Physiography of Tripura
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The physiography of
Tripura mainly consists of hills, valleys and plains which together form the
physical landscape of the state. Nearly 60% of the total geographical area of
Tripura is occupied by hills, while about 40% consists of valleys and plains. The
state shows a typical folded relief structure formed by tertiary sedimentary
rocks such as sandstone, shale and clay. These rocks were folded due to
tectonic movements, resulting in a series of parallel hill ranges separated by
valleys.
The physiographic relief of Tripura is considered geologically young and
immature. Erosion, weathering and river activities are still actively modifying
the land surface. Continuous deposition of sediments in valleys and plains and
erosion of hills are common processes shaping the landscape.
The hill ranges generally run from north to south direction and remain
almost parallel. Because of this arrangement, elongated valleys have formed
between them. The general slope of the land is from east towards west and
south-west, which controls river flow direction, settlement distribution and
agricultural patterns.
Major Physiographic
Divisions of Tripura
Physiographically, Tripura can be broadly divided into three main
divisions:
- The
Hilly Region (Structural Hill Ranges)
- The
Intervening Valley Region
- The
Plain Region
These three divisions together form the basic physical framework of the
state.
1. The Hilly Region
The hilly region is the most dominant physiographic unit of Tripura,
covering around three-fifths of the total area. These hills are structural
anticlines formed by folding of sedimentary rocks. The hills are not very high
but are elongated and continuous.
The five major hill ranges from west to east are:
a) Baramura–Devtamura
Range :- This westernmost hill range is about 47 km long. It stretches from the
northern border towards the south. The Gomati River originates from this range
and cuts through it, forming the famous Devtamura gorge. The highest peak here
is Satsum, about 813 feet high. This range acts as an important watershed.
b) Atharamura Range
:- This is one of the longest hill ranges of Tripura, about 106 km long.
The name means “eighteen hills.” The range runs almost straight north to south.
Average elevation is above 1000 feet, with the highest peak about 1627 feet.
Several smaller ridges branch off from this main range.
c) Longtharai Range
:- Located in central Tripura, this range is about 48 km long. It forms an
important physical boundary of certain administrative subdivisions like
Kailashahar and Kamalpur. The highest peak is around 515 metres.
d) Sakantang Range :-
This hill
range extends about 58 km, which forms the boundaries of the Dharmanagar and
Kailashahar Sub-division. Its northern portion is known as the Unakoti region.
The highest peak known as Sakhan which is around 840 metres. Forest cover and tribal
settlements are common here.
e) Jampui Hills :- This is the
easternmost and highest hill range of Tripura, about 74 km long. The highest
peak of the state, Betleing Sib (about 3080 ft), is located here. The region is
well known for orange cultivation, scenic beauty and moderate climate.
Besides
these major ranges, smaller structural features such as Gazalia–Mamunbhagna
anticline, Sonamura anticline and Agartala dome are also present. Spurs, minor
ridges, escarpments and narrow gorges formed by river erosion add complexity to
the hill relief.
2. The Valley Region
Between the parallel hill ranges, several elongated valleys have
developed. These valleys are synclinal depressions formed due to folding and
later modified by river deposition. They are generally fertile because rivers
bring alluvial soil from hills.
The valleys are usually 16–18 km wide and provide suitable land for
agriculture, settlement and communication. Most towns, roads and agricultural
activities are concentrated in these valleys.
Important valleys include:
- Agartala–Udaipur–Sabrum
valley
- Khowai–Teliamura–Amarpur
valley
- Ambassa–Gandacherra
valley
- Kailashahar–Kumarghat
valley
- Dharmanagar–Panisagar
valley
These valleys are economically very important because they support
cultivation of rice and other crops. They also act as communication corridors
linking different parts of the state.
3. The Plain Region
The plain region is mainly located in western and southern Tripura.
These plains are piedmont plains formed by deposition of sediments brought down
by rivers from surrounding hills. The approximate area of plains is about 3500
square kilometres.
The plains gradually merge with the Bangladesh plains. Rivers such as
Manu, Khowai, Titas, Gumti, Muhuri and Feni have contributed to their formation
through deposition and erosion. Because of fertile soil, gentle slope and
better accessibility, this region has relatively higher population density and
more developed agriculture compared to the hill region.
However, even within plains, isolated hillocks are found which indicate
past erosion of hills.
Minor Physiographic Features
Several smaller but important physiographic features add diversity to
Tripura’s relief.
Tillas are small isolated hillocks
scattered across Tripura. These are remnants of old eroded hill ranges. They
influence local drainage, agriculture and settlement patterns. Some villages
are located near these tillas for protection from floods.
Lungas are narrow
low-lying alluvial valleys found across plains of Tripura. These areas are
fertile because of deposition of fine sediments by rivers. However, during
heavy rainfall, these areas may experience temporary waterlogging.
Spurs, escarpments, minor ridges and gorges are also common features.
Rivers cutting through hills form narrow gorges and steep slopes. Continuous
erosion, landslides and deposition are common due to heavy rainfall.
These minor features,
though small in size, are very important for understanding local land use,
agriculture and settlement patterns.
Drainage of Tripura
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Tripura is
drained by several rivers and small streams. The state is crossed by many
rivers mainly because of its hilly relief. Most rivers originate from the hill
ranges of Tripura and then flow towards Bangladesh.
The hill ranges of Tripura run mainly from north to south direction.
Because of this, rivers flow mainly northward, westward and south-westward.
These rivers play an important role in shaping the land surface by erosion,
transportation and deposition. They also form fertile valleys and plains which
are suitable for agriculture and settlement.
There are about ten major rivers in the state, along with many smaller
tributaries and hill streams.
Classification of Rivers of
Tripura
According to location and direction of flow,
the rivers of Tripura are divided into four groups:
a) Northern Rivers
These rivers flow mainly
towards the north into Bangladesh.
Important rivers include:
- Dolai (Dhalai)
- Manu
- Juri
- Longai
These rivers generally originate from hill ranges such as Jampui, Sakhan
and Atharamura.
b) Western Rivers
These rivers flow mainly towards the west.
Main rivers:
- Khowai
- Howrah (Haora)
Some smaller tributaries like Lohar nala,
Sonai and Khata khal also belong to this group. These rivers are important for
the western plains and settlement areas.
c) Central Rivers
These rivers flow mainly through the central
part of Tripura.
Main river:
- Gumti (Gomati)
This is the largest and most important river
of Tripura and plays a major role in agriculture and water resources.
* ‘The Dumbur reservoir’ is
located in river Gomati.
d) Southern Rivers
These rivers flow mainly towards south-west
direction.
Main rivers:
- Fenny (Feni)
- Muhuri
Some parts of these rivers form the boundary
between India and Bangladesh.
Catchment Areas of Rivers
Most rivers of Tripura originate from hill
ranges which act as important catchment areas. The main hill sources include:
- Jampui hill range
- Atharamura hill range
- Longtharai hill range
- Baramura–Devtamura hill range
The Gomati river originates near the Dumbur
area, where an important water source is located. Rivers like Longai, Juri and
Deo originate from the Jampui hills. Some upper courses of rivers have local
names such as Saisilu, Tuilampui and Sai.
Many small tributaries join the main rivers
from both left and right banks, forming a well-developed drainage network.
Major Rivers of Tripura
1. Gomati
River
Formed
by the confluence of the Raima and Sarma rivers, the Gomati is the most
important and largest river in the state. It flows through the fertile plains
of Udaipur and Sonamura before entering Bangladesh. The famous Dumbur dam is
located on this river, generating hydroelectric power for the region.
2. Khowai
River
Originating
from the Longtharai Range, the Khowai River flows northwards through the Khowai
district. It is known for its seasonal fluctuations and plays a vital role in
the irrigation of the surrounding agricultural lands. It eventually crosses the
international border into the Sylhet district of Bangladesh.
3. Manu
River
As
the longest river in Tripura, the Manu originates from the Sakhan Range and
flows through the North Tripura and Unakoti districts. It passes through the
towns of Kumarghat and Kailashahar, a significant historical and
administrative center. The river is a major source of water for both domestic
and agricultural use in northern Tripura.
4. Haora
River
The Haora
River is the lifeline of the capital city, Agartala. It originates from the
Baramura Range and flows westward, providing the primary water source for the
city's inhabitants. Despite its relatively short length, its proximity to the
state's urban core makes it geographically and economically significant.
5. Muhuri
River
Flowing
through the South Tripura district, the Muhuri River originates from the
Deotamura Range. It passes through the town of Belonia and serves as a natural
boundary between India and Bangladesh in certain stretches. The Muhuri Char
area is a well-known geographical feature associated with this river.
6. Feni
River
The Feni
River serves as a vital international border between South Tripura and
Bangladesh. It originates from the hill ranges of South Tripura and eventually
flows into the Bay of Bengal. The Maitri Setu (Friendship Bridge) built over
this river has significantly boosted connectivity and trade between the two
countries.
7. Dhalai
River
Originating
from the Longtharai Range, the Dhalai River flows northwards through the Dhalai
district, to which it gives its name. It passes through Ambassa and Kamalpur
before entering Bangladesh. The river basin is characterized by dense forests
and is essential for the local tribal communities.
8. Juri
River
The Juri
River flows through the North Tripura district, originating from the Jampui
Hills. It follows a northward course through the Dharmanagar sub-division
before crossing into Bangladesh. Its waters are crucial for the tea gardens and
betel nut plantations prevalent in this region.
9. Deo
River
The Deo River
is a major tributary of the Manu River, originating from the Jampui Range. It
flows through the hilly terrain of North Tripura, joining the Manu near Kumarghat.
The river is known for its scenic beauty and the rocky terrain through which it
navigates.
10. Longai
River
Originating
from the Jampui Hills, the Longai River flows through the North Tripura
district and moves towards the Karimganj district of Assam before entering
Bangladesh. It is one of the few rivers in the state that provides a drainage
link towards the Barak Valley.
Characteristics of Rivers of
Tripura
Rain-fed rivers :- Most rivers depend mainly on monsoon
rainfall. Water level increases during rainy season and decreases in dry
season.
Origin from hills :- Almost all rivers originate from hill ranges
like Jampui, Atharamura, Longtharai and Baramura–Devtamura hills which act as
catchment areas.
Seasonal flow :- River water varies seasonally. Heavy rainfall
causes floods, while in dry months rivers become shallow.
Formation of fertile
land
:- Rivers carry silt
and sand from hills and deposit them in valleys and plains, making soil fertile
for agriculture.
Erosion and deposition :- Rivers erode hill slopes and deposit
sediments downstream, shaping the landforms of Tripura.
Importance
of Drainage System
Agricultural support :- Rivers
provide water for irrigation and help crop cultivation.
Soil fertility :- Alluvial
deposits from rivers increase soil fertility.
Settlement development :- Many towns
and villages develop near rivers due to water availability.
Economic use :- Rivers
support fisheries, small irrigation projects and local livelihood.
Physiographic influence :- Rivers
shape valleys, plains and overall landforms of the state.
Thus, the
drainage system of Tripura consists mainly of hill-origin rivers flowing
towards Bangladesh. These rivers play an important role in agriculture,
settlement, physiography and economic life of the state.