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Africa FAO Irrigable Soil Classes (GIS Coverage)
Entry ID: NBId0017_101

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Summary

Abstract: New-ID: NBI17

Irrigable soils of Africa.

The African Irrigable Soils Dataset documentation

Files: IRRIGUT.E00
Code: 100050-001
IRRIGUB.E00
100050-002
IRRIGLT.E00
100050-003
IRRIGLB.E00
100050-004

Vector Members
The E00 files are in Arc/Info Export format and should be imported
with the Arc/Info command Import cover In-Filename Out-Filename.

The African Irrigable Soils dataset is part of the FAO Irrigation
and Water Resource Potential for Africa. The base map used was the
UNESCO/FAO Soil Map of the World (1977), scale 1:5000000 and Miller
Oblated Stereographic projection. All sources were re-registered to
the basemap by comparing known features on the basemap and the source
maps. The digitizing was done with a spatial resolution of 0.002
inches or 0.05 mm. The maps were then transformed from inch
coordinates to latitude/ longitude degrees. The transformation was
done by an unpublished algorithm (by US Geological Survey and ESRI) to
create coverage"'"s for one-degree graticules. The source includes a
list of attributes for each soil unit including: slope, drainage,
texture and phase (re: UNEP/FAO/ESRI ITU 100004). All these components
were used in the evaluation of potential irrigable soils. Criteria by
FAO were established to estimate the proportion of each component soil
which would meet irrigation requirements. This is done in two
case. Criteria were established for: - Growing food crops under
irrigation which is called upland crops; - Lowland crops, flooded
rice. Then for both cases two maps were generated. One with all soils
which are suitable, and one where slope, texture, drainage and phase
were considered. Each different soil type is classed according to
suitability, S1 irrigation with no constrains, S2 irrigation with some
constrains, N1 not suitable without major improvements, N2 permanently
not suitable. Because one soil unit can consist of more soil
components (unit Af26-a can mean 30%Bf and 70% Af) the suitability is
expressed in percentage of the unit that is suitable (1 >50% suitable,
2 = 25-50% etc.). Then the soil characteristics are used to refine
the ranking. This refining is done were the original soil rank is
increased decreased or changed from their original suitability to a
new suitability (so or soil gets new class S1, N1 etc. or ranking
changes like, -1 lower soil rank by one, +1 raise soil rank with one).
The Ranking of Soils is as follows

The soils considered not suitable are:

Lithosols, Arenosols, Rendzinas, Yermosols, Podzols, Thionic Fluvisols,

Miscellaneous land units such as rock debris, desert debris,

Gypsum units,

Soils with stonic, lythic or petrogypsic phase.

Ranking by Drainage conditions
All crops Lowland
Fluvisols and Histosols 50% S1, 50% S2 50% S1, 25% S2 , 25% N1
Gleysols and Gleyic units 50% S2, 50% N2 50% S1, 50% N2
(except Cambisols)
Gleyic Cambisols 100%S2 100%S1
Planosols 50% S1, 50% N2 50% S1, 50% S2

Ranking by Special conditions
Calcaric units 50% S1, 50% S2 50% S2, 50% N2
Vertisols 50% S2, 50% N2 100% S2
Acrisols,Nitiosols,Ferrasols -1 -1
Solonchalks,Solonetz -1 -1
Thionic Fluvisols 100% N2 100% S1
Ranking of Slope conditions All crops Lowland crops
0-8%
Fluvisols,Gleysols,Gleyic unit no change no change
All other soils 50% S2, 50% N1 50% S2, 50% N1
8-30% all Soils 100% N1 100% N2
>30% all Soils 100% N2 100% N2
Ranking of Soil Texture conditions
Coarse textured 25% S2, 75% N2 100% N2
Medium textured no change no change
Fine textured -1 no change

Contact : FAO, Land and Water Development Division
via Delle Terme di Caracalla, 00100, Rome, Italy

Att: Mr. Thomas

The IRRIGUT file shows all soils that are irrigable for upland
crops. The IRRIGUB file shows soils that are irrigable for upland
crops, ranked by slope etc. The IRRIGLT file shows all soils that are
irrigable for lowland crops The IRRIGLB file shows soils that are
irrigable for lowland crops, ranked by slope etc.

References:

ESRI. Final Report UNEP/FAO world and Africa GIS data base. (1984).
Internal Publication byESRI, FAO and UNEP

FAO, UNESCO. Soil Map of the World (1977).
Scale 1:5000000. UNESCO, Paris

UNESCO. Geological Map of Africa (1975). Scale 1:1000000

FAO. Irrigation and Water Resource Potential for Africa. (1987)
Publication FAO, AGL/MISC/11/87. Rome, Italy

Source : FAO Soil Map of the World, scale 1:5000000
Publication Date : Nov1987
Projection : Miller
Type : Vector
Fromat : Arc/Info export non-compressed
Related Datasets : All UNEP/FAO/ESRI Datasets
ITU08-10 (100004) - Integrated Terrain Units
AQRANK, AQRANKSM (100046)
WATERBALLX FAO (100053) - Waterbalance
CROPS2 (100013) - Crops by administrative unit
ADMIN (100012) - Administrative units
WSHDLL (100018) - Watersheds
RAINFALL (100009) - Mean Annual rainfall
SOILS FAO/Unesco soil map (100007)

Comments : No boundary (outline) for Africa.

Related URL

Link: GET DATA
Description: Search and access the data from the UNEP Environmental Data Explorer.

Geographic Coverage

N: 40.0 S: -45.0 E: 60.0 W: -30.0

Location Keywords

CONTINENT > AFRICA

ISO Topic Category

FARMING
ENVIRONMENT
GEOSCIENTIFIC INFORMATION

Project

GTOS >Global Terrestrial Observing System [Information]

Access Constraints

Public

Keywords

AQUIFER

Agriculture > Agricultural Practices > Irrigation

CROPS

IRRIGABLE CROPS

IRRIGABLE SOILS

IRRIGATION

SOIL

WATER RESOURCES

WATERSHED

Originating Center

FAO

Data Center

Global Resource Information Database - Nairobi, Division of Early Warning and Assessment, United Nations Environment Programme
Data Center URL: http://gridnairobi.unep.org/

Data Center Personnel

Name: JOHANNES AKIWUMI
Phone: (+254-20) 7624214
Fax: (+254-20) 7624315
Email: Johannes.Akiwumi at unep.org
Contact Address:
Head, Data and Information Management Section
Division of Early Warning and Assessment (DEWA)
United Nations Environment Programme
P. O. Box 30552
City: Nairobi
Postal Code: 00100
Country: Kenya

Personnel

JOHANNES AKIWUMI
Role: TECHNICAL CONTACT
Phone: (+254-20) 7624214
Fax: (+254-20) 7624315
Email: Johannes.Akiwumi at unep.org
Contact Address:
Head, Data and Information Management Section
Division of Early Warning and Assessment (DEWA)
United Nations Environment Programme
P. O. Box 30552
City: Nairobi
Postal Code: 00100
Country: Kenya

Creation and Review Dates

Last DIF Revision Date: 2012-06-11

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