Transmission losses during two flood events in the Platte River, south-central Nebraska

- Two flood events provided unique data sets for the transmission loss analysis.
- The Platte River in this area had a large streambed leakance (l = 600 1/d).
- The transmission losses significantly enhanced the stream stage attenuation.
- The transmission losses decreased linearly downstream along the river.

SummaryThe Platte River in south-central Nebraska is a priority reach to maintain appropriate in-stream flow for healthy stream habitat. Transmission losses normally take place here when flood wave or reservoir-release water travels through during summer and fall. However, it is found that the reservoir-release water hardly arrived at the habitat area due to the transmission losses. Meanwhile, the limited reservoir water also is critical for crop irrigations during the same season. Therefore, to reconcile the water requirement conflict, the knowledge of the temporal-spatial variations of the transmission losses along the river is necessary to better manage the released water. Two flood events, which were only generated by upstream rainstorms, traveled through the nearly non-flowing reach of the Platte River in south-central Nebraska during the summer of 2013. The hydrological records during the two flood events provided unique data sets to study the transmission losses in the reach. The objective of this study was to investigate the temporal-spatial variation of the transmission losses during the two flood events in the reach. A numerical-analytical transmission loss model was developed to support the analysis. The results indicated that the transmission loss process in the study reach would be reasonably simulated using an effective aquifer transmissivity value of 2000 m2/d and an effective stream leakance value of 600 1/d. About 52% and 21% of the stream water flowed into the reach became the transmission losses during the two flood events, respectively. The transmission losses significantly enhanced the stream stage attenuation during the two events. Due to the stream stage attenuation, the total transmission losses decreased linearly between the upstream and downstream gauges, but its detailed spatial variation can be documented based on further hydrogeological data collection along the reach.