Duc Tran
University of Virginia, Virginia, United States
syu3cs@virginia.eduNOAA National Water Model - Flood Risk Impact Mapping
CIROH_HydroLearn
Problem Statement
When floods occur, first responders face challenges in identifying where vulnerable populations will be. However, hazard forecasts lack detailed information about exposure and vulnerability that would be used by decision-makers. In this module, the learner will learn how to generate the flood risk map through the case study of the 2024 Hurricane Helene in North Carolina. The step-by-step workflow to create impact-based flood forecasting will be provided, in which we will use the National Water Model (NWM) forecasted streamflow input for Hydrologic Unit Code (HUC)-8 level.
The first part of this module will show how to generate Flood Inundation Maps (FIMs) using the Office of Water Prediction Height Above Nearest Drainage (HAND)-FIM while the second part will incorporate the Social Vulnerability Index (SVI) on a census-tract level to generate the flood risk map. By completing this module, you can provide these maps as useful information for stakeholders and decision-makers to use for early-warning and evacuation plans.
Module Overview
You will learn to implement the HAND method for FIM along with SVI and OWP-NWM streamflow input to generate flood risk map for quick evacuation planning with low computational demands.
Topics Covered
Flood inundation mapping using HAND, SVI, and OWP-NWM input.
Prerequisites
The learner is expected to review documents mentioned in the Prerequisite Knowledge in the Section 3.1. Summary and Learning Objectives before starting the module.
Learning Objectives
At the end of this module, students will be able to:
1) Retrieve and process different NWM streamflow forecast ranges (i.e., short -18 hrs, medium - 10 days, long - 30 days) from the NOAA OWP-NWM at Hydrologic Unit Code (HUC) 8 subbasin-level over CONUS
2) Apply the HAND method to generate Flood Inundation Maps (FIMs) and depth maps
3) Integrate FIM, depth map, and Social Vulnerability Index (SVI) data to create flood risk impact maps
4) Develop actionable insights using generated flood risk maps for water resource management and decision-making
Course Adaptation
Are you wondering how this module can be put into practice? This training is ideally suited for professionals in hydrology, emergency management, hazard planning, and water-resource management. For authorities, community stakeholders, and other decision-makers, the techniques covered here provide tangible ways to enhance low-cost early-warning capabilities and refine evacuation strategies. In particular, the core skill of generating impact-based flood-risk maps, by combining the low-computational-demand HAND inundation method with the Social Vulnerability Index (SVI), directly addresses the challenge of quickly identifying who is most at risk during a flood.
You can use the step-by-step process outlined in this module to train your operational teams or adapt key sections into targeted workshops or briefings for planning groups. Delivered as a practical workflow and illustrated with a real-world case study (Hurricane Helene, 2024), the module aims to support learners in developing actionable, time-pressured information.
Course Authors
Hesham Elhaddad
Western Michigan University, Michigan, United States
h.elhaddad@wmich.eduTarget Audience
This module is designed for hydrologists, operators, and decision-makers who wish to apply the knowledge provided by this module to evacuation planning and disaster prevention efforts.
Tools Needed
Computer with access to Internet. In addition, this module requires learners to have Python and its dependencies installed on their local machine to execute the provided code. Additionally, while the output will be exported in raster (.tif) format, learners can choose to use GIS tools such as QGIS, ArcMap, or ArcGIS Pro for visualization or further analysis.
Expected Effort
The module instructors estimate between 5 to 6 hours for learner to complete this module.
Course Sharing and Adaptation
This course is available for export by clicking the "Export Link" at the top right of this page. You will need a HydroLearn instructor studio account to do this. You will first need to sign up for a hydrolearn.org account, then you should register as an instructor by clicking 'studio.hydrolearn' and requesting course creation permissions.
Recommended Citation
Tran, Duc & Elhaddad, Hesham (2025). National Water Model. HydroLearn. https://edx.hydrolearn.org/courses/course-v1:CIROH_HydroLearn+OP_040+2025/about
Data Disclaimer
This experimental data represents the NWS’s best approximation of the maximum inundation extent that occurred on Sep. 26 (or Sep. 27), 2024, as of Jan 6, 2025, based upon modeled river discharge. These maps were not publicly available during the event (coinciding with Hurricane Helene). This information should be used for educational purposes only.
Acknowledgments
This project received funding under award NA22NWS4320003 by National Oceanic and Atmospheric Administration (NOAA) Cooperative Institute Program to the Cooperative Institute for Research on Hydrology (CIROH) through the University of Alabama. The statements, findings, conclusions, and recommendations are those of the author(s) and do not necessarily reflect the opinions of NOAA.