Transit losses and traveltimes for reservoir releases during drought conditions along the Neosho River from Council Grove Lake to Iola, east-central Kansas

Abstract

Knowledge of the transit losses and water-wave traveltimes in the Neosho River for varying reservoir-release volumes and durations is necessary for proper management of water supply. To obtain this knowledge, the U.S. Geological Survey, in cooperation with the Kansas Water Office, studied two reaches along the Neosho River in east-central Kansas. The upper reach is from Council Grove Lake to John Redmond Reservoir, a distance of 83.0 river miles. The lower reach is from John Redmond Reservoir to lola, Kansas, a distance of 56.3 river miles. Channel and aquifer characteristics were estimated from available data and used in a streamflow-routing model. These estimated characteristics were verified using the model by comparing simulated reservoir releases to observed reservoir releases. The verified model then was used to simulate transit losses (or gains) and traveltimes for selected reservoir-release volumes and durations from Council Grove Lake to lola. Transit losses and traveltimes were investigated for the selected reservoir releases while under a severe-drought antecedent-streamflow condition (zero base flow) and a less-severe-drought antecedent-streamflow condition (2-percent drought base flows). The largest total transit loss from Council Grove Lake to lola occurred during the severe-drought antecedent-streamflow condition, small reservoirrelease rates, and long reservoir-release durations. The total transit loss included water that was temporarily lost to bank storage. For a severedrought condition, transit losses ranged from 1,100 acre-feet for a release volume of 1,840 acre-feet for a duration of 50 days to 6,280 acre-feet for a release volume of 6,280 acre-feet for a duration of 365 days. For a lesssevere-drought condition, transit losses ranged from 860 acre-feet to 3,234 acre-feet for the same release volumes and durations as for the severedrought condition. Antecedent streamflows associated with severe-drought conditions resulted in slower wave celerities and longer traveltimes than for less-severedrought conditions. Traveltimes to beginning of response from Council Grove Lake to lola ranged from 2.2 days for small release rates (less than 18.6 cubic feet per second) for the severe-drought condition to 2.0 days for the less-severe-drought condition. Traveltimes to full response {when the downstream discharge is equal to 80 percent of the sum of the reservoir release and base flow) ranged from 69 days for a release rate of 18.6 cubic feet per second to more than 365 days for a release rate of 8.69 cubic feet per second during the severe-drought condition. For the less-severedrought condition, traveltimes to full response ranged from 41 days for a release rate of 18.6 cubic feet per second to 200 days for a release rate of 8.69 cubic feet per second.