Geoscience Reference
In-Depth Information
300
250
200
150
100
50
0
Figure 6.3
Zero flow days
downstream Kotri Barrage. (Source:
Inam
et al
., 2004).
Years
for irrigation, by the time the Indus reaches the
Kotri Barrage (some two thirds of the way into
Sindh Province, or 200 km from the Arabian
Sea), there is inadequate flow to maintain the
natural ecosystems of the Indus delta (Meynell and
Qureshi, 1993).
Recurrent disputes over water use led the
government to set in place the Indus Water Accord
in 1991, which apportioned the use of the river's
water between the four provinces of Pakistan. It
also recognized - for the first time - the need to
allow some freshwater discharge into the delta to
safeguard the ecosystem, specifying a minimum
flow of 10 MAF (12 billion m
3
). In 1994, however,
because of drought and water shortages, Punjab
Province requested an exemption from the 1991
Water Accord and subsequently received a higher
allocation based on historical use (Meynell and
Qureshi, 1993).
Underlying the failure to take effective action,
either with respect to irrigation management or
the construction of new storages, is the pervasive
lack of trust. As Habib (2004) notes, 'facts about
water remain controversial and all domestic water
issues are explained in the context of provincial
antagonism'. There is justification for concern
in the view that residual flow to the Arabian
Sea is 'wastage' (Asrar-ul-Haq
et al
., 1997) or
'escapages' (Tarar, 1997) rather than an important
element of environmental sustainability. Failure
to recognize downstream ecosystem needs has
often led to water allocation decisions being made
that are neither economically nor ecologically
sound. Contrary to the dominant development
imperative that favours the allocation of water
to large-scale, commercial uses such as dams,
reservoirs, irrigation and hydropower schemes,
Pakistan's ecosystems, too, are economic users of
water. Yet the economic benefits of water-based
ecosystems are rarely factored into river basin
planning, or into water allocation decisions (IUCN,
2003). If the present trends continue the Indus
Delta will ultimately establish a transgressive beach
dominated by aeolian dunes, owing to lack of
sediment inputs and high energy waves (Wells and
Coleman, 1984; Haq, 1999).
Cost of environmental
degradation in the Indus Delta
Located on a high wave-energy coastline, the Indus
Delta is susceptible to erosion (Wells and Coleman,
1984) and rapid sea encroachment due to sea-level
rise (Haq, 1999). The reduction in the inflow of
fresh water has exposed this complex ecosystem
to environmental and social stresses in the form of
loss of habitat and biodiversity and a decline in the
productive values of the ecosystem.
Land degradation
It has been estimated that the area of the Indus
Delta has shrunk from 3000 km
2
to 250 km
2
(Hassan, 1992). The active delta is now only 10%
of its original area (Sheikh and Soomro, 2006).
It is estimated that up to 67 km of salt-water
intrusion has taken place resulting in damage
to deltaic ecosystems and adversely affecting the
groundwater aquifers (WWF - Pakistan, 2007). The
salinity in the delta has also increased (Amjad
et al
.,
