Periyar River Basin, Kerala, Western Ghats

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India, Kerala, Aluva Municipality

The Western Ghats is a mountain range located on the western coast of India, stretching approximately 1.600 kilometres from Gujarat to Tamil Nadu. The Periyar River Basin is situated within the Western Ghats in the southern Indian state of Kerala. It covers an extensive area, including the Periyar National Park and Wildlife Sanctuary, which is spread across Idukki and Pathanamthitta districts.

The Periyar River and its tributaries support fish such as Dawkinsia apsara, Bhavania australis, Schistura sp. Crimson and other diverse fish species including the critically endangered Tor remadevii. The biotope includes aquatic plants, algae, rocks, and stones that provide habitats for underwater life, including fishes, aquatic insects, crustaceans, and molluscs.

Submitted by
Devagya Uikey
Approved by
Sven Kullander, Friedrich Bitter & Sujoy Banerjee
9.2580290, 77.4086914
Geographical region
Southern Asia
Drainage Basin
Arabian Sea
River catchment
Chokkampatti Mala
Water body type
Water body name
Periyar River
Water body part
Water body course
Middle course
Water body: tributary of
Tributary name
Muthirapuzha, Mullayar, Cheruthoni, Perinjankutti

Videos above and below water

Water Chemistry

Water information

Water type
Fresh water
Water color
Clear water
Water transparency
Concentration of sediments
Water temperature
22-28 °C
Water flow/curent

Chemical parameters

150 mg/l
100 mg/l
Dissolved Oxygen
62.09 %

Substrate in nature

Stone form
Submerged terrestrial vegetation

Aquatic Biotope

Date of collecting
Collecting area
Water depth
Air temperature
Partial shade


Affected by human activity
Affected by human activity
Surrounding area

The surrounding area is a lush and verdant landscape, with hills, forests, and lakes. One of the major places in the surrounding area of the Periyar River is Periyar National Park, a UNESCO World Heritage Site and one of the most popular tourist destinations in Kerala.

The park is home to a wide variety of animals, including elephants, tigers, leopards, and deer. Another beautiful spot is Rajahmalai, a hill located in the Periyar National Park popular for hiking and birdwatching. The summit of Rajamalai offers panoramic views of the surrounding landscape.

The weather in the surrounding area can vary depending on the location. The higher elevations in the Western Ghats receive more rain than the lower elevations. The weather can also be affected by the monsoon winds, which can bring heavy rains to the region. Overall, the weather is warm and humid, with a monsoon season that brings heavy rains.

Underwater landscape

Along the Periyar River basin, there are sections with pools and rapids that vary in depths, widths, and speeds of water flow depending on the geological characteristics of the region.

The riverbeds consist of different types of sediments, including sand, gravel, and rocks. Beneath the layer of sediments, there is a bedrock that forms the solid foundation of the river bed. The bedrock can consist of various types of rocks such as granite, gneiss, and schist, which are prevalent in the region.

The river supports a variety of aquatic plants such as Eleocharis acicularis, Hydrilla verticillata, Vallisneria spiralis, Nymphaea lotus, and Eichhornia crassipes.


  • Bhavania australis (Balitoridae)
  • Schistura sp. Crimson (Nemacheilidae)
  • Neochela dadiburjori (Danionidae)

Aquatic plants:

  • Salvinia natans (Salviniaceae)
  • Pontederia crassipes (Pontederiaceae)
  • Spirodela polyrhiza (Araceae)
Threats to ecology

The Periyar River Basin is known for its rich and diverse vegetation. It is classified as one of the world’s eight “hottest hotspots” of biological diversity. The region harbours an incredible variety of plant species, including tropical evergreen forests, moist deciduous forests, grasslands, and shola forests (high-altitude montane forests). Some prominent tree species found in the region include teak, rosewood, bamboo, jackfruit, mango, cardamom, and a variety of palms.

The dense forests provide habitat for numerous mammal species, including elephants, tigers, leopards, gaur (Indian bison), sambar deer, sloth bears, wild boars, and various species of primates like the Nilgiri langur and lion-tailed macaque. The region is also home to a wide variety of reptiles and amphibians, including snakes, lizards, turtles, frogs, and unique species like the Nilgiri burrowing frog.

The Periyar River Basin is known for its extensive floodplains, which are periodically inundated during the monsoon season. These floodplains support rich biodiversity and provide breeding grounds for many aquatic organisms. They are characterized by shallow water bodies, wetlands, and marshes.

In addition to the river system, there are several small lakes and reservoirs within the Periyar River Basin that serve as habitats for various fish species. The reservoirs are also home to the highly endangered Nilgiri mahseer (a species of carp), which is a prized game fish.

Riparian zone

Trees near the aquatic habitat
Many -

Comment by the expert

Sven Kullander:

Friedrich Bitter: Good general information and detailed videos about the water. However, there could have been more, especially about the fish and plants present in the aquarium.

Sujoy Banerjee: Quiet a good documentation, but there are specific research papers on Periyar River System. The Crimson loach is recorded from the Nilambur, Kerala, southern India, Chalyiar River System much north of Periyar River. Also Neochela dadiburjori (Menon 1952). Danionidae: Danioninae. formerly dadiburjori, Laubuca Menon 1952 is from the Challakuddy River system which is usually regarded as a different river system than that of Periyar. Water parameters as mentioned in reference papers are more hard than soft. Water temperature is mostly below 25°C in day time falling more during the night time. Not as high as 28°C as mentioned.