Sponsored by National Science Foundation   

Integrated Hydrologic Model Intercomparison Workshop: Benchmark Simulations

March 10 - 11, 2011




A number of physically-based hydrological models have been developed that incorporate groundwater-surface water interactions. Different models use different approaches to solve the coupled groundwater and overland flow governing equations and integrated surface-subsurface exchange fluxes, including formulations based on pressure continuity, diffusion paradigms, boundary condition switching, and other schemes. These solution approaches can be broadly categorized as full coupling, sequential coupling, and loose coupling. In full coupling, the groundwater and overland flow governing equations are solved simultaneously. In sequential coupling, the governing equations are solved separately, with explicit discretization used for at least one of the equations or with an iterative cycle superposed on the overall system. In loose coupling, the equations are solved separately, with the output from one regime passed as input to the other, with iteration or other conditions imposed.

In this workshop we will compare the performance of several groundwater-surface water models in solving a set of simple hydrological problems or test cases designed to evaluate the coupled model behavior under a broad range of idealized conditions. Each test case simulates precipitation on a simple domain for a specified period, followed by a recession period with no precipitation during which the simulated hydrograph recesses to no-flow conditions. Test cases are divided into 1) integrated groundwater-surface water problems on a simple sloping plane, and 2) overland and channel flow problems on a simple v-tilted domain. For each case, pressure head distributions and hydrographs at the domain outlet will be compared between models. Test cases and model results are detailed below.

The workshop will run from 10:00 AM to 6:00 PM.


Workshop Description

1. Integrated groundwater-surface water modeling examples:

Example 1 is designed to assess the impact of surface-subsurface interaction on the runoff hydrograph.

Catchment Description:

Rainfall Event

Figure 1: Domain of groundwater-surface water test cases (Sulis et al 2010).

1.a Homogeneous soil test cases

This series of test cases is designed to evaluate surface-subsurface water exchange under Dunne and Horton runoff conditions for a homogeneous soil case. For each test case below, one horizontal discretization is used and results are compared for two vertical discretizations and slopes:

Additional details of each test case including hydraulic conductivity and initial water table configuration are provided below.

1.a.1 Runoff production by excess saturation:
In this case, saturation excess (Dunne) runoff is produced by ensuring complete saturation of the soil column and intersection of the water table with the land surface. This is achieved by specifying a hydraulic conductivity larger than the rainfall rate.

Tests notes:

Example results from the model ParFlow are shown in Figure 2.

Figure 2: Hydrograph of excess saturation runoff (Kollet and Maxwell, 2006).

1.a.2 Runoff production by excess infiltration:
In this case, excess infiltration (Hortonian) runoff is produced by ensuring surface saturation and ponding occur before complete saturation of the soil column. This is achieved by specifying a hydraulic conductivity smaller than the rainfall rate.

Tests notes:

Example results from the model ParFlow are shown in Figure 3:

Figure 3: Hydrograph of excess infiltration runoff (Kollet and Maxwell, 2006).

1.a.3 Return flow dynamics
In this case, dynamics of return flow is evaluated by tracking the evolution of the point of intersection between the water table and the land surface during a storm-interstorm simulation.

Surface saturation and ponding are achieved before the complete saturation of the subsurface by specifying a hydraulic conductivity smaller than the rainfall rate.

Tests notes:

1.b Heterogeneous soil test cases
Previous studies have demonstrated that spatial heterogeneity of subsurface hydraulic properties has a significant influence on runoff generation. This series of test cases is designed to evaluate the influence of heterogeneity on runoff generation under two scenarios: (1) uniform subsurface properties with a very low conductivity slab at the surface, and (2) realizations of random three-dimensional subsurface heterogeneity. Details of each heterogeneous test case are provided below.

1.b.1 Slab test
This case simulates infiltration and runoff generation from a domain with uniform soil properties, except for a low-permeability slab at the surface in the center of the domain. Details of the domain are as follows:

Example results from ParFlow are shown in Figures 4 and 5:

Figure 4: Hydrograph of homogeneous field with an impermeable slab (Kollet and Maxwell, 2006; Sulis et al 2010).

Figure 5: Saturation plots at different time steps for the slab case (Kollet and Maxwell, 2006; Sulis et al 2010)

1.b.2 Heterogeneous soil realizations
This case simulates infiltration and runoff generation from a domain with heterogeneous soil properties. Hydraulic conductivity fields are generated as independent realizations of three-dimensional correlated Gaussian random fields.

Tests notes:


2. Overland and channel flow
This series of test cases are designed to evaluate simulation of overland (surface) flow by coupled models. Tests are designed to consider overland and channel flow only.

Catchment Description

Rainfall Event

Figure 6: Simple V-catchment domain for overland and channel flow test cases (Kollet and Maxwell, 2006; Sulis et al 2010).

Summary of Test Case Parameters:





Saturation excess

Infiltration excess

Return flow


Random field 

 Horizontal mesh size, Δx = Δy (m) 80 80 5 10,1 10 20
 Vertical mesh size, Δz (m) 0.0125,0.2 0.0125,0.2 0.2 0.05 0.05 NA
 Water table depth at time 0, WT (m) 0.5,1.0 1.0 0.5 1.0 1.0 NA

 Saturated hydraulic conductivity,
 Ksat (m/min) 

6.94x10-4 6.94x10-6, 6.94x10-5 6.94x10-2  6.94x10-4, 6.94x10-6   3.3x 10-4 (Average) NA
 Rainfall rate, qr (m/min) 3.3x 10-4 3.3x 10-4 1.5x 10-4 3.3x 10-4  3.3x 10-4  1.8x 10-4
 Evaporation rate, qe (m/min) 0 0 5.4x 10-6  0 0 0

 Gauckler-Strickler conductance coefficient,
 ks (m1/3 /min)     

 -hillslope cells  3.0x103 3.0x103 3.0x103 3.0x103 3.0x103 4.0x103
 -channel cells    - - - - - 4.0x102
 Manning's roughness coefficient, n (m-1/3 min)
 -hillslope cells 3.3x10-4  3.3x10-4 3.3x10-4 3.3x10-4 3.3x10-4 2.5x10-4
 -channel cells  - - - - - 2.5x10-3


  1. Kollet, S.J. and R.M. Maxwell. Integrated surface-groundwater flow modeling: A free-surface overland flow boundary condition in a parallel groundwater flow model. Advances in Water Resources, 29(7), 945-958, 2006.

  2. Sulis, M., Meyerhoff, S., Paniconi, C., Maxwell, R.M., Putti, M. and Kollet, S.J. A comparison of two physics-based numerical models for simulating surface water-groundwater interactions, Advances in Water Resources, 33(4), 456-467, doi:10.1016/j.advwatres.2010.01.010, 2010.



This is free. To register click here.


Course Location

The course will be held at the GRL conference room, Colorado School of Mines in Golden, Colorado. The GRL conference room is in the General Research Laboratories (GRL) building (A5) in the campus map below.

PLEASE NOTE: Visitors to campus during operational hours - Monday-Friday 7 a.m.-5 p.m. - should park in the General (blue) and Commuter (yellow) lots. All visitor parking areas have a pay and display parking meter.  Please visit the pay stations to receive a parking permit.  Pay station meter rates for General (blue) parking are $1.50 per hour or $8 daily; rates for Commuter lots are $1.25 per hour or $6 daily. Metered parking permits must be displayed on your dashboard. Click for a printable visitor parking map.


Transportation and Lodging

The Colorado School of Mines is located in Golden, which is 20 minutes west of Denver, 1 hour west of the Denver International Airport and can be reached by taxi, airport shuttle or rental car.

Super Shuttle Service may be called at 303-370-1300 (and you must dial all 10 digits within Denver). To get to SuperShuttle when you land, take the train from the gate areas to the Main Terminal and proceed up the escalators to Level 5 / Baggage claim. Claim your luggage, and then proceed directly to the SuperShuttle counter in the middle of the terminal under the Ground Transportation signs. Purchase a ticket and their Guest Service Agents will direct you to the appropriate shuttle loading area on Island 3 of the East or West side of the Terminal.

Driving directions

From Denver International Airport and/or from I-25: Take I-70 west, exit Highway 58 to Golden. Exit Washington Street and turn left to enter into downtown Golden. Turn right on 13th Street and left on Maple to enter campus.

From Denver: Take 6th Avenue and head west into Golden. Turn right on 19th Street. Turn left on Elm Street to enter campus.

From C-470 or I-70: Head east to 6th Avenue. Follow the directions above from 6th Avenue.

From Boulder: Take Highway 93 into Golden. Turn left onto 19th Street. Turn left on Elm Street to enter campus. 


Lodging is available in Golden, within walking distance of the campus.

Hotels and Motels in Golden Area Distance from Campus Telephone Number
Dove Inn Bed & Breakfast
2 blocks
(303) 278-2209
Pansy's Parlor Bed & Breakfast 
2 blocks
Table Mountain Inn
2 blocks
(303) 277-9898
Golden Hotel
5 blocks
(303) 279-0100
Courtyard by Marriott
2.0 miles
(303) 271-0776
Residence Inn by Marriott
2.0 miles
(303) 271-0909
La Quinta Inn
2.0 miles
(303) 279-5565
Hampton Inn
2.4 miles
(303) 278-6600
Days Inn
3.2 miles
(303) 277-0200
Holiday Inn
3.3 miles
(303) 279-7611
Marriott Denver West
3.3 miles
(303) 279-9100
Fairfield Inn
5.1 miles
(303) 231-9939
Candlewood Suites
5.1 miles
(303) 232-7171
TownePlace Suites
5.1 miles
(303) 232-7790
5.2 miles
(303) 987-2000

Golden is located 15 miles west of downtown Denver, and 40 miles west of Denver International Airport. It is strongly recommended that for events held on the CSM campus, attendees select accommodations within .5 miles of the campus if a rental car or personal transportation will not be available, as taxi service and public transportation from other areas may involve significant delays and costs.

For more information, contact :
International Groundwater Modeling Center
phone: +1 303 273-3103
fax: +1 303 384-2037
email: igwmc@mines.edu


Last Update: February 24, 2011