The state government has submitted a ₹183 crore flood management project proposal to the Asian Development Bank (ADB) for the Bahini Basin in Guwahati. The plan focuses on enhancing the existing drainage infrastructure to tackle recurring flood issues in the region.
The National Highway (NH) drain, which plays a crucial role in conveying stormwater from the upper Bahini catchment to the Basistha River, is at the center of this initiative. The Basistha then drains into the Pamohi River, which flows into Deepor Beel before finally merging with the Brahmaputra. This drainage system also carries diverted water from the Meghalaya hills through a diversion structure constructed in the 1990s.
While the diversion infrastructure is still functional, most components have deteriorated due to age and now require extensive repairs. Additionally, sections of the NH drain are too narrow to handle peak monsoon runoff. Current widths of 1.2 to 1.5 meters are inadequate. The proposal suggests widening these sections to 4 meters to prevent overflow. In areas where open trench excavation is not feasible, trenchless technology will be deployed to carry out the works.
A key feature of the plan includes setting up a Bioremediation Facility for treating polluted drainage water during dry weather. This is crucial as the Bahini catchment currently lacks an efficient sewerage system, leading to poor water quality.
To mitigate soil erosion, the project proposes building drain sidewalls from Pibco Point to Hanuman Mandir, covering a stretch of 2 km. Further downstream, lining works will continue from Bahini to Beltola Bazar Road. At Beltola Market Road, a silt trap will be constructed to reduce sediment accumulation. Upstream of the silt trap, a mechanical screen will be installed to collect solid waste and debris from the flow.
In Rukminigaon, the plan includes the improvement of secondary and tertiary drains—excluding the Patkai Path area. Of the 36.17 km of drains in Rukminigaon, about 4.82 km will undergo upgradation. The aim is to re-section and strengthen underperforming drains to enhance water flow and hydraulic efficiency. Moreover, a new 0.54 km trunk drain is proposed along Patkai Path up to its outfall at Bahini.
The ADB noted that the Initial Environmental Examination (IEE) will be updated to incorporate the final designs and will reflect all required environmental and structural safeguards. The updated IEE will be reviewed, cleared, and disclosed by ADB prior to the commencement of construction work.
