Irrigation tanks in the Kaveri River Delta, South India

Mapping Irrigation Tanks

The Application

This application was created by Charlotte Evans (Lancaster University) and Chris Fleet (National Library of Scotland). It is part of a PhD project studying water histories and digital mapping in the Kaveri river delta.

The map aims to highlight the irrigation tank features on maps from the British Survey of India map collection from the first half of the 20th century. The side by side viewer allows the user to see how the landscape has changed over time through satellite imagery. It allows us to see whether the irrigation tanks are still visible, have become smaller, or have been replaced by buildings, roads, farmland etc.

The application uses open-source software, and we have made it available on Github for onward re-use.

Irrigation Tanks

These man-made features were once abundant across South India. This form of water management can be traced back to the Bronze Age in India (3000 BCE). They are used to capture and store monsoon rains, allowing the water to be used for irrigation and domestic uses throughout the dry season. To be successful, irrigation tanks require constant maintenance from the local communities. However, with newer ways to access and store water such as wells and canals, many of these tanks have fallen into disrepair.

Whilst irrigation tanks could never be the answer to India’s water scarcity problems, studying such ancient methods of water management allows us to understand one piece of the puzzle. They offer a sustainable, if intensive, strategy to water management. There are various projects aiming to rehabilitate tanks to provide a source of water for irrigation alongside already well-tapped wells and canals.

Tanjore / Thanjavur

The application so far maps irrigation tank features from Thanjavur (formerly Tanjore) district in South India. This region was highlighted for study during a AHRC funded research project ‘Life of Water’ with Dr Aditya Ramsh (University of Manchester). This project studied the changing rainfall patterns, cropping patterns and irrigation techniques in Thanjavur following the opening of the Mettur Dam in 1934. This dam, built in the British Madras Presidency, aimed to double the cropping season in Thanjavur by providing a new source of water storage to expand the canal network in the district.

The research was continued through my PhD project where I chose to trace irrigation tank features on the Survey of India maps. I hope to further this research following fieldwork to South India.

Maps and Digital Methods

The collection of Survey of India maps held at the National Library of Scotland date from 1916 to 1951. There are two editions of the maps held at the library, allowing great insights into changes in the landscape during this era. NLS Survey of India maps.

The PhD project aims to use methods from the field of Digital Humanities to offer new insights to the environmental pasts and presents of South India. Digital mapping and GIS (geographic information systems / science) are key to understanding the geographies and spatial connections of water and the landscapes for this project. Tracing the tank features of Tanjore was the first step in recognising an ancient method of water management in decline. This online web-application allows users to visually understand this change in a tangible and interactive manner.

The Future of this Project