29 Nov 2022

National Ordinary High Water Mark Field Delineation Manual for Rivers and Streams : Interim Version

Abstract: The ordinary high water mark (OHWM) defines the lateral extent of nontidal aquatic features in the absence of adjacent wetlands in the United States. The federal regulatory definition of the OHWM, 33 CFR 328.3(c)(7), states the OHWM is “that line on the shore established by the fluctuations of water and indicated by physical characteristics such as [a] clear, natural line impressed on the bank, shelving, changes in the character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that consider the characteristics of the surrounding areas.” This is the first manual to present a methodology for nationwide identification and delineation of the OHWM. A two-page data sheet and field procedure outline a weight-of-evidence (WoE) methodology to organize and evaluate observations at stream sites. This manual presents a consistent, science-based method for delineating the OHWM in streams. It also describes regional differences and challenges in identifying the OHWM at sites disturbed by human-induced or natural changes and illustrates how to use remote data to structure field inquiries and interpret field evidence using the principles of fluvial science. The manual demonstrates that, in many landscape settings, the OHWM may be located near the bankfull elevation.

26 Oct 2022

Hydrology and hydraulics section cross-train fellow employees

Members of the U.S. Army Corps of Engineers Louisville District Hydrology and Hydraulics Section conducted a stream walk where H&H Limnologist Zac Wolf spoke on biology, ecology and water quality and H&H Engineer Jake Allgeier discussed hydrology and geomorphology at Floyds Fork at Beckley Creek Park, in Louisville, Kentucky, Oct. 6. 

21 Sep 2022

Evaluation of Climatic and Hydroclimatic Resources to Support the US Army Corps of Engineers Regulatory Program

Abstract: Short-term climatic and hydrologic interactions, or hydroclimatology, are an important consideration when delineating the geographic extent of aquatic resources and assessing whether an aquatic resource is a jurisdictional water of the United States (WOTUS) and is therefore subject to the Clean Water Act (CWA). The now vacated 2020 Navigable Waters Protection Rule (NWPR) required the evaluation of precipitation and other hydroclimatic conditions to assess the jurisdictional status of an aquatic resource based on normal hydroclimatic conditions. Short-term hydroclimatic conditions, such as antecedent precipitation, evapotranspiration, wetland delineation, and streamflow duration assessments, provide information on an aquatic resource’s geo-graphic extent, hydrologic characteristics, and hydrologic connectivity with other aquatic resources. Here, researchers from the US Army Corps of Engineers, Engineer Research and Development Center (ERDC) evaluate tools and data available to practitioners for assessing short-term hydroclimatic conditions. The work highlights specific meteorological phenomena that are important to consider when assessing short-term hydroclimatic conditions that affect the geographic extent and hydrologic characteristics of an aquatic resource. The findings suggest that practitioners need access to data and tools that more holistically consider the impact of short-term antecedent hydroclimatology on the entire hydrologic cycle, rather than tools based solely on precipitation.

15 Aug 2022

Understanding and Improving Snow Processes in Noah-MP over the Northeast United States via the New York State Mesonet

Abstract: Snow is a critical component of the global hydrologic cycle and is a key input to river and stream flow forecasts. In 2016, the National Oceanic and Atmospheric Administration launched the National Water Model (NWM) to provide a high-fidelity numerical forecast of streamflow integrated with the broader atmospheric prediction modeling framework. The NWM is coupled to the atmospheric model using the Noah-MP land surface modeling framework. While snow in Noah-MP has been consistently evaluated in the western United States, less attention has been paid to understanding and optimizing its performance in the Northeast US (NEUS). The newly installed New York State Mesonet (NYSM), a network of high-quality surface meteorological stations distributed across New York State, provides a unique opportunity to evaluate Noah-MP performance in the NEUS. In this report, we document the methodology used to perform single-column simulations using meteorological inputs from the NYSM and compare the point evaluations against baseline NWM performance. We further discuss how enhanced surface energy balance measurements at a selection of NYSM sites can be used to evaluate specific components of Noah-MP and present initial results.

15 Jun 2022

Foundational Principles in the Development of AdH-SW3, the Three-Dimensional Shallow Water Hydrodynamics and Transport Module within the Adaptive Hydraulics/Hydrology Model

Abstract: This report details the design and development of the three-dimensional shallow water hydrodynamics formulation within the Adaptive Hydraulics/Hydrology model (AdH-SW3) for simulation of flow and transport in rivers, estuaries, reservoirs, and other similar hydrologic environments. The report is intended to communicate principles of the model design for the interested and diligent user. The design relies upon several layers of consistency to produce a stable, accurate, and conservative model. The mesh design can handle rapid changes in bathymetry (e.g., steep-sided navigation channels in estuaries) and maintain accuracy in density-driven transport phenomena (e.g., thermal, or saline stratification and intrusion of salinity).

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.

11 Mar 2022

Field Guide to Identifying the Upper Extent of Stream Channels

ABSTRACT: The upper extent of a channel is a transition zone from the hillslope to the beginning of the stream channel. Accurately and consistently identifying the upper extent of a channel in the field and locating where hillslope processes transition to stream-channel processes can be a difficult task. Physical characteristics located at the beginning of a channel (i.e., channel head), including geomorphic, sediment, and vegetation indicators, can vary significantly across different landscapes in the United States. Remote tools are useful for examining the upper extent of channels, but these remote tools have limitations for identifying the beginning of channels. Even as the resolution of remote data continues to increase, field observations are necessary to validate the remote data on the ground and to accurately and consistently identify and locate the transition from the hillslope to the stream channel. Use of a combination of remote and field evidence is likely the most successful strategy for identifying channel heads. This report presents a case study that demonstrates how a weight-of-evidence approach can combine field and remote evidence to locate the different parts of the transition and ultimately to identify the channel-head location.

7 Feb 2022

Celebrating World Wetlands Day

World Wetlands Day was celebrated this week with the theme ‘Call to Act’ for Wetlands. It's an appeal to invest financial, human, and political capital to save the world’s wetlands from disappearing and to restore those we have degraded. It highlights the need to raise national and global awareness about wetlands to reverse their rapid loss and encourage actions to conserve and restore them. To protect against further loss, the nation has in recent years adopted a policy of "no net loss" of wetlands. USACE, working in partnership with many other organizations, is helping to implement this policy by protecting, preserving, and restoring.

4 Jan 2022

The "New" National Inventory of Dams (NID)'s Redesigned Website Now With Flood Inundation Maps to Download and ‘Share’

The NID is the central repository for information about dams in the U.S. and its territories that

31 Dec 2021

Congratulating Achievements - IWR ANNUAL AWARDS Recap

Employee recognition at the Institute for Water Resources (IWR) is all about acknowledging the hard