Available Components

Data Components

The following table lists the data components currently available through pymt.




Access data and metadata from a GeoTIFF file, through either a local filepath or a remote URL.


Fetch and cache gridMET meteorological data.


Download the National Water Information System (Nwis) time series datasets.


Download the National Water Model datasets.


Download the soil property datasets from the SoilGrids system.


Fetch and cache NASA Shuttle Radar Topography Mission (SRTM) land elevation data using the OpenTopography REST API.

Model Components

The following table lists the model components currently available through pymt.




Avulsion dictates the movement of rivermouths along a coastline by modeling the changes of river channel angles through the floodplain as a stochastic random walk process.


The Coastline Evolution Model addresses predominately sandy, wave-dominated coastlines on time scales ranging from years to millenia and on spatial scales ranging from kilometers to hundreds of kilometers. CEM simulates planview coastline evolution due to wave-driven alongshore sediment transport. This model can incorporate river influence and transport fluvial sediment from one or more point sources along the coastline.



CHILD computes the time evolution of a topographic surface z(x,y,t) by fluvial and hillslope erosion and sediment transport.



ECSimpleSnow was orginally developed by Ross Brown and Bruce Brasnett in Environment Canada (EC). It is an empirical algorithm to melt snow according to the surface temperature and increase in snow depth according to the precipitation that has fallen since the last analysis time. It is a semi-empirical temperature index model. It provides a quick and acceptable answer when you only have very limited inputs. The one deficiency of the model is that it does not take account of the heat budget of the snowpack which means it will melt snow too quickly in the spring.



Exponential weathering of bedrock on hillslopes. Uses exponential soil production function in the style of Ahnert (1976).


Simulate lithospheric flexure.


Component to accumulate flow and calculate drainage area. This is accomplished by first finding flow directions by a user-specified method and then calculating the drainage area and discharge. Optionally, spatially variable runoff can be set either by the model grid field ‘water__unit_flux_in’.


Single-path (steepest direction) flow direction finding on raster grids by the D8 method. This method considers flow on all eight links such that flow is possible on orthogonal and on diagonal links.


Directs flow by the D infinity method (Tarboton, 1997). Each node is assigned two flow directions, toward the two neighboring nodes that are on the steepest subtriangle. Partitioning of flow is done based on the aspect of the subtriangle.


Find the steepest single-path steepest descent flow directions. It is equivalent to D4 method in the special case of a raster grid in that it does not consider diagonal links between nodes. For that capability, use FlowDirectorD8.


Single-path (steepest direction) flow routing, and calculates flow directions, drainage area, and (optionally) discharge.


From Nelson and Outcalt (1987), the ‘frost number’, a dimensionless ratio defined by manipulation of either freezing and thawing degree-day sums or frost and thaw penetration depths, can be used to define an unambiguous latitudinal zonation of permafrost continuity. The index is computed using several variables influencing the depth of frost and thaw penetration, and can be related mathematically to the existence and continuity of permafrost. Although the frost number is a useful device for portraying the distribution of contemporary permafrost at continental scales, it is not capable of detecting relict permafrost and should not be mapped over small areas unless numerous climate stations are located in the region of interest.



GIPL (Geophysical Institute Permafrost Laboratory) is an implicit finite difference one-dimensional heat flow numerical model. The model uses a fine vertical resolution grid which preserves the latent-heat effects in the phase transition zone, even under conditions of rapid or abrupt changes in the temperature fields. It includes upper boundary condition (usually air temperature), constant geothermal heat flux at the lower boundary (typically from 500 to 1000 m) and initial temperature distribution with depth. The other inputs are precipitation, prescribed water content and thermal properties of the multilayered soil column. As an output the model produces temperature distributions at different depths, active layer thickness and calculates time of freeze up. The results include temperatures at different depths and active layer thickness, freeze-up days.



Climate-driven hydrological water balance and transport model that simulates water discharge and sediment load at a river outlet. HydroTrend simulates water and sediment fluxes at a daily timescale based on drainage basin characteristics and climate. HydroTrend can provide this river flux information to other components like CEM and Sedflux2D or Sedflux3D



The Kudryavtsev et al. (1974), or Ku model, presents an approximate solution of the Stefan problem. The model provides a steady-state solution under the assumption of sinusoidal air temperature forcing. It considers snow, vegetation, and soil layers as thermal damping to variation of air temperature. The layer of soil is considered to be a homogeneous column with different thermal properties in the frozen and thawed states. The main outputs are annual maximum frozen/thaw depth and mean annual temperature at the top of permafrost (or at the base of the active layer). It can be applied over a wide variety of climatic conditions.



2D diffusion using an explicit finite-volume method.


Simulate overland flow using de Almeida approximations. Landlab component that simulates overland flow using the de Almeida et al., 2012 approximations of the 1D shallow water equations to be used for 2D flood inundation modeling. This component calculates discharge, depth and shear stress after some precipitation event across any raster grid.


Plume simulates the sediment transport and deposition of single-grain size sediment from a river mouth entering into a marine basin by creating a turbulent jet. The model calculates a steady-state hypopycnal plume as a result of river water and sediment discharge based on simplified advection-diffusion equations. The model allows for plume deflection due to systematic coastal currents or Coriolis force


The River Avulsion and Floodplain Evolution Model (RAFEM) is a cellular model that simulates river and floodplain morphodynamics over large space and timescales. Cell size is larger than the channel belt width, and natural levees, which maintain a bankfull elevation above the channel bed, exist within a river cell. The river course is determined using a steepest-descent methodology, and erosion and deposition along the river profile are modeled as a linear diffusive process. An avulsion occurs when the riverbed becomes super-elevated relative to the surrounding floodplain, but only if the new steepest-descent path to sea level is shorter than the prior river course. If the new path to sea level is not shorter, then a crevasse splay is deposited in the adjacent river cells. The model has been designed to couple with the Coastline Evolution Model through the CSDMS Basic Model Interface.


Sedflux3D is a basin filling stratigraphic model. Sedflux3d simulates long-term marine sediment transport and accumulation into a three-dimensional basin over time scales of tens of thousands of years. It simulates the dynamics of strata formation of continental margins based on distribution of river plumes and tectonics.



Landlab component that simulates root-zone average soil moisture at each cell using inputs of potential evapotranspiration, live leaf area index, and vegetation cover.


A simple, explicit implementation of a stream power algorithm.


The model is used to simulate the lithospheric load changes as the model evolves. Depending upon how the load distribution develops, this flexure can result in the basin uplifting or subsiding (or both). The pattern of subsidence in time and space largely determines the gross geometry of time-bounded units because it controls the rate at which space is created for sedimentation.



Hillslope diffusion component in the style of Carretier et al. (2016, ESurf), and Davy and Lague (2009)


Landlab component that simulates net primary productivity, biomass and leaf area index at each cell based on inputs of root-zone average soil moisture.

Zhou, X., Istanbulluoglu, E., & Vivoni, E. R. (2013). Modeling the ecohydrological role of aspect controlled radiation on tree grass shrub coexistence in a semiarid climate. Water Resources Research, 49(5), 2872-2895.


Generates a shallow-water wave climate for a longshore transport module based on a user-defined distribution.