Model, calibration and source notes
Module 1 water cycle: Turc (1954) annual actual evapotranspiration and catchment/reservoir water-balance equations. Turc uses ET = min(P, P/√(0.9 + (P/L)²)), L = 300 + 25T + 0.05T³, with P and ET in mm/year and T in °C. Annual land storage change is assumed zero: P = ET + runoff + recharge. Recharge is retained outside the lake model; it is not counted twice as river inflow.
Lake integration: a repeating 365-day balance, six-hour backward-Euler steps, seven spin-up years. ΔV = (river exchange + catchment runoff − net lake atmospheric loss) × Δt. Effective orifice connection width is fitted so positive annual exchange integrates to 41.5 km³ in the reference. One pressure bundle is fitted to 29.3 km³. Neither fit validates timing, geometry, causal attribution or the flood map. Module 2.2 uses submerged-orifice discharge with the lake stage solved from storage; Manning remains available in the Module 1 source library.
Observed versus illustrative: only the two period-average reverse-flow targets are observational constraints here. Mock values: reference rainfall 1,600 mm/year, mean temperature 27 °C, terrestrial catchment 70,000 km², runoff share 75%, effective discharge coefficient Cd = 0.70, effective depth 3 m and g = 9.81 m/s². Channel width is fitted, not surveyed. Net lake atmospheric loss is held at 110 m³/s and is separate from land Turc ET.
Inherited assumptions: synthetic area–stage curve A(H) = 1,800 + 1,300H km²; its storage integral V(H) = (1.8H + 0.65H²) × 10⁹ m³. Synthetic monthly forcing uses smooth interpolation. The runoff shape is normalized to the Turc catchment's annual runoff volume. Dam smoothing, stage incision and downstream backwater offsets remain teaching parameterizations. The empirical reverse-volume multiplier from the brief is a separate comparison, not an additional conservation equation.
Forest and fisheries: an assumed 3,300 km² forest ring floods progressively between lake stages 3.0 and 8.3 m. Annual catch scales as (scenario forest area-days / baseline forest area-days)0.65, capped at 1.6× the baseline. The exponent, habitat capacity and availability share are assumptions. Both catch ranges are scaling ranges, not confidence intervals. No fishing-effort, migration-barrier, temperature or species model is included.
Visuals: the original reference image is projected onto inferred relief. A separate blue water mesh rises over a traced basin. Flood extent is illustrative and does not establish a surveyed stage–area map. Levels use a shared model bed datum, not field gauge readings. The water color is chosen for clarity. Villages are illustrative markers; camera rotation is limited because unseen geometry is inferred.
Equation references: IIASA: annual Turc relation · USACE: Manning equation. Module 2.6 adds illustrative conditional flood damage at one representative town site.