questions

• Q.3 Naming an industry in each case, describe three different purposes for which manufacturing and processing industries use water. Ans. 1. Cooling water for iron and steel industry. 2. Washing / cleaning in textile industry. 3. For boiling in food processing. 4. As ice to preserve frozen food. 5. To provide humidity in textile mills.
• Small dams and large dams store water mainly for irrigation
• Major dams serve near and far areas, while small dams only serve local areas
• Both small and major dams provide water for domestic and industrial use
• Major dams are more multi-purpose than small dams
• Two major dams, Tarbela and Mangla, have the purpose of providing water to link canals, where water from Indus and Jhelum rivers is transferred to eastern rivers
• All major dams are major suppliers of HEP (Hydroelectric Power), while small dams supply little to no HEP
• The reservoirs behind both large and small dams are used for fishing and recreation; for example, the Mangla reservoir produces 2% of the inland fish catch
• Large dams are more important for flood control than small dams
• Q.5 State three problems caused by the storage of water in reservoirs and its use for agriculture. Ans. By storage of water. 1. People have to be moved from the area to be flooded for storage. 2. Silting of reservoirs. 3. Loss of silt downstream for agriculture. 4. Loss of water downstream for irrigation by inundation canals. By use for agriculture. 1. Water logging in irrigated areas. 2. Salinity in irrigated areas. 3. So much used in Punjab that parts of Sindh are suffering from a shortage of water.
• Q.6 What is silting and how is it caused. Ans. Silting means the deposition of silt, mud and sand on the bed of the reservoirs. Causes of siltation. 1. Rivers erode the material from bed / sides. 2. Large load carried by the river. 3. Deforestation.
• Q.7 Why is silting a problem / effects. Ans. 1. May damage the machinery. 2. May block the pipes. 3. Increases the risk of flooding. 4. May shorten the life of reservoir. 5. Decreases water holding capacity of the reservoir / canals which limits the HEP production / water for irrigation. 6. Has to be removed for drinking water. 7. Expensive / difficult to remove.
• Methods to control the silt 1. 2. Planting trees along the hill slopes surrounding the river valley. To build small dams in the river up streams from the dam. 3. To build small dams in the tributary streams joining the main river.
• Q.8 Other than supplying water to industry, for what purposes may reservoirs and dams be used? Ans. Storage of water. Hydro electric power. Domestic water. Irrigation. Fishing. Recreation of reservoir. Flood control, Road on dam.
• Q.9 Name in full the two institutions set up by the government to build the dams. Ans. 1. Water and Power Development Authority.(WAPDA) 2. Small Dams Organization.(SDO)
• Q.10 Why do the reservoirs of these dams hold large quantities of water? Ans. Deep valley / large valley. Steep sites. Large river / permanent flow / water from snowfields / glaciers. Low evaporation / cool climate. High rainfall.
• Q.11. Describe the site of the dam. Ans. Steep rock. Bare rock / rocky / barren. Deep and narrow valleys. Gravel / sand.
• Q.12. What evidence shows that the water level in the reservoirs is low? Ans. Dry ground / Silt / flat land at edge.
• Q.13. Compare the barrage shown in Photograph D with the dam in Photograph C. Ans. Barrage is:- Longer / wider / less high. Water on both sides. Low / flatter land. Dam is:- Steep rock. Bare rock / rocky / barren. Deep and narrow valleys. Gravel / sand.