"Two floods per year" — parameterised, falsifiable framing
This dossier evaluates the popular claim that parts of the Amazon basin experience "two annual flood waves." It applies the Harbour Breakwater Layer — a Claim Analysis Ledger that classifies claims as compatible, underdetermined, or inconsistent, with discriminant conditions for resolution.
Public introduction in plain language. The river, the question, the music analogy, and why it matters — no equations required.
Claim Analysis Ledger (5 entries: 2 pass, 1 provisional-pass, 2 pass-as-stated). EC gates, decision statements, citation anchors.
Corrected minimal seasonal model. Annual + semiannual harmonic decomposition, discriminant conditions DC-A and DC-B, structural two-maxima threshold.
Parameter ledger with reliability grades. Geometry, climate-mode modulation, routing physics, underconstrained variables UC-1 through UC-4.
Next falsification steps F-1 through F-3. Regime occupancy test, ENSO-conditioned shift, kernel drift / hysteresis check.
Primary finding: At Óbidos — the key integrating gauge for the Amazon mainstem — the climatological seasonal discharge is strongly annual. A small semiannual component exists (r ≈ 0.13) but is not indicative of a stable "two floods per year" regime. Observed shoulders and multi-peak structures arise from higher harmonics in seasonal forcing and distributed routing with time-varying kernels, strongly modulated by ENSO and Atlantic variability.
Status: Five load-bearing claims assessed. Two formal-pass (mathematical framework), one provisional-pass (Óbidos harmonic fit — upgrade gated on reproducible fit archive), two pass-as-stated (ENSO modulation, routing physics). Four underconstrained variables prevent full closure; three falsification steps define the path forward.
Key discriminant: Any "two floods per year" explanation must invoke (a) higher harmonics in forcing, or (b) nonlinearity / time variance in routing, or both. A single-frequency harmonic through a linear time-invariant kernel cannot generate two maxima per period.
Tidal bores / estuarine effects and seasonal river floods are scale-disjoint phenomena. Do not conflate causal explanations.
Clock networks: phase-coherent, near-linear dynamics until decoherence. Flood systems: dissipative, threshold-activated storage and backwater → hysteresis. Mapping allowed only at the level of causal filtering / control parameters, not energy landscape equivalence. Admissible mappings must preserve the distinction between causal ordering (which event gates which) and metric synchronisation (how tightly two processes track); conflating the two is grounds for quarantine.
Parameter values supported by UNH/GRDC, HESS, WRR/major journals are admissible anchors. Low-quality outlets (blogs, SCIRP) are quarantined unless independently confirmed.