Inputs Overview¶
Every Hydrata model is built from a set of geospatial inputs. Terrain and friction rasters are uploaded as files, or imported from global data; the rest are drawn directly in the map interface.
Input types¶
| Input | Format | Required | Description |
|---|---|---|---|
| Terrain | GeoTIFF (uploaded or imported) | Yes | The elevation surface the water flows over |
| Boundaries | LineString (drawn) | Yes | Domain boundary lines, each with a boundary condition type |
| Inflows | LineString (drawn) | One of the two | A flow rate or hydrograph injected along a line |
| Rainfalls | Polygon (drawn) | One of the two | A rainfall intensity or design storm applied over an area |
| Friction | Polygon (drawn) | No | Zones with a custom Manning's roughness |
| Friction Rasters | GeoTIFF (uploaded) | No | A per-cell Manning's n surface |
| Mesh Regions | Polygon (drawn) | No | Areas that get a finer mesh than the base mesh size |
| Structures | Polygon (drawn) | No | Building footprints and solid obstacles |
A scenario needs a terrain, a boundary, and either an inflow or a rainfall. It can hold one of each, so a rain-driven model with a creek inflow is one scenario, not two.
Catchments, nodes and links also appear as project layers, but they are produced in the Hydrology tab rather than drawn here.
Creating inputs¶
- Upload: drag and drop, or use the upload icon, for terrain GeoTIFFs and friction rasters.
- Import: pull free global terrain for any area on Earth, without supplying a file of your own. See Terrain.
- Draw: use the map editing tools to create features interactively. Each drawn feature opens an attribute form for its own fields.
An input is project-level data. Several scenarios can reference the same input, and an input cannot be deleted while any scenario still references it.
Coordinate systems¶
Inputs are stored in a projected coordinate system, and Hydrata reprojects an uploaded GeoTIFF into the appropriate UTM zone for its area. When a file arrives with no coordinate system of its own, Hydrata asks you to name the one it was authored in rather than guessing. Drawn features inherit the project's coordinate system automatically.
Vertical units are a separate question from the horizontal coordinate system, and Hydrata checks them separately. See Vertical datum.