76913 REL 9

2010-072-00 EXP SALMON BASIN RESTORATION

3/1/2019

2/29/2020

162. Analyze/Interpret Data

Work Element Usage Report

AO: 162 - RMRS: Lemhi Hydrologic Modeling 2019

The proposed project is to complete the analysis of the impact of water management on stream morphology and hyporheic flows and to convert the numerical modeling from DHI (Danish Hydraulic Institute) developed MIKE21 to US Army Corps of Engineers developed publically available hydraulic modeling software HEC-RAS 2D. This analysis will leverage on the previous works, including the developed numerical models, hydrological analysis and in-channel hyporheic fluxes and streambed elevation monitoring sensors installed in 2018.

RMRS will analyze the temperature data collected from the 12 temperature probes installed in 2 reaches of the Lemhi in fall 2018. The sensors are currently in the streambed and data will be downloaded in summer 2019. Analysis of the temperature signal between in stream and in the sediment sensors will quantify hyporheic fluxes and changes of streambed elevation. We will compare the monitored fluxes with those observed in literature where redds have been found. This will help to determine whether hyporheic fluxes are a limiting factor for aquatic habitat quality and whether the streambed is morphologically active. The data will be also used to validate a morphodynamic model that will be run with regulated and unregulated flows at the decade scale over 2 selected reaches. The two scenarios will highlight whether the water management resulted in subdue pools and riffles morphology presently observed along the Lemhi river. RMRS will develop a set of calibrated and validated HEC-RAS 2D models, which cover the entire extent of the previous MIKE21 models (Leadore to confluence with Salmon River).

This WE will 1) validate 2 dimensional hydraulic model of the entire Lemhi River; 2) analyze the temperature time series recorded with the sensors installed in 2018 to quantify hyporheic fluxes and streambed elevation changes; and 3) developed a morphodynamic model.

This is the final year of data collection using the CHaMP protocol.

The deliverables are 1) validate 2 dimensional hydraulic model of the entire Lemhi River, 2) elucidate the effect of flow-streambed interaction on aquatic habitat and streambed morphology, and 3) quantification of the impact of water management on in-channel river morphology. This information will be reviewed by BPA's hydraulic engineers.

$93,241

7.30%

03/01/2019

02/29/2020

Other

n/a

n/a

Recurring