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Stone Helps Lead Development of ASABE Standard

Jun 23, 2016

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Caption: Dr. Naresh Pai is Stone's representative on the ASABE process committee to develop standards for calibration and evaluation of HWQ modeling.

Work is well underway toward establishing American Society of Biological Engineers (ASABE) standards for calibration and evaluation of hydrologic and water quality (HWQ) models, and Stone Environmental (Stone) is playing a key role in that work.

Stone's Dr. Naresh Pai is a member of the working group that recently published "Hydrologic and Water Quality Models: Key Calibration and Validation Topics," an introduction/summary report of nine research articles that collectively present recommendations to enhance HWQ modeling.

Dr. Pai co-authored three of the nine research articles that provide modelers detailed topic-specific recommendations related to model calibration, validation, and use. Titles, abstracts, and download links to his three papers, which are summarized below:

  • A Recommended Calibration and Validation Strategy for Hydrologic and Water Quality Models provides a generalized structure and process to assist modelers in developing a calibration and validation (CV) strategy for HWQ modeling applications. The goal is to address the use of ad hoc, inconsistent, and incomplete CV processes to date that have made it difficult to interpret the myriad of published modeling studies, reduced the utility of many modeling applications, and slowed the advancement of HWQ modeling.
  • Hydrologic and Water Quality Models: Performance Measures and Evaluation Criteria performed a meta-analysis of previously published literature and provided guidelines on the statistical and graphical performance measures (PMs) that can be used to evaluate model performance. For each PM, corresponding performance evaluation criteria were developed to rate the model performance as either "very good", "good", "satisfactory" or "not satisfactory" when compared with measured data. These performance measures and evaluation criteria will allow for a more standardized evaluation of HWQ models.
  • Hydrologic and Water Quality Models: Documentation and Reporting Procedures for Calibration, Validation, and Use provides guidelines to properly document HWQ model calibration, validation, and use to support greater transparency in communicating methods used and decisions made when using HWQ models. The paper also raises issues about how to improve model documentation and reproducibility, and encourage open discussion of these topics in the HWQ modeling community.

Stone's modeling professional team regularly works with experts in academia, industry and government to improve performance and application of an array of environmental models. We are excited to be participating in this effort to standardize best practices for calibration and validation for hydrologic and water quality models, especially as they are increasingly used in the agrochemical industry to ensure realistic and accurate simulations.

This ASABE project began in 2013. From now through mid to late 2017, the working group will be developing guidelines to present to ASABE standards staff, who will then vote to approve and publish the standards.


To learn how the key outcomes of these research papers are being used to improve the quality and credibility of pesticide exposure modeling at Stone, contact Michael Winchell at