878
plains and is dendritic in the north western corner
of the region. The surface being generally sloping,
most of the rain water contributes to runoff. The
direction of runoff flow is radial on the outcrops
and easterly on the western rock plains. In either
case the runoff flows over the flood plain areas
against the riverain features.
4.3.3 Wind action
South-western corner of the region is a vast piedmont
plain over which extensive sand dunes have formed
as a result of wind action. The sources of sand
are apparently the beds of Indus river and the
Baran Nadi. Interdunal valleys are small. Sand dunes
appear to be stable. Presence of K.B. Feeder canal
along outskirts of these dunes restricts the flow
of runoff (1976 situation). Along the left bank of
the Feeder canal, south of Jamshoro, the areas are
ponded by seepage. But due to presence of sand
cover in the remaining left bank area, the situation
is not clear on the photographs.
4.3.4 Under-designed infrastructure
Several instances of progressive spreading of wet
bodies are studied on the two set of aerial photographs.
On 1953 scene, no appreciable ponding or seepage
is observed along the railway line, flood protection
embankments and canal system. However in 1976 scene,
surplus water stagnates along these features and
occasionally permeates across them. This situation
indicates that the urban infrastructure is largely
under-designed. In addition, around the peripheries
of the rock outcrops sizable pockets of open water
are observed on 1976 photography. The earlier situa
tion displays wetness only on limited patches.
Extensive wet areas were observed west of K.B.
Feeder. From the adjacent rock plains, these areas
receive runoff which occasionally accumulates along
the canal bank creating temporary ponding. This
ponding is not apparent on 1953 photographs.
It was understood (WAPDA, 1979) that the canals
system in the region does not create seepage zone?
along their courses due to entrenchment of three
canals below the ground surface and lining of the
fourth one. The study of 1976 photographs, however,
reveals that seepage zone does restrict subsoil flow
of water and contributes to the basinal areas through
old partially covered channel remnants. The entire
wet zone occuring along the western bank of the
canals is mainly due to restrictive action of the
seepage zone and inadequacy of surface water dispo
sal. On 1953 photographs, this area appears well
drained.
5 PROPOSALS FOR URBAN DEVELOPMENT
Most of the open areas available for urban expansion
adjacent to tne existing civic infrastructure are asso
ciated with drainage problems. The experience gained
from development of Latifabad has not been used
as guidelines for future developments. The develop
ment schemes along Hyderabad-Jamshoro road are
being implemented on a back-swamp area which is
being fed by seepage from canals and the river
and by runoff from the old city. The area has
high watertable and highly sloughing type of soil
material. It has been difficult to lay sewerage pipe
in the subsoil (Fig 4). Without provision of adequate
surface and subsurface drainage, this area would
behave exactly like parts of Latifabad Project where
most of the sewerage system has collapsed as a
result of sloughing action.
Urban expansion schemes along Hyderabad Tando
Mohammad Khan road are located on areas which
are flat. But may have rocks at shallow depth.
Fig.3 Stereogram showing complex altered drainage
pattern as a result of flooding, runoff and structure
of the basement rocks.
Fig.4 Photograph indicating difficulty in excavation
of trenches for laying sewerage pipes in very fine
sandy and silty sloughing material along Hyderabad-
Jamshoro highway.
These areas are saline and receive runoff from the
adjoining rocks. Subsoil water flow would be restricted
by the seepage zones of the canals in the east.
In addition, presence of restrictive clayey lenses
in the subsoil would locally create perched watertable
conditions. Open drains with proper arrangements
for disposal of drainage water are required.
On the right bank of the river, the Piedmont
Plains are quite suitable for urban expansion provided
adequate arrangements are made to dispose off the
storm w
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REFEREI
Abu B 1
Map
of P;
Ahmad
Pakist
Beg, M.
Hyde
Buringh
graphs
Interp
Goosen
Survi
Unite
Govern
Jalal-uc
-Soils
Lahoi
L.I.P.
Repo
Serv
Mian,
and
Desig
Mushtaq
Surv
Lahoi
PEPAC
Hyd
Soil
Soils
(SMS