The author has identified the following significant results. A map of the drainage of the whole country to include at least third order streams was constructed from LANDSAT imagery. This was digitized and can be plotted at any required scale to provide base maps for other cartographic projects. A suite of programs for the interpretation of digital LANDSAT data is under development for a low cost programmable calculator. Initial output from these programs has proved to have better resolution and detail than the standard photographic products, and was to update the standard topographic map of a particular region

Jackson, A. A.

English

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"Made available under NASA sponsorS!X1 ;
in the interest of early and wi , ' '	 s•
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Program information and	 44 ,	 tv
for any use made thrreor."	 !gATURAL
I.4'
3AT Follow-on Investitation 28090
E 7.6 - 1 0.2 7 8.
C1 - ' ,Y '^ yp"RESOURCLS RESF.ARCil AND DEVELOP"LEAT
LESOTiiU USING' LA.IDSA'I' IfIAGERY
RECEIVED
NASA STIFACILI
ACQ. BR.
- L ,r,,
APR 21 1976
A.A. Jackson,
DeDdrtm,:nt of Biology,
National University of Lesotho,
P.O. Ro;aa,
Lesotho,
Africa.
(E76-10278) NATURAL FESOURCES RESEARCH AND
DEVELOPMENT IN LESOTHC USING LANDSAT IMAGERY
Quarterly Re Fort, Dec. 1975 - Feb. 1976
(National Univ. of Lesotho, Roma.)
	 8 p
HC S3. 5C	 CSCL 08F G3/43
N76-21645
Unclas
00276
3 NARCII 1976
QUART' LY REPORl FOR TI L P. RIOD ll%CL^:B';R 1975	 FEBRUARY 1976
^go70	 I .
Government of Lesotho,	 ,I
I Ias (_..,ru
Lesotho.
RECEIVED
APR 14 1976
SIS 902.6
1. Investigation :Jo.	 2. Type of Report
	 3. Recipient's Catalogue
28090
	 Quarterly	 140.	
I ,
4. Title	 5. Report Date
Natural Resources Research Development
	 3 March, 1976
in Lesotho Using LA JDSA'T Imagery
	 6. Period Covered
Dec '75 - Feb 176
7. Principal Investigator	 S. No. of Pages	
I
'
A.A. Jackson	 6
9. Nar.,e and Address of Principal InvestiLazor's
Organisation
Dept. of Biology,
National University of Lesotho,
Roma.
Lesotho
12. Sponsori::g Agency Name and Address
Governriient of Lesotho,
Maseru
Lesotho.
10. Principal Inv ` stiga- r
ton's Report No.
LLIIl1
11. GSFC Technical 'moni-
tor Dr. R.D. Pried
13. Kcy !-lords (Selected
by Principal Inves-
tigator)
Land Systems, Surface
:tydrology, Digital
Interpretation
14. Supplementary Notes
Soma of the work described in this report was supported by USAID by a
research grant to the Princi pal Investigator through th,.: Environmental
Research Institute of Michigan.
15. Abstract
This report covers the first three months of the Lesotho LAIJDSAT-2
project. During this period a surface drainage map of the country
using LANDSAT imagery has been co,lpleted. The photographic imagery
seems to be ideal for the definition of land systems (mapping units
defined by a combination of gcomorpholoLy, soil type, vegetation
cover, land use etc.) which are probably of more use in a d=vloping
country :tuation than are the more usual maps of the individual
types of features. It has also been demonstrated that ^_.^latively low-
cost programmable calculator systems can bt of benefit in the inter-
pretation of digital data.
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fhis report covers the D--riou Dece.mb•ar 1975 to February 1976. Durin^
the reporting period, L1L.7 DSZ*xT-2 ima^,try E:athered durir., , July to
October 1975, as well as alr--ady existing Uy:IDSAT-1 imagery, 'g as beF,n
utilised for interpretation in the following fields. surface hydrolo—r,
soils, vegetation, airiculture, met.;orology.
B. iECK.4IQUFS
For most of the work, conventional ae.riai photointerpretation t .:!ch-
niques were used. P'iotographic ima gery, nor:.,,ally at a scale of
1:1 000000, was -.xamine:d usin`, IiLht tables, stereoscopes., low-power
Microscopes and an optical pantograph. After tracin7 the relevant
fe:aturc:s, these ware _Ii ,l itised usinD a .ie.^lett Packard 9864A di;*.iti-
scr attached to an ti-P 9830A pro(-raru.,able calculator and the data
stored on magnetic tape cassettes. The data could then bE. _)Iotted
any required scale and any necessary coordinate transforms applied.
A start has been made on the development of pro_ rags for th .,; nro -
grammablc calculator for the direct, automated interpretation of
diC,ital data from LAI:DSAT CC:'s. As the CCT's are not compatible
with the calculator, some preprocess_n- on a larZer computer systern
is necessary. This was carried out at the CSIR in Pretoria by
„r.d.: i'_oer. .:is pre-existing programs r^ere used to rer:,ove the1.
six line stripe, select test areas and dum p the required data onto
punched cards. For the experimental phase: of this project, four test
areas, teach about l0km by 5km, were selected fron. a LANDS".T-1 ima1*e
(1121-07315) covering the north-western section of Lesotho. Th(-
total number of pixels in each of th; four test sections is 10800.
Various programs for the processing of the di,-ital data have been
written and tasted. These: include:
(a) plotting of a 'di"ital colour conoosite' at anv
required scale:.
(b) pix,. 1 statistics and Listo -X:mn..s o f. response
distribution.
(c) simpl,2 non-iterative clusterin g,, with p lot or
print output
(d) maximum lilkc.lihood and probabilit .-r ratio assi.•nr.•cnt
of pixels for automat,_:d r,.appin, .
contd..
RI:PRODUCUill y OF TH!:
()1dM'. T AL PAGE IS POOR
I
a- 2 -
C.	 ACCOMPLISHMENTS
For the first time, the LANDSAT coverage during the reporting* 	 I
period showed significant snow cover. The maximum snow cover
shown on the imagery was on July 11-12 1975 when approximately
5% of the country was covered. The major snowfall of the season
occured on July 13-14, but by the time of the next satellite
pass (July 29-30) most of this fall had melted. Although snow
reports are received regularly from the various meteorological
stations in the country, the availability of the satellite
data allowed the accurate ,-apping of the snow cover for the
first time. In certain places, estimates of the depth of cover
could be made, especially at the edges of the covered areas
due to the differential ^,-netration of the snow by bands 5 and
7.
The availability of winter (dry season) coverage of the country
has greatly facilitated the mapping of the various soil and
vegetation types in the country. A reconnaisance map of the
country for soils and vegetation, based on the LANDSAT da`a.
is in the process of being produced. In the lowland regioi,6,
where the geomorphology is relatively uniform, the differen-
tiation of at least the major soil divisions seems feasible.
The lack of active vegetation and cloud cover in the latest
images has facilitated this interpretation. In the highlands
of the country, on the other hand, the character of the image,
in terms of colour in the composites and texture, see,is to be
not directly related to the vegetation cover and soil type.
The gcomophology of the highlands is somewhat varied. From
previous work it is known that most of the mountainous region
is covered by a sparse basaltic lithosol. The mappable units
of the photographic images seem to be more closely related to
land systems rather than to specific features of geomorphology
and vegetation cover, even in regions of uniform soil type.
The land systems, as mapped, relate to a combination of
geomorphology, soil type, vegetation cover, land use etc.
As such, these mapping units are probably of more use for
planning purposes than are straightforward maps of each of
these characters separately.
contd...
1
-3-
During the reporting period	 map of the surface hydrology of the
country has been campleted. Streams up to the third order over
the whole country, and to fifth order in certain regions, have
been mappud from the photographic imagery. These data have been
digitised as described above:, and can be plotted at any desired
scale. Ir is planned to use this map, at various levels of
detail, as the base map for future mapping work within the
country.
It was found, during the LANDSAT-1 investicyation, that indivi-
dual fields etc. are not discernable on the photographic imagery,
even at the limit of useable enlargement. As one of the major
points of the LANDSAT-2 investigation is in the field of
agriculture, it was decided to start experimenting with digital
techniques for the handling of CCT data. This was prompted by a
consideration of the relative resolution, both spatial and radio
metric, of the photographic and digital imagery. As explained
in section B above, the standard CCT' - are not com patible witty
the computing facilities currently available in the country. An
assessment of the possible benefits which could accrue from the
direct interpretation  of the data led to the desi^n of a
software system which could handle modest amounts of digital
data on the equipment which was already available. It must be
emphasized that the system is still in the early stages of
development but certain important features arc: already apparent.
If some means of overcoming the incompatibility of the standard
CCT's and most programmable calculators can be overcome, useful
digital interpretation work can he carried out on small
(10krn by 5km) areas with hardware costing as little as $15-20000.
The tim,_ takun to carry out a single analysis of the order of
hours rather than minutes, but with capital costs of this order,
of magnitude, it is not unr,.;asonabl,- to be able to dedicate
the: system to full tim•- data interpretation. Similarly, in
some developing country situations, large scale computer faci-
lities are not yet available and the cost is prohibitive,
whereas it is not unreasonable for ar aid agency to be able to
donate, funds of the order required to t_.,.ablish a system such
as that und•-. r de:vQlopm^_nt.
In ordv.r to produc, 'digital colour composites', density
mc.ps of each of thrt:c: St-lected bands are plotted out at the
RFTROPUCII1II,I1'Y OF TILE
)RICINAL PAGE IS POOP-	 J
- 4 -
	 f
required scale, usually 1:50 000 to correspond with the standard
local topographic map serifs, Eacn plot is then transferred to
diazo film of the appropriate colour and the three films sand-
wiched to produce the final prof uct. For the initial -2xperimcntal
products, the digital colour composites were made to correspond
as closely as pc.ssible to the standard band 4,5,7 composites.
It was originally thought that these composites would be of us,
only for identifying the precise location of the digital data
samples on the topographic maps, but the first one produced
showed suffieiv-nt detail to enable the updating of the
corres ponding part of the pre-existing map.
Maximum lilkelihood and probability ratio programs have been
written for automated mapping of features from training sets. As
currently under development, these programs will cope with up to
three recognised si€natures plus 'unknown'. They are at present
being modified to allow for the evaluation of 'mixed pixels'
with proportional assignment. In one of the test areas., the
use of these programs has brought to li`ht a problem which ma;,
occur in similar situations elsewhere. In attempting to map
standing water in dams, a large number of pixels were identi-
fied which were: known to correspond to non-water sites. P^ , fi-
nement of the training set failed to eliminate the problem.
Plotting of the multivariate probability distributions showed
some: overlap between the training set for dam water and the
distributions for certain soil types and activ ,_: veKetation.
Examination of tha dam sites concerned showed th•-, cause of the
signature degradation to be the amount of silt present in the
dams and algal growth due to sewage contamination. It should
be pointed out that the dams used to develop the signature art
typical of those present in the country and have a v=!ry small
surface area. This is of the order of 4 to 5 pixels.
D.	 SIGNIFICANT RESULTS
1. A snap of the drainage of the whole: country to include at least
third order streams has been constructed from LANDSAT imagery.
This has been digitis^_d and can be plotted at any required scale
to provide base maps for other cartographic proj(-,ets.
2. A suite of programs for the interpretation of di-ital (CCT)
LANDSAT data is under development for a low-cost progranjilable
- 5
calculator. Initial output from these programs has
proved to have bettk2r resolution and detail then the
standard photographic products, and has been used to
update the standara topo"raphi_c map of a particular
region of the country.
E. PUOLICAl'IUidS
Nil
F. PROBLE1:S
The major problems encountered so far in the project resat,.:
to coverai f- and tim..linF_ss of the data ; and are discussed
below.
G. DATA QUALITY
Thu resolution of the photographic imahery received from
LAADSAT-2 is generally superior to that received from
LAODSAT-1. It is not possible to state: whether the superior
resolution is du` to ir:provL-.d photon=raphic processing*, or to
greater sc:risitivity of the sensors on board the spacecraft.
Some  difficulty `ias been experienced due to the distortion
of paper prints of the. photographic in:at;ery. This has been
particularly apparent on colour composites. J oticeable dir-,en-
sional instability of the paper prints is obscrve•d when the
paper prints are compared with positive transparencies of
the same scenE. The magnitude of these distortions and
their consequent effect on the interpretation of the data
is being irivestibatcd.
Problems have arisen due to the: erratic nature of the cover
provided and the time lapse between gatherini: of the ir.+a:,es
and the receipt of the data. The test area, which covers
the whole of the: Kingdom of Lesotho, requires four images
for total coverage. Duu to the orbital paraniet-.rs, two
scenes are required on each of two successive days in order
to provide total coverage. This has only occured once
(orbits 2170 and 2171 11-12 July 1975). Listed below is
the data coverag;cJ of the various sections of the country:
contd..
^^R,ppUC1B1L1TY OF TI1D
PAGI'• POGO
r
J
-	 b -
Section of Country
,forth Last
South Last
North hest
South Uest
;:o. of Coverag^_,s
4
1
4
7
i
1
The Jorth Last of the country and tht: South East are overflown on
the same orbit, as are the ;Jorth !Jest and the. South hest. The dis-
parity in coverage between the two scenes overflown on the same
orbit is obvious, and is probably not due to differences in cloud
cover.
T1,„ average time lapse between seen(: gathering and data receipt is
113 days.
If com,-Jete coverage of the test site were availabl(: on successive
orbits, total data requirements could be reduced to one covera(-,e each
36 days. As the situati:)n is at the momLnt, however, much of the
data is lost uue to erratic coverage and lone delays between gathcrin,
and data receipt. The long dolay between gathering; and receipt also
precludes the investigation of short term anomalies in the images.
;i. RL'COMU' :,JDATIOJS
The usefulness of the data received mould be much enhanced if total
coverage of the test sits: on adjacent orbits were provided and the
time lab between image gathering and data receipt were reduced.
CONCLUSIO..S
I. C014CLUSIO14S
During the reporting period the completion of a surface drainage
map of the country has shown that LAiJDSAT data are eminently sui-
table for the mapping of -uch features. Furtht 2 r, the photovraphic
images provide a useful synopsis of ` lade systems' in regions of
varied geomorphology and /or soil type.
'	 It has also been shown that relatively low-cost programmable calcu-
lator systems may be used for the direct dif;ital interpretation of
limited quantities of L&iUSAT data with significantly useful results.
AJ / Adi'l


Natural resources research and development in Lesotho using LANDSAT imagery

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