C2VSim Workshop 5 - C2VSim Surface Water Representation

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The California Central Valley Groundwater-Surface Water Simulation Model (C2VSim) simulates the monthly response of the Central Valley’s groundwater and surface water flow system to historical …

The California Central Valley Groundwater-Surface Water Simulation Model (C2VSim) simulates the monthly response of the Central Valley’s groundwater and surface water flow system to historical stresses, and can also be used to simulate the response to projected future stresses. C2VSim contains monthly historical stream inflows, surface water diversions, precipitation, land use and crop acreages from October 1921 through September 2009. The model dynamically calculates crop water demands, allocates contributions from precipitation, soil moisture and surface water diversions, and calculates the groundwater pumpage required to meet the remaining demand.

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  • 1. The California Central Valley Groundwater-Surface Water Simulation Model Surface Water Processes CWEMF C2VSim Workshop January 23, 2013 Charles Brush Modeling Support Branch, Bay-Delta OfficeCalifornia Department of Water Resources, Sacramento, CA
  • 2. OutlineIWFM Surface Water Process Stream Reach BudgetIWFM Small-Stream Watersheds Process Small Watersheds BudgetC2VSim Results
  • 3. IWFM Surface Water Process
  • 4. Surface Water Process Inflow DiversionsRunoff Return Flows Groundwater Outflow
  • 5. IWFM
  • 6. Stream Flow and Stream-Aquifer Interaction• Assumption of zero storage at a stream node in computing stream flows; i.e. total inflow equals total outflow• Fully coupled stream and groundwater conservation equations• Simultaneous solution of stream and groundwater equations results in the computation of stream-aquifer interaction
  • 7. Stream Flow• Assumption of zero storage at a stream node Qs − Qsin + Qsout = 0 Qs = stream flow, (L3/T) Qsin = inflows into stream (flow from upstream nodes, return flow, rainfall runoff, tributary inflows, tile drain, lake outflow, bypass, user specified flows), (L3/T) Qsout = outflows from stream (diversions, bypass flows, stream- aquifer interaction), (L3/T)• Assumption requires simulation time step to be large enough for stream flow to travel from upstream to downstream in a single time step
  • 8. Stream-Groundwater Interaction      K Qsint = max hs,h − max h,h C  s   b    b    ; Cs =s LW       ds Qsint =stream-aquifer interaction, (L3/T) stream groundwater surface h = groundwater head, (L) table hs = stream surface elevation, (L) ds hb = stream bottom elevation, (L) W Ks = stream bed hydraulic h hb hs conductivity, (L/T) ds = stream bed thickness, (L) datum L = length of stream segment, (L) W = channel width, (L)
  • 9. Stream Diversions• Used to meet agricultural Non-recoverable and urban water demands Loss Diversion• User-specified fractions of Delivery diversion become recoverable (recharge to groundwater) and non- Stream recoverable (evaporation) Recoverable losses Loss• May be used to simulate spreading basins (100% recoverable and non- Groundwater recoverable losses)
  • 10. Lake-Groundwater Interaction• One or more elements can be specified as lake elements• Lakes are fully coupled with groundwater• Lake storage is a function of precipitation, evaporation, inflows, lake- aquifer interaction and lake outflow ∆Slk − Qlkin + Qlkout = 0 ∆t∆Slk = change in lake storage, (L3)Qlkin = lake inflow (precipitation, inflows from streams and upstream lakes), (L3/T)Qlkout = lake outflow (evaporation, lake spill, lake-aquifer interaction), (L3/T)
  • 11. Lake-Groundwater Interaction K Qlkint = lk max ( hlk ,hblk ) − max ( h,hblk )  ; Clk = lk Alk C   dlk Qlkint =lake-aquifer interaction, (L3/T) lake surface h = groundwater head, (L) hlk = lake surface elevation, (L) hblk = lake bottom elevation, (L) d lk i hlkmax Klk = lake bed hydraulic conductivity, hlk h blk i (L/T) dlk = lake bed thickness, (L) datum Alk = area of lake, (L)• Lake outflow is computed when lake surface elevation exceeds maximum lake elevation• Lake outflow can be directed to a stream node or a downstream lake
  • 12. InflowsMonthly at 38 locations
  • 13. Inflows File
  • 14. Inflows FileSacramento River
  • 15. DiversionsMonthly at 246 locations
  • 16. Surface Water Diversions• Diversions and imports – “Diversions” means water taken from a simulated river node, subject to availability – “Imports” generally means water taken from a source that is not modeled • Reservoirs outside the model area serving canals • Reservoirs inside the model area that are not modeled (for example Black Butte and Camanche) • Complex delivery systems (California Aqueduct)
  • 17. Surface Water Imports• Friant-Kern Canal – Release water from Millerton Lake to canal – Deliveries to contractors along canal – Wasteway flows to river beds for delivery to down-stream customers – Flows to Kern River
  • 18. Surface Water Imports• Friant-Kern Canal deliveries simulated as: – Imports to individual subregions – Separate diversions for • Agricultural • Urban • Refuges • Spreading (Aquifer Storage) – Diversions to some districts via river channels • Inflow “FKC Wasteway Deliveries to Tule River” • Diversion from river
  • 19. Surface Water Exports & Imports• California Aqueduct – Pump water from Delta to San Luis Reservoir (outside model area) – Release water from San Luis Reservoir for use inside model area – Release water from San Luis Reservoir for use outside model area• Simulated as exports and imports – Too complex to incorporate in a regional model
  • 20. Diversion Specification Diversion source and destination Source River Node (0 = import) Allocation to losses and delivery Destination subregion Land use (23 = Ag, 22 = urban)
  • 21. Diversion Specification Recharge area for recoverable losses
  • 22. Bypasses• Flood control• Kings River bifurcation• ASR programs
  • 23. Bypass Specification Source and destination river nodes
  • 24. Bypass Specification Recharge area for recoverable losses
  • 25. River Parameters
  • 26. Lake Parameters
  • 27. Stream Reach BudgetColumn Flow 08/31/2004 ProcessUpstream Inflow (+) IN 2,944Downstream Outflow (-) OUT 781Tributary Inflow (+) IN 0 SWSTile Drain (+) IN 0 GWRunoff (+) IN 0 LSReturn Flow (+) IN 2 LSGain from Groundwater (+) +/- -1,593 GWGain from Lake (+) +/- 0Diversion (-) OUT 0 LSBy-pass Flow (-) OUT 573Discrepancy (=) 0.00Diversion Shortage 0
  • 28. Lake BudgetColumn Flow 08/31/2004 ProcessBeginning Storage (+) 63,418Ending Storage (-) 51,052Flow from Upstream Lake (+) IN 0Flow from By-passes (+) IN 799Precipitation (+) IN 0Gain from Groundwater (+) +/- 1,939 GWLake Evaporation (-) OUT 15,104Lake Outflow (-) OUT 0Discrepancy (=) 0.30Lake Surface Elevation (FEET) 185
  • 29. Diversions & Imports
  • 30. Surface Water Destinations
  • 31. Surface Water Destinations 1922-1929 1960-1969 2000-2009
  • 32. IWFM Small WatershedsEvapotranspiration Precipitation Notes Surface Water Groundwater
  • 33. Small-Stream Watersheds• Calculate monthly ungaged surface water inflows and groundwater inflows• Areas and flow channels from CalWater watershed coverage• Grouped with nearest boundary node• Resulted in 210 small-stream watersheds• Approximately 5% of surface water inflow
  • 34. Small-Stream Watersheds
  • 35. Small-Stream Watersheds
  • 36. Small-Stream Watersheds Eliminate the gaged watershed
  • 37. Small-Stream Watersheds These are the ungaged watersheds
  • 38. Small-Stream Watersheds Overland flow paths
  • 39. Small Watersheds
  • 40. Small Watershed Parameters
  • 41. Small Watershed BudgetColumn Flow 08/31/2004 ProcessTotal SW Outflow OUT 6,049GW Base Outflow OUT 90,386Base Flow + Surface Percolation OUT 90,456Net Surface Outflow to Streams OUT 5,979
  • 42. Small-Watershed Inflows
  • 43. Small Watershed Inflows
  • 44. END