Revisiting Rennell's Dhaka map of 1776: Historical insights for the government's river, canal restoration plan

Among European settlers, the Portuguese were the first to arrive in eastern Bengal (present-day Chattogram, Bangladesh) in 1537 CE. Subsequently, other Europeans, such as the Dutch, British, French, Armenians, and Greeks, made their way to the region for trade and commerce. 

For their convenience in navigation and business activities, they prepared several maps of East Bengal. But as those maps were not drawn to scale, distances could not be measured accurately. 

The maps only provided general information about names and locations of places. After the East India Company took control of the region in 1757 CE, it recognised the need for a comprehensive map of Bengal, including Dhaka, for its own needs. 

To this end, in 1776 CE, British cartographer James Rennell prepared a precise and detailed map of Bengal. 

In order to achieve this, Rennell arrived in Bengal and was appointed as a Major in early 1764 CE. He later became surveyor general of the East India Company. 

Rennell spent 12 years in Bengal and produced the first detailed map of the region. His work required extensive travel across Bengal under extremely challenging conditions. He endured malaria, extreme heat and cold, and constant threats from crocodiles, snakes and tigers. 

Despite these hardships, he successfully completed the map with remarkable dedication and perseverance.

At that time, modern surveying instruments had yet to be developed. Rennell used a traditional compass, chain, and Hadley's Quadrant to record longitude and latitude. 

He first prepared small regional maps, which he compiled after returning home. In 1780 CE, he published the Bengal Atlas and a memoir. Though titled Bengal Atlas, it covered Bengal, Bihar, Odisha, and much of northern India. Rennell's map was the most reliable reference until modern cartography.

In his map, Dhaka was labeled as Jehanguirnagur, Tejgaon as Tizgong, the Buriganga River as Boorygonga, and the Arial Khan River as Arika. Initially, these maps were published in segments for the East India Company's use. 

Later, Rennell commercially published a comprehensive map and memoir for foreign travelers intending to visit India. At that time, it was the only dependable map of Bengal. Subsequently, more maps of Dhaka were prepared during the British period (1859, 1905, and 1924 CE), the Pakistan period (1966 CE), and in independent Bangladesh using modern technology.

According to Rennell's map published in 1780 CE, Dhaka was once interwoven with major rivers such as the Buriganga, Shitalakshya, Dhaleshwari, Bangshi, Balu, and Turag, as well as numerous canals forming a network across the city. 

These water bodies were integral to the natural hydrological system and closely connected to the city's geomorphology. They served as primary routes for transportation, trade and drainage of rainwater, playing a vital role in controlling waterlogging and maintaining environmental balance.

Unplanned urbanisation, infrastructure growth, illegal encroachment, land filling, and weak management led to the loss of many canals. Consequently, waterlogging, pollution, and decreased water retention have worsened.

The ruling Bangladesh Nationalist Party's 2026 Election Manifesto proposed excavating and restoring 20,000 kilometres of rivers and canals. The Urban Development Directorate (UDD) has started integrated research to assess the location, current condition, and functionality of lost and existing rivers and canals in Dhaka.

Through this research, it will be possible to identify the causes of failure in the natural drainage system, locate waterlogging-prone areas, and develop climate-sensitive spatial planning. It will also provide timely, data-driven guidance for policymaking in water management, including the development of a National Water Grid Management system.

Md Mahmud Ali is the director of the Urban Development Directorate.