CSDMS - User contributions [en]

User:Dlitwin3

2025-09-19T18:16:04Z

Dlitwin3:

{{Signup information member
|First name member=David
|Last name member=Litwin
|Picture member=Headshot1.jpeg
|Institute member=Temple University
|Department member=Earth and Environmental Science
|City member=Philadelphia
|Country member=United States
|State member=Pennsylvania
|Confirm email member=david.litwin@temple.edu
|Working group member=Hydrology Focus Research Group, Critical Zone Focus Research Group
|Emaillist group member=yes
|Description of your CSDMS-related interests member=Modeling in catchment hydrology, soil and landscape evolution.
|Memberagreement=I have read and agree to the Privacy Policy
}}

User:Dlitwin3

2024-09-16T13:10:07Z

Dlitwin3:

{{Signup information member
|First name member=David
|Last name member=Litwin
|Picture member=Headshot1.jpeg
|Institute member=GFZ Potsdam
|Department member=Earth Surface Process Modelling
|City member=Potsdam
|Country member=Germany
|Confirm email member=dlitwin@gfz-potsdam.de
|Working group member=Hydrology Focus Research Group, Critical Zone Focus Research Group
|Emaillist group member=yes
|Description of your CSDMS-related interests member=Modeling in catchment hydrology, soil and landscape evolution.
|Memberagreement=I have read and agree to the Privacy Policy
}}

2022 CSDMS meeting-021

2022-04-14T01:32:03Z

Dlitwin3:

{{CSDMS meeting personal information template-2022
|CSDMS meeting first name=David
|CSDMS meeting last name=Litwin
|CSDMS Pronouns=he/him
|CSDMS meeting institute=Johns Hopkins University
|CSDMS meeting city=Baltimore
|CSDMS meeting country=United States
|CSDMS meeting state=Maryland
|CSDMS meeting email address=dlitwin3@jhu.edu
}}
{{CSDMS meeting select clinics1 2022
|CSDMS_meeting_select_clinics1_2022=3) The Art of Modeling
}}
{{CSDMS meeting select clinics2 2022
|CSDMS_meeting_select_clinics2_2022=4) Xarray for Scalable Scientific Data Analysis
}}
{{CSDMS meeting select clinics3 2022
|CSDMS_meeting_select_clinics3_2022=1) Component Creation with Landlab
}}
{{CSDMS meeting abstract yes no 2022
|CSDMS meeting abstract submit=Yes
}}
{{CSDMS meeting abstract title temp2022
|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
}}
{{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
}}
{{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
}}
{{CSDMS meeting abstract template 2022
|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.
}}
{{blank line template}}

2022 CSDMS meeting-021

2022-01-27T20:50:59Z

Dlitwin3:

{{CSDMS meeting personal information template-2022
|CSDMS meeting first name=David
|CSDMS meeting last name=Litwin
|CSDMS Pronouns=he/him
|CSDMS meeting institute=Johns Hopkins University
|CSDMS meeting city=Baltimore
|CSDMS meeting country=United States
|CSDMS meeting state=Maryland
|CSDMS meeting email address=dlitwin3@jhu.edu
}}
{{CSDMS meeting select clinics1 2022
|CSDMS_meeting_select_clinics1_2022=3) The Art of Modeling
}}
{{CSDMS meeting select clinics2 2022
|CSDMS_meeting_select_clinics2_2022=4) Xarray for Scalable Scientific Data Analysis
}}
{{CSDMS meeting select clinics3 2022
|CSDMS_meeting_select_clinics3_2022=1) Component Creation with Landlab
}}
{{CSDMS meeting abstract yes no 2022
|CSDMS meeting abstract submit=Yes
}}
{{CSDMS meeting abstract title temp2022
|CSDMS meeting abstract title=The Hydrogeomorphic Evolution of Variable Source Areas
|Working_group_member_WG_FRG=Terrestrial Working Group, Hydrology Focus Research Group
}}
{{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.
}}
{{blank line template}}

2022 CSDMS meeting-021

2022-01-27T20:42:53Z

Dlitwin3: Created page with "{{CSDMS meeting personal information template-2022 |CSDMS meeting first name=David |CSDMS meeting last name=Litwin |CSDMS Pronouns=he/him |CSDMS meeting institute=Johns Hopkin..."

2020 CSDMS meeting-018

2020-02-07T16:31:18Z

Dlitwin3:

{{CSDMS meeting personal information template-2020
|CSDMS meeting first name=David
|CSDMS meeting last name=Litwin
|CSDMS meeting institute=Johns Hopkins University
|CSDMS meeting city=Baltimore
|CSDMS meeting country=United States
|CSDMS meeting state=Maryland
|CSDMS meeting email address=dlitwin3@jhu.edu
|CSDMS meeting phone=2162104723
}}
{{CSDMS meeting select clinics1 2020
|CSDMS_meeting_select_clinics1_2020=1) High-resolution Topography
}}
{{CSDMS meeting select clinics2 2020
|CSDMS_meeting_select_clinics2_2020=1) Deep Neural Network, Part I
}}
{{CSDMS meeting select clinics3 2020
|CSDMS_meeting_select_clinics3_2020=3) Deep Neural Network, Part II
}}
{{CSDMS scholarships yes no
|CSDMS meeting scholarships=No
}}
{{CSDMS meeting abstract yes no 2020
|CSDMS meeting abstract submit=Yes
}}
{{CSDMS meeting abstract title temp2020
|CSDMS meeting abstract title=TBD
}}
{{CSDMS meeting abstract template 2020}}
{{blank line template}}

2020 CSDMS meeting-018

2020-02-07T16:23:52Z

Dlitwin3: Created page with "{{CSDMS meeting personal information template-2020 |CSDMS meeting first name=David |CSDMS meeting last name=Litwin |CSDMS meeting institute=Johns Hopkins University |CSDMS mee..."

{{CSDMS meeting personal information template-2020
|CSDMS meeting first name=David
|CSDMS meeting last name=Litwin
|CSDMS meeting institute=Johns Hopkins University
|CSDMS meeting city=Baltimore
|CSDMS meeting country=United States
|CSDMS meeting state=Maryland
|CSDMS meeting email address=dlitwin3@jhu.edu
|CSDMS meeting phone=2162104723
}}
{{CSDMS meeting select clinics1 2020
|CSDMS_meeting_select_clinics1_2020=1) High-resolution Topography
}}
{{CSDMS meeting select clinics2 2020
|CSDMS_meeting_select_clinics2_2020=1) Deep Neural Network, Part I
}}
{{CSDMS meeting select clinics3 2020
|CSDMS_meeting_select_clinics3_2020=3) Deep Neural Network, Part II
}}
{{CSDMS scholarships yes no
|CSDMS meeting scholarships=No
}}
{{CSDMS meeting abstract yes no 2020
|CSDMS meeting abstract submit=No
}}
{{CSDMS meeting abstract title temp2020}}
{{CSDMS meeting abstract template 2020}}
{{blank line template}}

Model:GroundwaterDupuitPercolator

2020-01-07T16:21:11Z

Dlitwin3: Created page with "{{Model identity |ModelFramework=LandLab |Model type=Single }} {{Start models incorporated}} {{End a table}} {{Model identity2 |ModelDomain=Hydrology |Spatialscale=Landscape-S..."

{{Model identity
|ModelFramework=LandLab
|Model type=Single
}}
{{Start models incorporated}}
{{End a table}}
{{Model identity2
|ModelDomain=Hydrology
|Spatialscale=Landscape-Scale, Reach-Scale, Watershed-Scale
|One-line model description=The GroundwaterDupuitPercolator solves the Boussinesq equation for flow in an unconfined aquifer over an impermeable aquifer base and calculates groundwater return flow to the surface.
|Extended model description=The GroundwaterDupuitPercolator is appropriate for modeling shallow groundwater flow where the vertical component of flow is negligible. Where the groundwater table approaches the land surface, it calculates seepage that can be routed using other Landlab components. It can be implemented on both regular (e.g. rectangular and hexagonal) and irregular grids determined by the user. Recharge, hydraulic conductivity, and porosity may be specified as single values uniform over the model domain, or as vectors on the nodes (recharge, porosity) or links (hydraulic conductivity) of the grid. Link hydraulic conductivity can also be specified from a two-dimensional hydraulic conductivity tensor using an included function. For mass balance calculations, the model includes methods to determine the total groundwater storage on the grid domain, the total recharge flux in, and total groundwater and surface water fluxes leaving through the boundaries.
}}
{{Start model keyword table}}
{{Model keywords
|Model keywords=groundwater
}}
{{Model keywords
|Model keywords=hydrology
}}
{{Model keywords
|Model keywords=seepage
}}
{{Model keywords
|Model keywords=aquifer
}}
{{End a table}}
{{Modeler information
|First name=David
|Last name=Litwin
|Type of contact=Model developer
|Institute / Organization=Johns Hopkins University
|Town / City=Baltimore
|Postal code=21210
|Country=United States
|State=Maryland
|Email address=dlitwin3@jhu.edu
}}
{{Model technical information
|Supported platforms=Unix, Linux, Mac OS, Windows
|Programming language=Python
|Code optimized=Single Processor
|Start year development=2019
|Does model development still take place?=Yes
|Source code availability=Through web repository
|Source web address=https://github.com/landlab/landlab
|Program license type=BSD or MIT X11
}}
{{Input - Output description
|Describe input parameters=Gridded elevation, aquifer base elevation. Hydraulic conductivity, porosity, recharge.
|Pre-processing software needed?=No
|Post-processing software needed?=No
|Visualization software needed?=No
}}
{{Process description model
|Describe processes represented by the model=Groundwater flow and seepage
|Describe key physical parameters and equations=Boussinesq aquifer equation, Darcy's law.
|Describe any numerical limitations and issues=Explicit forward in time finite volume method limits maximum timestep/resolution combination. This can be managed using the adaptive timestep solver that is included.
}}
{{Model testing}}
{{Users groups model}}
{{Documentation model
|Manual model available=Yes
|Model website if any=https://landlab.readthedocs.io/en/release/reference/components/groundwater.html
}}
{{Additional comments model}}
{{CSDMS staff part
|OpenMI compliant=Not yet
|IRF interface=Not yet
|CMT component=Not yet
|PyMT component=Not yet
}}
{{Start coupled table}}
{{End a table}}
{{End headertab}}

{{#ifexist:Template:{{#sub:{{PAGENAME}}|0|1}}{{#sub:{{lc:{{PAGENAME}}}}|1}} download stats | ==Download statistics==
{{{{#sub:{{PAGENAME}}|0|1}}{{#sub:{{lc:{{PAGENAME}}}}|1}} download stats}} | }}

==Introduction==

== History ==

== References ==
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{{#ifexist:Template:{{PAGENAME}}-citation-indices|{{{{PAGENAME}}-citation-indices}}|}} 
{{Include_featured_references_models_cargo}} 

== Issues ==

== Help ==
{{#ifexist:Model_help:{{PAGENAME}}|[[Model_help:{{PAGENAME}}]]|}}

== Input Files ==

== Output Files ==

2019 CSDMS meeting-028

2019-05-16T19:58:21Z

Dlitwin3:

{{CSDMS meeting personal information template-2019
|CSDMS meeting first name=David
|CSDMS meeting last name=Litwin
|CSDMS meeting institute=Johns Hopkins University
|CSDMS meeting city=Baltimore
|CSDMS meeting country=United States
|CSDMS meeting state=Maryland
|CSDMS meeting email address=dlitwin3@jhu.edu
|CSDMS meeting phone=2162104723
}}
{{CSDMS meeting scholar and pre-meeting2019
|CSDMS meeting pre-conference2019=Software Carpentry Workshop
}}
{{CSDMS meeting select clinics1 2019
|CSDMS_meeting_select_clinics1_2019=3) Pangeo - Scalable Geoscience Tools Python
}}
{{CSDMS meeting select clinics2 2019
|CSDMS_meeting_select_clinics2_2019=1) PyMT - The CSDMS Python Modeling tool
}}
{{CSDMS meeting select clinics3 2019
|CSDMS_meeting_select_clinics3_2019=3) SALib - Model Sensitivity Analysis
}}
{{CSDMS scholarships yes no
|CSDMS meeting scholarships=Yes
}}
{{CSDMS meeting abstract yes no 2019
|CSDMS meeting abstract submit=Yes
}}
{{CSDMS meeting abstract title temp2019
|CSDMS meeting abstract title=Implicit-spectral solution for a simple landscape evolution model
}}
{{CSDMS meeting abstract template 2019
|CSDMS meeting abstract=In this study, implicit and explicit spectral solutions are considered for solving the linear diffusion term of a simple 2D loosely coupled landscape evolution model. Spectral methods are powerful tools for solving elliptical partial differential equations and are widely used in other fields, though they have received comparatively little attention in landscape evolution modelling. In the LEM considered, the land surface elevation is altered by three processes: regional uplift, fluvial incision, and linear hillslope diffusion. In the simplest case, these processes act in an undifferentiated way across the entire landscape. While a recent algorithm has provided a powerful implicit solution to for the fluvial incision term, explicit formulations of diffusion remain standard. However, when the desired grid is large, an explicit method may be restricted by stability to a time step too small for the timescales of interest. To solve this problem implicitly, I transform the problem into the spectral domain, solve the 2D diffusion equation with a Crank-Nicholson method, and compare the results to explicit finite difference and explicit spectral methods. In its most simple formulation, the spectral methods require periodic boundary conditions in both dimensions. Resulting from these conditions, I show a tessellating solution where the landscape takes the form of a flat torus.
}}
{{blank line template}}

2019 CSDMS meeting-028

2019-05-04T17:31:42Z

Dlitwin3:

{{CSDMS meeting personal information template-2019
|CSDMS meeting first name=David
|CSDMS meeting last name=Litwin
|CSDMS meeting institute=Johns Hopkins University
|CSDMS meeting city=Baltimore
|CSDMS meeting country=United States
|CSDMS meeting state=Maryland
|CSDMS meeting email address=dlitwin3@jhu.edu
|CSDMS meeting phone=2162104723
}}
{{CSDMS meeting scholar and pre-meeting2019
|CSDMS meeting pre-conference2019=Software Carpentry Workshop
}}
{{CSDMS meeting select clinics1 2019
|CSDMS_meeting_select_clinics1_2019=3) Pangeo - Scalable Geoscience Tools Python
}}
{{CSDMS meeting select clinics2 2019
|CSDMS_meeting_select_clinics2_2019=1) PyMT - The CSDMS Python Modeling tool
}}
{{CSDMS meeting select clinics3 2019
|CSDMS_meeting_select_clinics3_2019=3) SALib - Model Sensitivity Analysis
}}
{{CSDMS scholarships yes no
|CSDMS meeting scholarships=Yes
}}
{{CSDMS meeting abstract yes no 2019
|CSDMS meeting abstract submit=Yes
}}
{{CSDMS meeting abstract title temp2019
|CSDMS meeting abstract title=Implicit-spectral solution for a simple landscape evolution model
}}
{{CSDMS meeting abstract template 2019
|CSDMS meeting abstract=In this study, implicit and explicit spectral solutions are considered for solving the linear diffusion term of a simple 2D loosely coupled landscape evolution model. Spectral methods are powerful tools for solving elliptical partial differential equations and are widely used in other fields, though they have received comparatively little attention in landscape evolution modelling. In the LEM considered, the land surface elevation is altered by three processes: regional uplift, fluvial incision, and linear hillslope diffusion. In the simplest case, these processes act in an undifferentiated way across the entire landscape. While a recent algorithm has provided a powerful implicit solution to for the fluvial incision term, explicit formulations of diffusion remain standard. However, when the desired grid is large, an explicit method may be restricted by stability to a time step too small for the timescales of interest. To solve this problem implicitly, I transform the problem into the spectral domain, solve the 2D diffusion equation with a Crank-Nicholson method, and compare the results to explicit finite difference and explicit spectral methods. In its most simple formulation, the spectral methods require periodic boundary conditions in both dimensions. Resulting from these conditions, I show a whimsically tessellating solution where the landscape takes the form of a flat torus.
}}
{{blank line template}}

2019 CSDMS meeting-028

2019-02-06T21:52:07Z

Dlitwin3:

{{CSDMS meeting personal information template-2019
|CSDMS meeting first name=David
|CSDMS meeting last name=Litwin
|CSDMS meeting institute=Johns Hopkins University
|CSDMS meeting city=Baltimore
|CSDMS meeting country=United States
|CSDMS meeting state=Maryland
|CSDMS meeting email address=dlitwin3@jhu.edu
|CSDMS meeting phone=2162104723
}}
{{CSDMS meeting scholar and pre-meeting2019
|CSDMS meeting pre-conference2019=Software Carpentry Workshop
}}
{{CSDMS meeting select clinics1 2019
|CSDMS_meeting_select_clinics1_2019=3) Pangeo - Scalable Geoscience Tools Python
}}
{{CSDMS meeting select clinics2 2019
|CSDMS_meeting_select_clinics2_2019=1) PyMT - The CSDMS Python Modeling tool
}}
{{CSDMS meeting select clinics3 2019
|CSDMS_meeting_select_clinics3_2019=3) SALib - Model Sensitivity Analysis
}}
{{CSDMS scholarships yes no
|CSDMS meeting scholarships=Yes
}}
{{CSDMS meeting abstract yes no 2019
|CSDMS meeting abstract submit=Yes
}}
{{CSDMS meeting abstract title temp2019
|CSDMS meeting abstract title=Implicit-spectral solution for a simple landscape evolution model
}}
{{CSDMS meeting abstract template 2019
|CSDMS meeting abstract=In this study, a spectral solution to a simple two-dimensional landscape evolution model (LEM) is considered. Spectral methods are powerful tools for solving elliptical partial differential equations and are widely used in other fields, though they have received comparatively little attention in landscape evolution modelling. In the LEM considered, the land surface elevation is altered by three processes: regional uplift, fluvial incision, and hillslope diffusion. In the simplest case, these processes act in an undifferentiated way across the entire landscape. Even with this model, the dependence of the fluvial incision term on contributing area makes numerical solutions to this problem challenging. As a result of this term, the governing equation has the form of an integral PDE, which is resistant to implicit schemes. For this reason, many LEMs are solved explicitly. When the desired grid is large, an explicit method may be restricted by stability to a time step too small for the timescales of interest. To solve the problem implicitly, I draw the comparison between this LEM and a heat equation with a nonlinear sink (the fluvial incision term) and solve the diffusional problem with an implicit-spectral method by enforcing periodicity in one dimension. I compare this with an explicit solution and draw some preliminary conclusions on the usefulness of this method for landscape evolution modeling.
}}
{{blank line template}}

User:Dlitwin3

2019-02-04T21:26:55Z

Dlitwin3: Created page with "{{Signup information member |First name member=David |Last name member=Litwin |Picture member=Headshot.jpeg |Institute member=Johns Hopkins University |Department member=Envir..."

{{Signup information member
|First name member=David
|Last name member=Litwin
|Picture member=Headshot.jpeg
|Institute member=Johns Hopkins University
|Department member=Environmental Health and Engineering
|City member=Baltimore
|Country member=United States
|State member=Maryland
|Confirm email member=dlitwin3@jhu.edu
|Cell phone member=2162104723
|Working group member=Hydrology Focus Research Group, Critical Zone Focus Research Group
|Emaillist group member=yes
|Description of your CSDMS-related interests member=Modeling in catchment hydrology, soil and landscape evolution.
|Memberagreement=I have read and agree to the Privacy Policy
}}

2019 CSDMS meeting-028

2019-02-04T21:16:33Z

Dlitwin3:

2019 CSDMS meeting-028

2019-02-04T21:14:36Z

Dlitwin3: Created page with "{{CSDMS meeting personal information template-2019 |CSDMS meeting first name=David |CSDMS meeting last name=Litwin |CSDMS meeting institute=Johns Hopkins University |CSDMS mee..."