Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 10, 1645-1663, 2017
https://doi.org/10.5194/gmd-10-1645-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Model description paper
20 Apr 2017
The Landlab v1.0 OverlandFlow component: a Python tool for computing shallow-water flow across watersheds
Jordan M. Adams1, Nicole M. Gasparini1, Daniel E. J. Hobley2, Gregory E. Tucker3,4, Eric W. H. Hutton5, Sai S. Nudurupati6, and Erkan Istanbulluoglu6 1Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, USA
2School of Earth and Ocean Sciences, Cardiff University, Cardiff, UK
3Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA
4Department of Geological Sciences, University of Colorado, Boulder, CO, USA
5Community Surface Dynamics Modeling System (CSDMS), University of Colorado, Boulder, CO, USA
6Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
Abstract. Representation of flowing water in landscape evolution models (LEMs) is often simplified compared to hydrodynamic models, as LEMs make assumptions reducing physical complexity in favor of computational efficiency. The Landlab modeling framework can be used to bridge the divide between complex runoff models and more traditional LEMs, creating a new type of framework not commonly used in the geomorphology or hydrology communities. Landlab is a Python-language library that includes tools and process components that can be used to create models of Earth-surface dynamics over a range of temporal and spatial scales. The Landlab OverlandFlow component is based on a simplified inertial approximation of the shallow water equations, following the solution of de Almeida et al.(2012). This explicit two-dimensional hydrodynamic algorithm simulates a flood wave across a model domain, where water discharge and flow depth are calculated at all locations within a structured (raster) grid. Here, we illustrate how the OverlandFlow component contained within Landlab can be applied as a simplified event-based runoff model and how to couple the runoff model with an incision model operating on decadal timescales. Examples of flow routing on both real and synthetic landscapes are shown. Hydrographs from a single storm at multiple locations in the Spring Creek watershed, Colorado, USA, are illustrated, along with a map of shear stress applied on the land surface by flowing water. The OverlandFlow component can also be coupled with the Landlab DetachmentLtdErosion component to illustrate how the non-steady flow routing regime impacts incision across a watershed. The hydrograph and incision results are compared to simulations driven by steady-state runoff. Results from the coupled runoff and incision model indicate that runoff dynamics can impact landscape relief and channel concavity, suggesting that, on landscape evolution timescales, the OverlandFlow model may lead to differences in simulated topography in comparison with traditional methods. The exploratory test cases described within demonstrate how the OverlandFlow component can be used in both hydrologic and geomorphic applications.

Citation: Adams, J. M., Gasparini, N. M., Hobley, D. E. J., Tucker, G. E., Hutton, E. W. H., Nudurupati, S. S., and Istanbulluoglu, E.: The Landlab v1.0 OverlandFlow component: a Python tool for computing shallow-water flow across watersheds, Geosci. Model Dev., 10, 1645-1663, https://doi.org/10.5194/gmd-10-1645-2017, 2017.
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Short summary
OverlandFlow is a 2-dimensional hydrology component contained within the Landlab modeling framework. It can be applied in both hydrology and geomorphology applications across real and synthetic landscape grids, for both short- and long-term events. This paper finds that this non-steady hydrology regime produces different landscape characteristics when compared to more traditional steady-state hydrology and geomorphology models, suggesting that hydrology regime can impact resulting morphologies.
OverlandFlow is a 2-dimensional hydrology component contained within the Landlab modeling...
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