Allocating a shrinking reservoir in a dry Marathwada year
On 1 June, the Khandala medium irrigation project in Jalna district holds 18.0 million cubic metres (MCM) of live storage against a designed live storage of 31 MCM. The previous monsoon in its catchment was 58% of normal. The command area is 2,400 hectares: 300 hectares of standing sugarcane, 900 hectares of seasonal cotton and soybean, and 1,200 hectares that farmers usually leave fallow in a dry year. A town of 45,000 people and 12 tanker-fed villages depend on the reservoir; their combined drinking-water requirement until the next monsoon is estimated at 5.2 MCM. The irrigation department proposes a canal rotation of 8 days on and 12 days off for the whole command. The municipal council demands its full quota, sugarcane growers say their crop will die without water, and village sarpanches want releases to recharge wells. Dead storage is 2.0 MCM; evaporation and seepage losses to next June are estimated at 1.2 MCM. Canal conveyance efficiency is about 75%.
1. Prepare a water budget and a release priority for the year. State your assumptions and show the arithmetic.
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Water budget at reservoir level. Use only live storage; dead storage is not a supply.
- Live storage on 1 June: 18.0 MCM
- Less dead storage: 2.0 MCM
- Less evaporation and seepage to next June: 1.2 MCM
- Usable release: 18.0 − 2.0 − 1.2 = 14.8 MCM
- Drinking water first: 5.2 MCM
- Residual for irrigation releases: 14.8 − 5.2 = 9.6 MCM
- At 75% conveyance efficiency, water reaching fields: 9.6 × 0.75 = 7.2 MCM
Priority. Drinking water is first. For irrigation, protect the 900 ha of seasonal cotton and soybean before supplying the 300 ha of sugarcane, because the seasonal crop can still produce with one or two protective irrigations, while sugarcane is a high-water crop with lower priority in a scarcity year. At 0.55 m per hectare, seasonal crops need 900 × 0.55 = 4.95 MCM. That leaves 7.2 − 4.95 = 2.25 MCM at field. At 1.5 m per hectare, this can give protective irrigation to about 150 ha of sugarcane, not 300 ha. The defensible plan is therefore full drinking-water allocation, 900 ha of seasonal crops at 0.55 m, and only 150 ha of sugarcane; the other 150 ha must be sacrificed or the plan must be renegotiated. The proposed 8-on/12-off rotation for the whole command is not physically possible.
2. A farmer argues that because sugarcane is a perennial crop, it must get water before seasonal crops. Evaluate this claim under Maharashtra water policy and hydrological reality.
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The claim confuses agronomy with legal priority. Sugarcane's perenniality means that losing it is costly to the farmer, but it does not create a senior water right. Maharashtra's water policy and the Maharashtra Water Resources Regulatory Authority allocation framework place drinking water above irrigation, and within irrigation the state can impose rotational and protective supplies in a scarcity year. The reservoir has 14.8 MCM usable, of which 5.2 MCM is drinking water. If all 300 ha of sugarcane received 1.5 m, field demand would be 4.5 MCM; adding even 0.55 m on 900 ha gives 4.95 MCM, for a total of 9.45 MCM. That is above the 7.2 MCM that can actually be delivered. A rule that protects sugarcane first would fail the drinking-water guarantee and cause wider crop loss. The fair test is not 'perennial versus seasonal' but how much crop can be saved per cubic metre and who has an alternative. The farmer should be offered a negotiated deficit plan, drip support and a crop-switching option, not a blanket priority.
3. What single monitoring arrangement would you add to reduce tail-end capture and ensure the release plan is followed?
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Install a calibrated volumetric meter or flume at each distributary head and at the tail of the main canal, and publish daily releases. Pair this with a canal committee that includes at least two tail-end farmers and a sarpanch from the tanker-fed villages; the committee signs off the weekly rotation. Without measurement, head-reach farmers can take water first and the tail never receives its share. A simple logbook plus a staff gauge is better than an unmeasured '8 days on' rule. Add a penalty clause: if a distributary receives more than its allocated volume, the next rotation is cut. The same committee should check that drinking-water releases are actually lifted and not diverted. The arrangement works only if it is public; otherwise it becomes another paper record.