The author has identified the following significant results. It was concluded that direct identification and mapping of the various soil degradation forms and intensities from the color composite imager was generally difficult, if not impossible. The imagery, however, provided valuable information on some main environmental criteria which can be used in connection other available field data to assess actual soil degradation and estimate soil degradation hazards

Dudal, R. J.

Pecrot, A. J.

English

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xp ^  j^J» .^ S> Final Report - ERTS FOLLOW ON PROGRAMME
,/<>' .,& A/' ^  ,x£i • Introduction
'^;••&'^  g,^  1.1 Title: The Application of ERTS Imagery
c£^ <O^ <£' to the FAO/Unesco Soil Map of the World
<^ ;^^
 1.2 Investigation Number: 2810 M
1.3 Principle Co-ordinator: J.A. Howard \-K~/ cA
1.4 Principle Investigator: Raoul J. Dudal
1.5 Co-Investigator: Andre J. Pecrot
1.6 Organization: FAO, Rome, Italy
1.7 Type of Report: Draft Final Report
1.8 Date: May 15, 1977
2. Techniques
Colour composite prints at approximate scale 1:1 000 000 covering a
large part of West Africa were received in September 1976. The coverage
consisted of 241 prints, including wide gaps due to excessive cloud cover.
Most part of North Africa from North Morocco to Tunisia where soil erosion
is a priority problem were not covered.
The imagery was used through visual analysis with a view to collecting
additional information for the interpretation of the FAO/Unesco Soil Map of
the Wrold in terms of desertification mapping and assessment of actual soil
degradation and Degradation ' hazards. As already explained in the progress
report (March 1977), the digitized analysis of soil, climate and boundary
data which had been initiated on an experimental basis in South America,
has been abandoned because the time for storage of data and financial
resources required proved too great in relation to staff and budget
available and the results achieved.
1
 (E77-10236) THE APPLICATION OF EBTS IMAGERY H77-33567
'•TO THE FAO/ONESCO SOIL HAP OF THE HORLD
A Final Report (Food and Agriculture
Organization of the) H p HC A02/HF A01 Onclas
! CSCL 08B G3/U3 00236
https://ntrs.nasa.gov/search.jsp?R=19770026623 2020-03-22T08:07:44+00:00Z
-2 ' - •
ORIGINAL ?AGE IS
OF FOOR QUALITY
Accomplishments
A World Map of Desertification was published as a basic document for
the US Conference on Desertification which took place in Bairobi from 29
August to 9 September 197?» ^ks available Landsat imagery was thoroughly
utilized to estimate and map the vulnerability of land to desertification
on the fringes of the Sahara in West Africao One copy of the World Map of
Desertification is attached for information*
The Landsat imagery was also used in the FAO/UHEP project for World
Assessment of Soil Degradation. The assessment started with Africa north
of the Equator and will ultimately produce a world map at 1s5 00° 000 scale
showing the areas where soil degradation by wind or water erosions salinity,
waterlogging is active or presents a serious hazard0 The assessment is
essentially teased on the FAO/frnesco Soil Map of the World„ but the additional
information from the Laodsat imagery was valuable for improving the delineation
of broad physiographic units presenting .uniform soil degradation hazards such
as dune encroachment, sheet erosion on large areas, overgrazing and degradation
of natural vegetation around villageso Swamps and hydromorphic areas are not
easily distinguished from irrigated areas unless the latter have geometric
contours* Except in extreme cases of areas with a salt crust, saline soils can
.easily be confounded with other soils having a high reflectivity such as Tfdiite
'sends, bars light coloured soils of alluvial fanso _ .
There is little doubt however that Landsat imagery supported by a
;:iirdnrum of ground information provides an overall picture of some criteria
srtch as geomorphology, hydrography,, distribution of broad land use and vegetatio:
types which,, together with soil and climatic data, allow a reasonably accurate
assessment of the form and intensity of soil degradation* A report of these
findings and conclusions was attached to the first progress report on the
projecto . . ' ••
A more detailed study at 1:1 000 000 scale of soil degradation in
Morocco was also compiled, using a black and white mosaic of ERTS I and the
available colour composite Lacdsat imagery for the Central and Southern part
of the countrya The study resulted in a cotuatry map showing main physiographic
units which were subsequently characterized in terras of their actual soil
degradation and degradation hazardso
OBKiNAL PAGE IS
3 - OF MOB
Systematic use of the Laxidsat imagery for interpreting the.Soil lap
of the 'World and land resources evaluation was hampered "by the fact that of
the imagery requestedj only a partial -ewer of the region^  for one season
instead of two9 was availafeles
•She imagery is being used for specific speeial studies in FAO Headquarters
in connection with field projects as follows?
io Es*osion mapping in Benin,
iio Vegetation mapping in Guinea, \
iiio Preparing the soil map5 scale 1?1 000 0003 of Upper ?oita0
Results
Fr-os the abcve ^ pesiase© with the use of Laadeat imagery for soil
degradation, Etssessmeixl aad, oa|>ping as summarised in the report attached to
the Sfepcfc. progress yep©rt9 fit may "be concluded that direct identification and
mapping of the faricxs soii~d©^ adatica forms and intensities from the colour
composite ii-jasjary is S9202ially difficult, if not impossible
 0 13ie injagesyf
however^ presides •ttaluabl® iisfoyEatioa on sem© main environmental criteria
which can b© used in connection with other available field data to assess actual
soil de-gradation ancl estimate soil
Qfce Woc-ld 2>3ap of DfiserSifioa-fcior* (•??£;' -OO COC' scale} t©g@tfe©s> Kith a
not© was published s,s a 'b^io tsdbaieal doemassfe for the
en Besertif ioatibss? •
~ A map of Dsserfeifieatioa (tg5 000 CCO scale) fos? Af?iea8 Ho?th of tfee
was also prepar-sd for d3,sp3,ay at fid C^'j??c?-xic-Cc.
- A soil de^afiatioa nsap. of Africa e-:..--^ of /r.c Sjua-Sop t-All e© pyochaeed ia
clraf't form "by the ©£$1 ef the year-o
DO FgoMems
pyoMsms have fcesas
60 1 Sfeortsga of staff to wcrsr. fv.>l
6o2 Only partial delivery of the requested iraageryj had it "been
-that the HASA "budget for imagery was limited to §6 000, the order wcf.I;'
have fesen made .for a smaller region feut covered in two seasons, to
serve as a test casoo Only the western payt of Africa siorth of the
Equator is covered and there are extensive gaps in th© coverage
 0
Additional imagery is toeing ordered; 'for a total allocation not
exceeding US$8 000
 0 Such allocation however will. be insufficient
for a total coverage of Africa north of the Equator ia two seasons
which would fee th© maimum requirement to make ftall use of Laadeat
imagery for systematic assessment of soil
603 Prom the technical side there are difficulties when usixig only simple
techniques in correlating patterns on the images with the various
forms of degradation^ This requires further iEsrestigatioUc, particularly
on relations of such patterns with other exjvironmsntal factors such
as climate, vegetation, soils, geology
 c
•7° Data Quality and Delivery
Ihe quality is good and resolution is adequate for this studyo Kae limitation
in supply of images has restricted the area which could "be examiaedo
80 Conclusions
The Landsat data are valuable in the study of land degradation and evaluation
s
of land resourceso Budgetary limitations have hampered our application of the
imagery for a global appraisal and even for the whole of the priority regioa
selected for this contracto TSie imagery will continue to fee utilised,, asod addsd to9
V (N
for the ongoing project on soil degradation assessment o \


The application of ERTS imagery to the FAO/Unesco soil map of the world

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