4 May 2022

Calculation of Levee-Breach Widening Rates

Abstract: Inundation modeling is often conducted for levee systems to understand current flood risks. The extent of inundation caused by a breach in the levee is highly influenced by the widening rate of the levee breach. This study presents an approach for calculating levee-breach widening rates based on average flow velocity through the breach, embankment height, and erosion characteristics of the soil. Estimates of soil erodibility are derived through an analysis of the measurements of soil erodibility presented in the National Cooperative Highway Research Program (NCHRP) Report 915 database. Levee-breach widening rate curves are calculated based on these erosion properties to demonstrate the approach, and default curves are presented for typical levees built from coarse-grained soils and fine-grained soils. While the most accurate approach for a site is to calculate site-specific widening rate curves based on estimates of local soil erodibility, the default curves presented provide a suitable starting point for initial inundation modeling.

3 May 2022

Sediment Budget Analysis System (SBAS) 2020 User’s Guide: Version 1.0

Abstract: This special report acts as a user’s guide for the Sediment Budget Analysis System (SBAS) toolbox within ArcGIS Pro. The SBAS toolbox is a free toolset that allows the user to create and visualize a sediment budget using ArcGIS Pro. Included in this report are instructions on how to download the toolbox and create a sediment budget.

2 May 2022

Summary of Ground-Based Snow Measurements for the Northeastern United States

ABSTRACT: Snow is an important resource for both communities and ecosystems of the Northeastern United States. Both flood risk management and water supply forecasts for major municipalities, including New York City, depend on the collection of snowpack information. Therefore, the purpose of this study is to summarize all of the snowpack data from ground-based networks currently available in the Northeast. The collection of snow-depth and snow water equivalent information extends back several decades, and there are over 2,200 active sites across the region. Sites are distributed across the entire range of elevations in the region. The number of locations collecting snow information has increased substantially in the last 20 years, primarily from the expansion of the CoCoRaHS (Community Collaborative Rain, Hail, and Snow) network. Our summary of regional snow measurement locations provides a foundation for future studies and analysis, including a template for other regions of the United States.