Indus Plain: Upper Reaches & Landforms

• River Indus and its tributaries drain the Indus Plain throughout most of Punjab and the central part of Sindh.

Upper Indus Plain

• The northern part of the Indus Plain
• The five main tributaries of the Indus including the Beas have all joined together by Panjnad
• After the Sutlej joins the Chenab at Panjnad, the river is called the Panjnad
• The River Panjnad flows for a further 72 kilometers before joining the Indus near Mithankot.
• General slope towards the sea remains gentle, with an average gradient of one metre to five kilometres.

Landforms of the Indus Plain

• Active flood plains
• Old flood plains
• Alluvial terraces
• Rolling sand plains
• Piedmont plains
• Tidal deltas

Active Flood Plain

• The narrow strip of land on either side of the river
• Locally known as 'bet' or 'khaddar' land
• Inundated almost every year
• The land is marked with dry and braided channels rich in alluvium at the end of the rainy season
• Found along all the rivers except the southern half of the River Ravi
• The flood plain is around 40km wide where the Indus enters the Lower Indus Plain, making it an important farming area

Meanders and Oxbow Lakes

• Formed by erosion and deposition
• Shown where the Indus enters the Lower Indus Plain
• River deposits material on its bank to form levees

Old Flood Plain

• Covers the area between the alluvial terraces and the active flood plain
• Flooded only during heavy monsoon rainfall
• Covered with 'old alluvium'
• Features abandoned channels, meander scars and remains of oxbows

Alluvial Terraces

• Areas of higher ground between rivers formed by erosion of old alluvium
• Formed in the Upper Indus Plain in Chaj, Rechna and Bari Doabs
• Also called 'scalloped interfluves'
• Sandal Bar on Rechna Doab, Ganji Bar and Nili Bar on Bari Doab and Kirana Bar on Chaj Doab are prominent alluvial terraces
• Part of the Bahawalpur Plain falls within the boundary of the Indus Plain
• The Bahawalpur Plain is at the same height as the bars of the doabs and is also an alluvial terrace

Doab

• Land between two rivers at confluence
• When the rivers enter a mature valley, topographical features form on the doab because of erosion and deposition
• Favoured areas for farming, construction, and other industrial or business activities

Piedmont Plains

• Located at the foothills of the Sulaiman, Kirthar and Himalayan Mountains
• Most dominant features are alluvial fans or cones that develop eastward from the Sulaiman and Kirthar Mountains
• Most rivers or streams coming from the Sulaiman and Kirthar Ranges have low water flows and become active only during the rainy season
• Rivers become slow and split into narrow channels that fan out when they reach the foothills
• Gravel, sand and alluvium deposited by rivers form alluvial fans
• Sulaiman Piedmont plain is known as Derajat and is mainly agricultural

Tidal Delta

• Located to the south of Thatta
• Deltas are often triangular or fan-shaped with the main distributaries branching off like the ribs of a fan
• A river's speed is checked when it flows into the sea, and it drops its load of alluvium on the sea floor
• Deposition of alluvium on the banks of the distributaries form levees
• Sea water fills the troughs between the distributaries, causing swamps
• Has tidal flats with mangrove swamps
• Coastal area is generally low and flat

Indus Delta

• Located to the east of Karachi and includes Thatta, Keti Bandar, Jati, Ladian and other small settlements
• Has a low population density and agriculture is limited due to swampy land, saline soil and a low annual rainfall of 125mm-250mm
• Indus has the world's fifth-biggest river delta and the delta region is impacted by irrigation and sediment loss
• The Indus carried 300 million tonnes of sediment per year into the Arabian Sea
• By 2000, the river was bringing less than 100 million tonnes of sediment per year because sea erodes it

Cuestas

• Prominent features occurring on the Lower Indus Plain
• Ridges made of limestone
• Has a steep (or scarp) slope on one side and a gentle (or dip) slope on the other side

Economic Activities

• The Indus Plain is the most productive region of Pakistan and is known for agriculture
• Doabs of the Upper Indus Plain and the old and active flood plains of the Lower Indus Plains are excellent areas for farming
• More than 80% of the total cultivated area of Pakistan has been located in the Indus Plain
• The flat land is ideal for canal irrigation
• The most developed region of Pakistan, with dense transport network and electricity supply

Upper Indus Plain

• Located in the northern part of the Indus Plain
• River Indus and its major tributaries flow here
• The Jhelum, Ravi and Sutlej have joined the Chenab at Panynad to form the River Panjnad which joins the Indus near Mithankot
• Nearly flat and undulating plain sloping towards the southwest
• The average width of the Indus is 1.4 km till Kalabagh and 1.6 km near Sukkur
• River Indus is in its middle course in the north and enters its lower course towards the south
• Both erosion and deposition take place with deposition becoming increasingly dominant southwards
• Features Meanders, oxbow lakes, braided channels and levées in doab areas
• Has alluvial terraces or bars formed between the rivers
• Has a Piedmont Plain with alluvial fans to the north and west

Lower Indus Plain

• Located in the southern part of the Indus Plain
• The River Indus flows alone
• River Indus flows into the Arabian Sea south of Thatta through its distributaries which flow across its delta
• Nearly flat undulating plain sloping towards the south
• Width of the River Indus is 1.6 km
• River Indus is in its lower course
• Deposition is the main function of River Indus
• Features meanders, oxbow lakes, braided channels and levées
• Alluvial terraces or bars are non-existent
• Has a Piedmont Plain with alluvial fans to the west

Desert Areas

• Pakistan has three desert areas:
  • The Sindh Sagar Doab or Thal Desert lies between the River Indus and River Jhelum
  • The Thar Desert or South-Eastern Desert is in south-eastern Pakistan
  • The Kharan Desert
• Winds are the most important agent shaping desert areas
• Lack of vegetation and the water table remains low

Sand Dunes

• The most dominant desert feature
• A mound or a ridge of sand, formed where an obstacle occurs in the path of moving sand
• direction of sand dunes is mainly longitudinal