1. March 24, 2014 Rosa Aguilar Computational Hydraulics and Hydrology
Comparison of overland flow diffusion wave model with SWMM and HEC-HMS (Preliminary)
March 24, 2014
Rosa Aguilar
Computational Hydraulics and Hydrology

2.
Surface Runoff
Water flow that occurs when the soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land (wikipedia).

3. Modeling
Watershed runoff must be predicted to provide the information for certain activities:
Increased volume of runoff for proposed changes to land use in a watershed.
A model relates something unknown (the output) to something known (the input).

4. Modeling Systems Hydrologic Modeling System (HEC-HMS)
2013
EPA’s Storm Water Management Model (SWMM)
2011
Overland flow diffusion wave model

5. HEC-HMS US Army Corps of Engineers Four versions since HEC-1
Version 1: Graphical user interface.
Version 2: Continuous simulation.
Version 3: New computational features and graphical user interface.
Snowmelt, evapotranspiration, infiltration, data management, increase user efficiency.
Version 4: New computation features.
Surface erosion and channel sediment transport
Nutrient water quality simulation

6. HEC-HMS Routing Models Kinematic wave Lag Modified PuIs Muskingum
Muskingum-Cunge Standard Section
Muskingum-Cunge 8-point Section Confluence
Bifurcation

7. EPA SWMM
Routing models
Steady flow
Kinematic wave
Dynamic wave

8. EPA SWMM
Steady Flow: Instantaneous translation of a hydrograph with no time delay or change in shape due to conduit storage.
Kinematic Wave: Efficient but simplified approach that cannot deal with backwater effects, pressurized flow, flow reversal, and non-dendritic layouts. Numerical stability attained with moderately large time steps, on the order of 5 to 15 minutes
Dynamic Wave: Can represent these conditions. However, the procedure requires more computation time, due to the need for smaller time steps to maintain numerical stability.

9. Overland flow diffusion wave model
Simulates catchment dynamics using the diffusion wave model developed by Ponce (1986). The program is a numerical model of overland flow using an open-book schematization.

10. Overland flow diffusion wave model
Outflow hydrograph does not vary with the choice of grid size.
Physical diffusivity of Hayami:
Numerical diffusivity of Cunge:
Cell Reynolds number:

11. Overland flow diffusion wave model
Diffusion wave with dynamic components
Dynamic hydraulic diffusivity:
Numerical dispersion is minimized by setting the Courant number C equal to 1:

12. Fig. 1 Effect of grid resolution on the outflow hydrograph, 12-hr rainfall duration, 2 cm/hr rainfall intensity, 18-ha watershed area.

13. Further Studies Run HEC-HMS and SWMM.
Run the runoff simulation models with the data used in Overland flow of diffusion wave model.
Compare the results.

14. References
Ponce, V.M., Diffusion Wave Modeling of Catchment Dynamics Journal of Hydraulic Engineering, 112(8). pp
Wikipedia. (2014, March 23). Surface Water. Retrieved from
Mahomet Aquifer Consortium. (2014, March 23). MAC Educational Materials/ 2: Hydrologic Cycle. Retrieved from