The falling water table: canal or recharge package?
A semi-arid block of about 62,000 people receives roughly 240 mm of rain a year, and 78% of its net sown area is under paddy. In twelve years the number of registered irrigation tubewells has risen from 640 to 1,850, while the pre-monsoon water table in the block's 14 monitoring wells has fallen from about 8 m to 27 m; three of those wells are dry by May. Agricultural power is metered but not billed, and assured procurement makes paddy the most profitable crop per hectare in the first few seasons. The district must choose between two proposals: a 40 km canal from a perennial river to command 4,000 ha, estimated at Rs 480 crore; or a package of millet-pulse rotation, drip irrigation on 1,200 ha of horticulture, and 40 recharge shafts in the worst-affected watersheds, estimated at Rs 52 crore. Political pressure favours the canal because it can be inaugurated.
1. Identify the dominant cause of the falling water table and explain why no individual farmer is behaving irrationally.
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Start with the numbers. A rise from 640 to 1,850 tubewells is roughly a 2.9-fold increase in abstraction capacity, and the water table fell 19 m over the same period. Rainfall of 240 mm/yr cannot recharge that draft, and rainfall variability alone would produce fluctuation in the 14 wells, not a steady multi-year decline across all of them.
The decisive feature is the price signal. Power is metered but not billed, so a farmer's marginal cost of pumping one more hour is effectively zero. An extra hectare of paddy therefore costs the farmer only seed, fertiliser and labour, while the entire yield benefit is private. The cost of the extra metre of drawdown is shared across all 1,850 pumpers and all future users. That is a common-pool resource with an externality: the sum of many rational private decisions is a collectively irrational outcome.
Note the second incentive: assured procurement converts a water problem into a cropping-choice problem by rewarding the most water-intensive crop. Any policy that ignores the incentive structure and only adds supply will be captured by the same behaviour.
2. Which proposal would you fund first, and what single indicator would you monitor to test whether the choice is working?
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Fund the Rs 52 crore package first, on three grounds.
Cost-effectiveness: the canal costs about Rs 480 crore for 4,000 ha, roughly Rs 1.2 lakh per hectare of command, some nine times the per-hectare cost of the recharge-and-drip package. Efficiency: the block's problem is abstraction exceeding recharge, so adding supply without touching demand usually triggers an expansion effect - commanded paddy area grows until the new water is exhausted, and the canal brings seepage, waterlogging and salinity risk to soils that have never been irrigated. Reversibility: recharge shafts and drip can begin in one season and can be stopped if they fail, whereas a canal means 5-8 years of construction, land acquisition and irreversibility.
Indicator: pre-monsoon (May) depth to water in the same 14 monitoring wells, reported well by well alongside metered pumping hours in the block. Not canal kilometres, not 'acres irrigated'. Success is the rate of decline flattening within three to four years while pumped hours fall; a block average that hides the wells which go dry first is not a usable indicator.
3. The canal is sanctioned anyway. What conditions would you attach, and what evidence would make you revise your advice?
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Conditions: (i) metering and a tariff on every agricultural connection in the command, so the new supply does not simply become another unpriced input; (ii) a notified list of blocks where no new tubewells may be sunk; (iii) canal water allocated first to drinking water and only then to irrigation, with the annual allocation published; (iv) a cropping plan that prevents paddy expanding into the newly commanded area; (v) independent monitoring of waterlogging and soil salinity across the command.
I would revise the advice if the block's real constraint turned out to be quality rather than quantity - fluoride, arsenic or salinity - because recharge does not fix water quality. I would also revise if the proposed recharge sites overlie low-permeability clay or a confined aquifer, so shafts would not infiltrate; if the river supplying the canal were already fully allocated upstream, making the 40 km link a paper transfer; or if drinking-water demand alone could absorb the canal supply, in which case the canal is defensible on public-health grounds even though irrigation should still be metered.