The Maga Dam and the Logone Floodplain

The flood pulse is the ecosystem. The Logone floodplain is a working system driven by an annual flood that spreads over the Yaeres, recharges groundwater, deposits silt and leaves moisture in the soil as it retreats. Pasture quality and duration depend on the depth, extent and timing of that flood.

How the dam interferes.

• Peak reduction. Storing water for the perimeter lowers and shortens the downstream flood, so a smaller area is inundated. Less area flooded means less pasture, and the soil dries sooner, which explains reports of pasture drying three to four weeks earlier.
• Silt trapping. Sediment settles in the reservoir, so the floodplain no longer receives its annual silt and nutrient increment. The same siltation reduces reservoir storage, which is part of why water supply to the perimeter has become unreliable.
• Groundwater recharge. A smaller flood recharges the aquifer less, so residual moisture and dry-season water points decline, pushing herds further and earlier.
• Timing. Water released for irrigation does not match the natural flood season, so the cue for fish migration and for pasture growth is disrupted.

Feedback on the perimeter. Irrigation without adequate drainage has raised water tables and caused waterlogging and salinisation in parts of the scheme, which helps explain yields falling from 4.2 to 2.8 t/ha alongside the siltation-driven water shortage.

Conclusion. The dam converted a broad, shallow, silt-rich flood into a narrow irrigation supply. The costs appear downstream and later, which is why they were not counted when the scheme was designed. The decline in cattle numbers and the rise in conflicts are the social expression of that hydrological change.

Option 1: rehabilitate the irrigation scheme. Improves water delivery, drainage and yields on the best land, and supports the farmers who already depend on it. But it entrenches the withholding of the flood, so it does nothing for pasture and may worsen downstream conflict. Better drainage would address waterlogging and salinity, which is a genuine gain.

Option 2: restore the flood pulse. Delivers the largest downstream benefit: more pasture, longer grazing, groundwater recharge, silt distribution and fish. The cost is borne upstream, because a release reduces the water available to the perimeter in dry years. Its feasibility depends on how much water actually remains after siltation, which is unknown without a storage survey. It also requires an agreed release rule, not an annual negotiation.

Option 3: convert 2,000 ha. Sensible where land is saline, waterlogged or unreliably supplied. Recession agriculture uses the flood rather than fighting it and supports dry-season pasture. But 2,000 ha is a modest share of 7,000 ha, and conversion must not become cover for abandoning the scheme's viable core.

Recommendation: a phased combination.

1. Commission a storage and silt survey first; no option can be judged without knowing the water available.
2. Rehabilitate the most productive part of the perimeter only, with proper drainage, rather than the whole 7,000 ha.
3. Adopt a formal annual environmental release to restore a defined flood extent, written into the operating rules, with monitoring of pasture area and groundwater.
4. Convert the worst 2,000 ha to recession agriculture and pasture.

Why this order. The information gap is decisive. Rehabilitation of the whole perimeter is the most expensive option and locks in the downstream loss, while flood restoration alone would sacrifice rice yields without testing cheaper fixes. A conditional, monitored package manages the risk on both sides.

Who gains and who loses.

• Rehabilitation benefits farmers with plots in the better-drained sections and contractors; herders lose further as the flood shrinks; the state gains rice output and tax. Small farmers who cannot pay pumping costs may still be excluded.
• Flood restoration benefits herders, fisherfolk and downstream cultivators; it costs farmers whose supply is cut in dry years, and it costs the state in reduced rice output and in compensation claims. Benefits are diffuse and hard to measure, which makes them politically weak.
• Conversion benefits farmers on marginal land who switch to recession crops and herders who gain dry-season pasture; losses fall on those with capital invested in the irrigated sections.

Why conflict has risen. Eleven recorded conflicts in 2023 against three in 2020 reflects compressed resources: pasture dries earlier, herds concentrate on remaining water and crop residues, and the timing overlaps with rice transplanting and harvest. Conflict is a symptom of a shrunk floodplain, not of incompatible peoples.

Reducing conflict.

• Formalise the release rule. Publish the annual volume and timing so herders can plan and farmers cannot be surprised.
• Separate the calendars. Agree dates for crop residue grazing and for passage, and mark and map transhumance corridors so herds do not cross standing rice.
• Joint institutions. A floodplain committee with real farmer and herder representation and a small budget, meeting before each season, rather than meetings only after incidents.
• Compensation with evidence. Base any payment on measured pasture loss, not on negotiation, so it does not reward confrontation.
• Early warning. Radio and mobile alerts on release dates and water levels.

Judgement. Any of the three options can be made less conflictual by transparent rules and shared monitoring. What cannot be avoided is that the floodplain is finite: if rice takes the water, pasture loses it. The choice must be made explicitly, with the losses acknowledged and compensated, rather than left to be discovered by herders in a dry year.