1. RASM Streamflow Routing Bart Nijssen Joe Hamman

2. River 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.

3. Implementation of river routing in RASM A B 1B t 1B time Q/Qtot t 1A 1A1A Impulse Response Function 1 High Resolution Flow Network

4. Use existing high resolution flow networks Wu et al., WATER RESOURCES RESEARCH, VOL. 48, W09701, 5 PP., 2012 doi:10.1029/2012WR012313

5. 1’ RASM Grid Area Conserve Remapping (Jones, 1998) Up-scaling of Impulse Response Functions B 1

6. 1’ RASM Grid B

7. Visualizing impulse response functions Q/Q total

8. Routing flows B’ VIC Runoff and Baseflow at Time (t i ) B T=t i Contribution to Flow at Point B from fluxes at time (t i -t i+n ) Streamflow at Point B

9. Online streamflow routing in RASM Development 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 Observatory

10. r33RBVIC60 r33RBVIC70 Kolyma Note that the annual runoff volume is independent of the routing model Observed Streamflow (m 3 /s) RASM Streamflow (m 3 /s) Mean annual streamflow (1990-1999)

11. Observed and r33RBVIC* streamflow (1990-1999) Ob PechoraYenisey Yukon Streamflow (m 3 /s) Time (month)

12. Advantages: Incorporate effects of high resolution network topology Possible to calibrate timing based on observed flow observations Routing model implementation into RASM is extremely simple, since the major work (calculation of travel time) is done a priori Fast (both in execution and in implementation) Disadvantages: No explicit gridcell to grid cell routing No transport of constituents (although conservative, non- reactive tracers could be treated in a similar way) No water temperature information

13. Ongoing work Calibrate the travel times in the routing model Develop required inputs to capture all flow from the land to the ocean Move timestep to sub-daily (20min) interval Implement in RASM and connect to coupler Create data model option for routing using RASM runoff fields

14. Outstanding VIC issues Land use dependent albedo Flux from land surface to ocean Mixing between land and atmosphere