Arrah Canal

The concept for the Sone Canal System originated in 1853 with a proposal by Colonel C. H. Dickens. After significant delays caused by the Indian Rebellion of 1857, the project was initially undertaken by the East India Irrigation and Canal Company before being purchased by the government in 1868. Construction commenced the following year, and by 1873, the system was operational enough to supply water to the Arrah Canal and other channels to provide drought relief. The canal began regular, rated water supply for irrigation from the 1876–77 season.^[4] An early report names W.A. Inglis as the executive engineer of the Arrah Canal during this period.^[5]

According to a report from January 1875, the revised cost estimate for the Arrah Canal was £219,086. Early construction costs for the canal were recorded at £3,285 and 14 shillings per mile, exclusive of tools and plant.^[6] The Arrah Canal was developed as part of the British-era Sone Project. Major construction on the canal was completed by 1905. A detailed statement of expenditure from the period shows the total cost of construction was Rs. 7,21,039. The largest portions of this expenditure were for earth-work (Rs. 3,12,837), works (Rs. 1,96,530), and land acquisition (Rs. 1,23,553).^[2]

The Arrah Canal was engineered for both irrigation and navigation. It originates from the Main Western Canal at the fifth mile, taking off a designed discharge of 1,616 cubic feet of water per second.^[6] The Main Western Canal, from which the Arrah Canal branches, navigated the local topography through significant engineering works, including a large syphon aqueduct to cross the Kao Torrent.^[7]

The canal is sixty miles long, following a course that initially curves towards the Son River before turning north to pass the city of Arrah. It ultimately terminates in the Gangi River, through which its waters connect to the Ganges. To manage the 180-foot fall in elevation over its length, a system of thirteen locks was constructed,one of which was later abandoned, two of which are double locks.^[6] While the canal was designed for navigation, its utility was limited as the Gangi River connection to the Ganges was often impassable due to shoals, especially outside of the flood season.^[4]

The width of the canal was designed to narrow as its course progressed and its water was distributed. For the first fifteen miles from its origin at Dehri, the canal was built to be 86 feet wide at the base. This was reduced to 57 feet at the twenty-sixth mile and further narrowed to 47 feet at the thirty-second mile.^[6]

The engineering of the canal also included advanced water control systems for its time. On at least one of the weirs of the Arrah Canal, a movable dam was constructed based on a system developed by French engineer M. Chanoine. Furthermore, the canal was designed to serve a dual purpose as a flood control measure, with its structure acting as an embankment against the Son River on its western bank.^[8]

The canal was actively used for navigation, with contemporary accounts noting "numerous canal boats loaded with grain or stone" traveling towards the Ganges, destined for Calcutta. The boats used were described as being 15 to 25 feet long and about 10 feet wide. Lacking sails, these boats were propelled by teams of men, sometimes ten or more, pulling them along the towpaths.^[5]

To facilitate local transport across the canal, a network of crossings was built. Important roads were served by "well-constructed masonry or iron bridges." However, a structural issue was reported with many of the masonry bridges, where pressure from the earth embankments caused the abutments to crack. For smaller roads and footpaths, "catamaran-shaped ferryboats" were used to shuttle people and goods across the water.^[5]

The canal was a key piece of irrigation infrastructure for the Shahabad district. According to a 1905-1906 comparative statement, the Arrah Canal commanded a culturable area of 177,400 acres. In that year, it irrigated a total of 107,655 acres, with 61,211 acres being for Kharif crops and 46,444 acres for Rabi crops. The revenue from assessed water-rates for that year was Rs. 2,58,516.^[2]

While the canal was a key asset, initial economic forecasts for the Sone Canal system were overly optimistic. An 1875 estimate anticipated net profits of over Rs. 26 lakh from more than 1 million irrigated acres. However, these projections were "falsified" as the water supply from the Son River was less than expected. The maximum area irrigated by the system in a single year was recorded as 557,494 acres in 1901-02.^[4]

Historical data from the early 1900s provides insight into the canal's technical efficiency, measured in terms of water duty—the area of crop matured by a certain volume of water.

For the Kharif season of 1901 (defined as July to October), the Arrah Canal had an average utilized discharge of 1,197 cubic feet per second over 122 days of flow. The duty for this period was calculated at 82 acres irrigated per cubic foot per second, with an equivalent water depth of 35 inches on the fields.^[1]

Data for the Rabi season shows the duty of the Arrah Canal over a three-year period:

• 1899–1900: 85 acres per cusec
• 1900–01: 112 acres per cusec
• 1901–02: 114 acres per cusec

This demonstrates a notable improvement in the canal's irrigation efficiency during the Rabi season over this period.^[1]

The impact of the Sone canal system was considered vital for the region. An 1875 report stated, "There can be little doubt that these canals have conferred upon Sháhábád an entire immunity from future famines."^[6] The canal, however, was also vulnerable to the river's power. It was breached during a "disastrous" flood in July 1876 and again during another major flood on September 5th, 1901, when its banks broke in several places. On the latter occasion, the floodwaters "poured into many parts of Arrah, destroying some of the small hamlets on its outskirts" and inundated large tracts of land." and inundated large tracts of land between the Son River and the railway line.^[4][8]