Indian Geography > Physical Setting > Flashcards
Physical Setting Flashcards
Passes of J&K- northern boundary
- Mintaka pass 2. Parpik pass 3. Khunerjab pass 4. Aghil pass 5. Qara tag la 6. Yangi Dawan
Passes of J&K- NE boundary
1.Qara tag la 2. Yangi dawan pass
Passes of j&K- Aksai chin
- lanak la 2. Kepsang la 3. Chang la 4. Jara la 5. Imis la
Passes of j&K - within (W—> E)
1.Pir Panjal 2. banihal pass 3. Zoji La 4. Saser La 5. pensi La 6. Tasak la 7. Khardung la
Mintaka pass
- trijunction 2. North Kashmir with China
Parpik pass and Khunerjab pass
Indo-China Border
Aghil pass
- North of K2 2. at a height of 5000m 3. connects Ladakh with Sinkiang province 4. snow covered during winter
Banihal pass
across Pir-panjal range jawahar Tunnel for all year transport facility between Jammu and Srinagar another tunnel in 2013 for railway between jammu nd Baramulla snow covered during winter
Chang La pass?
- Indo-China border 2. 5300 m 3. joind Ladakh to Tibet 4. Steep road 5. Chang la baba temple 6. snow covered during winter
Khardung la pass?
- near Leh 2. 5600m 3. world’s highest motorable road 4. snow covered during winter
lanak La pass?
- 5000m+ 2. Ladakh with Lhasa 3. road constructed by China
Pir Panjal pass?
- across Pir panjal range 2. Mughal Road 3. shortest nd easiest metalled road between Jammu nd Kashmir valley 4. closed down due to partition
Qara tag La pass?
- Indo-China border 2. across karakoram range 3. 6000m+ 4. offshoot of great silk route 5. snow covered during winter
Imis La pass?
- Ladakh with Tibet 2. difficult terrain and steep slopes 3. snow covered during winter
Zoji la pass?
- 3800m 2. Srinagar with Kargil nd Leh 3. NH-1D: BRO 4.snow covered during winter
pensi la pass?
- East of Zoji La pass 2. Kahmir valley with Kargil
Passes in Himachal Pradesh
- Bara Lacha La 2. Debsa pass 3. Rohtang pass 4. Shipki La
bara Lacha La
- HP(mandi) with J&K(Leh): NH 2. snow covered during winter
Debsa pass
- 5000m+ 2. in Greater Himalayas 3. Kullu with Lahul with Spiti 4. better alternative to Pin Parbati pass between Kullu and Spiti
Rohtang pass
- 4000m 2. kullu with Lahul with Spiti 3. BRO 4. tourism- traffic jams
shipki La
- Indo-China border 2. 5600m 3. HP with Tibet— Hindustan-Tibet road 4. River Sutlej enters near this pass 5. snow covered during winter
Passes of UK
- Lipku Lekh 2. Mana pass 3. Mangsha Dhura 4. niti pass 5. Muling La
Lipu Lekh
- trijunction-UK, Tibet nd Nepal 2. Pithoragarh district 3. used in Kailash-mansarovar yatra 4. landslides avalanches
Mana pass
- little north of badrinath 2. UK with China 3. snow covered during winter
passes in UK used for Kailsh Mansarovar Yatra
Mangsha Dhura Lipu Lekh
Passes in Sikkim
- nathu La 2. Jelep La
nathu La
- Sikkim with Tibet 2. offshoot of ancient silk route 3. closed in 1962, reopened in 2006
Jelep La
- Sikkim-Bhutan border 2. Chumbi valley 3. important trade route connecting Darjeeling with Lhasa
passes of Arunachal
Arunachal with Tibet 1. Bom Di La 2. Yonggyap pass Arunachal with Myanmar 1. Dihang Pass 2. Diphu pass 3. Kumjawng pass 4. hpungan pass 5. Chaukan pass
__________ is an important land trade route between India and Myanmar and remains open throughout the yr.
Diphu pass
Evidence to prove that Himalayas are still rising?
- similar fossils in Shiwaliks and tibet 2. Dessication of lakes of Tibet 3. frequent EQ 4. young and rejuvenated himalayan rivers
proponents of Plate tectonic origin theory of himalayas?
Harry hess R.S. dietz W.J. Morgan Le Pichon
Chief characterestic features of Shiwaliks
- Flat scarps 2. Anticlinal crests 3. Synclinal valleys 4. width: 50km in HP and <15 km in AP 5. almost unbroken except by Tista river valley 6. altitude: 600m to 1500 m
Extent of Shiwaliks
2400km from Potwar plateau to brahmputra valley
different names of Shiwaliks?
->Jammu hill (jammu) ->Dafla, Miri, Abor and Mishmi hills (AP) >Dhang ra., Dudhwa ra. (UK) ->Churiaghat hills (Nepal)
Duns are found between?
Middle HM and Shiwaliks
examples of Duns?
DehraDun, Kotah, Patli Kothri, Chumbi, Kyarda and chaukhamba Jammu hills- Udhampur nd Kotli
What are Chos?
seasonal streams that dissect shiwaliks in Punjab and HP
T/F: Eastern part of Shiwaliks upto Nepal are covered with thick forest and thereafter they become thin
t
What are Lower Himalayas?
Middle Himalayas
Dimensions of Middle hima?
elevations: 3500 to 4500m 60-80km wide
T/F: All three parallel ranges of Himalayas have typical Hogback look.
True
Middle himalayas
- Dimensions 2. ‘typical’ hogback look 3. peaks >5000m 4.important ranges
names of Ranges of MH?
Pir Panjal Dhaula Dhar Mussorie Nag Tiba Mahabharat Lekh
Pir Panjal range?
- Longest nd M Imp range of MH 2. Jhelum to upper Beas 3. Kashmir vally 4.volcanic rocks 5. passes 6. Kishenganga, Jhelum and chenab cut through
Passes of Pir Panjal range?
- Pir Panjal pass 2. Bidil pass 3. Golabghar pass 4. banihal pass- Jammu-Srinagar HW and Jammu Baramulla railway
Kahmir valley- origin?
-> Wadia: synclinal basin -> de terra : recently depressed intermont basin -> general belief: lake in Pleistocene- sediment- uplifted
Dhaula dhar range?
- Pir panjal SE of Ravi 2. Dalhousie, Dharmshala and Shimla 3. southernmost 4. rarely>4000m
Kangra valley?
- HP 2. strike valley 3. foot of Dhaula Dhar to south of Beas
Kulu valley?
- in upper course of Ravi 2. transverse valley
Mussorie range?
- avg elevation: 2000-2600m 2. Mussorie to Lansdowne 3. Mussorie, nainital, Chakarta and Ranikhet
nag Tiba range?
abode of snakes
Mahabharat Lekh?
- southern nepal 2. continuation of Mussorie range 3. kathmandu valley to its north
hill stations in MH?
Shimla, Mussorie, Ranikhet, nainital, Almora and darjeeling
T/F: MH are also known as central Himalayas.
F GH are known as Central Himalayas
other names of GH?
Inner Himalayas Central —-“——– himadri
GH: dimensions? extent?
- avg elevation: 6100 m 2. avg width: 25 km 3. nanga parbat to Namcha Barwa
T/F: GH are most continuous mt. range of the world bar none.
T
rocks of GH?
crystalline (granite and gneiss) overlain by metamorphosed rocks
Mt. Everest?
Sagarmatha chomlungma peak XV——-> 1865 Qing dynasty in 1717
important peaks of GH in descending order of altitude?
Everest, Kunchenjunga, Lhotse, Makalu, Dhaulagiri, Manaslu, Cho Oyu, Nanga Parbat, Annapurna, Gosainthan /Shisha Pangma Nanda devi, Kamet, Namcha Barwa, Gurla Mandhata, Trisul, Badri Nath
important passes in GH?
J&K: Burzil pass, Zoji la HP: ThagaLa, Niti pass, Lipu Lekh pass Sikkim: Nathu la and Jelep La
what are Tibetan Himalayas?
Trans Himalayas
main ranges of TH?
- Zaskar 2. ladakh 3. Kailas 4. karakoram
TH: dimensions?
1000km length; avg elevation: 3000m; width: 40 km on ends and 225km in centre
Zaskar range?
-> 80 deg East -> nanga Parbat -> Deosai mt
Ladakh range?
- north of Zaskar and parallel to it 2. rakaposhi-haramosh ranges, beyond indus
Kailas range?
-> offshoot of ladakh range -> Mt. Kailas: highest peak -> River Indus originates
Karakoram range?
- northernmost of TH in India 2. aka Krishnagiri range 3. India-Afghanistan-china 4. watershed bn India and turkmenistan 5. great glaciers 6. K2- 8611m- aka Mt. Godwin austen/Qogir
important peaks of Karakoram range?
K2 Gasherbrum I (aka hidden peak) Broad peak Gasherbrum II
ladakh plateau?
-> NE of karakoram -> highest plateau of india ->dissected
ladakh dissected in to plains?
Soda plains Aksai chin Lingzi Tang depsang plains Chang chenmo
T/F: Krishnagiri range is entirely located in HP and UK.
False—–aka Karakoram
In east, himalays take a sudden southward turn at ?
Dihang gorge
Extent of Purvanchal? main feature?
- AP to Mizoram 2. softer rocks like sandstones and slate 3. height significantly less (2000-3000m) 4. height decreases N—> S
differnt names of hills and ranges of Purvanchal?
- Patkai Bum— AP and Myanmar 2. naga hills 3. Kohima hills 4. Manipur hills 5. barail range 6. Mizo hills (aka Lushai hills)
Highest peak of naga hills?
Saramati
watershed between india and Myanmar formed by?
Patkai Bum and Naga hills
____________ separates naga and Manipur hills.
barail range
barail range?
separates Naga and Manipur hills goes SW to Jaintia, Khasi and garo
highest point of Manipur hills
Blue mt.
Discuss evidences related to recent and ongoing process of Himalayan upliftment.: intro?
diastrophic movements which…late Cretaceous…with separation of India frm Gondwanaland…continued through eocene,Pliocene, upper Pleistocene and even today.
Discuss evidences related to recent and ongoing process of Himalayan upliftment.: body?
- Fossil evidences in shiwaliks: (i)Pleistocene swamp lifeforms eg. Pre-historic hippo and rhino in Nahan, Sirmor district (HP) ..proves…once at swamp levels…uplifted nw (ii) similar fossils at Tibet and shiwaliks…plateau has risen since then 2) Dessication of Tibetan Lakes: dried lakes in Tibetan region hv stones,gravels at higher elevations(60-100m higher than present sea level)…signifies upliftment of the region. 3) Evidences related to tectonic: (i) frequent EQ: zone IV and V (ii) Geothermal activity in manikarn, HP, Puga valley (iii) eveidences of volcanism in Kashmir valley : Lipa valley having steam eruptions 4) Remote sensing and gelogical studies: Indian plate is still moving @ 5cm/yr. avg height of HImalayas has increased frm 2440m to present 3050m. 5) rejuvenation of Himalayan rivers
Discuss evidences related to recent and ongoing process of Himalayan upliftment.:conclusion?
ongoing upliftment…associated with seismic hazard…Northern India in Seismic zone V… but also avenues of Geothermal energy.
Himalayas: Intro?
-> aka HImadri, Himavan or Himachal ->youngest and loftiest -> central axial range alone stretches over 2400km (over 22deg Longitude), frm Indus Gorge to Brahmputra Gorge. -> Width varies frm 500 kn in Kashmir to 200km in AP -> Total area is nearly 5Lkm2 -> connected to high ranges of Central Asia by Pamir knot, roof of the world -> extend eastward in an arcuate curve, convex to the south. -> southern bouandary well defined by 300 m countour line bt northern boundary is rather obscure and merges with edge of Tibet plateau. -> 14 peaks higher than 8000m
Discuss the origin of Himalayas. (self answered)
Several scholars… OHK Spate, DN Wadia, MS Krishnan, S Burrard, de Terra, TT Patterson etc.
Lakshdweep islands?
Lakshadweep is an archipelago consisting of 36 islands with an area of 32 sq km. Lakshadweep is India’s smallest Union Territory. Only 10 are inhabitated
Pitti island, which is uninhabited, has a bird sanctuary.
There are three main group of islands:
- Amindivi Islands
- Laccadive Islands
- Minicoy Island.
Amindivi Islands are the northernmost while Minicoy island is the southernmost. All are tiny islands of coral origin (Atoll) and are surrounded by fringing reefs.
Lakshadweep was given Union Territory status following Kerala state’s formation in 1956.
It has the highest population share of Muslims (96%) and Scheduled Tribes (94.8%) among the UTs.
Monsoon (from mindmap): defn?
- monsoon are seasonal winds which reverse their direction of flow with the change of season
- CS Ramage (1971) suggested the following four features of monsoon winds:
- prevailing wind direction should shift by at least 120o betn Jan and July
- Avg frequency of prevailing wind directions in Jan and JUly should exceed 40%
- Mean resultant wind velocity in at least one of the months should exceed 3m/s
- There should be fewer than one cyclone-anticyclone alternation every two yrs, in either month, over a five degree latitude/longitude grid
- On the basis of aboive criteria, he demarcated the area of monsoon region as a rectangle roughly extending from 35o N to 25o S and 30o W to 173o E
Monsoon (from mindmap): Mechanism: classical theory?
explained in 1686 by Sir Edmund Hailey
- resulting from thermal contrasts betn continents and oceans due to their differential heating
- his ideas are basically the same as those involved in land and sea breeze except being seasonal instead of being diurnal
- Diagram
- crticism:
- do not develop equally everywhere
- fails to explain various intricacies of the monsoon
Monsoon (from mindmap): Mechanism: Modern Theories: enumerate them?
- Flohn’s Air Mass Theory
- Jet Stream Theory
- MT Yin and Pedelaborde: gave the concept of northward shift of southern branch of westerly jet stream to cause monsoon burst
- P Koteshwaram: Easterly jet stream originating due to Tibet heating and descending near East Africa and flowing back in the form of SW monsoon winds
- Flohn’s explanation using summer and winter wind conditions over south Asia
Monsoon (from mindmap): Mechanism: Modern Theories: Flohn’s Air Mass theory?
- ITCZ is created near the equator where SE and NE trade winds meet. This area is the region of ascending air, maximum clouds and heavy rainfall
- shifting N and S in Summer and winter (NITCZ and SITCZ)
- trade winds cross the equator and are deflected due to coriolis force
- Front where SW monsoon meet the NE trade winds is known as monsoon front
- In July, ITCZ shifts over to Indi-Gangetic plain. ITCZ in this position is called the Monsoon trough
- Diagram
Monsoon (from mindmap): Mechanism: Modern Theories: Jet STream Theory: westerly jet stream?
Jet stream is a band of fast moving air frm west to east, usually found in middle latitudes, in the upper troposphere at a height of abt 12 km
Wind speeds in a westerly jet stream are commonly 150-300 kmph.
Main contributors:
- MT Yin and Pedelaborde:
- Flohn
- Stephenson
Explanation
WESTERLY JET STREAM
Winter.
- This is the season of outblowing surface winds but aloft the westerly airflow dominates.
- The upper westerlies are split into two distinct currents by the topographical obstacle of the Tibet Plateau, one flowing to the north and the other to the south of the plateau. The two branches reunite off the east coast of China (Fig. 5.7).
- The southern branch over northern India corresponds with a strong latitudinal thermal gradient which, along with other factors, is responsible for the development of southerly jet. The southern branch is stronger.
- Air subsiding beneath this upper westerly current gives dry outblowing northerly winds from the subtropical anticyclone over northwestern India and Pakistan.
- Winter rainfall or western disturbances: The upper jet is responsible for steering of the western depressions from the Mediterranean Sea. Some of the depressions continue eastwards. redeveloping in the zone of jet stream confluence about 30 N, 105 E beyond the area of subsidence in the immediate lee of Tibet.
- Diag5.7
Summer.
- With the beginning of summer in the month of March, the upper westerlies start their northward march, but whereas the northerly jet strengthens and begins to extend across central China and into Japan, the southerly branch remains positioned south of Tibet, although weakening in intensity. The weather over northern India becomes hot, dry and squally due to larger incoming solar radiation.
- By the end of May the southern jet begins to break and later it is diverted to the north of Tibet Plateau.
- Over India, the Equatorial Trough pushes northwards with the weakening of the upper westerlies south of Tibet, but the burst of the monsoon does not take place until the upper-air circulation has switched to its summer pattern (Fig. 5.8). The low level changes are related to the high level easterly jet stream over southern Asia about 150 N
- Diag 5.8
Monsoon (from mindmap): Mechanism: Modern Theories: Jet STream Theory: easterly jet stream?
OR
“Monsoon as a thermal engine”
EASTERLY JET STREAM (P Koteswaram)
Koteswaram, supported by Flohn, feels that because the Tibet Plateau is a source of heat for the atmosphere, it generates an area of rising air. During its ascent the air spreads outwards and gradually sinks over the equatorial part of the Indian Ocean (Mascarene High). At this stage, the ascending air is deflected to the right by the earth’s rotation and moves in an clockwise direction leading to anticyclonic conditions in the upper troposphere over Tibet around 300-200 mb (9 to 12 km).
It finally approaches the west coast of India as a return current from a south-westerly direction and is termed as equatorial westerlies . It picks up moisture from the Indian Ocean and causes copious rainfall in India and adjoining countries.
Diag 5.5
Monsoon (from mindmap): Mechanism: Teleconnections: enumerate them?
there seems to be a link between meterological events which are separated by long distances and large intervals of time. They are called meteorological teleconnections
- El Nino-La Nina
- Southern Oscillation
- Indian Ocean Dipole
Monsoon (from mindmap): Mechanism: Teleconnections: El nino and La Nina?
El Nino and La Nina are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region. They are opposite phases of what is known as the El Nino-Southern Oscillation (ENSO) cycle.
- Originally, the term El Niño applied to an annual weak warm ocean current that ran southwards along the coast of Peru and Ecuador at about Christmas time. However, over time the term has evolved and now refers to the warm and negative phase of the El Niño–Southern Oscillation and is the warming of the ocean surface or above-average sea surface temperatures in the central and eastern tropical Pacific Ocean
-
El Nino is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.
- It is the “warm phase” of a larger phenomenon called the El Nino-Southern Oscillation (ENSO).
- It occurs more frequently than La Nina.
-
La Nina, the “cool phase” of ENSO, is a pattern that describes the unusual cooling of the tropical eastern Pacific.
- La Nina events may last between one and three years, unlike El Nino, which usually lasts no more than a year.
- Both phenomena tend to peak during the Northern Hemisphere winter.
- El Nino was first recognized by Peruvian fishermen off the coast of Peru as the appearance of unusually warm water.
- The Spanish immigrants called it El Nino, meaning “the little boy” or “Child Christ” in Spanish.
- The El Nino event is not a regular cycle, they are not predictable and occur irregularly at two- to seven-year intervals.
- The Oceanic Niño Index (ONI), is a measure of the departure from normal sea surface temperature in the east-central Pacific Ocean, is the standard means by which each El Nino episode is determined, gauged, and forecast.
Monsoon (from mindmap): Mechanism: Teleconnections: El nino: how does it work?
Normal conditions
- In a normal year, a surface low pressure develops in the region of northern Australia and Indonesia and a high pressure system over the coast of Peru. As a result, the trade winds over the Pacific Ocean move strongly from east to west. It is a part of Pacific Walker Circulation.
- The easterly flow of the trade winds carries warm surface waters westward, bringing convective storms (thunderstorms) to Indonesia and coastal Australia. Along the coast of Peru, cold bottom cold nutrient rich water wells up to the surface to replace the warm water that is pulled to the west.
- Normal conditions:
https://1drv.ms/u/s!AvN_8sA-Zf0djUyl04UJ7WofMpqg?e=pbsGR1 - Walker Cell: https://1drv.ms/u/s!AvN_8sA-Zf0djU0B_7eq2TFjCBXR?e=CKnkbr
- https://1drv.ms/u/s!AvN_8sA-Zf0djU4O4D0j-wOInuGn?e=ChTZ34
- The Walker circulation (walker cell) is caused by the pressure gradient force that results from a high pressure system over the eastern Pacific ocean, and a low pressure system over Indonesia.
During El nino year
- In an El Niño year, air pressure drops over large areas of the central Pacific and along the coast of South America.
- The normal low pressure system is replaced by a weak high in the western Pacific (the southern oscillation). This change in pressure pattern causes the trade winds to be reduced == Weak Walker Cell. Sometimes Walker Cell might even get reversed.
- This reduction allows the equatorial counter current (current along doldrums) to accumulate warm ocean water along the coastlines of Peru and Ecuador.
- This accumulation of warm water causes the thermocline to drop in the eastern part of Pacific Ocean which cuts off the upwelling of cold deep ocean water along the coast of Peru.
- Climatically, the development of an El Niño brings drought to the western Pacific, rains to the equatorial coast of South America, and convective storms and hurricanes to the central Pacific.
- https://1drv.ms/u/s!AvN_8sA-Zf0djU_OcnLQ7NJAph0r?e=Ld1hzv
- https://1drv.ms/u/s!AvN_8sA-Zf0djVBwIq8qdFkYsEQx?e=7hYRry
Monsoon (from mindmap): Mechanism: Teleconnections: El nino: effect on major continents?
- Impact on Ocean: warmer than usual
- Africa: In Africa, East Africa—including Kenya, Tanzania, and the White Nile basin—experiences, in the long rains from March to May, wetter-than-normal conditions. Conditions are also drier than normal from December to February in south-central Africa, mainly in Zambia, Zimbabwe, Mozambique, and Botswana.
- Antarctica: El Niño conditions result in high-pressure anomalies over the Amundsen and Bellingshausen Seas, causing reduced sea ice and increased poleward heat fluxes in these sectors, as well as the Ross Sea. The Weddell Sea, conversely, tends to become colder with more sea ice during El Niño. The exact opposite heating and atmospheric pressure anomalies occur during La Niña.[92] This pattern of variability is known as the Antarctic dipole mode
-
Australia and the Southern Pacific: During El Niño events, the shift in rainfall away from the Western Pacific may mean that rainfall across Australia is reduced
- Over the southern part of the continent, warmer than average temperatures can be recorded
- onset of the Indo-Australian Monsoon in tropical Australia is delayed by two to six weeks, which as a consequence means that rainfall is reduced over the northern tropics
- The risk of a significant bushfire season in south-eastern Australia is higher following an El Niño event, especially when it is combined with a positive IOD event
- Fiji generally experiences drier than normal conditions during an El Niño, which can lead to drought becoming established over the Islands
- Other impacts include a decrease in the sea level, possibility of coral bleaching in the marine environment and an increased risk of a tropical cyclone affecting islands
- North America:
- In particular the majority of Canada generally has milder than normal winters and springs
- it has been historically associated with high rainfall in California, the effects of El Niño depend more strongly on the “flavor” of El Niño than its presence or absence, as only “persistent El Niño” events lead to consistently high rainfall
- El Nino reduces the instances of hurricanes in the Atlantic.
- South America
- Because El Niño’s warm pool feeds thunderstorms above, it creates increased rainfall across the east-central and eastern Pacific Ocean, including several portions of the South American west coast.
- An El Niño is associated with warm and very wet weather months in April–October along the coasts of northern Peru and Ecuador, causing major flooding whenever the event is strong or extreme
- Along the west coast, El Niño reduces the upwelling of cold, nutrient-rich water that sustains large fish populations, which in turn sustain abundant sea birds, whose droppings support the fertilizer industry. The reduction in upwelling leads to fish kills off the shore of Peru. The world’s largest fishery collapsed due to overfishing during the 1972 El Niño Peruvian anchoveta reduction.
- Asia
- As warm water spreads from the west Pacific and the Indian Ocean to the east Pacific, it takes the rain with it, causing extensive drought in the western Pacific and rainfall in the normally dry eastern Pacific.
Monsoon (from mindmap): Mechanism: Teleconnections: El nino: effect on Indian Monsoon?
- El Nino and Indian monsoon are inversely related.
- The most prominent droughts in India – six of them – since 1871 have been El Nino droughts, including the recent ones in 2002 and 2009
- However, not all El Nino years led to a drought in India. For instance, 1997/98 was a strong El Nino year but there was no drought (Because of IOD).
- On the other hand, a moderate El Nino in 2002 resulted in one of the worst droughts.
- El Nino directly impacts India’s agrarian economy as it tends to lower the production of summer crops such as rice, sugarcane, cotton and oilseeds.
Monsoon (from mindmap): Mechanism: Teleconnections: Southern Oscillation?
- Southern Oscillation (S.O.) is the name ascribed to the curious phenomenon of sea-saw pattern of meteorological changes observed between the Pacific and Indian oceans.
- This great discovery was made by Sir Gilbert Walker in 1920. While working as the head of the India Meteorological Service, he noticed that when the pressure was high over equatorial south Pacific, it was low over the equatorial south Indian Ocean and vice versa.
- The pattern of low and high pressures over the Indian and Pacific Oceans (S.O.) gives rise to vertical circulation along the equator with its rising limb over low pressure area and descending limb over high pressure area. This is known as Walker Circulation.
- The location of low pressure and hence the rising limb over Indian Ocean is considered to be conducive to good monsoon rainfall in India. In other words when there is low pressure over the Indian Ocean in winter months, the chances are that the coming monsoon will be good and will bring sufficient rainfall.
- Its shifting eastward from its normal position, such as in El Nino years, reduces monsoon rainfall in India.
- Due to the close association between an El Nino (E.N.) and the Southern Oscillation (S.O.), the two are jointly referred to as an ENSO event.
- The main difficulty with the Southern Oscillation is that its priodicity is not fixed and its period varies from two to five years.
- Different indices have been used to measure the intensity of the Southern Oscillation, but the most frequently used is the Southern Oscillation Index (SOI). This is the difference in pressure between Tahiti (17°45’S. 149°30 W) in French Polynesia, representing the Pacific Ocean and Port Darwin (12 30’S, 131°E), in northern Australia representing the Indian Ocean The positive and negative values of the SOI e. Tahiti minus the Port Darwin pressure are pointers towards good or bad rainfall in India
- Walker Cell in nonrmal yrs: https://1drv.ms/u/s!AvN_8sA-Zf0djU0B_7eq2TFjCBXR?e=CKnkbr
and
https://1drv.ms/u/s!AvN_8sA-Zf0djU4O4D0j-wOInuGn?e=ChTZ34 - During El nino yrs;
Monsoon (from mindmap): Mechanism: Teleconnections: Indian ocean Dipole?
- Although ENSO was statistically effective in explaining several past droughts in India, in the recent decades the ENSO-Monsoon relationship seemed to weaken in the Indian subcontinent. For e.g. the 1997, strong ENSO failed to cause drought in India.
- However, it was later discovered that just like ENSO was an event in the Pacific Ocean, a similar seesaw ocean-atmosphere system in the Indian Ocean was also at play. It was discovered in 1999 and named the Indian Ocean Dipole (IOD).
- The Indian Ocean Dipole (IOD) is defined by the difference in sea surface temperature between two areas (or poles, hence a dipole) – a western pole in the Arabian Sea (western Indian Ocean) and an eastern pole in the eastern Indian Ocean south of Indonesia.
- IOD develops in the equatorial region of Indian Ocean from April to May peaking in October.
- With a positive IOD winds over the Indian Ocean blow from east to west (from Bay of Bengal towards Arabian Sea). This results in the Arabian Sea (western Indian Ocean near African Coast) being much warmer and eastern Indian Ocean around Indonesia becoming colder and dry.
- In the negative dipole year (negative IOD), reverse happens making Indonesia much warmer and rainier.
- It was demonstrated that a positive IOD index often negated the effect of ENSO, resulting in increased Monsoon rains in several ENSO years like the 1983, 1994 and 1997. records of India Meteorological Department (IMD) show that IOD was positive in four of the 16 El Nino years during 1951-2017 (Table 5.1) and the rainfall was normal i.e. 96-104% of the Long Period Average (LPA) in three of these four years.
- Further, it was shown that the two poles of the IOD – the eastern pole (around Indonesia) and the western pole (off the African coast) were independently and cumulatively affecting the quantity of rains for the Monsoon in the Indian subcontinent.
- Similar to ENSO, the atmospheric component of the IOD was later discovered and named as Equatorial Indian Ocean Oscillation [EQUINOO][Oscillation of warm water and atmospheric pressure between Bay of Bengal and Arabian Sea].
-
Effect on Cyclonogenesis
- Positive IOD (Arabian Sea warmer than Bay of Bengal) results in more cyclones than usual in Arabian Sea.
- Negative IOD results in stronger than usual cyclonogenesis (Formation of Tropical Cyclones) in Bay of Bengal. Cyclonogenesis in Arabian Sea is suppressed.
Monsoon (from mindmap): IMD’16 parameters for Monsoon forecast?
- temperature related parameters
- El nino in curent yr
- El nino in previous yr
- Northern India (March)
- East Coast of INdia (March)
- Central India (May)
- Northern hemisphere (Jan and Feb)
- Wind related parameters
- 500 hPa ridge in April
- 50 hPa ridge trough extent (Jan and Feb)
- 10 hPa westerly wind
- Pressure anomaly
- Tahiti-Darwin (Spring)
- Darwin (spring)
- South America- Argentina (April)
- Indian Ocean Equatorial (Jan-May)
- surface pressure annomaly of NE hemisphere
- Snoe cover related
- Himalayan (Jan-March)
- Eurasian (Previous Dec)
It was observed in late eighties that whenever more than 50% parameters showed favourable signals, the monsoon rainfall in India was normal and when 70% or more parameters were favourable, the monsoon rainfall was above normal.
Monsoon: El nino Modoki?
- El Niño Modoki is a coupled ocean-atmosphere phenomenon in the tropical Pacific.
- It is different from another coupled phenomenon in the tropical Pacific namely, El Niño.
- Conventional El Niño is characterized by strong anomalous warming in the eastern equatorial Pacific. Whereas, El Niño Modoki is associated with strong anomalous warming in the central tropical Pacific and cooling in the eastern and western tropical Pacific (see figure below).
- El nino Modoki: https://1drv.ms/u/s!AvN_8sA-Zf0djVFtN32VllHv_vm8?e=nKZdh0
- Walker Cell for El Nino Modoki: https://1drv.ms/u/s!AvN_8sA-Zf0djVJI_ADR6Z3cPdye?e=6n1eJg
- impact
- The El Niño Modoki phenomenon is characterized by the anomalously warm central equatorial Pacific flanked by anomalously cool regions in both west and east.
- Such zonal gradients result in anomalous two-cell Walker Circulation over the tropical Pacific, with a wet region in the central Pacific.
CC and monsoon variations in NE: overall NE?
- This year, while most of India is enjoying a normal monsoon, the Northeast is once again grappling with a deficit. Excwpt Sikkim all the states were facing a deficit of ~30% till Aug 5th 2021
- unlike India’s other mountain states such as Uttarakhand,j&K and HP, NE states depend only on monsoon rf rather than glaciers
- gravity of the problem can be gauged from the fact that the Northeast, which receives the heaviest monsoon rains in the country, now has a higher chance of experiencing a meteorological drought than western India, which receives the lowest amount of the monsoon showers.
- A meteorological drought arises when the actual rainfall over an area is significantly less than its climatological mean, defines IMD.
- probability of a meteorological drought in the Northeast was 54 per cent between 2000 and 2014 as opposed to 27 per cent in western India
- variations as well: While six of the eight northeastern states have recorded an overall decreasing trend in monsoon showers during 1989-2018, some of the districts, particularly in Assam, have seen an increase in floods, which is not expected in an area that is receiving less rainfall than before.
- The other challenge is that monsoon showers in almost all the states remain extremely unreliable, particularly in July and August, the two months when most of the states receive bulk of the rains
- An increase in rf as well as its intensity has led to changes in many rivers’ flow: eg. two major tributaries of Brahmputra- Subansiri and Dibang, These tributaries have drastically altered their course in recent years, uprooting several villages along the way
- On the other hand, a decrease in the annual rainfall dries up mountain springs. Around 200 mountain springs have already dried up in the region, suggests a 2018 report by NITI Aayog. Over 94 per cent villages in Sikkim and >50% villages in Meghalaya, Mizoram and Manipur rely on mountain springs for water
- Declining vegetation cover due to drought stress also enhances soil erosion and can lead to desertification. As per the Land Degradation Map of India, prepared by ISRO, four of the six states with the most degraded land are in NE- Nagaland (47%) only behind UP (53%) and RJ (52%)
- degradation of land has a direct impact on this region’s rich biodiversity. Of the total 17,000 flowering plants in the country, about 5,000 species are found in the northeast, and many of them are already under stress
- The Union Ministry of Environment, Forest and Climate Change expects the region to be 1.8-2.1oC warmer by the end of 2030. This would increase the annual mean rainfall by 0.3 to 3 per cent, it says. The climate action plans of most of the northeastern states predict a wetter monsoon in the future along with warmer temperatures.
CC and monsoon variations in NE: Arunachal Pradesh?
- overall trend of decreasing monsoon rains
- While eight districts have reported a decrease in the monsoon rains—which explains the overall deficit in the state—only two, Upper Siang and Upper Subansiri, have reported an increase in rainfall.
- Upper Siang district is the starting point of the Siang river, Brahmaputra’s largest tributary, and Upper Subansiri district is home to the Subansiri river, another major tributary of Brahmaputra.
- Simultaneous with the increase in rainfall, more than 95 per cent of the monitoring stations in Upper Siang have reported a reduction in the number of rainy days. This translates into floods both in the district and downstream in Assam.
- most other districts of the state, particularly West and East Kemang on the western part, are reporting widespread drying up of mountain springs, which are often the primary water source for the families living in the villages nestled in them.
- 21 per cent variation or fluctuation in the amount of rainfall the state received during the monsoon season every year.
- case study: In upper siang district, due to increase in rf, The moist conditions are favourable for pests, and their population has drastically increased, this leads to crop failure especially in cases where organic farming is practised.
CC and monsoon variations in NE: Assam?
- overall decrease in the monsoon rains in the past decades, though the drop is not as significant as in Arunachal Pradesh.
- Assam is divided into three distinct geographical regions. To the north is the Brahmaputra river valley in the foothills of the Himalayas and to the south is the Barak river valley. In between the two valleys are the Karbi Anglong and Cachar hills.
- Most districts north of Brahmputra show a trend of increase in rainfall, though the increase is not significant. But they have seen a significant decrease in the number of rainy days. This means that the rainfall in these districts takes place in fewer days, increasing the intensity of the rains. This causes havoc in the districts south of the river even though they have registered a decrease in the monsoon rainfall.
- The impact of this can be seen clearly in Golaghat district, which houses the Kaziranga National Park. This area gets flooded due to the swelling of the Doyang river, which flows in from Wokha district of Nagaland.
- the riverine islands of the Brahmaputra have been identified as being the most vulnerable to diseases due to frequent floods that appear to be on the rise
- Food security: In 2005-06, Assam experienced a drought and it had an immediate impact on the rice production in the worst-affected areas of Dhubri, Nalbari
- The increase in floods in Assam’s Golaghat district is destroying forestland inside the Kaziranga national park. This is impacting the nearby villages and hampering the natural migration routes of animals. Claims of officials annexing farmlands to compensate for NP loss are also seen from the region
- case study:
- Residents of Mas Dihiri village in Assam have shifted their homes every year since 2012 due to the Kumutiya river that constantly changes its course in response to the erratic monsoons
- , heavy rainfall has pushed more coarse sand fragments of mountain rocks and construction debris from upstream areas into floodwaters, as against the fertile alluvial soil they usually carry. This debris impacts soil fertility when deposited along fields, hindering production of rice varieties such as Sali, Bao and Ahu downstream like Karpunpuli village along river Jiadhal, a sub-tributary of Brahmputra
CC and monsoon variations in NE: Nagaland?
overall drying trend but is witnessing an abnormal shift: monsoon rainfall is going down in the traditionally wetter districts in the north, central and the southwest parts of the state, while it is going up in the drier districts in the southern parts.
Even though the state is drained by four major rivers and a dozen minor rivers, unlike Arunachal Pradesh, it is not traditionally flood-prone, because of its mild gradient
Monsoons, which account for 68 per cent of the annual rainfall in the state, remain highly unpredictable with an almost 25 per cent variability in the past three decades.
In 2020, Nagaland was one of the few northeastern states to experience an overall deficit rainfall (29 per cent lower than normal).
The changing climate of Nagaland has also meant that only half of the 400-odd indigenous rice varieties are conducive to the region now. Rice productivity has decreased by around 50 per cent, while betel nut productivity has crashed by 40 per cent in the last four to five years
The same decreasing trend can be seen in the population of birds and butterflies in the region. Butterflies are extremely sensitive to temperature and rainfall changes, and serve as a reliable bio-indicator of the change in climate
CC and monsoon variations in NE: Sikkim?
While overall monsoon rainfall has only marginally increased in the past three decades, three-fourths of the state is growing drier.
This has been possible because the climate in the second smallest state of India varies from place to place due to the significant variation in elevation and topography. the northern regions are covered with high mountains while the southern region is primarily made up of plains that blend into WB.
The upward trend of the monsoons is most prominent in North Sikkim, which may be causing an increase in the flooding of the Teesta river. This in turn is leading to an increase in the landslide incidents downstream in South Sikkim, especially around Gangtok city and since 1997.
CC and monsoon variations in NE: Mizoram?
the only other northeastern state where the overall monsoon rainfall has seen a minor increase
The eight districts are equally split with four each showing minor increase and minor decrease
The three wettest districts—Lunglei in the centre, Kolasib in the north and Saiha in south— have seen an increase in the overall rainfall along with a substantial drop in the number of rainy days
CC and monsoon variations in NE: Meghalaya?
downward trend in the overall monsoon rainfall. imd data shows that deficit rainfall became a chronic problem after 2005.
While the three districts that are at the centre have seen minor changes in rainfall, the four districts on the outside have seen significant changes
The East Khasi Hill district, which receives the most rainfall, has recorded a minor increase in the monsoon rains but a significant decrease in rainy days
The state has one of the highest variations in the monsoon rainfall at almost 25 per cent.
Drought a persistent problem in Cherapunji
CC and monsoon variations in NE: Tripura?
perhaps the only northeastern state where all the districts have seen an overall reduction in the monsoon rains, though the change has not been significant.
This is likely to have an impact on the 10 major rivers in the state that are all rain-fed and ephemeral in nature.
CC and monsoon variations in NE: Manipur?
Various studies and Down to Earth’s earlier reportage suggest that the state has seen a downward trend in monsoon rainfall though IMD has not released the composite data for the 1989-2018
This is a cause for concern as Manipur is highly food insecure because of the paucity of farmland and the traditional practice of jhum
The state saw a significant increase in its annual rainfall between 1975 and 1989, followed by a phase of significant decrease in the rains between 1990 and 2007, says a study by the Central Agricultural University, Imphal, in 2016.
In 2019, Manipur received 56 per cent lesser rains during the monsoon season, as per imd. Chandel district, located in the southeast part of the state, reported an 82 per cent deficit that year. The trend continued in 2020, when the state received a deficit rainfall of 46 per cent.
CC and monsoon variations in NE: lack of appropriate data?
One logistical difficulty is that the monitoring stations often are not available in the places that are suffering from the maximum unpredictability. One such example is Pakke Kessang district in Arunachal Pradesh. The district’s lone rainfall monitoring station was washed away during a flood in 2004 and imd is yet to set it up again
CC and monsson variations in NE: case study of flooding due to hydro project upstream?
Runchan village on Nagaland’s NW border with Assam, gets flooded because of a hydropower project built a few kilometres upstream on the Doyang river. Although Nagaland is no stranger to floods and landslides owing to heavy rain, the northwestern part of the state has never been affected by such disasters. But the 2018 floods have displaced over 3,000 families in 400 villages downstream of the Doyang river
CC and monsoon variations in NE: impact on biodiversity: examples?
THE BLYTH’S Kingfisher is found only at 15 places Arunachal Pradesh, 13 of which are in Pakke-Kessang district, home of the scenic Pakke Tiger Reserve. The bird is rarely seen these days due to the decline in the population of the fish on which it feeds.
significant behavioural shift in the animals and birds due to the changing temperatures, rainfall patterns and deforestation. For example, there has been “a change in the migratory route of the elephants which earlier used to stop near Saibun, the natural saltwater lake
2020 was a La Nina year but states like Kerala, GJ, J&K, NE and Odisha saw rf deficit upto 30%. factors?
- It is El Niño’s little cousin in the Atlantic, known as the Atlantic Niño, or the Atlantic Zonal Mode. In 2021, Atlantic Niño has made an appearance. Sea surface temperatures in the eastern Atlantic have remained more than a degree higher than normal this summer.
- Every few years, from June to August, there is a warming in the eastern equatorial Atlantic
- Its impact on the monsoon has been known since 2014 when a study led by INCOIS showed that the number of low-pressure systems is greatly reduced by the Atlantic Niño, leading to deficit monsoons. This year has seen a sharply lower number of low-pressure systems, which contribute up to 60 per cent of the seasonal total rainfall over the core monsoon zone.
- The Atlantic Niño affects the monsoon by producing atmospheric waves, which propagate into the Indian Ocean. These waves affect air temperatures over the Indian Ocean and influence the land-ocean thermal contrast as well as LPSs.
- The biggest rainfall deficits from the Atlantic Niño tend to occur over the Western Ghats and the core monsoon zone. The deficit patterns are a tell-tale sign of the Atlantic Niño influence.
Delay in arrival and withdrawal of monsoon?
Normal date of the monsoon onset in India is June 1; and the normal date for withdrawal of monsoon is October 15
monsoon season has made a delayed entry into India in seven years since 2011, its has reported a delayed exit in all the years since 2011.
in a press release in April 2020, imd acknowledged that the monsoon now withdraws from northwest India almost 7-14 days later from the existing dates.
causes:
- overall CC but attribution studies are needed
- temperature on the periphery of monsoon wind system in Pakistan and Afghanistan now remains higher than normal in September, so it takes longer for the subcontinent to cool down as needed for withdrawal.
“Double Dip” phenomenon wrt Indian Monsoons?
- Consecutive La Ninas following a transition through ENSO neutral conditions are not uncommon and can be referred to as a “Double-Dip.”
- In 2020, La Nina developed during the month of August and then dissipated in April 2021 as ENSO-neutral conditions returned.
- For the upcoming winter season, which extends from December 2021 through February 2022, there is an 87% chance of La Nina.
Weather changes because of La Nina?
- The Horn of Africa and central Asia will see below average rainfall due to La Niña.
- East Africa is forecast to see drier-than-usual conditions, which together with the existing impacts of the desert locust invasion, may add to regional food insecurity.
- It could also lead to increased rainfall in southern Africa.
- It could also affect the South West Indian Ocean Tropical Cyclone season, reducing the intensity.
- Southeast Asia, some Pacific Islands and the northern region of South America are expected to receive above-average rainfall.
- In India, La Niña means the country will receive more rainfall than normal, leading to floods.
How is La Niña linked with the Northeast monsoon?
While La Niña conditions enhance the rainfall associated with the Southwest monsoon, it has a negative impact on rainfall associated with the Northeast monsoon.
During La Niña years, the synoptic systems — low pressure or cyclones — formed in the Bay of Bengal remain significantly to the north of their normal position.
- Besides, instead of moving westwards, these systems recurve. As they lie to the north of their normal position, not much rainfall occurs over southern regions like Tamil Nadu.
Theories of Evolution of Himalayan Rivers: intro? names of two theories?
Some of the unwarranted features of the Himalayan rivers such as,
- The longitudinal courses of the Indus, the Satluj and Brhamputra
- Deep gorges cut By The Rivers across the Himalaya
- Still westerly flowing tributaries in their upper reaches
are a great puzzle and require proper explanation. To serve this purpose, following theories are given
- Indo-Brahm or Shiwalik River Theory
- E. Ahmed’s Theory
- Multiple River Theory
Indo-Brahm or Shiwalik River Theory: by? Hypothesis?
- Given by Pascoe and Pilgrim independently in 1919
- Hypothesis: they assume that there was an ancient Mighty river flowing from Assam to Punjab. This hypothetical ancient River was called the Indo-Brahm by EH Pascoe, Who thought that the present day Indus and Brahmaputra river were the severed parts of the original river.
However it was named as Shiwalik river by EG Pilgrim who considered that the course of the primitive river is occupied by the present day Shiwalik hills. - Pascoe and Pilgrim assumed that the Shiwalik deposition occured along the this great river.
Indo-Brahm or Shiwalik River Theory: details?
- The river came into being due to Earth movements which took place in tertiary period and is believed to be the successor of the Himalayan sea.
- In the Eocene epoch, a Gulf extended from Sindh to Afghanistan and from there extended eastward and south-eastward through Kohat and PJ to the neighbourhood of Nainital.
- This gulf gave place to a great river. With its head water consisting of portions of the Brahmaputra, this master stream flowed along the foot of the Himalayas first westward and then Northwestward as far as northwestern Punjab where it turned Southward more or less along the course of modern Indus and emptied itself into the Arabian Sea
Indo-Brahm or Shiwalik River Theory: Dismembered into the following systems and sub-systems?
- The Indus
- The five tributaries of Indus in PJ
- The ganga and its Himalayan tributaries, and
- The stretch of the Brahmputra in Assam and its Himalayan tributaries
Indo-Brahm or Shiwalik River Theory: cause of dismemberment?
- Upheavels in the Western Himalayas including the Potwar plateau in the PLeistocee age, and
- Headward erosion by the tributaries of the Indo-Brahm river
Indo-Brahm or Shiwalik River Theory: Yamuna?
It is supposed that Yamuna was first a tributary of Indus. During the late Pleistocene and early holocene ages, it joined with Saraswati somewhere near Suratgarh and continued to flow as Ghaggar, finally joining the Indus.
Some other scholars believe that it reached Rann of Kutchh as an independent river, Later on it changed its course due to tectonic disturbance along the Aravali axis and was annexed by Ganga to become its tributary.
Indo-Brahm or Shiwalik River Theory: Tibet River?
Pascoe also envisaged a great ‘Tibetan river’ flowing NW along Tsangpo-Manasarovar Lakes-Satluj-Gartang - Indus trough.
This river might have emptied itself into the Oxus Lake, or might have debouched on to the plains by one of a number of transverse gaps such as Photu Pass.
This river also was disrupted by headward erosion by Ayeyarwadi-Chindwin, the Meghna-Brahmaputra, the Satluj and the Indus.
Indo-Brahm or Shiwalik River Theory: issues?
However, this theory has been challenged on the following grounds:
(1) It is not necessary to imagine a stream of the size of Indobrahma flowing all along the length of the Himalayas to explain the occurrence of the Shiwalik deposits. These could be brought down by the rivers flowing down the slopes of the Himalayas. M.S. Krishnan and N.K.N. Iyngar (1940) found it difficult to accept the existence of such a mighty river on geological as well as physiographical grounds.
(ii) The evidences furnished by the depositional history in the Ganga delta and in Assam does not fit well with the concept of Indobrahma river.
(iii) The width, thickness and lithology of the Tipam sand stones of Assam which were deposited in an estuary situated so close to the source of the Indobrahma also speak against this theory.
(iv) The upper course and the source of the Satluj river also do not fit in this theory. It is fed by underground water from the Manasarovar lake and it flows in a deep canyon cut in the soft fluviated beds of Nari Khorsum. The upper course of the Satluj is distinctly arid and the river appears to be a misfit. This could be explained if it were an old outlet of the Tibetan River’. Pascoe argues that the Satluj captured a part of the “Tilbetan river” and then lost again to the rejuvenated Tsangpo after the Dihang had cut back into the furrow. This argument has been rejected by many scholars
E. Ahmed’s Theory of Evolution of Himalayan Drainage: First Upheavel ?
He believed that the Tethys remained as a basin of sedimentation from the Cambrian to the Eocene. period but the major portion of the Himalayan region was occupied by the Gondwana landmass.
During the first Himalayan upheaval in Oligocene period,
- part of the Tethyian geosyncline and probably the Gondwana shield covering the major part of the Himalayan region was uplifted.Most probably, this marks the initiation of the Himalayan drainage.
- The Tethys was raised into a landmass with a median mass of high Tibetan plateau in the centre and two bordering ranges namely the Kun Lun in North and Himadri in the south.
- The drainage started from the southern edge of the median mass and flowed south towards the foredeep.
- As the formation of east-west ranges created east-west valleys, the rivers partly flowed along these valleys, This is indicated by the upper course of several rivers such as the Indus, the Satlay, the Brahmaputra, the Shyok, the Arun, etc.
- Since the whole of the Tethys was not fully raised to become land surface, there existed patches of sea along the margins and the drainage lines were not fully defined
E. Ahmed’s Theory of Evolution of Himalayan Drainage: Second Upheavel ?
- The second Himalayan upheaval during the mid Miocene period increased the altitude of the medium mass and the bordering ranges.
- The remnant sea was also raised to form landmass.
- The rise in land resulted in greater and more invigorated drainage.
- Along with these changes, the region to the south of the first Himalayan range was raised as Lesser Himalayan range.
- Earlier streams on the southern margin of the Tibetan plateau cut down deep valleys to maintain their courses.
- Along the southern slopes of the lesser Himalayas, a number of consequent streams also emerged which drained into the southern foredeep.
E. Ahmed’s Theory of Evolution of Himalayan Drainage: Third Upheavel ?
- The third Himalayan upheaval during the Pleistocene period resulted in the folding of the Shiwalik foredeep into hill ranges.
- Also the height of earlier ranges and the Tibetan plateau was raised. The rise in the Tibetan plateau blocked the streams that had gone northward into the Tibetan sea. These streams were diverted east or west which probably led to the formation of the trans-Himalayan master stream.
- This master stream was broken into two (the proto-Indus and the proto-Brahmaputra) by the formation of the Kailas Range.
- The uplift of the Shiwalik range gave rise to the last set of consequents originating on the crest of the range emptying into older streams.
Multiple River Theory of Evolution of HImalayan rivers?
- The protagonists of this theory find it difficult to accept the existence of a large river like the Indo-Brahm or Shiwalik on geological and physiographical grounds.
- This theory postulates that the Eocene sea before extended upto Sind, Rajasthan and from Punjab to Jammu and thereafter Lansdowne and Nainital. This was connected to Tethys.
- Existence of such a sea is evidenced by the presence of shallow water bodies indicative of coast near Landsdowne.
- This limit also coincides with the eastern continuation of one of the ridges of the Aravali Range which presumably acted as barrier.
- The sea was broken by the first upheaval of the Himalayas to form an isolated basin in which sediments were deposited.
- In the next upheaval, a pronounced foredeep all along the southern border of the Himalayas was formed. This foredeep contained numerous lagoons in which flowed streams from the Peninsula and the newly uplifted Himalayas. These streams brought sediments which later came to be known as Shiwalik deposits.
- The outlet of this foredeep was through the Rajmahal-Garo gap in the Bay of Bengal and the Arabian Sea in the west. Later on the lagoons got dried up and numerous transverse streams flowing from the Himalayan region formed what is now known as the Himalayan drainage.
Indus: path?
- near Mansarovar Lake from the glaciers of Kailas Range in Western TIbet
- ~250 km in NW direction in Trans HImalayan region under the name of Singge Khabab
- joined by Dhar
- enters INdia in Ladakh region at a place called Demchok
- continues to flow in the same NW direction betn Ladakh and Zaskar range; very gentle gradient
- encircles the town of Leh; joined by Zaskar river
- joined by Shyok near Skardu
- ~500km long antecedent and very deep gorge
- sharp southerly bend after reaching city of Gilgit and reaches Attock where it enters plains; joined by Kabul river from afghanistan
- flows through Potwar plain and crosses the SAlt range
- receives the panchnad just above Mithankot
- finally empties into Arabian sea, south of Karachi, forming a large delta
INdus : left bank tributaries?
Zaskar river, Suru river, Soan river, Jhelum River, Chenab River, Ravi River, Beas river, Satluj river, Panjnad river, Ghaggar-Hakra river, Luni river
INdus : right bank tributaries?
Shyok River, Gilgit river, Hunza river, Swat river, Kunnar river, Kurram river, Gomal River, and Kabul river
Shyok river?
- Rising from the Karakoram Range, it flows through the Northern Ladakh region in J&K
- It has a length of about 550km.
- A tributary of the Indus River, it originates from the Rimo Glacier.
- The river widens at the confluence with the Nubra River
- Shyok River marks the south-eastern fringe of the Karakoram ranges by forming a V-shaped bend around it.
Nubra river?
- It is the main tributary of the Shyok River.
- It originated from the Nubra Glacier, in a depression to the east of Saltoro Kangri Peak
- Nubra River meanders towards the southeast to join the Shyok River downstream of Shyok Valley at the base of the Ladakh range
- Nubra Valley, situated at an altitude of 3048m, is formed out of the Nubra River
- The catchment area is devoid of vegetation and human habitation due to high elevation and lack of rainfall.
Shigra river?
- It is a small right-bank tributary of the Indus River in its course through the Ladakh region of J&K
- It rises from the Hispar Glacier.
- It joins Indus at Skardu.
- The Shigar River descends down a very steep gradient
- Its entire catchment has been influenced by the action of glaciers.
Gilgit river?
- It is an important right-bank tributary of the Indus River in its course through the Ladakh region of J&K
- It originates from a glacier near the extreme northwestern boundary of the Himalayas
- The entire catchment area of the Gilgit River is bleak and desolate
- Bunji is the main human settlement along the river
- Ghizar and Hunza are the major right and left bank tributaries respectively.
Humza river?
- It is an important left-bank tributary of the Gilgit River
- It rises from a glacier north of the Karakoram Range in the northwestern part of J&K
- It flows southeast and cuts across the Karakoram Range through a spectacular gorge
- Downstream, the Hunza River follows a southwesterly direction in its middle course
- Then it cuts across an offshoot of the Karakoram range and changes course to the southeast in its lower course before merging with the Gilgit a little upstream of Bunji where the latter river empties itself into the Indus.
Zanskar river?
- It is one of the important left blank tributaries of the Indus
- Human settlements are sparse.
Jhelum : path?
- rises in Spring at Verinag in SE part of Kashir valley
- flows northwards
- reaches Wular Lake
- turns SW
- flows through Kashmir valley
- forms a 200m deep defile with almost vertical walls through the Pir Panjal range below Baramula
- tributaries like Lidar, Pohru, Sind join the river
- At Muzaffarabadriver takes a sharp hairpin swing southward; Kishenganga joins
- forms India-Pakistan boundary fr ~170 km
- emerges at Potwar plateau near Mirpur
- enters plains near city of Jhelum
- Chenab joins at Trimmu
Kishenganga river?
- It originates at Drass in the Kargil district of J&K
- The Neelam River enters Pakistan from India near the Line of Control and then runs west till it meets the Jhelum River
- It is also called as Neelam River (Neelum) either due to its sky cold water or due to the precious stone “ruby (Neelam)” that is found in this area
- It is famous for ice-cold water and trout fish.
Chenab: path? about?
- originates from near Bara Lacha Pass in Lahaul Spiti part of Zaskar range; two small streams on opposite sides of the pass, namely Chandra and Bhaga form its headwaters
- The united stream, called Chandrabhaga, flows in NW direction through Pangi valley, parallel to Pir Panjal Range
- enters J&K as Chenab
- Near Kistwar, cuts a deep gorge
- Turns southwards
- turns west and enters the plain area near Akhnur in J&K
- swings SW throgh Pak PJ plains
- reaches Panchnad where it joins satluj after receing waters of Ravi and JHelum
- Baghliar Dam has been constructed on this river
- The river is crossed in J&K by the world’s highest railways bridge name Chenab Bridge.
Ravi: path? about?
- in Kullu hills near Rohtang pass in Chamba district of HP
- NW direction; drains the area betn Pir Panjal and Dhaola Dhar range
- After crossing Chamba, takes a SW direction
- cuts a deep gorge in Dhaola Dhar range
- enters PJ plains near Madhopur
- enters Pakistan below Amritsar
- joins Chenab a little over Rangpur in Pakistani PJ
- major multipurpose project built on the river is the Ranjit Sagar Dam ( Thein dam as it is located in Theinvillage)
- Chamba town is situated on the right bank of the river.
- Shahpurkandi Dam project is located on the Ravi River in Pathankot district, Punjab, downstream from the existing Ranjit Sagar Dam.
Ravi river: tributaries?
- The right bank tributaries of the Ravi are the Budhil, Tundahan Beljedi, Saho and Siul; and its left bank tributary worth mentioning is Chirchind Nala.
- The Ujh river is a tributary of the Ravi River that flows through the Kathua district in the Indian union territory of Jammu and Kashmir.
- Ujh Multipurpose Project is planned to be constructed in Kathua District of Jammu & Kashmir on the River Ujh.
Beas : path?
- originates near Rohtang pass, on southern slope of Pir Panjal region, close to source of Ravi
- crosses Dhaola Dhar range through a deep gorge from Lorji and Talwara
- On meeting Shiwalik hills, takes a sharp Northward turn,
- then bending round the base of hills
- takes a southerly direction
- enters the plains and takes a SW direction
- meets Satluj at Harike
- a comparatively small river and lies entirely in India
Satluj: path?
- rises from Mansarovar-Rakas Lakes near Darma pass in western Tibet, within 80 km of the source of Tibet
- takes a NW course upto Shipki La on Tibet-HP boundary; Spiti river joins it at Namgia near Shipki La
- cuts deep gorges across Great Himalayas; In Nari Kharosan province of Tibet, it has created an extra-ordinary canyon, comparable to the Grand Canyon
- cuts a gorge in Naina Devi Dhar where the famous Bhakra dam has been constructed
- enters the PJ plain at rupnagar (Ropar) and turns westward
- joind by Beas at Harike
- forms INdo-pak boundaru betn Ferozepur to Fazilka
- receives the collective drainage of Ravi, Khelum and Chenab
- joins Indus above Mithankot
Plateaus and hill ranges of Peninsular India?
Peninsular Plateau is an aggregation of several smaller plateaus and hill ranges interspersed with river basins.
Plateaus of Peninsualr INdia:
- Marwar Upland
- Central Highland aka Madhya Bharat Pathar
- Bundelkhand Upland
- malwa plateau
- Baghelkhand
- Chhotanagpur Plateau
- Meghalaya Plateau
- Deccan Plateau
- CHH plain
https://1drv.ms/u/s!AvN_8sA-Zf0djTKpXWv8R9-S3Z2a?e=kJxu4Y
Hill Ranges of Peninsualr Plateau
- Aravali Range
- Vindhyan Range
- Satpur range
- Western Ghats
- Eastern ghats
Plateaus and hill ranges of Peninsular India: Marwar upland? (refer geog folder for individual and composite maps of plateaus)
- Upland of east RJ; lies east of Aravalis
- avg elevation 250-500m and slopes eastward
- made up of sandstone, shales and limestone of Vindhayan period
- Banas river, that originates in Aravalis and joins Chambal, and its tributaries (Berach and Khari rivers) have turne dthe region into a rolling plain
(Rolling Plain: ‘Rolling plains’ are not completely flat: there are slight rises and fall in the land form. Ex: Prairies of USA)
Plateaus and hill ranges of Peninsular India: Madhya Bharat ka Pathar?
- East of Marwar Upland
- open rolling plateau made of old rocks, interspersed with rounded hills of sandstone
- thick forests cover
- basin of Chambal river
- Ravines or Badlands of Chambal in the north
Plateaus and hill ranges of Peninsular India: Bundelkhand Upland?
- Yamuna river to the north, Madhya Bharat Pathar to the west, Vindhyan Scarplands to the east and south-east and Malwa Plateau to the south.
- spread over five districts of UP: Jalaun, Jhansi, Lalitpur, Hamirpur and Banda, and four districts of MP: Datia, Tikampur, Chhatarpur and Panna
- old, dissected upland of gneiss and granite; characteistic feature of rounded hummocky hills made of granite and sandstone
- slopes down from Vindhyan scarp towards Yamuna
- senile topography: erosional work of rivers has converted it into undulating area unfit for cultivation along with some steep gorges and waterfalls by streams of Ken, betwa and Dhasan
Plateaus and hill ranges of Peninsular India: Malwa plateau?
- The Malwa Plateau roughly forms a triangle based on the Vindhyan Hills, bounded by the Aravali Range in the west and Madhya Bharat Pathar to the north and Bundelkhand to the east.
- two systems of drainage: Narmada, Tapi and Mahi flow to AS while Chambal, Betwa join Yamuna and flow to BoB
- spread over an area of 1.5 L sq km
- composed of extensive lava flow and is covered with black soil
- there are rolling surfaces and flat topped hills dissected by rivers
Plateaus and hill ranges of Peninsular India: Baghelkhand?
- North of the Maikal Range is the Baghelkhand. bounded by the Son river on the north.
- Made of limestones and sandstones on the west and granite in the east.
- The central part of the plateau acts as a water divide between the Son drainage system in the north and the Mahanadi river system in the south.
- The region is uneven with general elevation varying from 150 m to 1,200 m.
- The Bhanrer and Kaimur are located close to the trough-axis.
- The general horizontality of the strata shows that this area has not undergone any major disturbance.
Plateaus and hill ranges of Peninsular India: Vindhya scarplands?
betn Ganga plain and Narmada - Son trough
made of Vindhyan sandstones
Plateaus and hill ranges of Peninsular India: chhotanagpur Plateau?
- Chotanagpur plateau represents the north-eastern projection of the Indian Peninsula.
- Mostly in Jharkhand, northern part of Chhatisgarh and Purulia district of West Bengal.
- Drainage:
- The Son river flows in the north-west of the plateau and joins the Ganga.
- The plateau is drained by numerous rivers and streams in different directions and presents a radial drainage pattern.
- Rivers like the Damodar, the Subarn rekaha, the North Koel, the South Koel and the Barkar have developed extensive drainage basins.
- The Damodar river flows through the middle of this region in a rift valley from west to east. Here are found the Gondwana coal fields which provide bulk of coal in India.
- This plateau is composed mainly of Gondwana rocks with patches of granite gneisses and Deccan lava
-
Basically consists of a series of plateaus at different elevations:
- The average elevation of the plateau is 700 m above sea level.
- Highest elevation is of mid-western portion known as Pat Lands at 1100m, consisting of mesas or pats. eg. Netarhat pat and Goru pat
- from here land descends in steps creating waterfalls
- North of the Damodar river is the Hazaribagh plateau with an average elevation of 600 m above mean sea level. This plateau has isolated hills. It looks like a peneplain due to large scale erosion.
- The Ranchi Plateau to the south of the Damodar Valley rises to about 600 m above mean sea level. Most of the surface is rolling where the city of Ranchi (661 m) is located. Most of the surface is rolling. At places it is interruped by monadnocks (an isolated hill or ridge of erosion-resistant rock rising above a peneplain. Ex: Ayers Rock in Australia) and conical hills.
- The Rajmahal Hills forming the north eastern edge of the Chotanagpur Plateau are mostly made of basalt and are covered by lava flows {Basaltic Lava}. They run in north-south direction and rise to average elevation of 400 m (highest mount is 567 m). These hills have been dissected into separate plateaus.
Plateaus and hill ranges of Peninsular India: Meghalaya Plateau?
- The peninsular plateau extends further east beyond the Rajmahal hills to from Meghalaya or the Shillong plateau.
- Garo-Rajmahal Gap separates this plateau from the main block. This gap was formed by down-faulting (normal fault: a block of earth slides downwards). It was later filled by sediments deposited by the Ganga and Brahmaputa.
- The plateau is formed by Archaean quartzites, shales and schists.
- The plateau slopes down to Brahmaputra valley in the north and the Surma and Meghna valleys in the south. Its western boundary more or less coincides with the Bangladesh border.
- The western, central and the eastern parts of the plateau are known as the Garo Hills (900 m), the Khasi-Jaintia Hills (1,500 m) and the Mikir Hills (700 m).
- Shillong (1,961 m) is the highest point of the plateau.
Plateaus and hill ranges of Peninsular India: Deccan plateau?
- It covers an area of about five lakh sq km.
- It is triangular in shape and is bounded by the Satpura and the Vindhya in the north-west, the Mahadev and the Maikal in the north, the Western Ghats in the west and the Eastern Ghats in the east.
- Its average elevation is 600 m. It rises to 1000 m in the south but dips to 500 m in the north.
- Its general slope is from west to east which is indicated by the flow of its major rivers.
- Rivers have further subdivided this plateau into a number of smaller plateaus.
- maharashtra Plateau
- KN plateau
- Telangana Plateau
Plateaus and hill ranges of Peninsular India: Deccan plateau: Maharashtra Plateau?
- The Maharashtra Plateau lies in Maharashtra.
- It forms the northern part of the Deccan Plateau.
- Much of the region is underlain by basaltic rocks of lava origin [Most of the Deccan Traps lies in this region].
- The area looks like a rolling plain due to weathering.
- The horizontal lava sheets have led to the formation of typical Deccan Trap topography [step like].
- The broad and shallow valleys of the Godavari, the Bhima and the Krishna are flanked [bordered on the opposite sides] by flat-topped steep sided hills and ridges.
- The entire area is covered by black cotton soil known as regur.
Plateaus and hill ranges of Peninsular India: Deccan plateau: Karnataka Plateau
- AKA Mysore plateau. Lies to the south of the Maharashtra plateau.
- The area looks like a rolling plateau with an average elevation of 600-900 m.
- Drainage:
- It is highly dissected by numerous rivers rising from the Western Ghats.
- contains the heads of Tungabhadra and Cauvery rivers
- The general trend of the hills is either parallel to the Western Ghats or across it.
- The highest peak (1913 m) is at Mulangiri in Baba Budan Hills in Chikmaglur district.
- The plateau is divided into two parts called Malnad and Maidan.
- The Malnad in Kannada means hill country. It is dissected into deep valleys covered with dense forests.
- The Maidan on the other hand is formed of rolling plain with low granite hills.
- The plateau tapers between the Western Ghats and the Eastern Ghats in the south and merges with the Niligiri hills there.
Plateaus and hill ranges of Peninsular India: Deccan plateau: Telangana Plateau?
- The Telangana plateau consists of Archaean gneisses.
- It’s average elevation is 500-600 m.
- The southern part is higher than its northern counterpart.
- The region is drained by three river systems, the Godavari, the Krishna and the Penneru.
- The entire plateau is divided into Ghats and the Peneplains (a vast featureless, undulating plain which the last stage of deposition process).
Plateaus and hill ranges of Peninsular India: Deccan plateau: Chhatisgarh Plain?
- The Chhattisgarh plain is the only plain worth the name in the Peninsular plateau.
- It is a saucer shaped depression drained by the upper Mahanadi.
- The whole basin lies between the Maikala Range and the Odisha hills.
- The region was once ruled by Haithaivanshi Rajputs from whose thirty six forts (Chhattisgarh) it derives its name.
- The basin is laid with nearly horizontal beds of limestone and shales.
- The general elevation of the plain ranges from 250 m in the east to 330 m in the west.
Aravali range?
- They are aligned in north-east to south-west direction.
- They run for about 800 km between Delhi and Palanpur in Gujarat.
- They are one of the oldest (very old) fold mountains of the world and the oldest in India. {Fold Mountains – Block Mountains}
- After its formation in Archaean Era (several 100 million years ago), its summits were nourishing glaciers and several summits were probably higher than the present day Himalayas.
- Now they are relict (remnants after severe weathering and erosion since millions of years) of the world’s oldest mountain formed as a result of folding (Archaean Era).
- They continue up to Hariddwar buried under the alluvium of Ganga Plains.
- The range is conspicuous in Rajasthan (continuous range south of Ajmer where it rises to 900 m.) but becomes less distinct in Haryana and Delhi (characterized by a chain of detached and discontinuous ridges beyond Ajmer).
- According to some geographers, one Branch of the Aravalis extends to the Lakshadweep Archipelago through the Gulf of Khambhat and the other into Andhra Pradesh and Karnataka.
- Prof S P Chatterjee:
- Aravali occupies the site of an ancient geosyncline and was uplifted and folded into a synclinorium for the first time during Algonkian age, 600-7– mya.
- In the past, it formed India’s main watershed, extending from Kumaon Himalaya to farthest end of Peninsular plateau, with possibly one of its arms reaching across Central India
- Its peaks reached beyond snow line. however it was gradually eroded.
- Evidence to suggest that in late Mesozoic time (100mya) the peneplained Aravali was uplifted for the second time
- It’s general elevation is only 400-600 m, with few hills well above 1,000 m.
- At the south-west extremity the range rises to over 1,000 m. Here Mt. Abu (1,158 m), a small hilly block, is separated from the main range by the valley of the Banas. Guru Sikhar (1,722 m), the highest peak, is situated in Mt. Abu.
- Pipli Ghat, Dewair and Desuri passes allow movement by roads and railways.
Vindhyan range?
- The Vindhyan Range, overlooking the Narmada valley, rises as an escarpment (a long, steep slope at the edge of a plateau or separating areas of land at different heights) flanking the northern edge of the Narmada-Son Trough
- It runs more or less parallel to the Narmada Valley in an east-west direction from Jobat in Gujarat to Sasaram in Bihar for a distance of over 1,200 km.
- The general elevation of the Vindhyan Range is 300 to 650 m.
- Most parts of the Vindhayan Range are composed of horizontally bedded sedimentary rocks of ancient age. {Rock System}
- The Vindhyas are continued eastwards as the Bharner and Kaimur hills.
- This range acts as a watershed between the Ganga system and the river systems of south India.
- The rivers Chambal, Betwa and Ken rise within 30 km of the Narmada.
Satpura range?
(refer Geog physical settings folder)
- Satpura range is a series of seven mountains
- The Satpura Range is a horst mountain and is flanked by Narmada Graben in the north and much smaller but parallel Tapi Graben in the south. At its eastern end, the Satpura range meets the hills of the Chotanagpur Plateau.
- The range rises in eastern Gujarat running east through the border of Maharashtra and Madhya Pradesh and ends in Chhattisgarh.
- It stretches for a distance of about 900 km.
- These hills seem to be effected by tectinic disturbances. Parts of the Satpuras have been folded and upheaved. They are regarded as structural uplift or ‘horst’. No other east-west tectonic mountain of peninsular India is as high as Satpura
- The 7 hills are:
- Rajpipla hills
- Gawligarh hills
- Mahadeo hills
- Maikal hills
- satmala hills
- ajanta hills
- nirmal hills
- Dhupgarh (1,350 m) near Pachmarhi on Mahadev Hills is the highest peak.
- Amarkantak (1,127 m) is another important peak.
-
drainage:
- The Narmada River originates from north-eastern end of Satpura in Amarkantak
- The Tapti River originates in the eastern-central part of Satpura, crossing the range in the center and running west at the range’s southern slopes
Western Ghats: about? origin?
- from mouth of Tapi river to Kanyakumari; almost 1600km; avg width 80km
- origin:
- Possibly not a mountain range but the western edge of peninsular Plateau
- originated due to separation of Indian plate from african plate in cretaceous age, 170mya
- During himalaya formation, the western part of WG slid down along vertical fault and was submerged. Thus, the remaining WG appeared to stand upright along the western coast.
- During creatceous-Eocene period lava outpour, the northern part of WG was covered and the present form of WG was achieved.
Western Ghats: Structure?
- North Sahyadri (Tapti to Goa):
- originated contemporaneous with Aravalli during Chernian movement; volcanic landforms like mesas and buttes are found
- Middle Sahyadri (Goa to Mangalore)
- granite and Gneiss are pre-dominant which are covered by lava layer at places
- undulating topography created due to erosion
- Southern sahyadri (Mangalore to Kanyakumari)
- granite and gneiss
