|
Special
Reports/Water Crisis |
Overcoming water shortages
By F. H. Mughal
 Water
discharge in the river’s lower region in 1892 was 185 cubic
km per year (150 maf, million acre-feet per year). In 1932,
the discharge was 105 cubic km per year (85.5 maf). In 1960,
the flow rate was 80 cubic km per year (64.5 maf), while in
1970, it got reduced to 43 cubic km (35 maf). In 1992, water
flow was just 12 cubic km (10 maf per year).
During the last 100 years, water flows got reduced in the
lower Indus region by over 93 per cent. In just 20 years, a
system, which nature had flourished for many centuries, has
irrevocably changed.
The suspended sediments load in the river comprising fertile
soil and nutrients, was reduced by 93 per cent, from 400
million tons in 1892, to 30 million tons in 1992.
Suspended sediments do ecological work by nourishing the
delta, and providing healthy ecosystems.
The massive reductions in water flows have impacted the
ecology of the area; principal components affected include
mangroves, fisheries, land (sea intrusion), livelihood,
animal husbandry, human health and water quality.
The impact of the undersea earthquake in South Asia, which
generated 10 meters high tsunami (seismic sea-waves) and
killed over 60,00 people, could have been minimised to a
large extent, if the mangroves in the coastal belts were not
removed replacing seaside hotels and shrimp ponds.
Species of mangroves were used against typhoons and storms
and could have saved thousands of life and massive economic
loss. They are the first line of defence against tsunami,
tidal wave and storms.
Global warming will further exacerbate the water depletion
problems. As average temperatures increase, snow in
Himalayan mountains, from where the river originates, will
melt in early summer season, producing more water in the
river.
During peak summer season when the water is needed most,
there will less flow.
According to the 1991 Indus Water Accord, the total water
apportioned among the four provinces was 141 cubic km
(114.35 maf per year).
The accord recognises the need for certain minimum flow to
sea, below Kotri, to check sea intrusion and, an optimum
level of 12.34 cubic km (10 maf/year), below Kotri, was
indicated.
Clearly, the water resources position is not encouraging
and, would become critical in years to come.
Freshwater shortages would create a series problems in
irrigation, drinking-water supplies, industries and in
ecological areas. However the good news is that steps can be
taken to prevent a freshwater crisis.
There are options which. when adopted, can prevent critical
water situation and they may even improve the water
availability position.
However, the basic requirement is that, the decision-makers
must realise that the water must be shared with the
environment and not taken away. Simply taking into account
the additional area irrigated, kilowatt-hours generated or
the populations served, will not do.
Ecosystems are acclimatised to the “natural water flowing
regimes” (natural cycle of floods, droughts, high flows and
low flows).
If this is obstructed, ecosystems will stop functioning. The
case of Aral Sea is a clear example. Nature has provided
water for ecosystems as well as for human-beings.
Water management must be sustainable for all components,
including ecosystems which perform valuable service for
human beings.
According to some estimates, wetlands provide service of the
order of Rs1.50 million per hectare per year (current
prices). The decision-makers ignore these facts.
The most urgent task is to provide a minimum quantity of
clean water for drinking and sanitation.
Reasonable access to safe drinking water is defined as the
availability of at least 50 liters per person per day. This
is the fundamental right of everybody and, everyone is
entitled to a healthier life.
There is a considerable scope for improving the water
productivity defined as the value of economic goods and
services per cubic meter of water used.
Agriculture is water-intensive. It uses about 80-90 per cent
of water from water resources and takes about 1,000 cubic
meters to grow one ton of wheat.
Three-fold areas in agriculture have a key to save huge
quantity of water which is enough to meet water requirements
of growing populations for the next 25 years. One is
delivering and applying water to crops more efficiently.
Called drip irrigation, the system delivers water directly
to the roots of the plants at low discharges through
perforated pipes installed on or below the soil surface.
As compared to the traditional flood or furrow irrigation,
drip system can save water by 70 per cent and, increase crop
yields by 90 per cent.
The other system is called micro-sprinklers (drip and
micro-sprinklers systems are called micro-irrigation), which
provide low discharge water directly to crops.
The older system of high-spray sprinklers for providing
spray of water droplets, at a height, is discouraged due to
the evaporation of the airborne aerosols.
The second is increasing the yields per litre of water
consumed so as to get more crop per drop.
Considerable opportunity exists in modifying the cropping
patterns and growing methods. High-yielding and
early-maturing rice varieties, for example, can increase
three-fold the amount of rice harvested per cubic meter of
water used.
It also helps reducing pest attacks. Together with
biological control of pest, cropping pattern modification
can reduce the use of pesticides, which in turn, will
minimise agrochemical pollution of surface water bodies.
The third is the promotion of rain-fed irrigation, to make
maximum use of rainfall and promoting saline agriculture in
areas affected by salinity.
It must be noted that a significant portion of water stored
behind dams and diverted through canals for irrigation,
never benefits a crop. Surface water efficiency ranges
between 25-35 per cent.
Water seeps in canals as a result, Its immediate use is
prevented and it is not available when and where needed.
Canal lining is an efficient way of reducing seepage.
Groundwater use for irrigation is presently uncontrolled.
Over pumping of groundwater leads to land subsidence.
Poor farmers in Bangladesh through micro-financing, bought
over one million human-powered, paddle-type pumps, called
treadle pumps.
They pumped shallow groundwater for small-plots irrigation,
providing income to poor farmers.
Individuals and organisations can also help in saving water.
Virtually everything a person buy or use (clothes, oil,
computers), takes water to make.
For example, it takes 18 litres of water to produce just one
litre of petrol; it takes 8.3 litres of water to produce one
kilowatt-hour of electricity.
Individuals can, therefore, purchase less material goods,
make their cars more fuel-efficient and conserve energy.
Reducing leaks in taps, using low-flush tanks for
water-closets, watering lawns with bare minimum water, or
using plants that thrive naturally in local climate, can
reduce water requirements.
Water utilities whose unaccounted-for water is of the order
of 30 per cent, should undertake leak repair programme.
The supply of water should be metered to discourage wastage.
Leak reduction in Karachi alone would mean saving of 680
million litres of water daily, enough to meet requirements
of additional 17 million people.
Substantial quantities of water can be saved, if dietary
choices are slightly changed. Various foods require
different amounts and their nutritional value also varies.
It takes 67 litres to supply 10 grams of protein from
potatoes, or 89 litres to supply 500 calories from potatoes.
It takes 204 litres to supply 10 grams of protein from rice,
or 251 litres to supply 500 calories from rice.
It takes 1,000 litres to produce 10 grams of protein from
beef (five times more water, as compared to rice), or 4,902
litres of water to supply 500 calories from beef.
In other words, a vegetarian diet would require half as much
water as required for a meat diet. Thus a shift away from
meat diet towards a vegetarian diet will result in savings
of 510 million cubic meters of water per year, enough to
feed additional 35 million people.
Re-use of treated municipal wastewater for irrigation
presents an opportunity to free water for the environment.
In a way, untreated wastewater of most cities and towns is
discharged in Indus River.
Even raw industrial wastewater is discharged in canals. It
is not advisable to use untreated wastewater for irrigation.
It is estimated that up to one-tenth of the world’s
population eats food produced using wastewater from towns
and cities.
Together with wastewater treated to a reasonable degree,
proper water application and personal hygiene, wastewater
can be used for irrigation.
However, industrial wastewater should not be used for
irrigation as it contains toxic heavy metals, which cannot
be removed by a conventional wastewater treatment plant,
unless relatively costlier tertiary wastewater treatment is
resorted to.
Rainwater harvesting allows maximum use of rainfall. Ponds,
small check dams and other structures can hold rainwater,
which can be used for irrigation during dry season.
They also re-charge the groundwater. The practice of deficit
irrigation, which provides 25 per cent less water (less than
normal requirements) to the crops, as long as the crops
receive adequate water during their critical growth stages,
can be adopted, which in turn, will save significant
quantities of water.
Water accounting is a tool, which can help in analysing the
water uses, water depletion and productivity of water in a
basin. It can assess impacts of agricultural interventions,
performance of irrigated agriculture and allocation among
various users.
Simply stated, the water accounting is like water
balance-sheet, which tracks water within water basins.
Rational water management at provincial level needs a
separate institutional setup.
The government should create a water department, like
renewable energy department, manned by persons qualified in
the field of environmental engineering.
The department should develop a strategic framework focusing
on increasing water productivity. It should also conduct
ecological risk assessment in lower Indus region, to assess
the water requirements of the ecosystems.
All components (populations, irrigation, and ecological
sensitive areas), irrespective of the locations, must be
provided with a rational share of water, after determining
requirements of each sector.
Courtesy :
The DAWN
|
Pakissan.com;
|
