North Platte River Chokepoint Investigation

The North Platte Chokepoint Reach is a section of the North Platte River upstream of its confluence with the South Platte River where channel capacity has decreased over time due to channel aggradation from sand deposition. Changes in channel capacity limit the ability of water managers to deliver water to downstream users and to replicate natural ecological dynamics for the benefit of species of concern without increasing flood risk to the City of North Platte. RDG was tasked with evaluating the root causes of decreased channel capacity and identifying potential solutions to increase conveyance through the North Platte Chokepoint while providing opportunities for conservation actions. RDG’s approach focused on remote sensing, field observations, hydrologic analysis, and hydraulic modeling. Ten hydraulic modeling scenarios were developed to address the key questions outlined in the scope of work. Modeling scenarios evaluated the sensitivity of channel capacity to the individual effects of bridge constrictions, irrigation diversion dams, accumulated sediment and vegetation encroachment. Recommendations were provided for sediment removal and flow management in the context of flood risk, irrigation operations, habitat conservation, infrastructure and recreation objectives.