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Pfafstetter Basin Codification. What is it? A topological system for codification of basins. Based on topology of the river network. References: Pfafstetter, 1989
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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 • References: • Pfafstetter, 1989 "Classification of hydrographic basins: coding methodology", unpublished manuscript, Departmento Nacional de Obras de Saneamento, Rio de Janeiro • Verdin, 1997 http://edcdaac.usgs.gov/gtopo30/hydro/P311.html • Why use it?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 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. 8 6 4 2
Pfafstetter Basin Codification 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. 9 8 7 6 4 5 2 3 1
Pfafstetter Basin Codification Subdivision of Tributaries: 9 8 7 29 6 26 4 5 22 25 27 28 2 23 3 24 21 1
Pfafstetter Basin Codification Subdivision of Interbasins: 9 8 79 78 7 77 6 76 4 5 72 75 2 74 3 73 71 1
Pfafstetter Basin Codification Codification when there are less than four tributaries: 9 9 9 6 4 2 5 2 4 3 2 3 1 1 1 Note: Basin 9 is always the main stem basin.
Pfafstetter Basin CodificationThe Pfaf_id Attribute • 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 BasinFirst 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.
Pfafstetter Basin CodificationExample - HUC 05010002 1st Division
Pfafstetter Basin CodificationExample - HUC 05010002 2nd Division (Basin 6)
Pfafstetter Basin CodificationExample - HUC 05010002 3rd Division ( Basin 6)
Pfafstetter Basin CodificationExample - 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 CodificationExample - 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 CodificationCoastal Example - HUC 03020106