RASM Streamflow Routing

RASM Streamflow RoutingBart NijssenJoe HammanRiver routing

VIC offline river network routing modelExample routing network

In essence a source-to-sink routing model with a pathway dependent travel time. However, the travel time from each location is time-invariant.Implementation of river routing in RASMAB1Bt1BtimeQ/Qtott1A1AImpulse Response Function1High ResolutionFlow Network3Use existing high resolution flow networks

Wu et al., WATER RESOURCES RESEARCH, VOL. 48, W09701, 5 PP., 2012 doi:10.1029/2012WR0123131RASM GridArea Conserve Remapping (Jones, 1998)Up-scaling of Impulse Response FunctionsB1Up-scaling of Impulse Response Functions1RASM GridBVisualizing impulse response functions

Q/QtotalRouting flowsBVIC Runoff and Baseflow at Time (ti)BT=tiContribution to Flow at Point B from fluxes at time (ti-ti+n)Streamflow at Point BOnline streamflow routing in RASMDevelopment of Impulse Response Functions is done as a preprocessing step.Final step is to apply VIC fluxes to impulse response functions. Additional flow produced at each timestep is added to the streamflow timeseries.

Figure: Arctic Great Rivers Observatoryr33RBVIC60r33RBVIC70

KolymaNote that the annual runoff volume is independent of the routing modelObserved Streamflow (m3/s)RASM Streamflow (m3/s)Mean annual streamflow (1990-1999)

Observed and r33RBVIC* streamflow(1990-1999)ObPechoraYeniseyYukonStreamflow (m3/s)Time (month)Advantages:Incorporate effects of high resolution network topologyPossible to calibrate timing based on observed flow observationsRouting model implementation into RASM is extremely simple, since the major work (calculation of travel time) is done a prioriFast (both in execution and in implementation)Disadvantages:No explicit gridcell to grid cell routingNo transport of constituents (although conservative, non-reactive tracers could be treated in a similar way)No water temperature information

Ongoing workCalibrate the travel times in the routing modelDevelop required inputs to capture all flow from the land to the oceanMove timestep to sub-daily (20min) intervalImplement in RASM and connect to couplerCreate data model option for routing using RASM runoff fieldsOutstanding VIC issuesLand use dependent albedoFlux from land surface to oceanMixing between land and atmosphere