1. Surface-Groundwater interactions on the Eastern Snake River, ID

2. Outline Objective: Estimate of seepage loss along a segment of the Eastern Snake river River Channel Generation (RCMM) Unsteady flow simulation(10 non-raining days) Compare the outflow hydrograph with the actual hydrograph Calculate volume of water lost to the aquifer

3. Misc. Facts about Idaho 3,100 miles of river, more than any other state 85% of all commercial trouts Number one producer of potatoes Paris and Montpellier 30 miles apart

4. Study area Unconfined aquifer Highly fractured basalt Water Supply from snowmelt Precipitation ~8 in/yr

5. Human impact on the Eastern Snake system Less surface water irrigation More efficient irrigation Increased pumping (source: IDWR)

6. Water Budget

7. Increased stress on the aquifer (source: IDWR)

8. Eastern Snake aquifer Model

9. Eastern Snake aquifer

10. River Channel generation

11. 3D Representation of river reaches Bathymetric data (Expensive, unavailable) 2D 3D representation 2D plan view (DOP) Calculate location of the thalweg Approximate cross-sections with analytical functions

12. 2D representation of the river segment Calculate Depth/Width for a 2 yr flow Offset the NHD flow line by W/2 to obtain the channel boundary Depth Width 2D Plan view

13. River Channel generation (RCMM) REQUIRES: 2D representation of the river segment GENERATES: 3D representation Thalweg: Calculates the radius of curvature Locates the thalweg using the radius of curvature/thalweg relationship Cross-sections: Analytical (Beta functions) from the thalweg location

14. Generated cross-sections

15. Exporting river channel into HEC- RAS

16. Unsteady simulation 10 day simulation Upstream boundary condition: USGS flow hydrograph (@Minidoka) Downstream boundary condition: stage hydrograph (@Kimberley) Compare the calculated/observed hydrograph

17. Acknowledgments Dr Merwade (CRWR) Allan Willie (Hydrologist, IDWR)

18. Any questions?