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Connectivity

Gravity-controlled flow is routed from one spatial object to the next using so-called connect files, which are available for the following objects:

Object

Connect file

HRU

hru.con

HRU-lte

hru-lte.con

Routing Unit

rout_unit.con

Aquifer

All connect files have the exact same structure, so to avoid repetition it is only described once instead of for every spatial object (see ). The connectivity between objects can be changed during the simulation using Decision Tables.

If the user wishes to connect an aquifer to more than one channel, the file can be used instead of the aquifer connect file.

'object'.con

This file defines the connectivity of spatial objects.

Field

Description

Type

Unit

Default

Range

Unique ID of the object

integer

n/a

id

Unique ID of the object

The unique ID of the object is a primary key that is referenced by obj_id.

Please be aware that the unique ID of the object is not necessarily the same as the ID in QSWAT+. The GIS interface numbers the objects when they are first created. Later in the process, some objects might be replaced by others, e.g. channels that are located within reservoirs. When the SWAT+ Editor writes the SWAT+ input files, it assigns consecutive ID numbers to those objects that are still included in the final setup of the model. It is extremely important to pay attention to this when identifying the channels that streamflow gauges are located on for comparing simulated and observed data.

name

Name of the object

The SWAT+ Editor assigns a name to every object, which is typically the abbreviation of the object type followed by the object number in QSWAT+. However, the name of the object is not used by SWAT+, so the user may change it.

gis_id

Object ID in QSWAT+

Please be aware that the ID in QSWAT+ is not necessarily the same as the unique ID of the object. The GIS interface numbers the objects when they are first created. Later in the process, some objects might be replaced by others, e.g. channels that are located within reservoirs. When the SWAT+ Editor writes the SWAT+ input files, it assigns consecutive ID numbers to those objects that are still included in the final setup of the model. It is extremely important to pay attention to this when identifying the channels that streamflow gauges are located on for comparing simulated and observed data.

area

Area of the object

The table below gives an overview of what the area represents and what it is used for in the model.

Even though some objects don't have an area, a value has to be specified in the area column to make sure the file gets read correctly by the model.

Object

Area

Use

lat

Latitude of the object

lon

Longitude of the object

elev

Elevation of the object

The elevation of HRUs is used to adjust precipitation and temperature when lapse rates are defined in parameters.bsn (plaps and tlaps). The elevation of the remaining objects is not used by the model.

Even though the elevation of most objects is not used by the model, a value has to be specified in the area column to make sure the file gets read correctly.

'obj'

Pointer to the object data file

The pointer to the object data file is a foreign key referencing the unique ID in the respective object data file. The header of this column is different in each connect file.

Connect file

Column header

Object data file

hru.con

hru

hru-lte.con

hlt

wst

Pointer to the weather station file

The pointer to the weather station file is a foreign key referencing name in weather-sta.cli.

cst

Pointer to the constituent file

ovfl

Pointer to the overbank flooding file

rule

Pointer to the decision table for hydrograph fractions

out_tot

Total number of outgoing hydrographs

The number of outgoing hydrographs determines, how many spatial objects receive flow from an object. The next four columns (obj_typ, obj_id, hyd_typ, frac) are repeated for each outgoing hydrograph.

obj_typ

Type of the receiving object

The table below lists the spatial objects that can be receiving objects and their respective character codes for specifying the type of receiving object. Recall, Export Coefficient, and Delivery Ratio objects cannot be receiving objects.

Spatial object

Code

HRU

hru

HRU-lte

hlt

Routing Unit

obj_id

ID of the receiving object

The ID of the receiving object is a foreign key referencing the object ID (id) in the connect file of the receiving object.

hyd_typ

Type of hydrograph that is sent to the receiving object

The types of hydrographs that can be sent depend on the sending object. The code tot is used for several spatial objects, but its meaning differs between objects. The table below lists the available codes and their definition depending on the type of object.

Code

Object

Definition

tot

Channel

Streamflow

tot

Aquifer

frac

Fraction of hydrograph sent to the receiving object

When editing the fractions, the user has to make sure that they add up to 1. Otherwise, water will be added or removed from the system and the water balance will not close.

aqu_cha.lin

This file is used to connect an aquifer to multiple channels.

A detailed description of this file will be added as soon as possible.

chan_surf.lin

detailed description of this file will be added as soon as possible.