The Antecedent Moisture Model Learning Library

Wet versus dry antecedent moisture conditions

Antecedent Moisture Model (AMM) Overview

Rainfall-runoff dynamics of surface water, combined sewer, and separate sewer systems can be highly impacted by antecedent moisture conditions, or the relative wetness or dryness of the system. Simulating these dynamics with a reasonable degree of accuracy is critical so that predictive models of systems can be developed for risk management, planning, and design of upgrades.

This page presents the results of 25 years of work formulating, applying and refining a hydrologic model that addresses the impacts of antecedent moisture conditions on the rainfall-runoff process. The AMM equations and model process are released into the public domain to aid engineers in analyzing and modeling these systems. References, resources and tools are presented here to help facilitate that process. Please contact us if you have any questions about these materials.

Click here for the publication of the equations in the peer reviewed Journal of Water Management Modeling.

Click here to join the AMM Users Google Group.

Click here to access the PC-SWMM Script for AMM (by RJN)

Click here to access the Python Script for AMM (by Confluency)

Resources on the Antecedent Moisture Model

Antecedent Moisture Modeling Overview (link)

Introduction to antecedent moisture effects, the AMM, and the modeling process. [PDF]

Reparameterizing the Antecedent Moisture Model (PDF)​

2024 paper accepted by the JWMM and currently under peer review. Designed to be timestep independent and more physically relatable, intuitive, and scaleable while remaining functionally equivalent to the original. [PDF]

Original AMM Development and Equations (link)

2020 Technical paper on the details of the model development and equations.  [PDF]

How to use the AMM (link)

A manual of practice that outlines the process to use the AMM for design. [PDF]

AMM Videos (link)

A series of short videos that shows an overview of the AMM and how to use the AMM tools within H2Ometrics. [Link]

Data Needs for Sanitary Sewer Peak Flow Projections (link)

Best practices for flow and rainfall data collection for sanitary collection systems for use with the AMM. [PDF of WE&T Article]

The Antecedent Moisture Model is in the public domain. What does that mean? (link)​

Understanding copyright and ownership of models, equations, programs and publications.

Example frequency plot from long-term continuous simulation

Frequency Analysis Spreadsheet Template (download)

Click to download an Excel workbook that contains a spreadsheet template of the frequency analysis process using the Log Pearson III methodology. [Spreadsheet]

Example frequency plot from long-term continuous simulation

AMM Users Conferene 2022 Materials (link)

Presentation slides and videos from the first ever AMM Users Conference held on May 26, 2022.

AMM Companion Spreadsheet (download)

Click to download an Excel workbook that contains a series of spreadsheets with the AMM equations and templates for building models. [Spreadsheet]

AMM and H2Ometrics

The H2Ometrics platform contains many tools that were specifically developed to aid in the development of AMMs such as data scrubbing toolsdiurnal filter toolsI&I computationsI&I metricsbase flow modelsAMM model development toolsaccuracy of fit metrics, and frequency analysis toolsContact us for more information.

The AMM process and equations are in the public doman. The documents and videos contained here are Copyright © 2020 by H2Ometrics. All rights reserved.