1. WaterSmart, Reston, VA, August 1-2, 2011 markstro@usgs.gov Steve Markstrom and Lauren Hay National Research Program Denver, CO Jacob LaFontaine GA Water Science Center Atlanta, GA

2. WaterSmart, Reston, VA, August 1-2, 2011 markstro@usgs.gov The WaterSMART initiative has identified a need for daily streamflow time series at ungaged locations to define ecological-flow goals, assess the effects of hydrologic alteration on ecological services, and understand the effects of change on water resources, such as changes from climate and land cover.

3. WaterSmart, Reston, VA, August 1-2, 2011 markstro@usgs.gov A comparison of streamflow estimates for a large-scale watershed will be made based on simulations from: 1) statistically-based methods (SBM) 2) a water balance model (WBM), and 3) a physically-based watershed model (PRMS).

4. WaterSmart, Reston, VA, August 1-2, 2011 markstro@usgs.gov 1) Aggregation of the NHD+ catchments 2) Monthly timestep 3) Natural flows

5. WaterSmart, Reston, VA, August 1-2, 2011 markstro@usgs.gov McCabe and Wolock 4x4 km Monthly Water Balance Model Runoff Precipitation Temperature PET AET Direct Runoff Surplus Soil Moisture Snowpack Snowmelt

6. WaterSmart, Reston, VA, August 1-2, 2011 markstro@usgs.gov McCabe and Wolock 4x4 km Monthly Water Balance Model Reference basins for model calibration and evaluation

7. WaterSmart, Reston, VA, August 1-2, 2011 markstro@usgs.gov Step 1: For the reference basins (gaged) compute: Hydrologic indices (basin area, LULC, slope, “wetness”, etc.) Hydrologic response (flow statics, hydrograph separation, etc.) Compute regression table of the indices and the responses. Step 2: For the ungaged basins: Compute the hydrologic indices Determine what the hydrologic response should be Step 3: For the ungaged basins: Run Monte Carlo search (ie 10,000 runs) with randomly generated parameter sets. Keep parameter sets which generate “appropriate” response.

8. WaterSmart, Reston, VA, August 1-2, 2011 markstro@usgs.gov

9. Capillary Reservoir Precipitation Plant Canopy Interception Solar Radiation Air temperature Evaporation Sublimation Preferential –Flow Reservoir Impervious-Zone Reservoir Gravity Reservoir Groundwater Reservoir Evaporation Surface runoff to stream Evaporation & Transpiration Rain Groundwater Recharge Groundwater flow to stream Fast Interflow to stream Groundwater Sink Slow Interflow to stream Upslope Flow Surface runoff to stream Soil-Zone Reservoir Snow Pack Throughfal l Snowmelt Rain

10. markstro@usgs.gov Watershed Scale Response to Climate Change Across the United States USGS Climate Change Conference March 11, 2010 PRMS statvar variable nameUnitsDescription from PRMS manual basin_cfscfsStreamflow from basin basin_etinchesEvapotranspiration on basin including et, snow evap and interception evap for timestep basin_gwflow_cfscfsBasin ground-water flow for timestep basin_gwininchesBasin area weighted average of inflow to groundwater reservoirs. basin_gwstorinchesBasin area weighted average of groundwater storage basin_horadlangleysPotential shortwave radiation for the basin centroid basin_imperv_evapinchesBasin area-weighted average for evaporation from impervious area basin_imperv_storinchesBasin area-weighted average for storage on impervious area basin_infilinchesBasin area-weighted average for infiltration. basin_intcp_evapinchesBasin area-weighted evaporation from interception. basin_intcp_storinchesBasin area-weighted average interception storage basin_perv_etinchesBasin area weighted average of pervious area ET. basin_pk_precipinchesBasin area-weighted average precip added to snowpack basin_potetinchesBasin area-weighted average of potential et basin_potswlangleysArea-weighted average of potential shortwave radiation for the basin basin_pptinchesArea weighted adjusted average precip for basin. basin_pweqvinchesAverage snowpack water equivalent for total basin area basin_raininchesArea weighted adjusted average rain for basin basin_snowinchesArea weighted adjusted average snow for basin basin_snowcovdecimal fractionAverage snow-covered area for total basin area. basin_snowevapinchesAverage evaporation and sublimation for total basin area basin_snowmeltinchesAverage snowmelt for total basin area basin_soil_moistinchesBasin area weighted average for soil_moist basin_soil_rechrinchesBasin area weighted average for soil_rechr basin_soil_to_gwinchesBasin average excess soil water that flows directly to groundwater reservoirs. basin_sroff_cfscfsBasin surface runoff for timestep basin_ssflow_cfscfsBasin subsurface flow for timestep basin_ssininchesBasin weighted average for inflow to subsurface reservoirs basin_ssr2gwinchesBasin average drainage from subsurface reservoir added to groundwater basin_ssstorinchesBasin weighted average for subsurface reservoir storage basin_storageinchesStorage in basin including groundwater, subsurface storage, soil moisture, snowpack, and interception. basin_tmax°FBasin area-weighted daily maximum temperature basin_tmin°FBasin area-weighted daily minimum temperature Description of selected PRMS output variables. [“inches” are depth over the basin area per daily time step; “cfs” are mean daily cubic feet per second over the daily time step. Temperatures are instantaneous value during the day. ]

11. For the reference basins (gaged) compute: Multi-step, multi-objective Shuffle Complex Evolution (Luca) Start in headwaters and move downstream, fixing parameter values for spaces which have already been calibrated. Compute objective functions which use gage data (as “measured”), and PRMS (as “simulated”) This is the approach that we use now. For the ungaged basins: Multi-step, multi-objective Shuffle Complex Evolution (Luca) Compute objective functions which use the results of the SBM and WBM (as “measured”), and PRMS (as “simulated”)

12. 1)Develop guidelines on the advantages/disadvantages/applicability of each method to estimate daily streamflow. 2)Develop an overall approach to regionalizing WBM and PRMS model parameters for ungaged basins across the United States. 3)A portal based on two prototypes: 1) current and future WBM output for the country (http://runoff.cr.usgs.gov/mows/wb/) and 2) the Southeast Regional Assessment Project Data Portal for integration of environmental simulation models (http://internalbrr.cr.usgs.gov/mows/serap/ -- click on Watershed Modelinghttp://runoff.cr.usgs.gov/mows/wb/http://internalbrr.cr.usgs.gov/mows/serap/ 4)Tools for defining HRUs and calibrating large areas that could be extended across the Nation. 5)Proposed publication titles: 1)“Comparison of statistically and physically based watershed models to estimate streamflow at ungaged basins” 2)“Physical and climatic explanations for the cross-correlation between streamflow time series”