Class 9 Geography Chapter 3 Drainage PDF Download
Drainage is the process of removal of excess water from the land surface or the subsurface by natural or artificial means. A drainage system is a network of watercourses or drains that carry away the surplus water. A drainage basin is an area of land that drains all the water to a common outlet such as a river, lake or sea. A watershed is the boundary that separates one drainage basin from another.
Drainage is an important topic in geography as it influences various aspects of the physical and human environment such as climate, soil, vegetation, agriculture, transportation, etc. In this chapter, we will learn about the different types of drainage patterns, the major rivers of India and their characteristics, and the drainage basins of India and their features.
The main objectives of this chapter are to:
- Understand the meaning and significance of drainage in geography
- Identify and describe the different types of drainage patterns
- Recognize and explain the characteristics and courses of the major rivers of India
- Analyze and compare the drainage basins of India and their river systems
- Develop geographical skills such as map reading, data interpretation and diagram drawing
Types of Drainage Patterns
A drainage pattern is the arrangement or shape of a river system in a region. It depends on various factors such as geological structure, topography, slope, climate, rainfall, vegetation and human activities. There are different types of drainage patterns such as:
- Dendritic: This is the most common type of drainage pattern. It resembles a tree with many branches. It develops in areas where the underlying rock is uniform and horizontal or gently sloping. The streams join at acute angles forming a dendritic network. Examples: Ganga river system, Deccan plateau rivers.
- Trellis: This type of drainage pattern forms in areas where hard and soft rocks alternate in parallel bands. The main river flows along a valley eroded by a soft rock while its tributaries cut across hard rocks at right angles forming a trellis-like pattern. Examples: Indus river system, Satluj river system.
- Radial: This type of drainage pattern develops when streams flow in different directions from a central highland or peak. The streams radiate outwards like spokes of a wheel. Examples: Narmada river system, Amarkantak hills.
- Rectangular: This type of drainage pattern forms in areas where rocks are jointed or faulted at right angles. The streams follow rectangular courses along these joints or faults forming right-angled bends. Examples: Chambal river system, Rewa plateau.
- Deranged: This type of drainage pattern forms in areas where the original drainage system has been disturbed or destroyed by natural or human factors such as glaciation, volcanism, erosion, deposition, etc. The streams have irregular and disconnected courses forming lakes, swamps and marshes. Examples: Canadian Shield, parts of Rajasthan.
Major Rivers of India
India has a rich and diverse river system that drains almost 75% of its land area. The rivers of India can be classified into two broad categories based on their origin and discharge:
- Himalayan rivers: These are the rivers that originate from the Himalayan mountains or the Tibetan plateau. They are perennial, meaning they flow throughout the year due to snowmelt and rainfall. They have long courses, large basins, high discharge and sediment load. They form meanders, oxbow lakes, floodplains, deltas and estuaries. Examples: Indus, Ganga, Brahmaputra.
- Peninsular rivers: These are the rivers that originate from the peninsular plateau or the central highlands of India. They are seasonal, meaning they depend on monsoon rainfall for their flow. They have shorter courses, smaller basins, lower discharge and sediment load. They form rapids, waterfalls, gorges, canyons and lagoons. Examples: Narmada, Tapi, Godavari, Krishna, Kaveri.
The following table summarizes the characteristics and courses of some of the major rivers of India:
| River | Origin | Length (km) | Basin Area (sq km) | Tributaries | Features |
|---|---|---|---|---|---|
| Indus | Mansarovar Lake in Tibet | 2880 (709 in India) | 321289 (114000 in India) | Zanskar, Shyok, Gilgit, Kabul, Chenab, Ravi, Beas, Sutlej | Forms a large delta in Pakistan; flows through Ladakh and Punjab; one of the longest rivers in Asia; part of the Indus Valley Civilization |
| Ganga | Gangotri glacier in Uttarakhand | 2525 | 861452 | Yamuna, Ghaghara, Gandak, Kosi, Son, Gomti, Chambal | Forms a large delta with Brahmaputra in West Bengal; flows through Uttar Pradesh, Bihar and West Bengal; one of the most sacred rivers in Hinduism; one of the most polluted rivers in the world |
| Brahmaputra | Chemayungdung glacier in Tibet | 2900 (916 in India) | 194413 (58000 in India) | Dibang, Lohit, Subansiri, Manas, Teesta | Forms a large delta with Ganga in West Bengal; flows through Tibet (as Yarlung Tsangpo), Arunachal Pradesh (as Dihang) and Assam (as Brahmaputra); one of the largest rivers in terms of discharge and sediment load; prone to floods and erosion |
| Narmada | Amarkantak hills in Madhya Pradesh | 1312 | 98796 | Banjar, Hiran, Tawa, Burhner | Flows through Madhya Pradesh and Gujarat; forms a rift valley with Vindhya and Satpura ranges; forms a large estuary near Bharuch; one of the westward flowing peninsular rivers; one of the most sacred rivers in Hinduism > |
| Tapi | Satpura range in Madhya Pradesh | 724 > | 65145 > | Purna, Girna, Panzara, Bori > | Flows through Madhya Pradesh, Maharashtra and Gujarat; forms a rift valley with Satpura and Sahyadri ranges; forms a small estuary near Surat; one of the westward flowing peninsular rivers > |
| Godavari | Nasik hills in Maharashtra | 1465 > | 312812 > | Flows through Maharashtra, Telangana, Chhattisgarh, Andhra Pradesh and Odisha; forms a large delta near Rajahmundry; one of the eastward flowing peninsular rivers; one of the longest rivers in India; known as the Dakshin Ganga or the South Ganga | |
| Krishna | Mahabaleshwar hills in Maharashtra | 1400 | 258948 | Bhima, Tungabhadra, Ghataprabha, Malaprabha, Musi | Flows through Maharashtra, Karnataka, Telangana and Andhra Pradesh; forms a large delta near Vijayawada; one of the eastward flowing peninsular rivers; one of the largest rivers in terms of basin area; known for its irrigation potential and hydroelectric projects |
| Kaveri | Brahmagiri hills in Karnataka | 765 | 81155 | Hemavati, Kabini, Bhavani, Amravati, Noyyal | Flows through Karnataka and Tamil Nadu; forms a small delta near Thanjavur; one of the eastward flowing peninsular rivers; one of the most sacred rivers in Hinduism; known for its cultural and religious significance and inter-state water disputes |
Drainage Basins of India
A drainage basin is an area of land that drains all the water to a common outlet such as a river, lake or sea. It is also called a catchment area or a river basin. A drainage basin has various features such as source, mouth, tributaries, distributaries, confluence, etc. A water divide is a highland or a ridge that separates one drainage basin from another. It can be continental or local.
India has four major drainage basins based on the direction and destination of the river flow. They are:
- Himalayan rivers basin: This basin covers about 33% of the total land area of India. It drains the northern and northeastern parts of India. It includes the Indus, Ganga and Brahmaputra river systems and their tributaries. It drains into the Arabian Sea and the Bay of Bengal. It is characterized by large and perennial rivers, fertile floodplains, extensive deltas and estuaries.
- Peninsular rivers basin: This basin covers about 43% of the total land area of India. It drains the central and southern parts of India. It includes the Narmada, Tapi, Godavari, Krishna and Kaveri river systems and their tributaries. It drains into the Arabian Sea and the Bay of Bengal. It is characterized by smaller and seasonal rivers, rocky and uneven terrain, narrow valleys and gorges.
- Coastal rivers basin: This basin covers about 7% of the total land area of India. It drains the western and eastern coastal plains of India. It includes several short and swift rivers such as Mahanadi, Subarnarekha, Mahi, Sabarmati, Periyar, etc. It drains into the Arabian Sea and the Bay of Bengal. It is characterized by low discharge and sediment load, saline water intrusion and lagoons.
- Inland drainage basin: This basin covers about 17% of the total land area of India. It drains the arid and semi-arid regions of western India such as Rajasthan and Gujarat. It includes several ephemeral streams such as Luni, Ghaggar, Banas, etc. It does not drain into any sea or ocean but ends up in salt lakes or marshes such as Sambhar lake or Rann of Kutch. It is characterized by high evaporation and salinity, low rainfall and vegetation.
Conclusion
In this article, we have learned about the drainage system of India and its various aspects. We have seen how drainage is an important topic in geography as it influences various aspects of the physical and human environment such as climate, soil, vegetation, agriculture, transportation, etc. We have also seen how different types of drainage patterns form in different regions depending on various factors such as geological structure, topography, slope, climate, rainfall, vegetation and human activities. We have also seen how the major rivers of India and their characteristics vary depending on their origin and discharge. We have also seen how the drainage basins of India and their features differ based on the direction and destination of the river flow.
This article has provided us with a basic understanding of the drainage system of India and its geographical significance. We hope that this article has helped you to prepare for your class 9 geography exam and to enhance your knowledge and interest in this subject. If you want to download the PDF version of this article, you can click on the link below.
Class 9 Geography Chapter 3 Drainage PDF Download
FAQs
Here are some frequently asked questions and their answers related to the topic of drainage:
- What is the difference between a drainage basin and a watershed?
- What are the factors that affect the formation of a drainage pattern?
- What are the advantages and disadvantages of having a large drainage basin?
- It provides more water resources for various purposes such as irrigation, hydroelectricity, navigation, etc.
- It supports more biodiversity and ecosystems such as forests, wetlands, etc.
- It offers more opportunities for tourism and recreation such as boating, fishing, etc.
- It poses more challenges for management and governance such as water sharing, pollution control, flood prevention, etc.
- It faces more threats from natural hazards such as floods, droughts, landslides, etc.
- It creates more conflicts and disputes among different regions and states over water issues.
- What are the benefits and drawbacks of having a perennial river?
- It ensures a constant supply of water throughout the year for various purposes such as drinking, agriculture, industry, etc.
- It maintains a stable ecological balance and supports more aquatic life forms such as fish, plants, etc.
- It enhances the scenic beauty and aesthetic value of the landscape.
- It requires more maintenance and regulation such as dams, barrages, canals, etc.
- It causes more environmental problems such as siltation, erosion, flooding, etc.
- It increases the water demand and consumption by various sectors such as agriculture, industry, domestic, etc.
- What are the causes and consequences of water pollution in rivers?
- Domestic sewage and waste disposal from urban and rural areas
- Industrial effluents and chemicals from factories and mines
- Agricultural runoff and pesticides from farms and fields
- Religious and cultural practices such as immersion of idols, cremation of bodies, etc.
- Accidental spills and leaks from oil tankers, pipelines, etc.
- Deterioration of water quality and quantity for human and animal consumption
- Loss of aquatic biodiversity and habitats due to toxicity and eutrophication
- Spread of waterborne diseases and infections such as cholera, typhoid, dysentery, etc.
- Reduction of aesthetic and recreational value of the river landscape
- Damage to the socio-economic and cultural aspects of the riverine communities
A drainage basin is an area of land that drains all the water to a common outlet such as a river, lake or sea. A watershed is the boundary that separates one drainage basin from another. For example, the Ganga river basin is an area of land that drains all the water to the Ganga river and its tributaries. The Himalayan range is a watershed that separates the Ganga river basin from the Indus river basin.
The factors that affect the formation of a drainage pattern are geological structure, topography, slope, climate, rainfall, vegetation and human activities. Geological structure refers to the arrangement and orientation of rocks in a region. Topography refers to the shape and elevation of the land surface. Slope refers to the angle or gradient of the land surface. Climate refers to the average weather conditions in a region. Rainfall refers to the amount and distribution of precipitation in a region. Vegetation refers to the type and density of plants in a region. Human activities refer to the interventions and modifications made by humans in a region.
The advantages of having a large drainage basin are:
The disadvantages of having a large drainage basin are:
The benefits of having a perennial river are:
The drawbacks of having a perennial river are:
The causes of water pollution in rivers are:
The consequences of water pollution in rivers are:
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