The Model of Riverine Physical Habitat and Ecogeomorphic Dynamics (MoRPHED) is based on the idea that we can make morphodynamic modeling of gravel-bed rivers more simple and efficient, while still producing results that are accurate and apply over meaningful space and time scales. It's easy to get weighed down by the small details of modeling how a river will evolve - details like tracking each sediment particle as it moves downstream, and recomputing the characteristics of the flow at very fine timesteps. Without a doubt, these fine-scale, detail-oriented modeling techniques have given us major breakthroughs in our understanding of river behavior. But they can also slow down our simulations, or require computing power beyond our means - meaning the timescales over which we can predict are limited.
At the heart of MoRPHED is a question: how simple can we make our model while still achieving physically realistic results? That is, what hydraulic and sediment transport processes do we need to include and which ones can we do away with? How often do we need to re-run our model to produce phenomena we see in natural rivers, like avulsions and bar formation/erosion?
Initial development and testing of MoRPHED have given us some answers to these questions, but more exploration is needed. That's why this site not only provides tutorials and example datasets to help you run the model, but also encourages you to improve on it - download the source code, explore the effects of altering the way the model is run, and even include your own process modules. MoRPHED is as much a morphodynamic model as it is a modular framework for testing the advantages and drawbacks of how we model river evolution.
How it Works
The operation of MoRPHED is straightforward: you provide an initial digital elevation model, or DEM, that describes the initial topography of your river reach of interest. You also provide a hydrograph that details the flood or series of floods you'd like to model, and MoRPHED computes the evolution of the river reach and outputs a new DEM. The way MoRPHED computes that evolution is far simpler than many other morphodynamic models, for two main reasons:
- MoRPHED simulates river evolution at the event scale. That is, the timestep over which the model operates isn't a second or a minute, but rather a flood.
- MoRPHED transports sediment according to a path-length distribution, which simply specifies the amount of mobilized sediment that is deposited a given distance downstream. These can take many forms (see above), but in any case, the use of the path-length distribution drastically simplifies the computational overhead needed to model river evolution, since MoRPHED doesn't need to track individual sediment particles on their way downstream.
MoRPHED was originally conceptualized, and is written, by Alan Kasprak, Konrad Hafen, and Joe Wheaton at Utah State University. Extensive development assistance was provided by Philip Bailey (North Arrow Research), Matt Nahorniak (South Fork Research), James Brasington (Queen Mary University of London), and James Hensleigh, Sara Bangen, and Eric Wall (all of Utah State University and EcoLogical Research).
Development of MoRPHED is made possible with funding from the National Science Foundation (Award #7086465).