ngen HY_Features-based data scheme

The hy_geom.R script in this directory creates a number of sample outputs for development and testing purposes. All dependencies of this script are available on CRAN with: install.packages(c("dplyr", "sf", "nhdplusTools", "jsonlite"))

• nhdplus_subset.gpkg contains a complete set of nhdplus data for the area around the smaller subset in other files.
• .csv files contain edge lists for the data described below.
• .geojson files contain basic parameters and geometry for the data described below.

Hydrologic and Hydrodynamic Graphs:

Narrative
At the top level we have a hydrologic graph of catchments and nexuses and a hydrodynamic graph of waterbodies that “pins” to the catchment graph at nexuses.

I think it would be wise to model both catchments and nexuses as labeled nodes with unlabeled directed edges between.

Any catchment node of degree 1 with an outward edge is a headwater and degree 1 with an inward edge is an outlet.

Any catchment node of degree 2 is a typical catchment that has a coincident set of (one or more) waterbodies in the waterbody graph.

Using this graph scheme, headwater catchments contribute either to the upstream end of a river (flow path) or to the shore of a waterbody that breaks up the coverage of catchment areas.

Data
Two edge lists describing the graphs.

Catchment:

Narrative
Every catchment has a catchment area realization. The catchment area would be implemented as a local water budget model which takes inputs from the atmosphere and non-surficial hydro geologic systems and contributes outputs to an outlet nexus. There is a potential to have a catchment contribute flow incrementally along the waterbody(ies) that flow through it but this would be an advanced case.

Every catchment of degree 2 will have a flow path that has an association with an upstream and downstream extent of a hydrdynamic model represented as a waterbody.

Data
Single valued catchment properties that correspond to catchment area.

Nexus:

Narrative
All nexuses must be of degree 2 or more. A nexus can receive flow from one or more catchment and contribute it to one or more catchments or waterbodies.

Data
An edge list between nexuses in the catchment graph and nexuses in a hydrodynamic model graph. Edge list not required if shared nexus IDs are used.

Waterbodies

Narrative
Waterbodies either reside over (rivers and floodplains) or break apart the catchment area coverage (large lakes). Flow can be passed from catchments to waterbodies at nexuses.

Data
Parameters of hydrodynamic model and/or storage discharge or reservoir operations.