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Dr.A. Edukondal Dept of Geology Osmania University Hyderabad Telangana Geomorphic Cycles and Landscape Development.

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Presentation on theme: "Dr.A. Edukondal Dept of Geology Osmania University Hyderabad Telangana Geomorphic Cycles and Landscape Development."— Presentation transcript:

1 Dr.A. Edukondal Dept of Geology Osmania University Hyderabad Telangana Geomorphic Cycles and Landscape Development

2  Geomorphic cycle also called a geographic cycle, or cycle of erosion, theory of the evolution of landforms. American Geographer William Morris Davis (1850-1934) was the first geomorphologist who proposed the model of the cycle of erosion. William Morris Davis  Davis postulated his concept of the ‘geographical cycle’ popularly known as the ‘cycle of erosion’ in 1899 to present a genetic classification and systematic description of landforms.  He developed a model showing sequential changes in landform through time. On the lines of Charles Darwin, Davis tried to study the evolution of the landforms as an organic form passing through the stages of Youth, Maturity, and Old.

3  The initial, or youthful, stage of landform development began with an uplift that produced fold or block mountains. Upon dissection by streams, the area would reach maturity and, ultimately, would be reduced to an old-age surface called a peneplain, with an elevation near sea level. The cycle could be interrupted by uplift during any period of the life cycle and thus returned to the youthful stage; this return is called rejuvenation.  The geomorphic cycle could be applied to all landforms such as hill slopes, valleys, mountains, and river drainage systems.

4  Structure – The term structure included more than what its literal meaning. It included the manner of disposition of underlying rocks, level of hardness, porosity, folds and faults etc.  Process: It includes all types of weathering river, wind and glacial erosion, mass movements etc.  Stage : It means the time duration during which the processes operate on a structure  According to Davis three factors viz. structure, process and time play important roles in the origin and development of landforms of a particular place.

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6 Youthful stage: Erosion starts after the completion of the upliftment of the landmass. The top surfaces or the summits of the water divides are not affected by erosion because the rivers are small and widely spaced. Small rivers and short tributaries are engaged in head-ward erosion due to which they extend their lengths. T he process is called stream lengthening (increase in the lengths of the rivers). Because of steep slope and steep channel gradient rivers actively deepen their valleys through vertical erosion aided by pothole drilling and thus there is gradual increase in the depth of river valleys. This process is called valley deepening. The valleys become deep and narrow characterized by steep valley side slopes of convex plan.

7 The youthful stage is characterized by rapid rate of vertical erosion and valley deepening because :  The channel gradient is very steep,  Steep channel gradient increases the velocity and kinetic energy of the river flow,  Increased channel gradient and flow velocity increases the transporting capacity of the rivers,Headward erosion is maximum.  Increased transporting capacity of the rivers allows them to carry big boulders of high caliber (more angular boulders) which help in valley incision (valley deepening through vertical erosion) through pothole drilling.  Valleys are of V shape characterized by convex valley side slopes.  Overall valley form is gorge or canyon and Waterfalls are formed.

8  River capture or river piracy takes place in which case, one river reaches the course of another one and if the couse of the second river is diverted because of the great gradient of the earlier river, this is called river piracy.  The point where the course of the second river is diverted is known elbow of capture. The captured river is called the Misfit-river. Wind gap no water flow.

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10 YOUTHFUL STAGE  1) Drainage develops well.  2) River start erosional work.  3) Vertical erosion is more than lateral erosion leading to formation of “V” shaped valley.  4) Relief increases gradually  5)Inter flow ridges are broad in the beginning and become smaller and smaller with development of youthful stage.  6) Youthful stage ends when initial surface is totally remove.

11 B. MATURE stage : In this stage the long profiles of rivers are found to have obtained equilibrium streams and a drainage system. The power of erosion of the river is also much reduced and balance with its transporting capacity. Many erosion features are formed on the valley floor due to various geological actions. MATURITY STAGE  1) Maturity is said to have reach when relief is maximum.  2) Initial surface is totally removed.  3) In the area any part is only a part of valley slope.  4) Then with development of maturity vertical erosion stops and lateral erosion becomes more important.  5) Meanders, Ox-bow Lake and flood plain occur.  6) Lateral erosion, reduces the interflow it just further.  7) These finally lead to old stage.

12 MATURITY STAGE  1) Maturity is said to have reach when relief is maximum.  2) Initial surface is totally removed.  3) In the area any part is only a part of valley slope.  4) Then with development of maturity vertical erosion stops and lateral erosion becomes more important.  5) Meanders, Ox-bow Lake and flood plain occur.  6) Lateral erosion, reduces the interflow it just further.  7) These finally lead to old stage.

13 OLD STAGE 1) The upper uplifted area is almost removed. 2) The region becomes a vast erosional plain. 3) This is called peneplain “which means almost a plain”. 4) The region is covered with thick Alluvium. 5) Slope is very low and so drainage becomes poor. 6) Residual rock stand out and res OLD stage: In this stage the river valleys become very wide due to lateral cutting. The irregularity in the topography of the region is slowly smoothened out and the process of erosion becomes extremely slow. Depositional process is very high. The movement of river is very slow due fewer gradients and they reaches the ocean with wide mouth where extensive deposition of sediments taken place.

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15  STAGES OF RIVER For any river system it is developed from the starting point where it originate up to the end point where it reaches the ocean.  The entire journey of river can be clearly distinguished into different stages. The stages of river are mainly divided into three stages, they are A.  YOUTH or INITIAL stage : In the initial stage of river the irregularly flowing running water is concentrated within the depression to form ‘stream’. At the youth stage the flowing water is found to cause appreciable erosion of the valley and tributaries gradually developed. Many erosion features are formed along the valley side due to various geological actions.

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17 FLUVIAL CYCLE The entire journey of river starts from initial or youth stage up to old stage complete one cycle of process is called ‘Fluvial cycle’.

18 FLUVIAL CYCLE  Introduction  Stages of river  Fluvial cycle  Geological process of rivers  1. River erosion and its features  2. River transportation  3. River deposition

19 GEOLOGICAL ACTION OF RIVER The water flows in a river along its seaward course erode the land over which it flows brings about its mechanical breakdown of rocks,chemical decomposition of rocks, denudation of the country rock, transport the rock debris which are formed during process of weathering and finally deposit the transported material under favorable conditions. So the geological action of river includes various processes, they are 1.River erosion 2.River transportation 3.River deposition

20 RIVER EROSION The river erosion brought large scale changes on the surface of the earth. These changes are made by different distinct erosion processes, they are A.Hydraulic action : It is a process of mechanical breaking down of rock masses mainly due to continuous impact of water moving with great velocity along the channel is called ‘hydraulic action’. B.This process also leads to the domination of erosion process along the upper part of the river where gradient of the surface generally is very high. C.The wear and tear of the rocks due to continuous impact of running water produce large debris is dropped through discharge.

21 Deflation action of wind and hydraulic action of river are similar and more powerful processes in which kinetic energy are associated. The product of hydraulic action by river are of variable in size from large boulders to fine silt and clay and these are transported along with the flow until they drop down and settle under suitable condition. B. Cavitation : It is a distinct and rare type of hydraulic action performed by running water. It is particularly observed where river water suddenly acquires exceptionally high velocity such as at the location of a waterfall. C.Abrasion : The process of mechanical breaking down of the bed rocks due to the impact of fragments which is carried by water during their flow on the floor of the river valley.

22 This process is called ‘abrasion’. It is just similar process of wind abrasion. The effect of abrasion of river along the course in the development of ‘pot holes’ formed upon the valley floor. D. Attrition : It is the process of mechanical breaking down of the transported rock fragments due to impact among themselves has been described as ‘attrition’. The mechanical collision among fragments naturally causes further wear and tear of themselves in addition to caused by abrasion. The rolling boulders, pebbles and small fragments travelled in suspension collide with one another during their transportation. E. Corrosion : The slow but steady ‘chemical (especially solvent ) action of the stream water on the rocks is expressed by the term corrosion.

23 The extent of corrosion depends much on the composition of rocks and also on the composition of flowing water. Thus, all rocks are not equally susceptible to corrosive action of stream water. Limestone, gypsum and rock salt bodies are soluble in water to varying degrees. The stream may hardly corrode sandstone, quartzite, granites and gneisses.

24 EROSIONAL FEATURES : These are formed along the river floor due to combined effect of river erosion. The features are of different types, they are 1) POT HOLES : These are the features are formed by the effect of abrasion along the course of a river are called ‘pot holes’. They are generally cylindrical or bowl like depression of dimension ranging from a few inches to several feet. Pot holes are formed along the valley floor made up of comparatively softer rocks are boulders and pebbles of harder rock are caught up in eddies of water and allowed to have a swirling motion upon the floor of the channel

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26 2.V-SHAPED VALLEYS : Valleys are defined as a low land or depression surrounded by inclined hill slopes and mountain. The origin deepening lengthening and widening of river valleys developed due to deferential erosion processes. The V- shaped of the river valley developed in the initial stages of river. The transverse profile of the river valley is look like ‘V’ shape.

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28 3) WATER FALLS : These are defined as magnificent jumps made by stream or river water at certain specific parts of there is a sudden and considerable drop in the gradient of the channel. In a water fall the streams from a considerable height. Successive falls of smaller heights are sometimes referred as ‘rapids’ and ‘cascades’. Gently upstream sloping strata of alternate hard and soft characters are favorable for the formation of waterfalls, rapids and cascades. Ex: JOG FALLS in Gerusoppe found in Sharavathi river.

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31 MEANDERS : Rivers are flowing usually in a curved manner along during its course. This curving nature more or less Zigzag paths and the curvatures along the course are known as ‘Meanders’. These are developed mostly in the middle and lower reaches of major streams where lateral erosion and deposition along opposite banks due to different geological processes. Meanders are present initially during any river course since the running water has the tendency to follow the direction of maximum slope of the topography.

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33 OX-bow lake : Due to the excavation of pre- existing of meanders along the outer curve by the erosion resulting river takes up in the plains round-about course and during floods the running water may cut straight through a meander and follow a shorter course abandoning its previous round about track. Such abandoned meanders containing some confined water, give rise to ‘horse- shoe’ or ‘ox-bow’ lakes.

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35 RIVER TRANSPORTAION A)SUSPENSION : In the processes of transportation its velocity depends upon the gradient of the valley floor, shape and size of the channel and discharge of the river. Abrasion and attrition always work together and produce fine river particles like fine sand, silt and clay are transported to a greater distance in suspension. Suspension is one of the processes of transportation of fine rock particles for a longer distance and suspended particles are settled when the velocity checked A)B) SALTATION: In the process of saltation the particles are transported by means of series of jumps resulting in the development of smooth surface and also particles get sorted.

36 C) SOLUTION: Solution is one of the process in which readily soluble substances are dissolved in water and removed in solution and some soluble constituents are soluble in solution. Ex ; Carbonate rocks are easily dissolved and removed in solution during their course of journey in different terrain

37 RIVER DEPOSITION As soon as the velocity of running water decreases, its transporting capacity decreases. As a result of its load is dropped down. The larger particles are deposited its enroot and the lighter and smaller particles are transported in suspension and saltation to a very great distance, in keeping with the gradual fall of the power of transportation of the river along its seaward course. The deposition along the course of a river known as ‘fluvial deposits’. There are different types of fluvial deposits in which alluvial fans and delta deposits are important.

38 ALLUVIAL FANS : The rock fragments of the size of boulders and pebbles transported due to velocity of the river is considerable. Such accumulation of boulders and pebbles at the point where running water enters into the plains is known as ‘alluvial fans’. The name alluvial fans are so because the rock fragments are arranged in a ‘radiating fan like pattern’. The term ‘alluvial fan’ is used when the slope of the deposit is below 10° and ‘alluvial cone’ when the slope is in the range of 10°-50°.

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40 DELTAS Delta: Deltas are defined as alluvial deposits of roughly triangular shape that are deposited by major rivers at their mouths i.e. where they enter sea. The term Delta was first used by Herodotus, about 2500 years ago, for the delta ( △ ) shaped deposit of the river Nile (in Egypt) at its entry into the Mediterranean Sea. Structures : Deltas are quite complex in their structures because of their formation, evolution and modification with passage of time. A typical simple delta is commonly made of three layers of which only the top layer may be sub aerial i. e. exposed on the surface

41 1.The bottom-set beds which form the base of the delta and are characterized by a gentle seaward inclination. These are generally made up of fine-sized particles. 2.The fore-set beds intermediate layers and often show very steep inclination. The fore set are made up of thick layers of sand and clay. 3.The top-set beds are relatively thin layers also showing gentle slopes over the fore set beds. These are laid down on the fore set beds again and again during subsequent flooding.

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46 Drainage Pattern:  The flow of water through well-defined channels is known as ‘drainage’ and the network of such channels is called a ‘drainage system’.  Natural or artificial action of draining something or removal of surface or subsurface water remove from an area.  The typical shape of a river course as it completes its erosional cycle is referred to as the Drainage Pattern of a stream.  The drainage systems mainly depend upon the geological structure of the region and the resistance of the erosion capacity of the rock to erosion

47 Drainage patterns are controlled by following factors: 1) Initial slope. 2) Lithology and lithological variation. 3) Structures. 4) Geologic and geomorphic history of the area. 5) Climate and rainfall of the area.

48 Degree of Uniformity It is relatively homogeneity of pattern over an area. it indicates the boundaries between the area of different characteristics and uniformity of erosional history and the behavior of the material of erosion. Orientation It refers to direction and indicates the control and effects due to the presence of geological factors like structural features and tectonic movements etc. Degree of control It is the most important feature in geological interpretation. The streams are shaped by the tectonic features like folding, faulting, fracturing etc. The tectonism products anomalies directional changes and adjustment which are useful in tectonic analysis of a terrain.

49 Angularity It is abruptness of directional change furnished by the component streams of a drainage pattern. These serve as guides for revealing the hidden features like fractures, faults, shear zones and other features including underground structures. Angle of Junction Normally we find an acute angle in the upstream direction between stream and its tributary. It is a function of the channel slopes of two streams.

50 The flow of water through well-defined channels is known as ‘drainage’ and the network of such channels is called a ‘drainage system’.  The Drainage System of India  Classification of Drainage Systems in India  On the basis of discharge of water – the Arabian Sea drainage, the Bay of Bengal drainage and inland drainage.  On the basis of the size of the watershed – Major, Medium and minor  On the basis of the mode of origin, nature and characteristics– the Himalayan drainage and the Peninsular drainage.

51 The Himalayan drainage  Evolution  Major River systems The Peninsular drainage  Evolution  Major river systems Differences between the Himalayan and Peninsular river systems The shifting courses of rivers.

52 Before we study India’s Drainage system, it is imperative that we understandthe basic terminology associated with a river and its drainage.

53 Drainage system Before we start with the drainage system of India, let’s look at the broad framework along which we will proceed. Basic Terminology Source of a river  Confluence  Tributary  Distributary  Mouth of a river  River basin, catchment area and watershed  River Rejuvenation  River Regime and River Discharge

54 Some basic terms: Source of a river: The beginning or start of a river. Confluence: The point at which two rivers or streams join. Distributary: The small river that branches out from the main river and thennever meets again. It thus decreases the river’s water volume. Distributariesare commonly found on deltas but are also important in the formation ofalluvial fans and cones. Tributary: A stream or smaller river which joins a larger stream or river and thus increases its water volume. Mouth: The point where the river comes to the end, usually when entering a sea. Determination of left/right bank of a river: Stand facing the mouth of the river in the direction of its course. Your left hand side will be the left bank and your right hand side, the right bank.

55 A drainage basin is a portion of the Earth's surface that contains a main stream and its tributaries or the area from which the water flows to form a stream. All of the precipitation (rain or snow) that falls within a drainage basin eventually flows into its stream, unless some of that water is able to cross into an adjacent drainage basin via groundwater flow. Drainage divide- a ridge or strip of high ground dividing one drainage basin from another. It determines into which basin precipitation flows. The upland between tributaries is called interfluves. Perennial streams- permanent streams that flow all year. Intermittent stream : a stream that carries water only part of the year.

56 River basin, catchment area and watershed Generally, the area drained by a river and its tributaries is called its river basin or catchment area or a watershed. But, there are subtle differences between them. River Basin: All the area drained by a river and its tributaries. Catchment area: It refers to all the area of land over which rain falls and is caught to serve a river basin. The catchment area of large rivers or river system is called a river basin while those of small rivers, a lake, a tank is often referred to as a watershed. Watersheds are small in area, generally less than 1000 ha. There are many smaller watersheds within a river basin. Example: watershed of Yamuna + water shed of Chambal + watershed of Gandak + …. = Drainagebasin of Ganga.

57 A drainage basin is all the land that supplies a river and its tributaries with water. If you could look down on a river from above, you would see that it branches. This is called a drainage pattern. The amount of water in the stream increases steadily as more streams, called tributaries, join it. Eventually the stream becomes big enough to be a river. Topographically high areas called divides separate drainage basins from adjoining ones.

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59 Stream Order  As with drainage density, this allows for quantitative study of drainage basins and therefore comparison between different basins.  When a first order stream meets another first order stream, the resulting flow is a second order stream. The second order stream picks up additional first order streams, but remains second order. Only when two second order streams meet is the result a third order stream.  Streams of different order may join together for example a second and third order stream. The order given is that of the highest order stream. An entire drainage basin is named after the highest order stream found within it, for example, a fourth order drainage basi n  First order streams: original, single source tributaries.  Second-order streams: the joining of two first order streams.  Third order streams: the merging of two-second order streams.

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64  The study of drainage network and its characteristics of a particular region can be classified in two ways namely  Descriptive approach and Genetic approach.  The descriptive approach includes the characteristics study of the stream forms and its pattern of a specific region.  whereas the genetic approach comprises the evolution process of stream based on tectonics, lithologies, structure and topography of a region.  Therefore, drainage system means the origin and development of surface runoff (streams) through time and drainage pattern defines the different pattern of arrangement form by drainage system in terms of geometrical shapes in the areas. Drainage pattern are strongly influenced by the rocks types, geological structure, climatic conditions and denudational history.  Generally, the evolution of drainage system of an area is controlled by nature of initial surface and slope and geological structure.

65  Streams and drainage system are classified into two classes based on in initial slope and geological set up. 1.Sequent stream(Concordant): : The stream flow along the natural slope and geological fault such as i) Consequent stream, ii) Subsequent stream, iii) Obsequent stream iv) Resequent stream. 2. Insequent stream(Discordant): The stream that do not flow along the natural slope and drain over the geological structure such as i) Antecedent stream ii) Superimposed stream.

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68 ANTECEDENT STREAM

69 Examples: Many Himalayan rivers are good examples of antecedent origin. These rivers originated well before the Himalayan region was uplifted.Himalayan The rivers Indus, Brahmaputra, Sutlej, Kosi and Subansiri originated on the Tibetan side and now traverse the existing mountain ranges, cutting deep gorges.IndusBrahmaputraSutlejKosiSubansirigorges

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71 Superimposed Drainage A stream formed on one surface and structure has science cut down through unconformity to flow over older rocks, which have structure discordant with that above the unconformity. Such a stream is then said to be superimposed on older rocks.

72 SUPERPOSED

73  Consequent stream-  The early stage of stream development and its courses in accordance with initial slope and geological fold is known as consequent stream.  The consequent stream which follows the natural landscape slope is called a dip stream while the stream developed along the folded structure formed the master consequent stream also called a synclinal consequent stream.  The master consequent is the main stream of the drainage system of a particular consequent stream of a region.  Domes and volcanic cones are the favorable topography for the formation of consequent drainage system.  The drainage system of the Indian coastal plains is the best example of consequent stream. Godavari, Krishna and Kaveri, descending from the Western Ghats and flowing into the Bay of Bengal, are some of the consequent rivers of Peninsular India.

74 There are two types of consequent stream: i) Longitudinal consequent- Stream which follow along the syncline or depression axis in a geological folded structure. ii) Lateral consequent- stream which follow from the lateral sides to join the depression axis. Thus the lateral consequent stream normally joins at almost right angle to longitudinal consequent stream.

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76  Subsequent stream- The stream drained from the anticlines or ridges axis which developed after master consequent stream and joined the mainstream is called subsequent stream.  A stream that has developed on a weak substructure, such as a clay or in regional joint or fault pattern, at right angles to streams consequent to the dip of the slope.  Generally, it defines as the transverse stream to the master consequent. For example, the Asan river and Song river are the subsequent stream which also a tributary of the Yamuna and Ganga river are again the master consequent stream. The Chambal, Sind, Ken, Betwa, Tons and Son meet the Yamuna and the Ganga at right angles.

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78 Obsequent stream  A stream that flows in the opposite direction to a consequent stream, often against the direction of dip.  The stream drained along the slope of landscape, thus, Obsequent stream is also type of consequent.  The stream developed from the northern slopes of the Himalayas ranges of east west direction flow northward to join the tributary drain east west direction (subsequent stream) of the southward flowing master consequent stream.  For example, numerous stream originating from the Siwalik ranges flow northward due northern slopes and meet east west subsequent stream of the southward flowing master consequent of the Ganga and Yamuna river. Thus, the tributaries flowing northward from the Siwalik ranges are the Obsequent stream.

79  Resequent stream- The stream (tributary) which lately developed and drained in the parallel direction to the master consequent is referred as requesent stream. Since, the stream is of recent evolution as compared with master stream, thus called requesent.  The resequent stream is originated from folded geological structure during the starting of second cycle of erosion.  The anticlinal ridges and synclinal valleys are converted into anticlinal valleys and synclinal ridges in due time during the first cycle of erosion in folded mountains. Thus, the longitudinal stream initiated by the end of first cycle of erosion in the anticlinal valleys and the development of new valleys in the syncline with the beginning of second cycle of erosion. Later, the stream originated in the synclinal area that flow parallel to the original longitudinal consequent form at the first cycle of erosion become resequent stream.

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85 DRAINAGE PATTERN  The drainage pattern defines the geometrical shapes of the stream system and the spatial array of stream in a specific area or region.  The drainage pattern of a particular area is not identical with to another region which relatively depends on nature of slope, lithological and structural factors, vegetative area and environmental conditions. Generally, there are different types of drainage pattern namely, 11Dendritic pattern,. 2-Trellised pattern, 3. rectangular pattern, 4. centrifugal or radial pattern, 5. centripetal pattern, 6. annular pattern, 7. barded pattern, 8. pinnate pattern 9.parallel pattern and 10.herringbone pattern.

86 Dendritic Drainage (dendritic comes from the Latin word"dendron", meaning tree )  This stream pattern is far most commonly developed in the area where the unconsolidated rock formation can be easily eroded in tree-shaped structure.  Such dendritic pattern is independent of structural and lithological controls but associated with homogenous lithology, slope and permeability of rock is the most ideal condition for the development of stream. Moreover, the stream network is more extensive in such land surface having flat surface, gentle slopes and permeable rocks.  This pattern develops in different structural and lithological environments such as in the mountains (Himalayas), plateau (Deccan plateau), peneplain surface (Indian Peninsular), alluvium plain (North Indian Plain), desert plain (the Rajasthan Plain ).

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91 Parallel drainage pattern  It is characterized by numerous stream flowing along the regional slope and parallel to each other.  Such type of drainage pattern is commonly occurred in continuous uniform slope and sinking rock beds like newly emerged coastal plains.  The stream originated from the ridges of Western Ghat drained along the slope and maintained their water course towards west to feeds the Arabian Sea.  Similarly, the eastern coastal plains of India also formed parallel drainage network.

92 Parallel drainage pattern

93 Trellis Drainage Pattern  It is formed by the array of tributaries lateral stream and major consequent stream flowing the natural land slope and well adjusted to the geological structures.  Such drainage pattern is originated in the region having alternated parallel valleys (synclinal) and ridges (anticlinal).  Numerous master consequent longitudinal streams is developed in the elongated synclinal valley whereas lateral stream originated from both side of the ridges and join at almost right angle to master consequent stream.  Hence, the stream arrangement form by the combination of consequent longitudinal stream and lateral consequent stream is called trellised pattern.  The main difference between trellis and rectangular pattern based on the stream space between them. In the trellis pattern, the stream gaps are closed whereas rectangular pattern is formed by the wide gaps of stream.

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95  It is normally originated in the land surface where numerous surface runoff (rills) along weathered and eroded rocks along the interfaces of joints, faults and fractures form rectangular pattern. Rectangular Drainage Pattern  These small rills increase the width and length with passage of time become channels which drained at the lines of faults.  Thus, the tributaries stream strike the master stream almost at right angles, thus formed the rectangular drainage pattern.  Both rectangular and trellis pattern have certain similar properties showing each tributary stream connect their master stream at right angle.  But the difference between them is defined by the confluence angle is guided by strikes and dip angles of the bed rocks and narrow space tributary in trellis pattern while rectangular pattern have the confluence angle is determined by the weak faults lines and wide streams gaps. E.g. Streams found in the Vindhya mountain range; Chambal, Betwa and Ken. Folding and Faulting

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97 Radial Drainage Pattern  Stream which divert away water tributary from central high point to various directions along the natural gentle slope of landmass is called radial pattern.  Such stream also known as centrifugal pattern.  The favorable land structure for the evolution of radial pattern are dome structure, volcanic cones, batholiths and laccoliths, residual hills and isolated uplands respectively. . The rivers originating from the Amarkantak range; Narmada and Son (tributary of Ganga). the upland area of Ranchi city.

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99  Another name of centripetal pattern is known as inland pattern which is opposite to the radial pattern. Centripetal pattern  Inland drainage pattern is developed in the low lying or cone of depression area where numerous streams converge or direct towards at a particular region forming water accumulating zone or a basin.  A series of stream that originated from surrounding elevated land surface come together at a specific low central area which may be a basin or carter lake.  The central low lying area at the top of Riagarh Dome in the lower Chambal basin is the example of centripetal drainage pattern.  During wetter portions of the year, these streams feed ephemeral lakes, which evaporate away during dry periods.  E.g. Loktak lake in Manipur

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101 Radial Drainage Centripetal

102  Barbed pattern It is rare kind of stream pattern generally formed due to river capture. Barbed pattern is developed when the tributaries flow in opposite direction and join the master stream in hook-shaped bend.  Most barbed drainage patterns are the result of river-capture which reverses the direction of flow. However, the tributary channels continue to flow in their original direction.  The A run River (Nepal), a tributary of the Kosi is an interesting example of barbed drainage pattern.  when a stream or river drainage system or watershed is diverted from its own bed, and flows instead down the bed of a neighboring stream.

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104 Annular pattern  Annular pattern represents that part of a drainage pattern in which the subsequent streams follow the curving or arcuate courses before joining the consequent stream  The other term of annular pattern is known as circular pattern. Such pattern is appeared in the area characterized by a mature and dissected dome mountain having parallel and alternate group of soft and hard rock beds.  The different rate of erosion of soft and hard rocks produce ringed structure with resistant hard rock strike outward and less resistant soft rock form circular fissure.  The master consequent stream develop at the dome diverse down the slope like radial drainage pattern and the tributary streams develop by the soft bed erosion have arcuate shape finally meet again the master consequent stream, thus formed the annular drainage pattern.  An example of annular drainage pattern is the dissected Sonapet dome of Uttaranchal. Pithoragarh (Uttarakhand), Nilgiri Hills in Tamil Nadu and Kerala

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106  Pinnate pattern :Pinnate stream similar the feature of leaf veins.  Such pattern is formed when master stream is developed at the narrow valley and their tributaries from the steep sides of parallel ridges meets the longitudinal main stream at acute angle.  The upper Son and Narmada river network represent pinnate drainage pattern.

107  Herringbone pattern :The term herringbone is derived from the bone pattern of herring fish. Such drainage pattern is known as rib pattern.  It is developed in the board valley mountainous area which is flanked by steep slopes of parallel ridges.  The master stream occupies the longitudinal valley and the lateral consequent tributaries develop from the parallel ridges join the longitudinal consequent stream almost at right angle.  The upper Jhelum river in the Kashmir Vale feeds by numerous tributaries from the both sides is an example of herringbone drainage pattern.

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