Drainage System

Correct Answer: (d) The Damodar

The Damodar river was known as the 'Sorrow of Bengal' because it used to frequently flood the plains of West Bengal, causing widespread destruction of life and property. It flows through Jharkhand and West Bengal and was notorious for its devastating floods before the Damodar Valley Corporation (DVC) was established to control them.

Correct Answer: (c) The Ganga

The Ganga has the largest river basin in India, covering about 8.6 lakh sq. km. It drains a vast area encompassing parts of Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, and West Bengal, along with portions of neighbouring countries. Its numerous tributaries from both the Himalayas and the Peninsular plateau make its basin the most extensive in India.

Correct Answer: (c) The Indus

'Panchnad' literally means 'five rivers' and refers to the five rivers of Punjab: the Jhelum, the Chenab, the Ravi, the Beas, and the Sutlej. The Indus is the main trunk river into which all these five rivers ultimately drain, but it is not itself counted among the five rivers of Panchnad.

Correct Answer: (b) The Narmada

The Narmada flows in a rift valley formed due to faulting (tectonic activity). It flows westward between the Vindhya Range in the north and the Satpura Range in the south through a trough (graben) created by the down-throwing of a block of land between two parallel faults. Because of this, it does not form a delta but an estuary at its mouth.

Correct Answer: (d) Deva Prayag

The Alaknanda and the Bhagirathi meet at Deva Prayag (Devprayag) in Uttarakhand, and from this confluence the combined river is known as the Ganga. The Alaknanda itself is formed by several tributaries joining at various Prayags (confluences) higher up in the Himalayas.

Differences between River Basin and Watershed:

| Basis | River Basin | Watershed |
|---|---|---|
| Definition | The entire area drained by a river and its tributaries is called a river basin. | The boundary line separating one drainage basin from another is called a watershed. |
| Size | River basins are large in area, covering extensive regions. | Watersheds are generally small in area. |
| Nature | It is a low-lying area that collects and channels water towards the main river. | It is an elevated area (ridge or hill) that divides two adjacent drainage basins. |
| Function | It acts as a catchment area for the river system. | It acts as a dividing line between two river systems. |
| Example | The Ganga basin, the Mahanadi basin. | The Western Ghats act as a watershed between rivers flowing west and east. |

Differences between Dendritic and Trellis Drainage Pattern:

| Basis | Dendritic Pattern | Trellis Pattern |
|---|---|---|
| Shape | Resembles the branches of a tree; tributaries join the main river at acute angles. | Resembles a garden trellis; primary tributaries are long and parallel, joined by short secondary tributaries at right angles. |
| Development | Develops on a uniform or homogeneous land surface where rocks offer equal resistance to erosion. | Develops where hard and soft rocks alternate in a parallel arrangement (e.g., fold mountains). |
| Terrain | Found in areas with uniform slope and rock structure. | Found in areas with alternating bands of hard and soft rock. |
| Example | Common in the plains of northern India. | Found in the Himalayan region and Appalachian mountains. |

Differences between Radial and Centripetal Drainage Pattern:

| Basis | Radial Pattern | Centripetal Pattern |
|---|---|---|
| Direction of flow | Streams flow outward in all directions from a central elevated point (hill or dome). | Streams flow inward from all directions towards a central depression or basin. |
| Topography | Develops on a central elevated feature such as a volcanic cone, dome, or hill. | Develops in an inland basin, depression, or valley surrounded by higher ground. |
| Result | Water disperses away from the centre. | Water converges towards the centre, often forming a lake. |
| Example | Rivers originating from the Amarkantak plateau (Narmada, Son, Mahanadi). | Rivers draining into Loktak Lake in Manipur. |

Differences between Delta and Estuary:

| Basis | Delta | Estuary |
|---|---|---|
| Definition | A triangular-shaped landform of sediment deposited at the mouth of a river where it meets a sea or lake. | A funnel-shaped mouth of a river where tidal effects are prominent and the river merges with the sea. |
| Formation | Formed when a river carries a heavy load of silt and deposits it at its mouth due to reduced velocity. | Formed when a river flows through a rift valley or where tidal action is strong enough to remove sediment. |
| Shape | Triangular or fan-shaped. | Funnel-shaped or trumpet-shaped. |
| Sediment | Rich in sediment; very fertile land. | Sediment is swept away by tidal action; no deposition. |
| Example | Ganga-Brahmaputra delta (Sundarbans), Mahanadi delta. | Narmada estuary, Tapti estuary. |

Socio-economic advantages of inter-linking of rivers in India:

The inter-linking of rivers would provide the following socio-economic benefits:

1. Irrigation: Surplus water from flood-prone rivers can be transferred to drought-prone and water-deficit regions, thereby increasing the irrigated area and agricultural productivity.
2. Flood and Drought Control: It would help in controlling floods in the Ganga-Brahmaputra basin and mitigating droughts in the Peninsular and western regions simultaneously.
3. Hydroelectric Power: The canals and reservoirs created can be used to generate hydroelectric power, meeting the energy needs of the country.
4. Navigation: The inter-linked waterways can serve as inland navigation routes, reducing transportation costs and boosting trade.
5. Employment and Economic Growth: Increased agricultural output and industrial activity due to assured water supply would generate employment and promote overall economic development.

Three characteristics of Peninsular rivers:

1. Seasonal flow: Most Peninsular rivers are seasonal (non-perennial) in nature. They are fed mainly by rainfall and tend to dry up or have very little water during the dry season (summer).

2. Fixed and shallow course: Peninsular rivers flow in fixed, well-defined courses over hard rock surfaces. They have a limited capacity to change their course and are generally shallower compared to Himalayan rivers.

3. Short and swift with limited basin: Peninsular rivers are comparatively shorter in length with smaller basins. They originate from the Western Ghats or the central highlands and flow eastward or westward, covering shorter distances before meeting the sea. They do not receive glacial meltwater and hence depend entirely on monsoon rainfall.

Characteristic Features of North Indian (Himalayan) Rivers:

1. Perennial: North Indian rivers are perennial (ever-flowing). They receive water both from monsoon rainfall and from the melting of glaciers and snow in the Himalayas throughout the year.

2. Long course and large basins: These rivers originate in the Himalayas and travel long distances across the plains before meeting the sea. They have very large drainage basins (e.g., the Ganga basin covers about 8.6 lakh sq. km).

3. Antecedent drainage: Many Himalayan rivers (e.g., Indus, Ganga, Brahmaputra) are older than the Himalayas themselves. They cut through the rising mountains, forming deep gorges — a feature called antecedent drainage.

4. Heavy silt load and meandering: These rivers carry a heavy load of silt eroded from the young Himalayan mountains. In the plains, they flow slowly, deposit silt, and form meanders, oxbow lakes, and broad floodplains.

5. Delta formation: They deposit large amounts of sediment at their mouths, forming extensive and fertile deltas (e.g., the Sundarbans delta).

Differences from Peninsular Rivers:

| Feature | North Indian (Himalayan) Rivers | Peninsular Rivers |
|---|---|---|
| Source of water | Glaciers + monsoon rainfall (perennial) | Only monsoon rainfall (seasonal) |
| Course | Long, with meanders in plains | Short, swift, and straight |
| Age | Older than the mountains (antecedent) | Older rivers with fixed courses |
| Valleys | Deep gorges in mountains, broad plains | Shallow valleys on hard rock |
| Silt load | Very heavy | Comparatively less |
| Delta/Estuary | Form large deltas | Some form estuaries (Narmada, Tapti) |
| Basin size | Very large | Comparatively smaller |

Important rivers encountered while travelling from Haridwar to Siliguri along the Himalayan foothills:

Travelling from west to east, the major rivers one would cross are:
1. The Ganga (at Haridwar)
2. The Ramganga
3. The Gomti
4. The Ghaghra (Saryu)
5. The Gandak
6. The Kosi
7. The Mahananda (near Siliguri)

Characteristics of the Kosi River:

The Kosi is one of the most important and notorious rivers of this region. Its key characteristics are:

1. Origin: The Kosi originates in the glaciers of Tibet (near Mount Everest) and enters India through Nepal. It is formed by the confluence of several streams including the Arun, the Sun Kosi, and the Tamur.

2. Perennial river: Like other Himalayan rivers, the Kosi is perennial — it receives water from glacial melt as well as monsoon rainfall throughout the year.

3. Heavy silt load and shifting course: The Kosi carries an enormous amount of silt from the young Himalayan mountains. Due to this heavy sediment load, it constantly shifts its course. Over the past 250 years, it has shifted its course westward by about 120 km, causing widespread flooding and destruction.

4. 'Sorrow of Bihar': Because of its frequent and devastating floods, the Kosi is called the 'Sorrow of Bihar'. It inundates vast areas of the North Bihar plains every year, causing immense loss of life and property.

5. Drainage basin: The Kosi drains a large area of Nepal and the Bihar plains before joining the Ganga near Kursela in Bihar.

6. Flood plains: It forms broad, fertile flood plains in the Bihar plains due to deposition of alluvial silt, which makes the soil very productive when floods recede.