|
Extent of Waterlogging in Indus Basin.
Water logged area ( m.ha). |
|
Province |
Area surveyed |
0-1.5 m |
1.5-3 m |
Total water logged |
% of surveyed areas |
|
Punjab |
9.964 |
0.998 |
3.1888 |
4.184 |
41.0 |
|
Sindh |
5.852 |
1.061 |
3.405 |
4.464 |
76.3 |
|
NWFP |
0.538 |
0.043 |
0.140 |
0.183 |
34.0 |
|
Balochistan |
0.036 |
0.005 |
0.031 |
0.036 |
100.0 |
|
Pakistan |
16.390 |
2.115 |
6.764 |
8.869 |
54.1 |
The magnitude of the problem can be guaged from the
fact that the area of productive lands was being damaged by salinity
at a rate of about 40,000 ha/year at one stage. However, according to
WAPDA authorities, it has not only been checked but also reversed and
at present the reclamation rate is 80,000 ha per annum. On one hand,
our land resource is subjected to a great threat from salinity and
waterlogging, while on the other, our population is increasing at a
very fast rate of 3.1% per annum. It is expected that our population
will grow to 148.1 million in the year 2000 and we shall need at least
40-80% more wheat, edible oil, sugar, milk and wood products at the
present rate of consumption.
|
Water budget for Indus
Basin
( million acre feet ) |
|
Average annual flow in rivers |
145 |
|
Flows to Arabian sea |
35 |
|
Diversion into irrigation system |
110 |
|
Losses from irrigation system |
98 |
|
Conveyance losses |
28 |
|
Delivery losses |
51 |
|
Field application losses |
19 |
|
Net available water for irrigation |
12 |
|
Water pumped from tubewells |
45 |
|
Effective rainfall |
14 |
|
Net water available for use by crops |
71 |
Availability of water through efficient water
management is the main right path for crop production. The Indus basin
irrigation system encompasses the Indus river and its three major
water storage reservoirs, 19 barrages/headworks, 12 link canals, and
43 canal commands covering about 90,000 villages/chaks. It covers
about 39,000 miles. The three major reservoirs, Mangla, Tarbela and
Chashma were built by Pakistan on signing the World Bank sponsored
Indus water basin treaty between India and Pakistan. Irrigation in
this country, depends on both surface and underground water resources.
The quantum of water entering the rivers aggregates to about 145
million acres feet per year. Of this about 110 million acre feet is
transferred to canals for irrigation annually (72 per cent) and
remaining 35 million acre feet flows down into the sea because of lack
of storing facilities. The quantum of water entering irrigation water
courses from the canals amounts to 98 million acre feet per annum.
Water obtained from 480,000 public and private tubewells for
irrigation purposes has been estimated at 45 million acre feet
annually. Thus, the total quantum of water entering the water courses
both from canals and tubewells aggregates to 122 million acre feet
annually. Of the 145 million acre feet water entering the canals each
year, about 28 million acre feet (i.e. one fourth) is lost in transit
due to a number of factors. Besides, about 40 million acre feet (i.e.
40 per cent lost within the water courses themselves). Thus, only 73
million acre feet water reaches the field. Also, about 18 million acre
feet water is wasted in the fields. Taking into account all the losses
as indicated above, only 55 MAF water is normally left for the
irrigation of crops. While, 90 MAF water annually goes waste. Thus,
the wastage comes to about 62 per cent. The farmers normally need 3.5
MAF water per acre for cultivation, our crops get only 1.5 MAF water
per acre.
|
Projected population and requirement
of different Agricultural commodities
|
|
Year |
Population |
|
|
|
|
Requirements |
| |
|
wheat |
oil edible |
sugar |
milk |
Wood
product |
| |
Million |
|
( m.tons ) |
|
|
m.cu.meters |
|
1947 |
31.3 |
4.6 |
0.27 |
0.30 |
3.01 |
28.80 |
|
1985 |
94.7 |
13.0 |
1.17 |
1.20 |
9.11 |
85.65 |
|
2000 |
148.1 |
20.2 |
1.83 |
1.67 |
14.25 |
189.57 |
Water is the earth's most distinctive constituent
and is an essential ingredient of all life. Its deficit is one of
the most common environmental factors limit crop productivity. Most
of the water in the hydrosphere is salty and much of the fresh water
is frozen. It has been estimated that oceans all over the world
contain about 97% of the planet's water, seven continent of about
2.8%, and the atmosphere about 0.001%. Similarly, about 77% of the
associated with land is found in ice caps and glaciers and about 22%
is found in ground waters, much of which is uneconomical to
retrieve. This scenario leaves only percentage of readily manageable
fresh water as a resource of the water supply for the population.
Plants transpire about 100-300 times more water during the
assimilation of CO2 than is required for their growth and the
production of a usable yield. It has been estimated that 600 kg of
water is transpired to produce 1 kg of dry maize, and to produce 1
kg dry biomass, normally 225 kg of water is transpired. It was
further reported that to produce 1 kg of sucrose, sugar beet plants
transpire 465 kg of water, and to produce 1 kg dried biomass, they
transpire 230 kg water. The world's land surface occupies about
13.2x109 ha, of which 7 x 109 ha is arable; only 1.5 x 109 ha of
which is cultivated land. The cultivated lands, about 0.3 x 109 ha
(23%) is saline and another 0.56 x 109 ha (37%) is sodic. Although,
the data are tenuous, it has been estimated that one-half of all
irrigated lands (about 2.5 x 108 ha) are seriously affected by
salinity or waterlogging.
The northern regions of Pakistan is full of
world's largest glaciers. They are almost at the height of 4720
meters above the sea level. They form the biggest function of
glaciers on earth giving birth to a pool of snow lake, in the
surrounding of mountains. The Himalayas, the Karakorams the Hindu
Kush and the Pamirs in the north of Pakistan gave birth to the
thickness of and the most amazing duster of the highest peaks and
largest glaciers in the world away from the Polar regions. The
valleys of mighty Karakorams to the west of Himalayas is more than
1500 square miles. About 37 per cent of the surface area of
Karakoram is under glaciers as compared to 17 per cent of the
Himalayas in Nepal, India and China put together and 22 per cent of
the European Alps. There are also about 3000 small glaciers and
tributaries. The hundred miles of cool, rush, splashing and
scintillating winnowing torrents gushing out of the shorts of these
glaciers mingle together to form about 3180 kilometers long Indus
river, which flows the plains of Pakistan into Arabian sea near
Karachi. Some of the important glaciers located in the mountainous
regions of Pakistan are mentioned below:
|
Name of
some important glaciers of Pakistan |
|
Name |
Area covered in square kilometers |
length in kilometers |
|
Siachin |
685 |
71 |
|
Baltoro |
529 |
62 |
|
Biafo |
383 |
65 |
|
Hispar |
343 |
49 |
|
Panmah |
258 |
42 |
|
Chorgo lugma |
238 |
44 |
|
Batura |
220 |
56 |
|
Khurdoin and Yukshin |
135 |
37 |
|
Braldu |
123 |
36 |
|
Barpu |
123 |
33 |
|
Yaqlil |
114 |
31 |
|
Virjerab |
112 |
38 |
|
Mohmil |
68 |
26 |
|
Gasherbrum |
67 |
25 |
|
Malanguthi |
53 |
22 |
All these glaciers are the sources of water,
which after melting in the summer season enters into river Indus,
travelling distances of about 1800 miles and finally enters into
Arabian sea near Karachi.
