Pampa, Meenachil, Achankovil and Manimala, four major rivers in Kerala flow through the Kuttanad region. The South West monsoons and the North East monsoons bring with them the perennial problem of floods, engendered by the region's four major rivers.
Kuttanad is divided in to six agro- ecological zones based on the climate, height from the mean sea level, influence of rivers, flood risk, risk of saline water intrusion, soil type and fertility and the cropping pattern.
- Upper Kuttanad: The south eastern side of Kuttanad with comparatively high lands has elevation ranging from 0.5 to 6 m above MSL. Three major rivers include Achenkovil, Pampa and Manimala enter Kuttanad in this zone & it experiences low risk from saline intrusion and flood.
- Purakkad Kari: The western side of Upper Kuttanad zone, near to sea has high soil and water acidity owing to the presence of peaty soil (partially decomposed organic matter in high proportions). The risk of saline water intrusion is high compared to other zones, since it is near the sea coast.
- Lower Kuttanad: Lying north of Upper Kuttanad, the area lies 1 - 2 m below MSL in some parts. The risk from flood and saline water intrusion is the highest here & the flood season is slightly of more duration compared to other zones.
- Kayal lands: Located north of Lower Kuttanad it includes Kayal rice fields, reclaimed by earthen bunding of the shallow portions of south eastern part of then Vembanad lake. These fields lie 1 to 2m below MSL. The flood risk and saline water intrusion is high here.
- North Kuttanad: This zone lies north of Kayal lands. It was formed by the natural reclamation of Vembanad Lake due to the silt carried by Meenachil River and its distributaries. The western portions lie 0.5m below MSL and the eastern portion lie 1m above MSL. Even though the flood risk is high, saline water intrusion is the major problem here since it is very near to the Cochin estuary.
- Vaikom Kari: This zone lies at the northern most end of Kuttanad. It lies 0.5m below MSL in western portions and upto 6m above in eastern portions. The area lies at the northern side of Thanneermukkom barrage, so the risk of saline water intrusion is the highest here in summer.