20 Mar 2023

Numerical Modeling of Supercritical Flow in the Los Angeles River: Part I: Adaptive Hydraulics Numerical Modeling of the 1943 Physical Model

Abstract: The Los Angeles District of the US Army Corps of Engineers is assisting the City of Los Angeles with restoration efforts on the Los Angeles River. The city wishes to restore portions of the channelized river to a more natural state with riparian/vegetative green spaces for both wildlife and public recreation usage. The Los Angeles River provides an important role for the City of Los Angeles from a flood-control perspective, and functionality needs to be preserved when contemplating system modifications. This report details the development of an Adaptive Hydraulics (AdH) numerical model capable of representing this complex system consisting of both subcritical and supercritical flow regimes. Due to limited hydraulic data in the study area, an extensive model validation to observed data was not possible. To bridge the data gap, a numerical model was developed from a previously completed physical model study with extensive quantitative measurements and qualitative reports of hydraulic conditions. This approach allowed engineers to evaluate the effectiveness of the AdH model in representing this complex hydraulic system along with determining the best methodology to accurately represent the existing conditions. This study determined appropriate model parameters that will be utilized in further numerical modeling efforts to evaluate system modifications associated with restoration efforts.

15 Mar 2023

23-015 Dworshak Dam to increase releases at the end of March

AHSAHKA, Idaho –Dworshak Dam will be increasing releases starting March 27 from 1,700 cubic feet per second to approximately 4,000 to 6,000 cfs over a two-day period. Operations at Dworshak will change the height of the Clearwater River downstream of the dam by approximately 1.5 feet, over the two-day period.

7 Mar 2023

Upper basin runoff forecast below average; Gavins Point releases to increase for navigation flow support; April public meetings

The updated 2023 calendar year runoff forecast for the Missouri River Basin above Sioux City, Iowa, continues to be below average. The 2023 calendar year runoff forecast above Sioux City is 21.5 million acre feet, 84% of average. The runoff forecast is based on current soil moisture conditions, plains snowpack, mountain snowpack, and long-term precipitation and temperature outlooks. February runoff in the Missouri River Basin above Sioux City was 1.0 MAF, 86% of average.

8 Feb 2023

Guarding the Treasure Valley: A history of Lucky Peak Dam

Every year, snowmelt from the surrounding mountains flows into creeks and streams that join the Boise River. When flows reach 7,000 cubic feet per second or higher, the river is considered at flood stage.

7 Feb 2023

Below average runoff continues for the upper Missouri River Basin in 2023

The updated 2023 calendar year runoff forecast for the Missouri River Basin above Sioux City, Iowa, continues to be below average. January runoff in the Missouri River Basin above Sioux City was 1.1 million acre-feet, 134% of average. Runoff was above average due to warmer-than-normal temperatures in the upper basin resulting in some snowmelt runoff.

10 Jan 2023

Through fair or foul weather: A history of the Mill Creek Project

In 1931, a torrent of brown water roared down Mill Creek, with water levels rising at a rate of one foot per hour. The water escaped the confines of the riverbanks and rushed through the City of Walla Walla, destroying homes, roads and bridges. Born in the wake of this disastrous event, the Mill Creek Project now stands to protect the city from floods like this.

6 Jan 2023

Dry Conditions expected to persist for the Missouri River Basin

For the 2022 calendar year, Missouri River basin runoff above Sioux City, Iowa totaled 19.3 million acre-feet, 75% of average. This was the 30th lowest annual runoff for the Missouri River Basin in 125 years of record-keeping. The ongoing drought shows little relief in sight and the U.S. Army Corps of Engineers predicts runoff into the mainstem reservoir system will remain below normal. For 2023, runoff in the Missouri River basin above Sioux City, Iowa is forecast to be 20.8 MAF, 81% of average.

19 Dec 2022

USACE Holding C&SF Flood Resiliency Study Planning Meetings Jan. 11-12 in Fort Lauderdale

The Jacksonville District of the U.S. Army Corps of Engineers (USACE) will hold a two-day planning charrette meeting for the Central and South Florida (C&SF) Flood Resiliency Study on Jan. 11-12 in Fort Lauderdale. Options for virtual and in-person attendance will be provided.

6 Dec 2022

Releases from Gavins Point Dam reduced to winter rates

Flow support for the 2022 Missouri River navigation season ended Nov. 21 as releases were reduced toward winter rates at Gavins Point Dam. “Releases from Gavins Point Dam are being reduced to the winter release of 12,000 cubic feet per second,” said John Remus, Chief of the Missouri River Basin Water Management Division.

30 Nov 2022

Automation of Gridded HEC-HMS Model Development Using Python: Initial Condition Testing and Calibration Applications

Abstract: The US Army Corps of Engineers’s (USACE) Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) rainfall-runoff model is widely used within the research community to develop both event-based and continuous rainfall-runoff models. The soil moisture accounting (SMA) algorithm is commonly used for long-term simulations. Depending on the final model setup, 12 to 18 parameters are needed to characterize the modeled watershed’s canopy, surface, soil, and routing processes, all of which are potential calibration parameters. HEC-HMS includes optimization tools to facilitate model calibration, but only initial conditions (ICs) can be calibrated when using the gridded SMA algorithm. Calibrating a continuous SMA HEC-HMS model is an iterative process that can require hundreds of simulations, a time intensive process requiring automation. HEC-HMS is written in Java and is predominantly run through a graphical user interface (GUI). As such, conducting a long-term gridded SMA calibration is infeasible using the GUI. USACE Construction Engineering Research Laboratory (CERL) has written a workflow that utilizes the existing Jython application programming interface (API) to batch run HEC-HMS simulations with Python. The workflow allows for gridded SMA HEC-HMS model sensitivity and calibration analyses to be conducted in a timely manner.