Geoscience Reference
In-Depth Information
delta is comprised of
Avicennia marina
(WWF -
Pakistan, 2007). Mangroves play a vital role in
coastal protection by acting as a natural barrier
during storm surges.
A WWF study (Dehlavi
et al
., 2008) conducted
at Keti Bunder estimated that the total economic
value of the deltaic ecosystem within a given area
of 40 874 ha is equal to PKR 11 billion (US
(Gonzalez
et al.
, 2005). The water management
paradigm that emerged was overwhelmingly
technocentric in nature and based on two facets:
engineering solutions and water storage. This
paradigm was partly inherited from the British
colonial era. Beginning with the construction of the
Sindhani project on the Ravi River (now in India)
in 1886, a range of large, highly capital-intensive
projects have been built to date (Bengali, 2009).
The Indus Water Treaty (IWT) signed by
Pakistan and India in 1960, resulted in an
altered distribution of flows in the river system.
Extensive infrastructure development took place
that included link canals, barrages and reservoirs.
There is no evidence that environmental aspects
were considered during the discussions preceding
the IWT (Gonzalez
et al
., 2005). During the
1960s and 1970s, a large portion of investment
in the water sector was directed at very large
Indus Basin projects: the Mangla Dam, the Tarbela
Dam, five barrages, one siphon and eight link
canals. In Pakistan today, the Indus River system
consists of the Indus River and its tributaries, three
major reservoirs, 19 barrages, two headworks,
43 canal commands and 12 link canals, running
into 56 000 km of canals and 1.6 million km of
watercourses and field channels. There are 550 000
tubewells (Bengali, 2009). Thus the world's largest
contiguous irrigation system came into existence
(Figure 6.2).
Pakistan's socio-economic development plans
depend heavily on expanding land under irrigated
crops (Government of Pakistan, 2001) and a large
number of new developments are planned which
indicate that the amount of fresh water available
to the Indus will continue to fall (IUCN, 1991).
There are several new dams such as Diamer-
Basha, Kalabagh and Bunji that are now under
consideration.
13
million). This includes direct use value (fisheries
resources), indirect use value (carbon sequestration
by mangrove forests) and non-use value (values
placed on species protection by a representative
sample of Karachiites). More than 60% of the
rural population use the delta's mangroves as
their major source of domestic fuel, estimated
to account for around 18 000 tons (16 392 t) of
firewood (Khalil, 1999) which is worth up to
US
$
460 000 a year (Mahmood and Ali, undated).
Mangroves are also used by coastal villagers as
fodder for domestic animals. In addition to cattle,
sheep and goats kept permanently in the delta, it
has been estimated that at certain times of the year
about 16 000 camels are herded into the mangroves
(Meynell and Qureshi, 1993; Khalil, 1999). In
total, the Indus delta's natural ecosystems are
thought to contribute about 67 000 tons (60 781 t)
of leaves and 20 000 tons (18 144 t) of grasses as
livestock pasture and fodder each year, together
worthuptoUS
$
1.35 million (Mahmood and Ali,
undated). At least three quarters of the delta's
rural population depend, directly or indirectly, on
fishing as their main source of income, and most
of Pakistan's commercial marine fishery operates
in and around the mangrove creeks on the coast
of Sindh Province. A large proportion of fish and
crustaceans spend at least part of their life cycle in
the mangroves, or depend on food webs originating
there (Meynell and Qureshi, 1993).
$
Building the world's largest
irrigation infrastructure
Reduced flow of the River
Indus: causes and consequences
Pakistan depends on irrigation and water resources
for 90% of its food and crop production (World
Bank, 1992). Historically, irrigation water has been
provided in the region year by year since 1859
The vast irrigation network affords Pakistan the
highest irrigated to rain-fed land ratio in the world.
This
impressive irrigation system is, however,
