| Physical |
| Cauvery basin spans an area around 81155 km2 and runs from a northwest to south eastern direction along a general south easterly slope. Catchment area of this basin can be divided into three sections; upper catchment areas with steep slopes; middle catchment area mostly in Tamil Nadu and lower catchment area which is confined to the plains in Tamil Nadu. |
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| Soil: |
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| Soil types vary all across the basin but the red soils are the predominant category of soils followed by black soils. The highland areas which fall in Karnataka have lateritic soils, reddish brown in colour. These soils are shallow, acidic to neutral and are fertile, good for agricultural practices. Highlands of Kerala also have red loam soils along with some areas of black soils which are fertile, rich in organic content and because of high nitrogen content are excellent for agriculture. |
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| Lowlands and plains of Karnataka have reddish brown soils which are neutral to acidic in nature and are well drained. In some lowlands though, the soils are neutral to weakly alkaline and have higher water holding capacity.
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| The soils in Tamil Nadu on the other hand are deep soils with increasing depth towards the coast. These soils have high clay content, low draining capacity, poor nitrate, poor phosphorus and high potassium and lime content. In the south eastern corner of the basin, some area is swampy which is predominantly alluvial clay with poor drainage. |
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| Colour of Soil |
Location |
| Red Loamy |
The Eastern slope of Western Ghats in Karnataka State and upper reaches of the Karnataka basin area around KR Sagar & also entire Vrishabhavathi valley south of Mandya |
| Red Sandy |
Bhavani sub basin of Palghat Disttin Kerala, Major part of the middle and lower Karnataka basin, Tanjavur, COimbatore, Nilgiris, Periyar, Dharmapuri, Anna, Salem in Tamilnadu |
| Laterite |
A small part north west of Mercara, a small part in Wayanad Distt of Kerala State |
| Forest Loamy |
Wayanad District of Kabani basin |
| Loamy Organic |
Coimbatore district of Tamil Nadu |
| Medium Black Soil |
Idukki District of Kerala State |
| Reddish Brown |
Thanjavur, Tiruchim Salem, Periyar, Anna & Coimbatore District. |
| Black |
Thanjavur & Coimbatore District of Tamil Nadu |
| Sandy |
South Arcot |
| Alluvial Clay with around 50,000 Ha of Sand |
Extreme south-east corner of the Cauvery basin |
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| Source: CPCB, 1995: Comprehensive river basin report |
