380
Figure 7. Malekote settlement with coral for cattle.
Banana and maize crop along inner bend of the river.
from those of the neighbouring communities i.e. the
Pokomo. the Orma or the Somali. The latter group is
present in this zone in the dry season only, staying
in crude loose leaf shelters or manyattas surrounding
the separate night enclosures for their sheep and
goats, camels and cattle.
Malekote and Wanyoyaya have no specialization. Shif
ting agriculture is the mainstay but also some animal
husbandry, spear fishing and honey collection is
practised. The Somali in this zone are nomadic pasto-
ralists.
Shambas (agricultural fields) are abandoned after
signs of exhaustion of the soils or other negative
trends appear to set in. Most shambas are located on
the levee lands. The alluvial floodplain of the river
basin land is narrow and the few cut-off meanders are
highly sought after as arable land.
By far the most remarkable and distinctive method by
the Malekote and Wasanya that does not appear in any
downstream zones of the river is the reclamation of
river basin land by cutting a straight channel for
the river through the narrow land separating two
succesive meanders.
The reclamation of this meander is with the technolo
gy of these groups quite an effort. Explanations for
these great efforts can be found in the fact that:
- there is a general shortage of agricultural land
- the alluvial floodplain is only slightly developed,
the general state of physiography and soils (ferti
lity limit the viability of arable and flood depen
dent agriculture as practised downstream.
Reduction in flooding frequency and sediment load in
the river will both adversely affect the carrying
capacity of the described land utilization. Village
irrigation may h e promoted as a remedy. Reduction in
flooding frequency will also accelerate degradation
of riverine forests and floodplain morphology and
therefore reduce the carrying capacity for grazing
being a refuge for Somali herds.
4. Discussion and conclusions
4.1 Methods
In the previous sections the use of a microlight
aircraft in the survey has been illustrated with
photographs. However, the value of the use of the
aircraft cannot be illustrated with photographs.
One of the land use specialists in the study also
flew the aircraft for a great deal of the time. These
flights were for the pilot similar to a photo inter
pretation and yielded the specialist a very clear
insight in land use patterns and its relation with
the flooding regime and related aspects, which were
of crucial importance in the survey.
Also the production capability of the whole system
has not been mentioned yet. When the pilot got more
experienced in a period of 13 days 40 hours of flight
were made, during which 1100 vertical B&W
panchromatic photographs were produced, of which 900
had a good to reasonable quality and 300 oblique
colour photographs were made. The vertical photog
raphs usually had a scale of 1 : 6,000 and were taken
from an altitude of 1,000 ft., which could even in
turbulent conditions be maintained reasonably well.
The vertical photography was produced with overlap
for stereoscopic analysis of preselected areas, or
strips which were selected during the flight, the
longest of which had a length of 10 km and a width of
350 m. Also photoblocks were photographed of areas to
300 ha. with reasonable sidelap and overlap.
The study was set up to identify different land
utilization types, without quantifying these land
utilization types. Upon completion of the surveys it
was however realized that it would have been techni
cally feasible to perform an inventory as well in a
quantitative way, given the production capacity of
the system.
With respect to the aircraft type it is concluded
that the Eagle is indeed not a very stable platform
for aerial photography given its rather large wing
surface and low speed. Other modern "third genera
tion" microlights will have a much better performance
in this respect.
4.2 Environmental impact analysis
The results of the inventory of land utilization
types are combined with the result of modelcalcula-
tions on the morphology of the river in the future.
The combination of these two types of results lead to
a number of statements on impacts per land utiliza
tion type and recommendations for remedial measures
and further study, which go beyond the scope of this
article.
In summary the impact of changes in the river regime
as a result of structures planned include:
- reducing for a large area the flooding to virtually
nil and thereby preventing a great deal of the
present small scale cultivation and interfering
with the livestock grazing now practiced on the
annually temporary inundated land
- changes in the sedimentation pattern that may lead
to a meandering system whereby irrigation schemes
are being cut off from their water supply
- permanent inundation of parts of the floodplain,
creating whole new ecosystems
It is concluded that the concept of land utilization
types can be used in combination with results of
model calculations in river morphology, when land
utilization types are well defined in terms of the
relation with the dynamics of the river.
Alan S
Cranfiel
Six Lai
England
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