A simple sediment transport option is available in MIKE HYDRO Basin for use in connection with Reservoir sedimentation simulations.
The Sediment transport page and the Reservoir sedimentation simulations are enabled through activating the ‘Include reservoir sedimentation’ option in the ‘Simulation specifications/modules’ page.
The overall approach for the sediment transport and reservoir sedimentation feature is, that sediment is transported un-disturbed through the river network and potentially deposited in Reservoirs.
The input required for the sediment transport calculations are sediment properties for the sediment fractions included. These definitions are made in the Sediment properties dialogue.
Additionally, sediment loads must be defined. These are defined as time series input through a combination of a Total sediment load time series and sediment fraction percentage time series. Sediment load are defined as input to Catchments and consequently, added as sediment load to the river at the location of the specific Catchment node.
Sediment transport and Reservoir sedimentation approach
The reservoir sedimentation module is not a sediment transport model. Sediment is supplied by catchments and is routed through the river network under the assumption that no erosion or deposition takes place in the rivers and deposition of sediments will solely occur in the Reservoirs.
If a reservoir is filled with sediments or other conditions prevents inflowing sediments to deposit in the specific Reservoir, sediment surplus will be transported further downstream in the system. The sediment is routed to the river downstream of the reservoir and to users supplied by the Reservoir. Sediment is distributed between connected rivers and users according to the discharge distribution.
Reservoir sedimentation change the properties and storage capacity of the reservoirs. The Level-Area-Volume (LAV) curve of each reservoir is continuously updated during a simulation based on the amount of sediment deposited in the reservoirs.
The frequency at which LAV is updated during simulation can be controlled by the user. The update frequency is specified in the Time step control dialogue (cf. 4.4 Time Step Control (p. 53)).
If the bottom level of the Reservoir due to deposition reaches the dead zone level, a warning will be issued, and no more sediment will be deposited in this reservoir.