Joint CSDMS-SEN annual meeting 2016: Capturing Climate Change

Integrating a 2-D Hydrodynamic Model into the Landlab Modeling Framework

Jordan Adams

Tulane University, United States

Landscape evolution models often generalize hydrology by assuming steady-state discharge to calculate channel incision. While this assumption is reasonable for smaller watersheds or larger precipitation events, non-steady hydrology is a more applicable condition for semi-arid landscapes, which are prone to short-duration, high-intensity storms. In these cases, the impact of a hydrograph (non-steady method) may be significant in determining long-term drainage basin evolution. This project links a two-dimensional hydrodynamic algorithm with a detachment-limited incision component in the Landlab modeling framework. Storms of varying intensity and duration are run across two synthetic landscapes, and incision rate is calculated throughout the hydrograph. For each case, peak discharge and total incision are compared to the values predicted by steady-state to evaluate the impact of the two hydrologic methods. We explore the impact of different critical shear stress values on total incision using the different flow methods. Finally, a watershed will be evolved to topographic steady-state using both the steady- and non-steady flow routing methods to identify differences in overall relief and drainage network configuration. Preliminary testing with no critical shear stress threshold has shown that although non-steady peak discharge is smaller than the peak predicted by the steady-state method, total incised depth from non-steady methods exceeds the steady-state derived incision depth in all storm cases. With the introduction of a incision threshold, we predict there will be cases where the steady-state method overestimates total incised depth compared to the non-steady method. Additionally, we hypothesize that watersheds evolved with the non-steady method will be characterized by decreased channel concavities. This work demonstrates that when modeling landscapes characterized by semi-arid climates, choice of hydrology method can significantly impact the resulting morphology.

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Of interest for:
  • Terrestrial Working Group
  • Hydrology Focus Research Group