India’s coastline just got longer, ‘added’ more than 3,500 km —Know how it acquired

The coastline of India has increased by 3,582 km, or nearly 48 per cent after accurate measurements without any acquisition of territory. In addition, the country's islands have also increased slightly following the reassessment without changing the ground situation.

In the 1970s, the length of the coastline was measured at 7,516 km. But, following the assessment, it is now measured to be 11,098 km. The previous measurement was based on data that were of the scale of 1:4,500,000 or smaller. Later, with the passage of time, enhanced and accurate resolution data became available, calculating the length of the coastline using data that had a scale of 1:250,000, as per the Indian Express report.

Coastlines are naturally uneven and complex, but when data resolution improves, it’s like switching from a larger measuring stick to a smaller one. For instance, a one-kilometer ruler would overlook minor variations in the land’s shape that a one-meter ruler would easily detect.

With higher resolution, we can map the coastline’s curves and indentations in much finer detail. Lower-resolution data tends to smooth out these features, making jagged coastlines appear more linear, which results in a shorter total length.

Can coastline be measured precisely?

Previously, coastline measurements were done using traditional, manual techniques. Now, advanced GIS software allows for much more precise mapping of terrain irregularities. Another factor behind the increased length is the inclusion of coastal stretches of offshore islands that earlier calculations missed. These islands were often too small to show up in low-resolution maps or were excluded due to the limitations of manual measurement processes.

Although the newly revised measurement of India’s coastline is more accurate than before, it still doesn’t reflect the coastline’s true length. In reality, the exact length of India’s, or any, coastline cannot be precisely measured. This is due to what’s known as the coastline paradox.

Natural formations like coastlines are extremely irregular and don’t have a fixed length. The measured length depends entirely on the resolution used. The finer the measurement scale, the more details are captured, and the longer the coastline appears.

This paradox also applies to other natural features like mountain chains and river systems. Rivers, for instance, flow in winding, unpredictable paths, and their banks are rarely straight.

Trying to measure the length of a river by tracing its banks runs into the same issue as measuring a coastline. However, river lengths are typically measured along the main course rather than the edges, which avoids this complication.