Waterlogging in a Wards 4–6 Drainage Scheme
A pourashava in a low-lying district receives 180 mm of rain in six hours during the monsoon. Ward 4 (population 9,000) floods to knee depth; Ward 5 (population 6,500) floods only at one culvert; Ward 6 (population 4,000, mostly farmland) drains within a day. The existing drains were built in 2005 for a design rainfall of 90 mm in 24 hours. A consultant proposes a single 2.5 m wide concrete channel running through Wards 4 and 5 to the river, costing about 40 crore taka. Residents of Ward 4 want it immediately; Ward 6 farmers object that the channel outlet will erode their land. The pourashava has 12 crore taka available this year and must decide what to build first.
1. Identify the main reason the current system fails, and judge whether the consultant's single large channel is an appropriate first response.
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The design standard is the core failure: the drains were sized for 90 mm in 24 hours, but the storm delivered 180 mm in six hours - roughly eight times the design intensity. So the system is not merely blocked; it is under-sized for current rainfall. A single 2.5 m channel would help Ward 4, but it concentrates all flow into one outlet and shifts the erosion problem onto Ward 6 farmland, creating a new dispute. It also costs 40 crore against 12 crore available, so it cannot be the first step. A better first response is to separate the problem: (a) verify and clear blockages and silt in Ward 4's existing drains, since Ward 5 floods at only one culvert - a local constriction, not a capacity failure; (b) add local detention or recharge pits in Ward 4 to reduce peak flow; (c) commission a hydrological study to set a new design standard before committing to a large channel. The channel may eventually be justified, but only after the study and with an erosion-protection plan agreed with Ward 6.
2. Ward 4 residents demand immediate action and threaten protest. As the engineer advising the pourashava, propose a one-year plan within 12 crore taka and justify the trade-offs.
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A defensible one-year plan: 1) Immediate (0–2 months, ~1 crore): clear and repair Ward 4 and Ward 5 drains, fix the single Ward 5 culvert, and remove solid waste from the outfalls. This is cheap, fast, visible, and addresses the Ward 5 constriction directly. 2) Short term (2–6 months, ~4 crore): build small detention ponds or recharge structures at two low points in Ward 4 to cut peak flow, plus raise the plinth of the most flood-prone lane. 3) Study and consultation (3–9 months, ~1 crore): a hydrological study to set a new design standard and an erosion assessment for the Ward 6 outlet, with a written agreement on compensation or protection works. 4) Reserve (~6 crore): hold for the first phase of a properly designed channel once the study reports, rather than starting a 40-crore scheme that cannot be finished. Trade-off: Ward 4 does not get the big channel this year, but it gets measurable relief within months, and the money is not sunk into a design that may be wrong or contested.
3. A councillor says: 'Ward 6 barely floods, so it should get no money.' Evaluate this claim using the evidence in the case.
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The claim confuses current flooding with risk created by the proposal. Ward 6 drains within a day today, but the proposed channel discharges into the river across Ward 6 farmland, so the scheme itself would create erosion risk there. A ward that is currently safe can still be harmed by an intervention elsewhere, and those affected have a legitimate claim to protection or compensation. There is also an equity point: Ward 6 has the smallest population (4,000) but includes farmland that supports livelihoods beyond the ward. Fair allocation is not simply 'money follows the deepest flood'; it weighs who bears the cost of a solution as well as who receives the benefit. The correct position is not to give Ward 6 a drainage budget, but to include erosion protection and consultation in the channel design and to record the farmers' concerns formally.