Dynamic Behavior Model of Ephemeral Stream

Ephemeral stream hydraulic features are dynamic and respond to the variable streamflow available to move sediment. Streamflow varies both from the runoff-producing storms and transmission losses that decrease the runoff volume and peak. The channel profile in an ephemeral stream tends to be concave up because of the transmission losses and concave down because there is more flow downstream due to tributary inflow. These phenomena were modeled for the main channel of the Walnut Gulch Experimental Watershed using a geomorphic approach to describe the channel and its tributaries and a hydraulic-hydrologic model for the runoff-sediment movement. Runoff and sediment transport were synthesized using the Diskin-Lane stochastic runoff model with a deterministic sediment transport relationship using the Manning and Laursen equations.