Eri Systems in Tamil Nadu
Overview: The Eri system is a traditional water management practice in Tamil Nadu, primarily designed for irrigation and groundwater recharge. These systems consist of a series of tanks, channels, embankments, and sluice gates, and they have been integral to the region's agricultural success for centuries.
Components of the Eri System
Tanks:
- Function: The main storage structure that collects and stores rainwater.
- Example: The Veeranam Tank in Cuddalore district, which is one of the largest tanks in Tamil Nadu, with a capacity of 1.465 billion cubic feet.
- Design: The tanks are typically designed to capture surface runoff during the monsoon season and have a large storage capacity to provide water during dry periods.
Channels:
- Function: Channels distribute water from the tank to the agricultural fields.
- Example: The network of channels in the Kollidam sub-basin, which distributes water from various Eris to the fields.
- Design: Channels are often unlined earthen structures that guide water using gravity. They are strategically placed to cover the maximum agricultural area.
Embankments:
- Function: Embankments form the boundary of the tank, holding the stored water.
- Example: The earthen embankments around the Perumal Eri in Tirunelveli.
- Design: Embankments are constructed using locally available materials such as soil and stones. They are regularly maintained to prevent breaches.
Sluice Gates:
- Function: Control the release of water from the tank to the channels.
- Example: The manually operated sluice gates in the Madurai district's Eris.
- Design: Sluice gates are typically made of wood or metal and are operated by villagers to regulate water flow based on the irrigation schedule.
Veeranam Tank Irrigation System in Tamil Nadu
Overview: The Veeranam Tank is one of the largest and most well-known irrigation systems in Tamil Nadu. Located in Cuddalore district, it has played a crucial role in supporting agriculture and providing drinking water to the region. This traditional tank system exemplifies the components and operation of effective tank irrigation in Tamil Nadu.
Components of the Veeranam Tank Irrigation System
Tanks:
- Description: The Veeranam Tank covers an area of about 14,000 acres with a storage capacity of 1.465 billion cubic feet. It is a vast reservoir designed to capture and store rainwater during the monsoon season.
- Role: The primary function of the tank is to store water, which is then used for irrigation and drinking purposes. The tank receives inflows from the Kollidam River, especially during the northeast monsoon.
Channels:
- Description: The Veeranam Tank has an extensive network of channels that distribute water to agricultural fields. These channels are essential for delivering water from the tank to the farmers.
- Key Channels: Some of the primary channels include the Vadavar Channel, which is a major feeder canal that channels water from the Kollidam River into the Veeranam Tank. Smaller distributary channels then convey water from the tank to the fields.
- Function: Channels help in the equitable distribution of water across the fields, ensuring that even distant fields receive adequate water supply.
Embankments:
- Description: The tank is surrounded by robust earthen embankments, which are critical for holding the stored water.
- Construction: These embankments are built using local soil and are regularly maintained to prevent breaches and seepage.
- Function: The embankments not only contain the water but also prevent overflow and protect nearby areas from flooding.
Sluice Gates:
- Description: Sluice gates are strategically placed along the embankments to control the release of water from the tank into the channels.
- Operation: The gates are manually operated, allowing precise control over the amount of water released. This ensures that water distribution aligns with the irrigation needs of the crops.
- Function: Sluice gates help manage the water levels in the tank, prevent wastage, and ensure that water is available throughout the irrigation period.
Real Example of the Veeranam Tank
Location:
- The Veeranam Tank is situated in the Cuddalore district of Tamil Nadu, approximately 14 km from the town of Chidambaram.
Historical Significance:
- The tank dates back to the Chola dynasty, illustrating the advanced water management practices of ancient Tamil Nadu. It has been a lifeline for agriculture in the region for centuries.
Modern Usage:
- Besides irrigation, the Veeranam Tank is also a crucial source of drinking water for the city of Chennai, especially during periods of water scarcity.
- The tank supports the irrigation needs of thousands of acres of paddy fields, making it an integral part of the local agricultural economy.
Challenges and Maintenance:
- Regular desilting is necessary to maintain the storage capacity of the tank.
- The embankments require constant monitoring and reinforcement to ensure their integrity.
- Managing water distribution efficiently, especially during drought periods, is critical to balancing the needs of agriculture and urban water supply.
Conclusion
The Veeranam Tank irrigation system is a prime example of traditional water management in Tamil Nadu. With its vast storage capacity, extensive channel network, robust embankments, and effective sluice gates, it continues to play a vital role in supporting both agriculture and urban water needs. Proper maintenance and efficient water management are key to sustaining the benefits provided by this historic irrigation system.