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

Comparison of Modeling Approaches Used to Estimate Streamflow at Ungaged Basins

Steve Markstrom and Lauren HayNational Research Program

Denver, CO

Jacob LaFontaineGA Water Science Center

Atlanta, GA

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

Comparison of Modeling Approaches Used to Estimate Streamflow at Ungaged

Basins

WaterSmart, Reston, VA, August 1-2, 2011markstro@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).

General Approach

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

Water Balance Model (WBM)

1) Aggregation of the

NHD+ catchments

2) Monthly timestep

3) Natural flows

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

McCabe and Wolock4x4 km Monthly Water Balance Model

• Runoff• Precipitation• Temperature• PET• AET

• Direct Runoff• Surplus• Soil Moisture• Snowpack• Snowmelt

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

McCabe and Wolock4x4 km Monthly Water Balance Model

Reference basins for model calibration and evaluation

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

Calibration of the WBM in Ungaged Basins

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.

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

WB Calibration Strategy

CapillaryReservoir

Precipitation

Plant Canopy Interception

Solar Radiation

Air temperature

Evaporation

Sublimation

Preferential –FlowReservoir

Impervious-Zone Reservoir

GravityReservoir

GroundwaterReservoir

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

Res

ervo

ir

Snow Pack

Throughfall

Snowmelt

Rain

Physically-Based Watershed Model (PRMS)

markstro@usgs.gov

Watershed Scale Response to Climate Change Across the United StatesUSGS Climate Change Conference

March 11, 2010

PRMS statvar variable name Units Description from PRMS manual

basin_cfs cfs Streamflow from basin

basin_et inches Evapotranspiration on basin including et, snow evap and interception evap for timestep

basin_gwflow_cfs cfs Basin ground-water flow for timestep

basin_gwin inches Basin area weighted average of inflow to groundwater reservoirs.

basin_gwstor inches Basin area weighted average of groundwater storage

basin_horad langleys Potential shortwave radiation for the basin centroid

basin_imperv_evap inches Basin area-weighted average for evaporation from impervious area

basin_imperv_stor inches Basin area-weighted average for storage on impervious area

basin_infil inches Basin area-weighted average for infiltration.

basin_intcp_evap inches Basin area-weighted evaporation from interception.

basin_intcp_stor inches Basin area-weighted average interception storage

basin_perv_et inches Basin area weighted average of pervious area ET. basin_pk_precip inches Basin area-weighted average precip added to snowpack basin_potet inches Basin area-weighted average of potential et

basin_potsw langleys Area-weighted average of potential shortwave radiation for the basin

basin_ppt inches Area weighted adjusted average precip for basin. basin_pweqv inches Average snowpack water equivalent for total basin areabasin_rain inches Area weighted adjusted average rain for basinbasin_snow inches Area weighted adjusted average snow for basinbasin_snowcov decimal fraction Average snow-covered area for total basin area.

basin_snowevap inches Average evaporation and sublimation for total basin area

basin_snowmelt inches Average snowmelt for total basin area

basin_soil_moist inches Basin area weighted average for soil_moistbasin_soil_rechr inches Basin area weighted average for soil_rechrbasin_soil_to_gw inches Basin average excess soil water that flows directly to groundwater reservoirs.

basin_sroff_cfs cfs Basin surface runoff for timestep

basin_ssflow_cfs cfs Basin subsurface flow for timestepbasin_ssin inches Basin weighted average for inflow to subsurface reservoirsbasin_ssr2gw inches Basin average drainage from subsurface reservoir added to groundwater

basin_ssstor inches Basin weighted average for subsurface reservoir storage

basin_storage inches Storage in basin including groundwater, subsurface storage, soil moisture, snowpack, and interception.

basin_tmax °F Basin area-weighted daily maximum temperaturebasin_tmin °F Basin 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. ]

PRMS Calibration Strategies

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”)

Products1) 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 Modeling

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”