These notes provide questions and answers relating to the chapter of development of water resources in Pakistan for cambridge students.

1. Development of Water
Resources in Pakistan
Notes for Cambridge International Examinations

2.  Q. Why is irrigation necessary for growing crops in many areas of
Pakistan?
 A. In Pakistan, rainfall is highly variable in time and distribution. It is
less in quantity. Many areas of Pakistan are arid and semi arid for
example Baluchistan and Sindh which is why there is scanty rainfall
there. In Karachi there are less than 10 days of rainfall.The monsoon
system flows in heavy showers over a short period of time and the
land does not absorb it, either because it drains away too quickly or
because its evaporation rate is very high. This is why we cant
depend on rainwater for irrigation. Agriculture is the backbone of
Pakistans economy and we need water for planting the crops
which is why irrigation is done in many areas of Pakistan

3.  Q. Why are rivers important for Pakistan?
 A. They are a good place of settlement and add to the scenic
beauty of an area.
 Fishing can also be done on rivers and lakes.
 Rivers provide water which can be used for hydroelectric powers in
mountainous areas.
 It provides water for irrigation which is vital for Pakistans economy.
 It provides water which can be used for industrial and domestic
purposes.

4.  Q. Why was the Indus Water Treaty necessary for Pakistan?
 A. It was necessary because Pakistans economy depends on
agriculture which is why we need the rivers for irrigation. If there had
been no treaty, India would’ve stopped the flow of water from the
headworks of the rivers and there would’ve been food shortages in
Pakistan leading to economic crisis and other problems.

5.  Q. Naming an industry in each case, describe three different purposes for which
manufacturing and processing industries use water.
 A. Pharmaceutical industry:
 1. For making syrups
 2. For making injections
 3. For making drips
 Food industry:
 1. For making beverages
 2. For making juices
 3. For making squashes
 Textile industry
 1. Blueing
 2. Dyeing
 3. Printing

6.  Q. State the differences between dams and barrages
 • Dams are used for hydro electric power making whereas barrages
don’t.
 • Dams are made in mountaineous terrains, barrages can be made on
flat land
 • Dams are comparatively more expensive to build, barrages are
comparatively cheaper to build.

7.  Q. Explain the differences between:
 1. Lined canals and unlined canals
 A. Lined canals are man made and are made of cement and they have
strong embankments
 Unlined canals are naturally made and they have loose embankments
 2. Perennial canals and inundation canals
 A. Perennial canals supply water throughout the year and cause water
logging and salanity
 Inundation canals flow only in the summer seasons when the rivers flood
and they actually keep a balance between evapo transpiration and
rainfall and thus, they do not cause water logging and salanity.

8.  Q. Describe the problems which have resulted from the use of
unlined canals to supply water for irrigation in Pakistan?
 A. Unlined canals have loose embankments. They do not stop
the flow of water seeping underground, so the water drains into the
ground thus increasing the water table and causing the twin
problems of water logging and salanity making the land unfit for
agriculture.

9.  Q. Other than supplying water to industry, for what purposes may
reservoirs and dams be used?
 A. Dams are important for making hydro electric power. They
provide recreation. Dams are important for supplying water for
agriculture because the canals are connected to it. Dams are a
good source of flood control. Water can be stored up in reservoirs
during heavy monsoon rainfalls and this can be later used in times
of difficulty for example in times of drought. Dams also provide
water for domestic use.

10.  Q. Describe the Persian Wheel method of irrigation.
 A. In the Persian wheel method, there is a vertical wheel and
buckets/earthenware pots are slung on it and it is turned by a
system of cogs. It is powered by a blind folded bullock or an ox
which is used to drive a horizontal wheel around in circles. In this
way the vertical wheel draws up water from the well and the
buckets/earthenware pots unload the water into a channel which
takes the water to the fields for irrigation.

11.  Q. What is siltation and what are its causes and effects?
 A. Siltation is the deposition of mud and silt in the rivers. Its main cause is
erosion. Due to deforestation, the trees are cut down. The trees hold the soil
and stop it from being washed by heavy rains. When there are no trees the
rains wash down the soil and flow into rivers. Siltation has many negative
effects. The silt settles at the bottom and thus it reduces the water storage
capacity of a dam, which ultimately means that there is less hydro electric
power production. Siltation also blocks canals. It traps the turbines and
damages them. It also weakens the foundation of the dams.