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By:
M.Y.Khuhwar,
T.M. Jahangir, S.M.Leghari and A. Leghari
- University of
Sindh, Jam Shoro
River indus repesants one of the major water
distribution system of south east and is eleventh largest river in the
world
in the terms of drainage. river discharge and sendiment transport. The
hydrology of river indus has altered singnificantly by the construction
of
channels. barrages. embankments, dykes and dams for hydro elective
power,
irrigation and flood control, there had reduced the dischage,in the
delta
region to about 1/5 t.h persently little were is allowed down the kotri
barrage for than ten months of year. Kotri barrage is situated about 200 km from arabian sea and
is
used to regulate the water flow for agriculture purpose and as a source
of
drinking water for the hyderabad and Karachi cities. the surplus water
is
allowed to drain down the sea. Down the kotri barrage reverie agriculture is not extensive;
banana platation in the region has economical importance.A large number
of
people inhibit on both sides of the river, which not only depend on
river Indus for their livelihood, but also as a source of drinking water.
The work examines the effect of reduced water discharge down
the Kotri barrage on the water quality, agriculture, underground water and
biological life inhibitingin riverain track. seven to eight simples
were
collected in each simpling scheme from Korti barrage to Keti bunder or from kotri barrage to shah bander during 1997 20002. The
same
were analyzed for over 20 physicochemical parameters
including conductivity, nutriants metal contents, flora and fauna. some
of
the samples of soil and underground water also analyzed.
When the water samples were collected on 27_07-97 with water
discharge of 68939 cusecs down the kotri barrage, conductivity
chloride,
total dissolved solid and hardness remained nearly constant upto gharo
with
fresh water flora and fauna and a significant effest of sea water was
not
abserved. The results of sampling scheme carried out on 27_4_97 with
same
water discharge down the kotri barrage suggested that water quality of
river
lndus remained constant up to sijawal bridge but some effects of sea
water
were observed up to derwash and Uderolal about 60 km from the mouth of
river
,with a sagnificant decrease in the fresh water plankton species.
How ever when si,pling scheme was carried out on 23_4_2000
with
zero discharge down the Kotri barrage for several days, the chemical
analysis indicated intresting resulats. Total dessolved solid (TDS) in
water
above kotri barrage within the safe limits of 500 ppm recommended by
W.H.O
for drinking water. down the kotri barrage TDS race steeply and reached
to
the limit of 3200 ppm at sujawal bridge. the international guidelines
for
irrigation water suggest sever effects for water with TDS above 2000
ppm. Indus below Sujawal bridge was increasingly under the
influence of
marine water. The lindus river near villages Abdullah Jat and Mohammad Jat
on left bank of river lindus, about 20-30 km from mouth of river was full of
sea water with TDS 42750 ppm.
The flora was also observed completely of ,arine origin. the lindus down the
kotri barrage up to sujawal bridge with reduced water discharge has
converted into water pools with high salt contents with a growth of aquatic
sub merged plants of brackish water.
The fresh water fishes have also decreased due to high salinity.
A survey during july 2002 indicated that fertile agriculture
lands
on the bank of river lindus near village swanda had changed into barn
with
salts contents 10 to 20 times higher than river bank bed due to the use
of
lndus water with high salts contents.The black flow of seawater along
with
river is also affacting under ground water with the delta region. the
fishing village along left bank was using under ground water with total
denoted solids (TDS) up to 4300 ppm. The maximum permissible limits
for
human consumption by WHO for TDS is 1500 ppm.
lt is the therefore concluded that the reduced water discharge
down Kotri barrage is affacting the agriculture lands and human living in
the
region and there is a need to assess the needs of water down the Kotri
barrage. |
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