# Presentation: 820614

## Pfafstetter Basin Codification

- What is it?
- A topological system for codification of basins.
- Based on topology of the river network.
- References:
- Pfafstetter, 1989
-     "Classification of hydrographic basins:  coding methodology", unpublished manuscript, Departmento Nacional de Obras de Saneamento, Rio de Janeiro
- Verdin, 1997
-     http://edcdaac.usgs.gov/gtopo30/hydro/P311.html
- Why use it?
- Hydrologically ordered
- Provides a unique ID for each FFMP small basin
- Efficiency of digits

## Pfafstetter Basin Codification

- 2

- 4

- 6

- 8

- First, identify the four tributaries with the highest flow accumulations (largest drainage areas) along the main stem.
- These are assigned even digits from downstream to upstream.

## Pfafstetter Basin Codification

- 2

- 4

- 6

- 8

- Next, assign odd digits to the interbasins along the main stem.
- Note:  In the Pfafstetter system, basin 9 is defined as a main stem basin and has a higher flow accumulation value than tributary 8.

- 1

- 3

- 5

- 7

- 9

## Pfafstetter Basin Codification

- 2

- 4

- 6

- 8

- 1

- 3

- 5

- 7

- 9

- 26

- Subdivision of Tributaries:

- 22

- 24

- 28

- 21

- 23

- 25

- 27

- 29

## Pfafstetter Basin Codification

- 2

- 4

- 6

- 8

- 1

- 3

- 5

- 7

- 9

- 76

- Subdivision of Interbasins:

- 72

- 74

- 78

- 71

- 73

- 75

- 77

- 79

## Pfafstetter Basin Codification

- 2

- 4

- 6

- 1

- 3

- 5

- 9

- Codification when there are less than four tributaries:

- 2

- 4

- 1

- 3

- 9

- 2

- 1

- 9

- Note:  Basin 9 is always the main stem basin.

## The Pfaf_id attribute is a 13-character string

The first four digits represent the 8-digit HUC basin
For example, each Pfaf_id for FFMP basins in HUC 03010102 will begin with "1150".

8-digit HUC Basin	First 4 digits in the Pfaf_id
	03010102		    1150XXXXXXXXX
	03010103		    1151XXXXXXXXX
	03010104		    1152XXXXXXXXX
	03010105		    1153XXXXXXXXX
	.		                     .
	.		                     .
  etc.		                   etc.

- The first four digits represent the 8-digit HUC basin
- For example, each *Pfaf_id* for FFMP basins in HUC 03010102 will begin with "1150".
- _8-digit HUC Basin_	_First 4 digits in the __*Pfaf_id*_
- 	03010102		    1150XXXXXXXXX
- 	03010103		    1151XXXXXXXXX
- 	03010104		    1152XXXXXXXXX
- 	03010105		    1153XXXXXXXXX
- 	.		                     .
- 	.		                     .
-   etc.		                   etc.

- Pfafstetter Basin CodificationThe *Pfaf_id* Attribute

## 
The last nine digits represent the "local" Pfafstetter ID internal to the HUC
The first digit of the "local" Pfafstetter ID is generally a "2", but can be any other digit if:
More than one outlet exists in the HUC basin
The HUC basin is along the coast
The HUC basin is closed or contains natural sinks.
Note:  The actual Pfafstetter ID begins with the 6th digit of the 13-digit Pfaf_id.

The combination of these 13 digits ensures a unique Pfaf_id for each small basin in the country.

- The last nine digits represent the "local" Pfafstetter ID internal to the HUC
- The first digit of the "local" Pfafstetter ID is generally a "2", but can be any other digit if:
- More than one outlet exists in the HUC basin
- The HUC basin is along the coast
- The HUC basin is closed or contains natural sinks.
- Note:  The actual Pfafstetter ID begins with the 6th digit of the 13-digit *Pfaf_id*.
- The combination of these 13 digits ensures a unique *Pfaf_id *for each small basin in the country.

- Pfafstetter Basin CodificationThe *Pfaf_id* Attribute

## Pfafstetter Basin CodificationExample - HUC 05010002

- 1st Division

## Pfafstetter Basin CodificationExample - HUC 05010002

- 2nd Division (Basin 6)

## Pfafstetter Basin CodificationExample - HUC 05010002

- 3rd Division ( Basin 6)

## Pfafstetter Basin CodificationExample - HUC 05010002

- Add a leading "2" and trailing zeros to create the 9-digit "local" Pfafstetter ID.

- Local Pfafstetter ID:
- "2" + "699" + "00000"

## Pfafstetter Basin CodificationExample - HUC 05010002

- Add the 4-digit HUC identifier to create the 13-digit *Pfaf_id*.

- 13-digit *Pfaf_id*:
- "1459" + "269900000"

## Pfafstetter Basin Codification

- Pfafstetter Ids along the coasts and Mexican and Canadian borders are assigned in a clockwise manner.

## Pfafstetter Basin CodificationBorder Example - HUC 15080302

- Pfafstetter Basin CodificationBorder Example - HUC 15080302

## Pfafstetter Basin CodificationCoastal Example - HUC 03020106