Group - E
5.1. Answer any two questions from the following (5 x 2 = 10)
5.1.1 Describe with sketches the landforms developed by combined action of wind and running water in the arid region.
Answer: The combined action of wind and running water (flash floods) in arid regions creates several distinctive landforms. In deserts, rain occurs rarely but torrentially, leading to short-lived streams. The major landforms include:
1. Wadi: Wadis are dry river beds or gullies found in deserts. During sudden rainfall, these channels are filled with water and carry sediment, but they remain dry for most of the year. They are formed by vertical erosion of water.
2. Pediment: A pediment is a gently sloping, rock-floored surface found at the base of a mountain in an arid region. It is formed by the erosion of the mountain front through weathering and stream wash. It connects the steep mountain slope to the lower basin.
3. Bajada: A bajada is a depositional feature formed by the coalescence of several alluvial fans at the foot of the mountain range. It consists of loose sediments like sand and gravel deposited by streams as they lose velocity upon entering the flat plain.
4. Playa: In the lowest part of a desert basin, water from the streams collects to form a temporary lake called a Playa. When the water evaporates due to high heat, salt deposits are left behind, forming a salt flat or Salina. These lakes are temporary and shallow.
5.1.2 Describe with sketches three landforms produced by depositional work of rivers in its middle course.
Answer: In the middle course, the slope of the river decreases, and the volume of water increases due to tributaries. The river's speed reduces, leading to lateral erosion and significant deposition. Three major landforms are:
1. Meander: As the river flows over flat land, it swings from side to side to avoid obstacles, forming large S-shaped bends called meanders. The water flows faster on the outer bank causing erosion, while slower flow on the inner bank leads to deposition, accentuating the curves.
2. Ox-bow Lake: In a mature meander, the neck of the loop becomes very narrow. During floods, the river may cut through this narrow neck to flow straight. The old curved loop gets cut off from the main channel, and sediment seals the ends, forming a horse-shoe-shaped lake known as an Ox-bow lake.
3. River Cliff and Slip-off Slope: In a meandering river, the outer bank is undercut by the swift current, forming a steep slope called the River Cliff. Conversely, on the inner bank where the current is slow, sediments like sand and gravel are deposited, forming a gentle slope known as the Slip-off Slope or Point Bar.
5.1.3 Explain three major factors causing temperature variation in the atmosphere.
Answer: The temperature of the atmosphere varies from place to place due to several factors. Three major factors are:
1. Latitude (Insolation): This is the most important factor. The sun's rays fall vertically over the equator and obliquely towards the poles. Vertical rays cover less area and lose less heat, making the equatorial region hot. Oblique rays cover a larger area and pass through more atmosphere, losing heat, making polar regions cold. Thus, temperature decreases from the equator to the poles.
2. Altitude: Temperature decreases with an increase in height from sea level at a rate of 6.4°C per 1000 meters (Normal Lapse Rate). This happens because the atmosphere is heated primarily from below by the earth's radiation. The air at lower levels is denser and absorbs more heat, while air at higher altitudes is thinner and colder. That is why hill stations are cooler than plains.
3. Distance from the Sea: Land heats up and cools down faster than water. Coastal areas have a moderate or equable climate due to the influence of land and sea breezes. In contrast, places far from the sea (continental location) experience extreme temperatures—very hot summers and very cold winters—known as a continental climate.
5.1.4 State the factors controlling the origin of the ocean currents.
Answer: Ocean currents are the continuous flow of huge amounts of water in a definite direction. The factors controlling their origin include:
1. Planetary Winds: This is the primary cause. Prevailing winds (Trade winds, Westerlies) drag the surface water of the ocean along with them. For example, the Trade winds drive equatorial currents from east to west.
2. Rotation of the Earth (Coriolis Force): The earth's rotation deflects moving water. According to Ferrel's Law, currents deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, influencing their direction.
3. Difference in Temperature: Warm water near the equator expands and is lighter, so it flows as surface current towards the poles. Cold water near the poles is denser and heavier, sinking and flowing towards the equator as a subsurface current to replace the warm water.
4. Difference in Salinity: Water with high salinity is denser and heavier, causing it to sink and flow as a deep current. Water with low salinity is lighter and flows on the surface. For example, currents flow from the Atlantic to the Mediterranean due to salinity differences.
5.2. Answer any two questions from the following (5 x 2 = 10)
5.2.1 State the physiographic differences between eastern and western coastal plains of India.
Answer: The differences between the Eastern and Western Coastal Plains are:
1. Width: The Eastern Coastal Plain is much wider (80-100 km) and stretches between the Eastern Ghats and the Bay of Bengal. The Western Coastal Plain is narrow (10-80 km) and lies between the Western Ghats and the Arabian Sea.
2. Formation of Deltas: The large rivers of the Eastern Coast (Mahanadi, Godavari, Krishna, Kaveri) have formed large, fertile deltas due to gentle slopes. The rivers of the Western Coast (Narmada, Tapti) flow swiftly through steep slopes and do not form deltas; they form estuaries.
3. Surface Nature: The Eastern plain is more leveled, having a smooth coastline with fewer natural harbors. The Western plain is more rugged and indented, which favors the development of many natural ports and harbors (like Mumbai, Kochi).
4. Lagoons: The Western Coast, especially the Malabar coast, is famous for backwaters or lagoons locally called 'Kayals' (e.g., Vembanad). Such features are less common on the Eastern Coast, though Chilika and Pulicat lakes exist there.
5.2.2 Explain the major factors controlling the climate of India.
Answer: India has a 'Tropical Monsoon' type of climate. The major controlling factors are:
1. Latitude: The Tropic of Cancer passes through the middle of India. The southern part lies in the tropical zone and remains hot, while the northern part lies in the subtropical zone and experiences extreme temperatures.
2. The Himalayas: The Himalayas act as a climatic barrier. They prevent the cold winds from Central Asia from entering India, keeping the winters milder. They also intercept the moisture-laden South-West Monsoon winds, causing heavy rainfall in Northern India.
3. Monsoon Winds: This is the most dominating factor. The reversal of winds brings distinct seasons. The South-West Monsoon brings rain in summer (June-Sept), while the North-East Monsoon brings dry, cool weather in winter.
4. Distance from Sea: Peninsular India, surrounded by the sea, has an equable (moderate) climate. The interior parts of North India, far from the sea, experience a continental climate with very hot summers and cold winters.
5. Jet Streams: The Westerly Jet Stream in winter brings Western Disturbances causing rain in NW India. The Easterly Jet Stream in summer helps in the onset of the Monsoon.
5.2.3 Give an account of favourable physical conditions required for cultivation of tea in India.
Answer: Tea is a plantation crop and a major beverage of India. The favourable physical conditions are:
1. Land/Relief: Tea grows best on mountain slopes where water can drain off easily. Waterlogging at the roots is harmful to tea plants. Hence, the hill slopes of Darjeeling, Assam, and Nilgiris are ideal.
2. Climate (Temperature): It requires a hot and humid climate. The ideal temperature range is 20°C to 30°C. Frost is harmful to the crop. Warmth helps in the rapid growth of tender leaves.
3. Rainfall: High rainfall is essential, ranging from 150 cm to 250 cm annually. The rainfall should be well-distributed throughout the year for continuous leaf growth. Morning fog and dew are also beneficial.
4. Soil: Tea requires fertile, iron-rich, acidic soil with high humus content. Virgin forest soils on hill slopes are very suitable.
5. Shade: Direct scorching sunlight can damage the plants, so shade trees are planted in between tea bushes to provide protection.
5.2.4 Explain the factors responsible for the concentration of iron and steel industry in eastern India.
Answer: The Iron and Steel industry is largely concentrated in Eastern India (Chota Nagpur Plateau region - Jharkhand, West Bengal, Odisha) due to the following advantages:
1. Availability of Raw Material (Iron Ore): High-grade hematite iron ore is abundantly available in the Singhbhum district of Jharkhand and Mayurbhanj/Keonjhar districts of Odisha, which are close to the steel plants.
2. Availability of Coal: Good quality coking coal, essential for smelting, is available from the Jharia, Raniganj, and Bokaro coalfields located nearby.
3. Other Minerals: Limestone, dolomite, and manganese, used as flux and hardening agents, are available in the Gangpur and Sundargarh regions of Odisha.
4. Water Supply: Perennial rivers like the Damodar, Subarnarekha, Mahanadi, and Brahmani provide sufficient water for cooling and processing in the steel plants.
5. Transport and Port Facilities: A dense network of railways (South Eastern Railway) connects the mines to the plants. The Kolkata and Haldia ports are nearby, facilitating the export of steel and import of machinery.
6. Cheap Labor: Densely populated states like West Bengal, Bihar, and Jharkhand provide abundant cheap labor.