2022 CSDMS meeting-021: Difference between revisions

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{{CSDMS meeting abstract title temp2022
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|CSDMS meeting abstract title=The Hydrogeomorphic Evolution of Variable Source Areas
|CSDMS meeting abstract title=Evolving hydrological landscapes: diverse morphologies and hydrological processes emerge from a coupled hydrogeomorphic model
|Working_group_member_WG_FRG=Terrestrial Working Group, Hydrology Focus Research Group
|Working_group_member_WG_FRG=Terrestrial Working Group, Hydrology Focus Research Group
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{{CSDMS meeting authors template
|CSDMS meeting coauthor first name abstract=Greg
|CSDMS meeting coauthor last name abstract=Tucker
|CSDMS meeting coauthor institute / Organization=CIRES, Department of Geological Science, CU Boulder
|CSDMS meeting coauthor town-city=BOULDER
|CSDMS meeting coauthor country=United States
|State=Colorado
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{{CSDMS meeting authors template
|CSDMS meeting coauthor first name abstract=Katherine
|CSDMS meeting coauthor last name abstract=Barnhart
|CSDMS meeting coauthor institute / Organization=CIRES, Department of Geological Science, CU Boulder, now at U.S. Geological Survey, Landslide Hazards Program
|CSDMS meeting coauthor town-city=Golden
|CSDMS meeting coauthor country=United States
|State=Colorado
}}
{{CSDMS meeting authors template
|CSDMS meeting coauthor first name abstract=Ciaran
|CSDMS meeting coauthor last name abstract=Harman
|CSDMS meeting coauthor institute / Organization=Environmental Health and Engineering, Johns Hopkins University
|CSDMS meeting coauthor town-city=Baltimore
|CSDMS meeting coauthor country=United States
|State=Maryland
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{{CSDMS meeting abstract template 2022
{{CSDMS meeting abstract template 2022
|CSDMS meeting abstract=In some watersheds saturated areas that shed runoff (variable source areas) and the flowing stream network expand and contract in response to precipitation, while in other watersheds saturated areas are relatively fixed despite changes in precipitation and water storage. These variations in saturated area can be understood as the result of the competition between supply of water from upslope and the ability of the subsurface to transport that water downslope. But this does not explain the genesis of the landscape conditions that determine the outcome of this competition. What geomorphic aspects of these landscapes make their hydrological function different? To what extent are variable source areas the emergent product of long-term critical zone evolution? Here we use a coupled model of landscape evolution and runoff generation from shallow subsurface flow to explore these questions. The model solves the non-linear, transient hydraulic groundwater equations to predict the water table location given prescribed time-varying recharge. Water in excess of the subsurface capacity for transport becomes overland flow, which may detach and transport sediment, modifying the landscape form that in turn affects runoff generation. We nondimensionalize the model and examine the effects of both subsurface and climatic conditions (storm intensity, duration, frequency) on coevolved landscapes under stochastic precipitation. Preliminary results show that we can produce both watersheds with low variability in saturation relative to variability in storage and vice versa by varying subsurface and climatic properties. With the same mean annual precipitation, evolved landscapes have more spatially dynamic saturated areas when the time between storms is large relative to the time to drain hillslope aquifers. Quantifying the coevolution of geomorphic properties and variable source areas will deepen our understanding of runoff generation processes and could improve prediction of trends in saturation and erosion as a result of climate change.
|CSDMS meeting abstract=Features of landscape morphology including slope, curvature, and drainage dissection are important controls on runoff generation in upland landscapes, while over long timescales runoff plays an essential role in shaping these same features through surface erosion. Many hydrologists have speculated about the importance of this coevolution and its potential for generating hydrological insights; however, observational and computational limits have long prevented direct study of coupled hydro-geomorphic systems over long timescales. What kinds of hydrological features do landscapes exhibit when their runoff is `in-tune' with the form of the landscape? Here we answer this question using a new coupled hydro-geomorphic model that is sophisticated enough to capture saturated and unsaturated zone storage and water balance partitioning between surface flow, subsurface flow, and evapotranspiration, but efficient enough to drive a landscape evolution model over millions of years. We nondimensionalize the model to arrive at a minimal set of dimensionless numbers that provide insight into how hydrologic and geomorphic parameters together affect the ultimate state. Model results show a diverse array of behaviors observed in real watersheds, including the presence of variable source areas and nonperennial streams. We also found some results that were unique and surprising, such as non-dendritic drainage networks. We hope that these results will inspire hydrologists to consider the role that landscape history plays in the hydrological processes observed today and inspire geomorphologists to consider the role of more nuanced hydrological processes in long-term landscape evolution.
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Latest revision as of 19:32, 13 April 2022


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Evolving hydrological landscapes: diverse morphologies and hydrological processes emerge from a coupled hydrogeomorphic model

David Litwin, (he/him),Johns Hopkins University Baltimore Maryland, United States. dlitwin3@jhu.edu
Greg Tucker, CIRES, Department of Geological Science, CU Boulder BOULDER Colorado, United States.
Katherine Barnhart, CIRES, Department of Geological Science, CU Boulder, now at U.S. Geological Survey, Landslide Hazards Program Golden Colorado, United States.
Ciaran Harman, Environmental Health and Engineering, Johns Hopkins University Baltimore Maryland, United States.



Features of landscape morphology including slope, curvature, and drainage dissection are important controls on runoff generation in upland landscapes, while over long timescales runoff plays an essential role in shaping these same features through surface erosion. Many hydrologists have speculated about the importance of this coevolution and its potential for generating hydrological insights; however, observational and computational limits have long prevented direct study of coupled hydro-geomorphic systems over long timescales. What kinds of hydrological features do landscapes exhibit when their runoff is `in-tune' with the form of the landscape? Here we answer this question using a new coupled hydro-geomorphic model that is sophisticated enough to capture saturated and unsaturated zone storage and water balance partitioning between surface flow, subsurface flow, and evapotranspiration, but efficient enough to drive a landscape evolution model over millions of years. We nondimensionalize the model to arrive at a minimal set of dimensionless numbers that provide insight into how hydrologic and geomorphic parameters together affect the ultimate state. Model results show a diverse array of behaviors observed in real watersheds, including the presence of variable source areas and nonperennial streams. We also found some results that were unique and surprising, such as non-dendritic drainage networks. We hope that these results will inspire hydrologists to consider the role that landscape history plays in the hydrological processes observed today and inspire geomorphologists to consider the role of more nuanced hydrological processes in long-term landscape evolution.


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