Kumizhithoombu of Chola Period

KUMIZHITHOOMBU OF CHOLA PERIOD

A Kumizhithoombu is a scientifically designed system to remove water and silt from a lake.

1. The Importance of Kumizhithoombi

The Tamils have been managing irrigation water effectively by establishing a water management system called Kumizhithoombi in the big lakes of Tamil Nadu 2000 years ago. This Kumizhithoombi system not only provided water for irrigation but also prevented the lakes from the formation of silt and losing the depth.

Proof

1. 'Tamil Irrigation System Two Thousand Years Ago' - Kudavayil Balasubramanian.

2. 'Pity of a Dust Storm on a Waved Lake' - Kula. Shanmuga Sundaram.

The Causes for Lake / Pond Draining Away

The main reason for the water bodies losing the depth is that when rainwater comes to water bodies like lakes, ponds through drains and streams, they come together with water, silt and sediments.

The Difference between Sluice and Bubble (Kumizhi)

The sluices do the job of draining the water. The bubbles, in addition to draining water, also remove sediments from lakes, ponds and sluices.

2. Structure of Kumizhithoombi

Bubbles that release water to irrigation canals are not cosntructed like sluices on lake shores. The bubble (Kumuzhi) is set in the lake 200-300 feet away from the lake shore.

A strong embankment is built on the ground level of the lake. Then, a black stone tank is made under it. On the top of the tank, there is a large drain hole for the water to flow. They drill a hole of the same size under the tank and connect it to the irrigation canal outside the lake through a tunnel.

‘Thoombukkal' is used to close and open the hole for water to flow into the tank. There is a stone frame to move the Thoombukkal up and down.

There are three small holes on the side (or) ground level of the tank. They are called 'Serodi hole'.

3. The Mechanism of the Kumizhithoombu

When water is needed for irrigation, they swim in the lakes and dive to lift the thoombu stone that blocks the water hole above the tank. Hence, water required for irrigation is released. In this system under the lake, the water flows through the water hole at a pressure equal to the water level of the lake. The water pressure at the bottom of the lake is high. The pressure inside the stone plate is less. Due to this, slit and slimy water will seep in quickly through Serodi hole.

80% good water comes out of the lake through the Neerodi hole while 20% of the pulp water comes out of Serodi. In the same speed, good water is washed away. The soil water is also washed away. This will reduce silting in the lake.

Evidences

1. Rajarajan Thoombu: 'Sembian Mathevi Pereri' is the lake cut by Paranthak Chola's youngest son Kandarathitha in accordance with the wishes of his second wife, Sembian Mathevi. One of the sluices is named Rajarajan Thoombu in the name of Rajarajan.

2. The Kumizhithoombi erected during the reign of king Rajarajan contains inscriptions of the king. So it is the property of the government. It means that the Vandals will be punished by declared through an inscription that he will carry the sand of the feet of those who maintain such Kumizhithoombus.