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  1. 1. Drainage
  2. 2. The term Drainage describes the river system of an area. The area drained by a single river system is called a drainage basin. Any elevated area, such as a mountain or an upland which separates two drainage basins, is known as a water divide.
  3. 3. A drainage system is the pattern formed by the streams, rivers, and lakes in a particular drainage basin. They are governed by the topography of the land, whether a particular region is dominated by hard or soft rocks, and the gradient of the land. Dendritic drainage systems are the most common form of drainage system. In a dendritic system, there are many contributing streams (analogous to the twigs of a tree), which are then joined together into the tributaries of the main river (the branches and the trunk of the tree, respectively). They develop where the river channel follows the slope of the terrain. The geometry of a trellis drainage system is similar to that of a common garden trellis used to grow vines. As the river flows along a strike valley, smaller tributaries feed into it from the steep slopes on the sides of mountains. These tributaries enter the main river at approximately 90 degree angles, causing a trellis-like appearance of the drainage system. Trellis drainage is characteristic of folded mountains. Rectangular drainage develops on rocks that are of approximately uniform resistance to erosion, but which have two directions of jointing at approximately right angles. The joints are usually less resistant to erosion than the bulk rock so erosion tends to preferentially open the joints and streams eventually develop along the joints. The result is a stream system in which streams consist mainly of straight line segments with right angle bends and tributaries join larger streams at right angles. In a Radial drainage system, the streams radiate outwards from a central high point. Volcanos usually display excellent radial drainage. Other geological features on which radial drainage commonly develops are domes and laccoliths. On these features the drainage may exhibit a combination of radial and annular patterns.
  4. 4. Himalayan Rivers Nature of flow – Himalayan rivers are Perennial as receive water from rainfall as well as snow melting. Catchment area - Very large basins Erosion - Deep valleys and gorges in the Himalaya due to intensive erosion Nature of the course - Meandering course and shifting beds in the Great plains Other features - V-shaped valleys, high waterfalls and huge delta. Penisular Rivers Nature of flow - Seasonal dependent on rainfall alone Catchment area – have shorter and shallower courses as compared to Himalayan rivers Erosion - Shallow graded valleys with little erosion Nature of the course - Straight and linear course. Other features - Shallow valleys, small waterfalls, delta and estuaries
  5. 5. The Indus River System – Rises in Tibet , near Lake Mansarowar, enters India in the Ladakh district of Jammu and Kashmir. Tributaries in Kashmir are Zaskar, Nubra, Shyok and Hunza. Flows through Baltistan and Gilgit, emerges from the mountains at Attock. Satluj, Beas, Ravi, Chenab and Jhelum join together to enter the Indus near Mithnakot in Pakistan, eventually reaches Arabian sea, east of Karachi. Total length 2900 km. one of the longest rivers of the world. Drainage basin covers, states of Jammu and Kashmir, Himachal Pradesh, Punjab and the rest is in Pakistan.
  6. 6. The Ganga River System – Bhagirathi is joined by Alaknanda at Devprayag in Uttranchal to form Ganga. At Haridwar the Ganga emerges from the mountains on to the plains. Tributaries from the Himalayas – Yamuna, Ghaghara, Gandak and Kosi Himalaya. Chambal, Betwa and Son come from the Peninsular uplands. The Ganga flows eastwards till Farakka in West Bengal. This is the northernmost point of the Ganga delta. The river bifurcates here : Bhagirathi-Hooghly flows southwards. Mainstream flows southwards into Bangladesh and is joined by the Brahmaputra. Here it is knows as Meghna, finally flows into the Bay of Bengal before forming the Sunderban delta. Length of Ganga is 2500 km. The plains from Ambala to Sunderbans is nearly 1800 km but the fall in the slope is hardly 300 metres, resulting in large meanders.
  7. 7. The Brahmaputra River System – Rises in Tiber east of Mansarowar lake, flows eastwards parallel to the Himalayas, reaching Namcha Barwa (7757 m), it takes a ‘U’ turn and enters India in ArunachalPradesh. Is called Dihang, joined by Dibang, Lohit, Kenula and many other tributaries to form the Brahmaputra in Assam. In India it passes through a region of high rainfall, carries a large volume of water and considerable amount of silt, has a braided channel, forms many riverine islands. During the rainy season, the river overflows its banks, causing widespread devastation due to floods in Assam and Bangladesh.
  8. 8. An estuary is a partly enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and ocean environments and are subject to both marine influences, such as tides, waves, and the influx of saline water; and riverine influences, such as flows of fresh water and sediment. The inflows of both sea water and fresh water provide high levels of nutrients in both the water column and sediment, making estuaries among the most productive natural habitats in the world A river delta is a landform that is formed at the mouth of a river, where the river flows into an ocean, sea, estuary, lake, or reservoir. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river. Over long periods of time, this deposition builds the characteristic geographic pattern of a river delta.
  9. 9. The Peninsular River – The main water divide in Peninsular India is formed by the Western Ghats. West flowing river Narmada and Tapi are the west flowing rivers of peninsular India These rivers make estuaries at their mouth These rivers drain into Arabian sea East flowing river Mahanadi, Godavari, Krishna and Kaveri are the east flowing rivers of peninsular India These rivers make deltas at their mouth These rivers drain into Bay of Bengal Drainage basins are comparatively small in size
  10. 10. The Narmada Basin – Rises in the Amarkantak hills in Madhya Pradesh, flows west in a rift valley, creates many picturesque locations. ‘Marble rocks’, near Jabalpur and the ‘Dhuadhar falls’ are some of the notable ones. Narmada basin covers parts of Madhya Pradesh and Gujarat.
  11. 11. The Tapi Basin – Rises in the Satpura ranges, in the Betul district of Madhya Pradesh. Flows in a rift valley parallel to the Narmada, but it is much shorter in length. Basin covers parts of Madhya Prdesh, Gujarat and Maharashtra.
  12. 12. The Godavari Basin – Largest Peninsular river, rises from the slopes of the Western Ghats in the Nashik district of Maharashtra. Length about 1500 km, drains into the Bay of Bengal, largest drainage basin amongst peninsular river, covers parts of Maharashtra, Madhya Pradesh, Orissa and Andhra Pradesh. Tributaries – Purna, Wardha, Pranhita, Manjra, Wainganga and the Painganga. Becouse of its length and area it covers, is also known as ‘Dakshin Ganga’.
  13. 13. The Mahanadi Basin – Rises in the highlands of Chattisgarh Flows through Orissa to reach Bay of Bengal, length about 860 km. Drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand and Orissa.
  14. 14. The Krishna Basin – Rises from a spring near Mahabaleshwar, flows for about 1400 km, reaches the Bay of Bengal. Tributaries – Tungabhadra, Koyana, Ghatprabha, Musi and the Bhima Drainage basin is shared by Maharashtra, Karnataka and Andhra Pradesh.
  15. 15. The Kaveri Basin – Rises in the Brahmagri range of the Western Ghats, reaches the Bay of Bengal in south of Cuddalore, in Tamil Nadu. Total length is about 760 km, drrains parts of Karnataka, Kerala and Tamil Nadu. Tributaries are Amravati, Bhavani, Hemavati and Kabini.
  16. 16. Lakes Lakes differ from each other in size and characterstics. Most lakes are permanent, some contain water only during the rainy season, some of the lakes are the result of the action of glaciers and ice sheets, some are formed by wind, river action and human activities. Meandering river forms cut-offs that later develop into ox-bow lakes. Spits and bars from lagoons in the coastal areas, e.g. the Chilika Lake, the Puliket lake, the Kolleru Lake. Lakes in the region of inland drainage are sometimes seasonal, the Sambhar lake in Rajasthan is a salt water lake.
  17. 17. Most of the fresh water lakes are in the Himalayan region. They are of glacial origin. The Wular lake (the largest freshwater lake in India) in Jammu and Kashmir is the result of tectonic activity. Dal Lake, Bhimtal, Nainital, Loktak and Barapani are some other important fresh water lakes. The damming of the rivers for the generation of hydel power has also led to the formation of Lakes such as Guru Gobind Sagar (Bhakra Nangal Project).
  18. 18. Importance of Lakes – Helps to regulate the flow of a river, prevents flooding during heavy rainfall and during the dry season helps to maintain even flow of water, can be used for developing hydel power, moderate the climate of the surroundings, maintain the aquatic ecosystem, enhance natural beauty, helps develop tourism and provide recreation. Role of Rivers in the Economy Water from the rivers is a basic natural resource The river banks have attracted settlers from ancient times, many have developed as big cities Using rivers for irrigation, navigation, hydro-power generation is of special significance
  19. 19. River Pollution The growing domestic, municipal, industrial and agricultural demand for water from rivers naturally affects the quality of water. As a result, more and more water is being drained out of the rivers reducing their volume. On the other hand, a heavy load of untreated sewage and industrial effluents are emptied into the rivers. This affects not only the quality of water but also the self-cleansing capacity of the river. But the increasing urbanization and industrialization do not allow it to happen and the pollution level of many rivers has been rising. Concern over rising pollution in our rivers led to the launching of various action plans to clean the rivers.