literature are provided for each strategy element. The comprehensive C/V strategy described herein will allow for better interpretation of future modeling studies, improved utility of modeling applications, and more systematic advancement of H/WQ models.

Hydrologic and Water Quality Models: Key Calibration and Validation Topics

“…These recommendations build upon and confirm previous general parameterization recommendations by Refsgaard and Storm (1996) and Engel et al (2007). Daggupati et al (2015) discuss various C/V strategies for H/WQ modeling. The authors recommend that a comprehensive model C/V strategy should consider and document: (1) goals of model use, (2) data used for model calibration and validation, (3) model input parameters and output variables be calibrated and validated, (4) strategies used to calibrate and validate the model, and (5) measures and criteria used to characterize model performance.…”

“…Daggupati et al (2015) recommend single-site calibration for areas with uniform characteristics (e.g., soil, slope, vegetation, and meteorology) across the entire modeled area. A multi-site calibration method is recommended for large areas (or watersheds) with more varied, complex physical characteristics and/or when observed data for a given process are available at multiple locations within the study area.…”

Simulated Effects of Winter Wheat Cover Crop on Cotton Production Systems of the Texas Rolling Plains

“…Simulations for both dryland and irrigated treatments were run over the period from 2000 to 2015, and the results for the year 2000 were excluded from the analysis by considering it as the model warm-up period (Daggupati et al, 2015). The auto-irrigation tool in the DSSAT CSM was used for estimating irrigation requirements for cotton over the growing season under the CwoC-I treatment.…”

Challenges in modelling of water quantity and quality in two contrasting meso-scale catchments in Poland

“…Hence, a complex calibration and validation strategy was implemented as the most appropriate [DAGGUPATI et al 2015]. Calibration phase was conducted in SWAT-CUP -program that allows to optimize the SWAT model using a number of different algorithms [ABBASPOUR 2015].…”