Updated Hypothesis Document

Buffalo River Watershed — Running Hypothesis Document

Last updated: 2026-06-30 (Day 122 — Third consecutive zero-QPE day (basin-max 0.000"). Pure recession at all seven gauges — Event-22 tail. Each daily max = 00:00 reading. Recession-band points added: St. Joe 943→764 cfs (~7.9 cfs/hr @~850), Harriet 1230→966 cfs (~11.6 cfs/hr @~1100), Pruitt 4.47→4.18 ft / 334→246 cfs (~3.7 cfs/hr @~290), Ponca 180→137 cfs (~1.9 cfs/hr), Boxley 2.63→2.44 ft (~0.008 ft/hr seepage), Richland 1.12→1.03 ft (NEW post-event low), Bear 27.8→23.5 cfs / 2.19 ft (NEW post-event low). Threshold cascade: Ponca crossed 150 → Too Low ~16:00 CDT (Event-22 Ponca window fully closed); Pruitt (246), St. Joe (764), Harriet (966) all mid-Optimal. Signal separators Richland & Bear both flat at new lows → confirms zero forcing. 7-day antecedent collapsing as Event-22 rain ages out of window: Boxley zone 5.02"→1.63", Richland driest (0.62–0.83"). NO rating-curve step — ~17 days post-Event-20 record peak; Bear/Richland cfs still stepping smoothly in 0.7–0.8-cfs increments. Boxley pool-drain from 3.93-ft Day-119 peak now at 2.44 ft (Day 4, ~0.5 ft/day slow phase). Nothing to attribute — no QPE peak anywhere, no lag/transfer computed.) Events observed to date: 22 confirmed/inferred rainfall-runoff events (Event 22 FULLY CLOSED on Day 121; Days 120–122 = zero-QPE propagation/recession tail) + multiple sub-threshold non-detections + 9 clean recession-only baseline days (Days 92, 95, 97, 102, 103, 104, 107, 108, 109) + light/trace/near-zero-rain non-detection-on-recession days (Days 108 trace, 110 light, 111 trace, 112 near-zero, 116 light, 118 light-0.25") + Day-120, Day-121 & Day-122 zero-QPE pure recession/propagation days

Study Context

• 90-day MRMS/USGS empirical study, Buffalo River HUC8 11010005 (Mar 1 – May 29 nominal, data collection from Feb 27; extended through Day 122 = Jun 30 as bonus calibration data). Curated 2026-06-12 against deterministic truth cards (see curation_audit.md); Day-114 Event-21 flood backfilled 2026-06-29 (was mis-logged as a data gap — see curation_audit.md).
• 7 gauges (5 mainstem + 2 tributary signal-separators); 37 HUC12s including 8 ungauged below Harriet (39% of basin area is St. Joe contributing).
• Pre-study calibration anchors: Ponca + Pruitt rating curves recalibrated Feb 17, 2026.
• Local-knowledge calibration targets in active use: Hailstone pool-and-drop pre-fill; Pruitt low-flow river-right channel scour; Ponca historical ~48-hr rating-curve lag during rises; Hailstone recreational thresholds (3.7/4.4/5.9 ft); upper-Richland recreational thresholds (3.2/4.0/6.0 ft); Boxley-Ponca section thresholds (3.2/3.7/5.0 ft).
• Days 91–122 are post-study bonus data — calibration-grade, with multiple major rainfall-runoff events captured (Events 16–22) plus Event-20 multi-day recession (Days 107–112), Event-21 recession (Days 116–118), Event-22 onset (Day 119), trunk integration (Day 120), final closure (Day 121) and Day-122 pure-recession tail. NOTE (corrected 2026-06-29): the Days 113–115 daily summaries WERE present; Event 21's Day-114 flood peak was fully characterized in analysis/daily/2026-06-22.md but never integrated into this rolling doc during the 06-21→06-25 max_tokens truncation window (the nightly hypothesis rewrite was quarantined those nights). Now integrated from that daily + the deterministic truth card — see curation_audit.md.

Events

• Event 1 (Day 5–6, Mar 5–6): First confirmed event. Headwater-concentrated storm, Boxley HUC12 1.038" with 0.751"/hr peak (study-record intensity to that date). Dry antecedent (~0.4" 7-day). Boxley +0.87 ft biphasic (slow fill 8 hr → rapid 0.46 ft/hr pulse), peak at 15:15 with ~11 hr lag from peak rain — classic "pool and drop" signature. Ponca 84 → 179 cfs (+113%), 4.5-hr Boxley→Ponca lag (15:15 → 19:45). Pruitt +0.63 ft / +144 cfs (+231%) arriving Day 6, 15-hr Ponca→Pruitt lag at ~150 cfs flow (~0.46 m/s). Pruitt rating curve shifted mid-event (a real USGS update). St. Joe non-response — first evidence that 0.5" distributed across 1342 km² is sub-threshold. Transfer ratios: Boxley 0.84 ft/in (dry); Pruitt brief Optimal crossing.

• Event 2 (Day 7–8, Mar 7–8): Watershed-wide major storm, 1–2.5" basin-wide. Ponca zone hotspots Whiteley 2.55"/0.96"/hr, Pruitt zone Cove 2.43"/0.74"/hr. Wet antecedent from Event 1 (~1.0–1.5" 7-day Ponca/Pruitt). First flood-threshold crossings of study: Ponca 2120 cfs (>1600), Pruitt 2610 cfs (>2000, 3.5 hr above). St. Joe 8.01 ft / 3230 cfs at 04:15 Day 8 (4.56 ft rise, 22.1-hr lag from zone QPE 1-hr peak 06:06). Harriet 6.83 ft / 3050 cfs (0.99 ft/hr peak rise, fastest of study). Bear Cr first sustained response: 1.2" → +0.59 ft, ~14.5-hr lag (zone QPE peak 07:06 → gauge peak 21:30). Transfer ratios: Boxley 0.71 ft/in (wet); Ponca ~1030 cfs/in (wet); Richland zone 1.24" → +1.39 ft (~1.1 ft/in wet). Propagation cascade: Ponca→Pruitt 5.75 hr at 1500–2000 cfs (~1.2 m/s), Pruitt→St. Joe 15 hr, St. Joe→Harriet 8.25 hr. Total Ponca→Harriet 29 hr at flood flow. (Ponca peaked 07:30 Day 7 under direct forcing, before Boxley's delayed local peak 16:15 — no clean Boxley→Ponca pair this event.)

• Event 3 (Day 11, Mar 11): Stacked on Event 2 recession. 0.5–0.8" upper-basin focus on already-elevated baseflow. Boxley +0.66 ft from 0.811" (0.81 ft/in wet, ~9.7 hr lag — Boxley lag ≈ constant across antecedents in 1.0"-class events). Ponca 197→547 cfs (+178%). Pruitt biphasic: local +0.10 ft then propagated +1.32 ft, peaking 5.93 ft / 857 cfs. St. Joe 6.02 ft / 1420 cfs Day 12 (+1.00 ft from trough), 25-hr Ponca→St. Joe lag. Harriet 5.42 ft / 1510 cfs Day 12, 33-hr Ponca→Harriet. Ponca→Pruitt 7.5 hr at ~500 cfs (~0.93 m/s) — confirms velocity ∝ Q^0.35 trend.

• Event 4 (Day 34–36, Apr 3–5): Three-pulse compound: lower-watershed primer Apr 3 (0.4–0.7"), then watershed-wide 1.2–1.95" Apr 4 (Shop Cr 1.95" hotspot). Wet/wet antecedent. Boxley +2.05 ft from 1.57" = 1.30 ft/in (wet, highest observed) — confirms pool-fill primer mechanism. Pruitt 5.97 ft / 867 cfs at 23:15 Day 35 (2.55 ft rise on Pruitt day; no flood crossing). St. Joe 7.40 ft / 2630 cfs at 12:30 Day 36 (4.0 ft rise, ~32.5-hr lag from Day-35 zone QPE peak — distributed-forcing slower than concentrated). Harriet 6.55 ft / 2720 cfs at 19:15 Day 36 (2.96 ft rise). Bear Cr 4.6 → 203 cfs (+4300%), 0.97 ft/in transfer. Pruitt→St. Joe 13.25 hr; St. Joe→Harriet 6.75 hr. Sustained Optimal at Pruitt ~135 hr; St. Joe/Harriet Optimal duration ~21 days (with stacking).

• Event 5 (Day 41–42, Apr 10–11): Localized two-zone event. Harriet zone 0.6–1.1" (Water Cr 1.10") → Harriet +0.10 ft / +73 cfs at +1–5 hr lag (first clean Harriet-zone-only pair). Boxley zone 0.55" → +0.22 ft delayed (~0.40 ft/in, moderate antecedent) → propagated through Ponca +20 cfs and Pruitt +0.12 ft / +34 cfs, with Boxley→Pruitt ~19.5-hr peak-to-peak at ~185 cfs. Cove Cr 0.66" produced compound Pruitt response. Transfer-ratio non-linearity confirmed: ~0.40 ft/in at 0.55" zone QPE vs 0.71–0.84 at 1.0"+ — Boxley has threshold-type response.

• Event 6 (Day 46–47, Apr 15–16): Two-pulse Apr 15-16 (Richland-Cave bullseye) + Apr 18 (upper basin 0.4–0.7"). Cleanest propagation cascade of early study. Pulse 1: Boxley peak ~12:45 → Ponca 17:00 (+4.25 hr) → Pruitt 07:15 Day 48 (+14.25 hr Ponca→Pruitt at low flow, velocity-discharge curve confirmed) → St. Joe peak 22:30 Day 48 (~46.5 hr from pulse-1 forcing) → Harriet 18:00 Day 49 (timing contaminated by the Day-49 upper-basin pulse). Pulse 2 propagated separately with similar cascade. Boxley 0.85"-cumulative → +0.48 ft, 0.56 ft/in moderate antecedent (intermediate between dry 0.40 and wet 0.84). Pruitt briefly re-entered Optimal.

• Event 7 (Day 55–57, Apr 24–26): Tier 2 event after 6-day dry spell. Pruitt zone 1.353" (Cove 1.34", Hoskin 1.36", Flatrock 1.40"). Dry-to-moderate antecedent (0.30–0.70" 7-day). Cascade: Boxley peak 3.21 ft Day 55 16:30 → Ponca 347 cfs 18:15 (+1.75 hr) → Pruitt 5.31 ft / 612 cfs 03:00 Day 56 (+8.75 hr from Ponca) → St. Joe 5.99 ft / 1460 cfs 17:15 Day 56 (+14.25 hr) → Harriet 5.52 ft / 1610 cfs 02:00 Day 57 (+8.75 hr). Total Boxley→Harriet 33.5 hr. Transfer ratios: Boxley 0.82 ft/in (dry, but high-intensity bursts overrun pool storage); Bear Creek first true flash response: 0.90" → +0.24 ft / +18 cfs, ~30.5-hr lag (long dry-antecedent lag at Bear Cr). Richland 0.98" → +1.18 ft (did not reach 3.2 ft).

• Event 8 (Day 59–62, Apr 28–May 1): Two-pulse Tier 2-3 major event. Pulse 1 (Apr 27 evening): lower-watershed primer 0.5–0.85" on dry antecedent. Pulse 2 (Apr 28): watershed-wide 1.0–1.7" peak hour 14:00–16:00 CDT. Saturated antecedent post-Pulse 1. Spatial extremes: Falling Water 1.40"/0.99"/hr; Hoskin 0.81"/hr. Richland +2.90 ft in 60 min at 21:45 (largest hourly rise of study to that date — "wet/saturated + high intensity" mode; later exceeded in Event 15: Richland +3.07, St. Joe +3.14 on Day 89), peak 4.89 ft (above Upper Richland Optimal 4.0). Boxley peak 4.10 ft at 00:30 Day 60 — above Hailstone Low-Floatable (3.7) ~7 hr, above the Boxley–Ponca section threshold (3.2) ~26 hr. Pruitt 5.98 ft / 893 cfs at 10:15 Day 60 (1.42 ft/in wet). St. Joe 6.96 ft / 2260 cfs at 00:30 Day 61 (lag ~30 hr, 2.0 ft/in wet cumulative). Harriet 6.29 ft / 2430 cfs at 09:30 Day 61 (~1.3 ft/in wet, 9-hr St. Joe→Harriet at high flow). Bear Cr +1.49 ft / +525 cfs in 1 hr to 3.88 ft peak at 02:30 Day 60, ~6.5 hr after the Day-59 Bear-zone QPE peak (20:02). Total Boxley→Harriet ~33 hr. Recession sequence at St. Joe: 33→16→10→6.6→5.8 cfs/hr per 24-hr window (geometric decay ratio ~0.6–0.9).

• Event 9 (Day 66–68, May 5–7): First clean dry-antecedent calibration event after 6-day dry spell. Single-pulse Day 66 morning, Boxley 1.23"/0.53"/hr. Dry antecedent (7-day 0.07–0.30"). Boxley +0.87 ft, ~7.2-hr lag (zone QPE 1-hr peak 05:02 → gauge peak 12:15), transfer 0.71 ft/in (dry, intensity-elevated). Bear Cr 0.92" → +0.32 ft / +34 cfs, ~14.2-hr lag and 0.35 ft/in (vs 1.45 ft/in wet) — confirms ~4× transfer damping under dry. Richland 1.04" → +0.26 ft, transfer 0.25 ft/in dry (vs 1.0+ wet). Pruitt 0.45" → +0.65 ft / +194 cfs, transfer 1.44 ft/in dry — IDENTICAL to wet (~1.4). Pruitt antecedent-independence finding: confirmed. Cascade: Boxley→Ponca 3 hr (dry slower), Ponca→Pruitt 10.75 hr, Pruitt→St. Joe 20.5 hr dry (vs 14 hr wet, ~46% slower). St. Joe→Harriet 10.25 hr — antecedent-insensitive. Total Boxley→Harriet 44.5 hr dry (~35% longer than 33 hr wet).

• Event 10 (Day 71–74, May 10–13): Tier 2 multi-zone with concentrated Richland forcing. Falling Water 1.40"/1.08"/hr, Boxley 1.32"/0.67". Moist antecedent (~1.0–1.5" 7-day). Richland +1.92 ft from intraday low 1.32 (1.34 ft/in moist + high-intensity — HIGHER than wet 1.0), 4.7-hr lag. Briefly reached Low-Floatable Upper Richland. Boxley 0.67 ft/in (moist, with sustained-rain pool-fill pattern: gradual 4 hr + step +0.63 ft at 21:45). Bear Cr 0.054 ft/in (sub-threshold on still-dry soil, the +0.06 ft / +1.4 cfs micro-response). Double-peak structure at St. Joe: Primary 4.66 ft / 646 cfs at 12:30 Day 72 (Richland-tributary-driven, peaked 1.5 hr BEFORE Pruitt — first explicit demonstration of tributary dominance over mainstem); Secondary 4.53 ft / 584 cfs at 13:15 Day 73 (Pruitt-mainstem-driven, 23.25-hr Pruitt→St. Joe at low-mid flow). Harriet primary 4.48 ft 03:00 Day 73 (14.5 hr St. Joe→Harriet); secondary 4.41 ft 01:45 Day 74 (12.5 hr, 76% cfs retention vs 85% primary).

• Event 11 (Day 80–82, May 19–21): Major watershed-wide flood-scale forcing on extreme-dry antecedent. DRIEST antecedent of any major event (7-day 0.07–0.30"). Pruitt zone 1.93" (highest of any zone — first Pruitt-dominant event), Ponca 1.52", Boxley 1.16", St. Joe 1.60", Bear Cr 1.11" (spatial minimum). Direct-forcing dominance — every zone simultaneously: Boxley first rise 10:15 CDT, Ponca 10:00, Pruitt 09:00, St. Joe 10:00, Harriet 09:15 (parallel direct responses, not sequential cascade). Boxley +0.72 ft (0.62 ft/in dry); Pruitt +1.17 ft / +297 cfs (0.61 ft/in dry — confirms Pruitt dry transfer ratio); St. Joe 5.22 ft / 949 cfs (1.09 ft/in dry — surprisingly close to wet, 37-hr lag from peak QPE); Harriet 5.00 ft / 1130 cfs (0.76 ft/in dry, 52-hr lag — longest peak-to-peak lag of study); Richland +1.02 ft (0.73 ft/in dry); Bear Cr near-total non-response (+0.17 ft / +10.8 cfs from 1.11"!) = 0.09–0.17 ft/in dry — Bear Cr structurally damped under dry. St. Joe→Harriet ~13 hr (dry-antecedent lower-mainstem signature). Total cascade Boxley→Harriet ~36 hr.

• Event 12 (Day 83–85, May 22–24): Moist-antecedent spatially-shifting multi-day convective. Day 83 lower-watershed-heavy (Bear Cr 0.685", Richland 0.443", Harriet 0.563"); Day 84 shifted NW to Pruitt/Whiteley/Cave (Pruitt 0.319"). Moist antecedent (1.0–2.5" 7-day). Richland 0.443" + 0.036" → peaked 1.85 ft. Bear Cr two-peak hydrograph: D83 +0.05 ft (~30 min lag) + D84 +0.15 ft delayed (37-hr lag from D83 QPE) = 0.25 ft/in total (moist anchor). Pruitt two-mode response confirmed: 6.5-hr surface peak D84 + 19.75-hr karst/subsurface secondary peak D85 — consistent with local-knowledge karst losses between Ponca and Pruitt. MAJOR FINDING: moist Event 12 transfer ratios LOWER than dry Event 11 at all gauges (Boxley 0.0 vs 0.62; Pruitt 0.17 vs 0.61; Richland 0.35 vs 0.73). Forcing magnitude and spatial coherence matter more than antecedent moisture below threshold — distributed sub-1.0" forcing produces diffuse non-coherent hydrographs even on wet soils.

• Event 13 (Day 87, May 26): Richland-bullseye event — Falling Water 0.942"/0.466"/hr, Headwaters Richland 0.695". Moist antecedent (1.77–1.97" Richland 7-day). Richland +0.74 ft from low / 0.90 ft/in (moist, event-scale anchor), 3-hr lag — first event-scale Richland calibration of study. Bear Cr +0.36 ft / +31.2 cfs, 9.5-hr lag, 0.94 ft/in (moist-saturated) — flagged anomaly at the time, now contextualized as wet-mode behavior. Boxley non-detection (0.282" sub-threshold despite moist antecedent — pool-fill mechanism intact). Single-day event; recession Day 88.

• Event 14 (Day 88, May 27): Upstream-shifted bimodal forcing. Bear/Lick Cr afternoon pulse + heavy Boxley/Ponca/Little Buffalo overnight (Boxley 0.706"). Carryover from Event 13: Richland peak propagated to St. Joe morning Day 88 at 4.25 ft / 461 cfs (Richland → St. Joe 19.5 hr; St. Joe → Harriet 12 hr to 4.29 ft / 581 cfs). St. Joe Richland-source transfer ~0.37 ft/in. Event 14 Boxley response began late evening (+0.04 ft, peak pending). Transitioned directly into Event 15.

• Event 15 (Day 89–90, May 28–29): MAJOR WATERSHED-WIDE FLOOD-SCALE EVENT — FIRST lower-mainstem (St. Joe/Harriet) flood-threshold exceedance of study (Ponca/Pruitt first crossed in Event 2). Largest 24-hr basin QPE of study to that date. Ungauged hotspot Long Cr 6.087" with 1.584"/hr (approaching March 2024 reference event scale). Pruitt zone 2.60", St. Joe 2.14", Bear 2.63", Richland 2.63", Harriet 2.67". Moderate-to-wet antecedent. Pruitt 8.55 ft / 2610 cfs (>flood 2000) bimodal (Mode 1: 13:45 from local Cove/Hoskin/Flatrock; Mode 2: 18:00 from Ponca-zone backwater) — 1.9 ft/in moist. Bear Cr 6.30 ft / 3090 cfs bimodal, 1.53 ft/in (wet/stage-dependent). Richland 8.89 ft (far above Upper Richland High 6.0), 2.69 ft/in — channel-geometry nonlinearity once out-of-bank (now exceeded by Event 20's 9.25 ft). St. Joe 15.05 ft / 14,500 cfs at 01:30 Day 90 (~1.8× flood threshold) (now exceeded by Event 20's 19,600 cfs), 11-ft rise, ~3 ft/in event-scale. Harriet 14.24 ft / 15,000 cfs at 07:30 Day 90 (~1.6× flood threshold) (now exceeded by Event 20's 21,800 cfs), +5.69 ft in 7.5 hr (1.68 ft/hr peak). Pruitt→St. Joe ~11.75 hr, St. Joe→Harriet 6 hr at flood flow. Approaches March 2024 reference event magnitude but distributed forcing (not Richland-only) produced same St. Joe stage from less concentrated rain.

• Event 16 (Day 91, May 30): Late-afternoon Cave Cr / Big Cr / Bear Cr / Spring Cr convective sub-event on saturated antecedent (7-day 3.5–5.1"). Cave 0.88"/0.85"/hr, Headwaters Bear 0.59"/0.45"/hr. Bear Cr +1.23 ft / +956 cfs in 2 hr, ~4.5-hr lag, 2.08 ft/in vs the concentrated Headwaters-Bear HUC QPE 0.59" — highest Bear Cr transfer in study (confirmed by Events 20 onset & completion). Refined finding: Bear Cr transfer is stage-dependent, not purely antecedent-dependent — pre-event low stage (3.54 ft, steep rating-curve zone) amplifies ft-per-inch response. Signal separation textbook: Richland gauge flat → St. Joe rebound confirmed as Cave/Big Cr / mainstem-misc source. St. Joe rebound peak D92 01:15 at 9.84 ft / 5550 cfs (~9.25-hr lag, 2.5 ft/in wet-antecedent for concentrated sub-zone forcing). Harriet rebound D92 07:00 at 9.02 ft / 6000 cfs (5.75-hr St. Joe→Harriet propagation — second confirmation of ~6-hr high-flow timing).

• Event 17 (Day 93–94, Jun 1–2): Wet-antecedent multi-cell convective. Cove 1.02"/0.72"/hr, Falling Water 0.93"/0.83"/hr, Headwaters Bear 0.55"/0.41"/hr, Dry Cr 0.80". Very wet antecedent (4–5" 7-day Cove, Falling Water; Bear ~4.15"). Bear Cr was the cleanest pair: 0.51 ft/in, ~10-hr lag (zone QPE peak 18:02 Day 93 → gauge peak 04:00 Day 94), 3.07 → 3.38 ft — confirms stage-dependence finding (mid-stage on recession from prior pulse → lower ratio than Event 16's near-baseline 2.08). Pruitt non-response to its zone's 1.02" Cove Cr bullseye — most striking finding, indicating Pruitt's response dominated by upstream routing rather than local-zone forcing when mainstem is in active recession. Richland near-zero rise despite 0.93" Falling Water — saturated channels above gauge had absorbed pulse. Major refinement: Bear Cr wet-antecedent transfer ratio range 0.5–2.0 ft/in depending on initial stage (rating-curve steepness near baseflow vs. floodplain flattening at high stage).

• Event 18 (Day 96–97, Jun 4–5): Late-evening upper-basin convective pulse — Boxley zone 0.302"/0.246"/hr on drying antecedent (1.85" 7-day, down from 2.83"). Sub-threshold confirmed: zero Boxley response through end of Day 97. Confirms ~0.3" insufficient on drying antecedent — pool-fill threshold not crossed. Cleanest in-study example of USGS rating-curve revision artifact: Bear Cr 60.0 → 71.7 cfs step at 18:30 with zero height change and zero zone QPE — discrete cfs-table update applied mid-day. Validates local-knowledge guidance: height > cfs for cross-event comparison; post-major-event field visits produce visible step changes.

• Event 19 (Day 98–101, Jun 6–9): MAJOR UPPER-BASIN MULTI-PULSE EVENT — second flood-scale event of study. Pulse 1 Day 99 AM (Boxley 2.97 ft from 0.532"/hr Terrapin Branch peak, dry-leaning antecedent 0.45–1.2"). Pulse 2 Day 99 PM (smaller, sustained 4-ft+ baseline). Pulse 3 Day 100: STUDY-RECORD Boxley 5.50 ft (Hailstone Optimal+, exceeded all prior peaks), from 0.699"/hr peak in HUC 0201, 3.7-hr peak-to-peak lag, 2.28 ft/in (very wet, intensity-elevated — highest Boxley transfer of study). Ponca 1920 cfs (>1600 flood threshold) at 15:30 Day 100, ~2.75 hr above flood. Pruitt 7.98 ft / 2130 cfs (>2000 flood threshold) at 21:45 Day 100, ~1.75 hr above flood — second flood-threshold event at Pruitt of study. Day 101 propagation peaks: St. Joe 7.63 ft / 2900 cfs at 10:30 (36% of flood threshold) — ~24.5 hr from Day 100 peak QPE → St. Joe peak; Harriet 6.67 ft / 2860 cfs at 18:45 (30% of flood threshold) — 8.25 hr St. Joe→Harriet. CRITICAL CROSS-EVENT FINDING vs Event 15: upstream-only forcing → upstream-only flood. Watershed routing/storage attenuated flood pulse to ~30–36% of flood threshold at mid/lower mainstem. Pruitt flood was ONLY because of constructive interference between upstream cascade and local Pruitt-zone rain. Bear Cr only +0.06 ft (signal separation: Harriet rise = pure mainstem propagation). Recession tail (Days 102–104): St. Joe ~32→14.5→8.6 cfs/hr, Harriet ~37→19.3→11.6 cfs/hr falling. St. Joe/Harriet remained mid-Optimal through Day 104; Event 19 delivered a multi-day Optimal window (≥6 days confirmed). Ponca first to exit Optimal (dropped below 200 cfs into Low-but-Floatable ~01:45 Day 104).

• Event 20 (Day 105–106, Jun 13–14 — COMPLETE; recession Days 107–112): LARGEST EVENT OF STUDY. FIRST MID/LOWER-BASIN-CONCENTRATED FLOOD-SCALE EVENT — the spatial complement to Event 19's upper-only flood — that propagated to a study-record trunk flood.

• Day 105 (onset): Evening convective complex migrating SW→NE; basin-max 24-hr QPE 3.792" (Richland zone). Bullseyes: Headwaters Richland 3.867" (1.269"/hr), Falling Water 3.716" (1.483"/hr), Outlet Richland 3.864", Headwaters Bear 3.766" (1.695"/hr), Cave Cr 3.414", Headwaters Big Cr 3.361", Calf Cr 3.315", Water Cr 3.309", Cove Cr 2.751". Upper basin much lighter (Boxley 0.753", Ponca 0.729"). Moist-but-not-saturated antecedent (Richland 7-day 1.41", Bear 0.97" driest, Pruitt 2.18–2.68"). Tributary floods (onset values): Pruitt +5.34 ft in final hour to 10.11 ft / 4150 cfs at 23:30; Bear surging through 8.72 ft / 7580 cfs; Richland 8.35 ft. Harriet +2.61 ft to 7.19 ft / 3500 cfs (37% flood, 5.97-hr Water-Cr lag). Ponca +294 cfs to 431 cfs. St. Joe barely moved same-evening (+0.50 ft to 5.02 ft / 834 cfs). Boxley near-flat (+0.02 ft, pool-fill pending). Forcing direct/distributed (Event-11-like).
• Day 106 (completion — overnight trunk integration): New study-record peaks at every gauge that flooded — Pruitt 10.23 ft / 4290 cfs @00:00 (two-mode: + secondary 8.90 ft / 2930 cfs @07:00); Bear 11.20 ft / 12,900 cfs @01:30; Richland 9.25 ft @00:15 (study-record). St. Joe 17.59 ft / 19,600 cfs @08:00 (≈2.45× flood — STUDY RECORD, EXCEEDS the March-2024 reference of ~15 ft); +10.43 ft / +17,160 cfs intraday surge; double structure (Richland sub-peak 10.23 @02:00 then Cave/Big main 17.59 @08:00). Event-scale transfer ~6.1 ft/in (~8,800 cfs/in), tributary-amplified. Harriet 17.54 ft @14:30 / 21,800 cfs @13:30–14:00 (≈2.33× flood — STUDY RECORD); compound source (Bear confluence early bump @01:15 + St. Joe propagation main surge); ~4.1 ft/in (~8,260 cfs/in). Boxley delayed pool-fill +2.17 ft to 4.51 ft @08:00 (crossed Hailstone Optimal 4.4 briefly; 1.42 ft/in on 2-day cumulative 1.53", wet/primed; QPE-peak-to-peak lag 5.97 hr). Ponca direct +1067 cfs to 1320 cfs @09:45 (1220 cfs/in wet; lag 7.72 hr). St. Joe→Harriet 6–6.5 hr at flood flow (matches Event 15). Richland→St. Joe tributary arrival 1.75 hr.
• Day 107 (recession limb — zero QPE): Pure flood-limb recession. St. Joe held above its 8000-cfs flood threshold ≈ 22 hr; Harriet held above 9370 ≈ 23.5 hr. Both re-entered Optimal mid-day. No rating-curve steps. Boxley 3.39→2.96 ft; Richland 3.63→2.75 ft; Bear 3.99→3.33 ft / 264 cfs; Ponca 579→319 cfs; Pruitt 1290→688 cfs.
• Day 108 (recession Day 3 — near-dry, basin-max 0.146"): Flood-limb recession; zero attributable response to trace QPE. St. Joe 3600→2350 cfs, Harriet 4780→3070 cfs (mid-Optimal). Ponca 323→230 cfs. Pruitt 684→488 cfs. Boxley 2.93→2.67 ft. NO rating-curve step. Reinforces Open Q10: 0.146"-zone / 0.175"-HUC pulse on a still-wet antecedent (Bear 7-day 4.51") produced no rise.
• Day 109 (recession Day 4 — DRY, basin-max 0.000"): Pure flood-limb recession, 9th clean recession-only baseline day. KEY: Ponca crossed below 200 cfs into Low-but-Floatable around midday (Open Q12e CLOSED, mirroring Event-19 Day-104). St. Joe 2310→1670 cfs, Harriet 2980→2200 cfs (mid-Optimal). Pruitt 484→370 cfs. Boxley 2.66→2.49 ft. NO rating-curve step — four days post-record-peak.
• Day 110 (recession Day 5 — first measurable rain since Day 107, basin-max 0.216" Boxley): Light distributed low-intensity rain on a still-wet receding basin → ZERO attributable response. Centers: Shop Cr 0.316"/0.254"/hr (day's highest 1-hr), Spring Cr 0.202", Boxley 0.216"/0.134"/hr. St. Joe 1650→1230 cfs, Harriet 2230→1730 cfs (mid-Optimal). Pruitt 367→287 cfs. KEY: Ponca crossed below 150 into Too Low (~16:00 CDT). NO rating-curve step.
• Day 111 (recession Day 6 — trace basin-wide, basin-max 0.043" Boxley): Trace distributed rain → ZERO attributable response. Every gauge pure recession. St. Joe 1220→967 cfs, Harriet 1700→1350 cfs (mid-Optimal); Pruitt 287→235 cfs (approaching 200 boundary); Ponca 141→122 cfs (Too Low); Boxley 2.33→2.21 ft. St. Joe ~11 cfs/hr @~1100; Harriet ~15 cfs/hr @~1500. NO rating-curve step — six days post-record-peak.
• Day 112 (recession Day 7 — near-zero, basin-max 0.005" Boxley): Effectively zero rain → ZERO attributable response; pure recession. KEY: Pruitt crossed 200-cfs Optimal→Low-but-Floatable (low 197 cfs @20:30) — second mainstem gauge below Optimal. St. Joe 955→796 cfs and Harriet 1330→1110 cfs (mid-Optimal, St. Joe now below Event-19 Day-104 ~800-cfs reference); Ponca 122→109 cfs (Too Low); Boxley 2.21→2.11 ft (seepage); Richland 1.57→1.43 ft and Bear 58.7→46.4 cfs / 2.45 ft (post-event lows, deep overshoot). St. Joe ~7 cfs/hr @~875; Harriet ~9.3 cfs/hr @~1220. NO rating-curve step — seven days post-record-peak.
• ANSWERS Open Q4 (March-2024 signature): Event-20 exceeded March-2024 at St. Joe (17.59 ft / ~13 ft rise vs 2024 ~15 ft / ~11 ft) from a 3.4–3.9" multi-tributary concentration. A 2024-scale (and larger) trunk flood is reproduced when Richland + Cave + Big + Bear flood simultaneously, even at sub-4" totals.

• MAJOR CROSS-EVENT REFINEMENT (vs Event 19): Lower/mid-basin-concentrated forcing (≈52% of basin area) DOES drive a study-record trunk flood with an overnight lag — unlike upper-only forcing (Event 19) which attenuated to 30–36% of flood threshold. Clean spatial complement established.

• Event 21 (Days 114–117, Jun 22–25 — the study's BIGGEST event; recession Days 116–118): CORRECTED 2026-06-29 — previously logged here as a "data gap" (a confabulation: the Day-113–115 summaries were present; the Day-114 flood was characterized in analysis/daily/2026-06-22.md but never integrated during the 06-21→06-25 max_tokens truncation window). Day 114 (Jun 22) was a DRY-antecedent (7-day 0.1–0.32" basin-wide, on the draining Event-20-tail baseflow) UPPER-BASIN FLASH FLOOD — basin-max 3.377" (Boxley zone, 1.30"/hr), Ponca zone 3.114" (Smith Cr 3.807"). STUDY RECORDS: Boxley 9.06 ft (prior 5.50, E19 D100; +5.0/+7.06 ft, lag 3.47 h), Ponca 8,700 cfs (prior 2,120, E2; 5.4× the 1,600 flood threshold; 2,756 cfs/in, lag 4.47 h), Pruitt 14.27 ft / 9,710 cfs (prior 4,290, E20; 4.85× the 2,000 flood threshold; ROUTING-DOMINATED — local zone only 1.357", the peak is the routed upper wave, lag 9.72 h). Tributaries: Richland +0.81 ft (0.527 ft/in, 6.97 h, stayed below 3.2 floatable); Bear +1.84 ft / +838 cfs (1.16 ft/in, ~2.0 h — dry-soil non-linearity, Pattern #6). DOWNSTREAM ATTENUATION (the key finding): the upper flood routed through the DRY intervening ~1,342 km² basin and ATTENUATED to just-below-flood — St. Joe 11.34 ft / 7,890 cfs @02:45 D115 (99% of the 8,000 threshold; Pruitt→St. Joe ~11 h), Harriet 9.60 ft / 6,870 cfs @09:15 D115 (73% of the 9,370 threshold; St. Joe→Harriet 6.5 h); recession Days 116–118 (St. Joe 2,430→1,180 cfs, Harriet 3,160→1,590 cfs). This is the upper-only-flood-attenuation archetype at FLOOD scale — the flood-magnitude analog of Event 19 (sub-flood upper-only → 30–36%) and Event 22 (sub-1" upper-only → 17–18%): a study-record upper flood (Ponca 5.4× flood) still failed to flood the lower mainstem because the intervening basin was dry. This event directly motivated the propagation-magnitude recalibration (rainfall-distribution + antecedent model, fit on 152 events) deployed 2026-06-29. Day 117 (Jun 25) secondary pulse — Harriet-zone bullseye Spring Cr 0409 1.952"/0.965"/hr @16:02 CDT, Water Cr 1.021", plus heavy ungauged (Hickory 2.176", Boat 1.808") — produced a clean Harriet-zone-only response: Harriet 1720 cfs / 5.63 ft (15:30) → ~2040 cfs / 5.94 ft (~22:00), +0.31 ft / +~320 cfs, ~5–6 hr lag (Spring-Cr peak 16:02 → Harriet peak ~22:00). A small Pruitt-zone morning pulse (Cove 0.795", Flatrock 0.833", Hoskin 0.577") gave Pruitt +0.33 ft (06:15–07:30) and a faint St. Joe bump (1370→1470). Bear gauge stayed in recession (Bear zone 0.524" flat) — signal separation: Harriet rise = Harriet-zone direct, NOT Bear-confluence. Net: Event 21 re-loaded a SECOND multi-day lower-mainstem Optimal window on top of the Event-20 tail and reset Pruitt back into Optimal after its Day-112 exit.

• Day 118 (Jun 26 — Event-21 recession limb, non-detection): Light, distributed, low-intensity rain (basin-max 0.246" Bear zone; Headwaters-Bear 0.27"/0.083"/hr @03:02 CDT, Water Cr 0.207"/0.079"/hr, Calf Cr 0.216", ungauged Hickory 0.21") on a still-WET, actively-receding basin produced ZERO attributable gauge response anywhere — pure recession (each daily max = 00:00 reading). St. Joe 1450→1180 cfs (5.92→5.53 ft) and Harriet 1910→1590 cfs (5.81→5.50 ft) — both mid-Optimal; Pruitt 488→374 cfs (Optimal); Ponca 278→213 cfs (Optimal, approaching 200); Boxley 2.99→2.80 ft (seepage); Richland 1.42→1.36 ft and Bear 61.4→51.0 cfs / 2.49 ft (new post-event lows). Recession points: St. Joe ~12 cfs/hr @~1300; Harriet ~14 cfs/hr @~1750. Persistent Harriet limb offset (~410 cfs higher at near-identical stage). NO rating-curve step. Raises the receding-basin absorbed-pulse floor to at least ~0.25" zone-average.

• Event 22 (Day 119–121, Jun 27–29 — FULLY CLOSED; Harriet peak captured Day 121; recession tail Day 122): Clean UPPER-BASIN-CONCENTRATED single-pulse event (peak 1-hr ~09:02 CDT) on a very-wet antecedent, interrupting the Event-20/21 recession. Spatial complement of Event 20; smaller (sub-flood) analog of Event 19 — and it BEHAVED like a small Event 19: upper-only forcing attenuated to a modest non-flood trunk bump.

• Day 119 (onset): Zone QPE: Ponca 0.864" basin-max (Beech 0.979"/0.689"/hr, Whiteley 0.834", Smith 0.780"), Boxley 0.851" (Terrapin 0.851"/0.738"/hr — day's highest intensity), Pruitt 0.609" (Cove 0.726", Flatrock 0.635", Hoskin 0.492"); sharp downstream falloff to St. Joe 0.271", Harriet 0.213", Bear 0.145", Richland 0.056" (dry). Boxley +1.19 ft (low 2.74 @07:45 → peak 3.93 ft @14:00), ~5.0-hr lag (09:02 QPE peak → 14:00), 1.40 ft/in (wet/primed) — third reproduction of the wet/primed ~1.3–1.42 anchor (Events 4, 20). Crossed Hailstone Low-Floatable (3.7 ft) ~13:30–15:30 (~2 hr) and Boxley-Ponca section (3.2 ft) from ~12:45 — first Hailstone-runnable window since Event 20; consistent with "Hailstone almost never runnable >24 hr." Ponca +562 cfs (low 196 @07:15 → peak 758 cfs @16:30); dipped to 196 (<200) @07:15 — the Day-118-projected Optimal exit OCCURRED, then the event REVERSED it back to solidly Optimal. In-zone lag 16:30 − 09:02 = 7.47 hr; Boxley→Ponca 14:00→16:30 = 2.5 hr (parallel-forcing-contaminated). Transfer ~651 cfs/in — ~40% BELOW the wet anchor (1000–1220) — FLAG; attributed to Event-12 sub-1.0"-forcing dilution + recession-suppressed baseline.
• Day 120 (trunk integration, ZERO QPE): Pure propagation. Pruitt peak captured at the day boundary: 5.81 ft / 838 cfs @~23:45 Day 119 / 00:00 Day 120 (rose +1.32 ft / +498 cfs from low 4.49 ft / 340 cfs; height transfer 2.17 ft/in — routing-dominated by the Ponca cascade stacked on local 0.609", NOT a clean local-zone transfer). Ponca→Pruitt ~7.25 hr at ~500–840 cfs — matches the 7.5-hr/~500-cfs node. St. Joe rose +0.66 ft / +439 cfs (low 991 cfs / 5.23 ft @03:00 → peak 1430 cfs / 5.89 ft @~16:00), then receded (1300 cfs @22:45). Pruitt→St. Joe ~16.25 hr at ~500–1400 cfs (~1.05 m/s assuming sinuosity 1.7 over 36.1 km straight-line = ~61.4 km channel) — intermediate moist-recession value, within the 11–23 hr band. St. Joe own-zone 0.271" produced NO direct response — confirmed; the trunk response is pure propagation. Boxley pure recession 3.33→2.90 ft. Bear (34.3 cfs / 2.33 ft) and Richland (1.21 ft) at NEW post-event lows.
• Day 121 (final closure — ZERO QPE, second consecutive dry day): Harriet peak CAPTURED — 1610 cfs / 5.52 ft @00:30 CDT (day opened still rising, crested @00:30, then receded all day to 1250 cfs / 5.14 ft). St. Joe peak 1430 cfs @16:00 Day 120 → Harriet peak 1610 cfs @00:30 Day 121 = 8.5 hr peak-to-peak (~0.99 m/s assuming sinuosity 1.7 over 17.9 km straight-line = ~30.4 km channel) — MODERATE-flow node, matching Events 2/19's ~8.25 hr, slower than the 6–6.5-hr flood node. Harriet 1610 cfs = 17% of flood (9,370), proportionally identical to St. Joe's 1430 cfs = 18% (8,000) — UPPER-ONLY-ATTENUATION RULE CONFIRMED at sub-flood magnitude (vs Event-19 flood-scale upper-only → 30–36%, Event-21 study-record upper flood → 73–99%). Total Event-22 Boxley→Harriet ~34.5 hr (Boxley peak 14:00 Day 119 → Harriet peak 00:30 Day 121) — wet/moist band. Open Q12a fully ANSWERED. All six other gauges pure recession (max = first reading): Boxley 2.89→2.63 ft (~0.011 ft/hr seepage), Ponca 258→183 cfs, Pruitt 4.90→4.48 ft / 488→337 cfs (low 4.46/331 @23:15), St. Joe 1280→961 cfs, Richland 1.20→1.12 ft (NEW post-event low), Bear 34.3→27.8 cfs / 2.25 ft (NEW post-event low). Signal separation textbook: Richland & Bear both flat at new lows → Harriet crest = pure mainstem propagation, NOT Bear-confluence/Richland-sub-basin. Ponca crossed 200 cfs → Low-but-Floatable ~18:00 CDT (203 @17:45 → 196 @18:00) — Event-22 Ponca Optimal window closed; smallest drainage first to exit, as in every event. Pruitt (337 cfs), St. Joe (961 cfs), Harriet (1250 cfs) all remain mid-Optimal. NO rating-curve step — ~16 days post-Event-20 record peak. EXPECTATION CONFIRMED — Event 22 = small upper-only attenuation archetype, fully documented across three days.
• Day 122 (Jun 30 — recession tail, THIRD consecutive zero-QPE day): Pure recession at all seven gauges (each daily max = 00:00 reading), no rainfall anywhere (basin-max 0.000"). Recession-band points: St. Joe 943→764 cfs (~7.9 cfs/hr @~850), Harriet 1230→966 cfs (~11.6 cfs/hr @~1100), Pruitt 4.47→4.18 ft / 334→246 cfs (~3.7 cfs/hr @~290), Ponca 180→137 cfs (~1.9 cfs/hr), Boxley 2.63→2.44 ft (~0.008 ft/hr seepage), Richland 1.12→1.03 ft (NEW post-event low), Bear 27.8→23.5 cfs / 2.19 ft (NEW post-event low). Threshold cascade: Ponca crossed 150 → Too Low ~16:00 CDT (150 @15:15 → 147 @16:00) — Event-22 Ponca window fully closed (Low-but-Floatable exit was Day 121, Too Low exit Day 122). Pruitt (246), St. Joe (764), Harriet (966) all mid-Optimal. Signal separators Richland & Bear flat at new lows → confirms zero forcing. 7-day antecedent collapsing as Event-22 rain ages out of window: Boxley zone 5.02"→1.63", Ponca ~1.6", Richland driest (0.62–0.83"), Bear (0.85–1.25"). NO rating-curve step — ~17 days post-Event-20 record peak; Bear/Richland cfs still stepping smoothly in 0.7–0.8-cfs increments. Boxley pool-drain from 3.93-ft Day-119 peak: 3.93→3.33→2.90→2.63→2.44 ft (Day 4, ~0.5 ft/day slow phase). Nothing to attribute — no QPE peak anywhere.

Recession Behavior

• Two-phase recession universally observed: fast interflow phase (first 24–48 hr post-peak) → slow groundwater/baseflow phase. Geometric decay with daily ratio ~0.5–0.9 per 24-hr window.
• St. Joe canonical sequence (Event 8 wet): 33 → 16 → 10 → 6.6 → 5.8 cfs/hr over Days 1–5 post-peak. (Event 9 dry: 6.96 → 5.1 → 3.2 → 1.1 → 0.78 cfs/hr — faster fractional decay under dry, smaller absolute slope.) Event 19 tail: Day 102 ~32 cfs/hr; Day 103 ~14.5; Day 104 ~8.6 at ~800 cfs. Event 20 began on this drained baseflow (706 cfs at Day-105 start). Event-20 flood-limb series: St. Joe ~700 cfs/hr near peak → ~415 @8000 → ~103 @3800 → ~90→50 @3500→2700 → ~28 @2000 → ~18.5 @1400 → ~11 @1100 → ~7 @875. Event-21 ADDS a fresh-limb baseflow-band point (Day 118): St. Joe ~12 cfs/hr @~1300 cfs. Day 119 (Event-22 onset): St. Joe still receding ~6–7 cfs/hr @~1050–1170. Day 120 (Event-22 fresh limb): St. Joe falling-limb post-16:00-peak ~19 cfs/hr @~1350. Day 121: St. Joe fresh-limb recession ~14 cfs/hr @~1100 (1280→961 over 22.75 hr). Day 122: St. Joe recession ~7.9 cfs/hr @~850 (943→764 over 22.75 hr) — continued baseflow-band decay, slightly below Day-121 fresh-limb rate.
• Harriet sequence: tracks St. Joe at high flow; converges to near-identical absolute recession rates once the propagation pipeline empties. Event-20: ~700 @12,500 → ~135 @5,000 → ~116→70 @4,500→3,300 → ~33 @2,600 → ~22 @1,980 → ~15 @1,500 → ~9.3 @1,220. Event-21 ADDS Day-118: ~14 cfs/hr @~1750. Day 119: Harriet still receding ~11 cfs/hr @~1310–1560. Day 120: Harriet still RISING on the Event-22 propagation pulse (1200 @14:00 → 1540 @22:45). Day 121: Harriet PEAKED 1610 cfs @00:30, then fresh-limb recession ~16 cfs/hr @~1400 (1610→1250 over 22.25 hr). Day 122: Harriet recession ~11.6 cfs/hr @~1100 (1230→966 over 22.75 hr). Persistent limb offset confirmed again — Harriet sits ~200 cfs higher than St. Joe at near-identical stage because it peaked ~8.5 hr later.
• Boxley pool drain: ~4 days for full drain from a typical major-event peak (longer for larger peaks — Event 20 ~7 days). Slow seepage phase ~0.005–0.015 ft/hr. Pool-fill timescale (dry → response): ~36 hr for first 0.5" pulse. Days 107–112 drain: 3.39→2.11 ft. Event-21 re-filled to ~3.49 ft (Day 116); Days 116–118 drained 2.99→2.80 ft. Event 22 (Day 119): pool PRE-FILLED by the wet antecedent → 0.851" produced a fast +1.19 ft to 3.93 ft with only ~5-hr lag (1.40 ft/in). Days 120–122: Boxley draining 3.33→2.90→2.63→2.44 ft (~0.008–0.018 ft/hr seepage) — Day 4 of drain, ~0.5 ft/day slow phase, consistent with ~4-day drain for a ~1.2-ft-class peak.
• Bear Cr: flashy recession, 90%+ depletion in 4 days from major peak; k ≈ 0.017–0.024 /hr. (Event 20 reset Bear to study-record 12,900 cfs then flashed ~94% in <22 hr. Event-21 re-elevated Bear to 94.4 cfs / 2.77 ft (Day 116); Days 118–122 receding to 23.5 cfs / 2.19 ft, NEW post-event low; light QPE Days 118–119 and zero QPE Days 120–122 produced NO perturbation. Cfs stepping smoothly 27.8→27.0→26.3→25.6→24.9→24.2→23.5 in 0.7-cfs increments.)
• Richland Cr: very flashy, returns below pre-event baseline within 3–4 days post-major-peak. (Event-21 re-elevated Richland to 1.55 ft (Day 116); Days 118–122 receding to 1.03 ft, NEW post-event low; 0.056"-zone QPE Day 119 and zero QPE Days 120–122 produced no perturbation.)
• Day 65 "dry-spring baseflow" anchor was a moment in continuing decline, not a true floor. By Days 75–79, all gauges dropped below Day 65 values. No stable seasonal baseflow floor observed.
• Day 95 and Day 97 baselines: cleanest recession-only days, "pipeline-empty" reference. St. Joe/Harriet ~0.020–0.022 ft/hr / ~10–15 cfs/hr. High-flow analogs: Event-20 Days 106–112 fill the curve from flood-limb (~700 cfs/hr) through the deep baseflow floor (~7–9.3 cfs/hr @875–1220). Event-21 Day 118 + Event-22 Days 119–122 add fresh-limb-through-baseflow-band points (St. Joe ~7.9 @850; Harriet ~11.6 @1100). Fifteen+ points now bracket the dQ/dt-vs-Q curve.
• Sub-threshold pulses produce delayed subsurface baseflow support: Day 78 finding (Bear flat after 0.11" on saturated soils). Absorbed-pulse floor for an actively-receding watershed (forcing-magnitude-gated, NOT antecedent-gated): ~0.10" Day 104; 0.146" Day 108; 0.216" Day 110; 0.043" Day 111; 0.005" Day 112; 0.246" Day 118 — ALL fully absorbed. Receding-basin absorbed-pulse floor is at least ~0.25" zone-average. Day 119 contrast: the 0.86" Ponca / 0.85" Boxley pulse DID register strongly — confirms the floor is between ~0.25" and ~0.85" for upper-zone forcing on a very-wet antecedent; Boxley/Ponca thresholds remain ~0.5". Days 120–122: 0.000" → pure recession.
• Pre-event baseline overshoot: after major events, Pruitt and Richland routinely recess BELOW pre-event values during the slow phase. Days 109–112 (Event 20) and Days 118–122 (Events 21–22): Richland (1.03 ft) and Bear (23.5 cfs / 2.19 ft) again at new post-event lows below pre-event starting values.

Rating Curve Observations

• Ponca + Pruitt calibrated Feb 17, 2026, two weeks pre-study — both initial baselines reliable.
• Pruitt mid-event rating shift Day 5/6 (Event 1): CFS dropped 67.9 → 50.9 with stable height.
• Pruitt low-stage CFS unreliable (height < ~3.7 ft, CFS < ~150). Local-knowledge channel scour shifts flow to river right; gauge on river left under-reads. Persistent Ponca > Pruitt CFS at low flow — NOT a karst-loss signal at low flow. Height is the reliable Pruitt metric below ~150 cfs. (Note: at Day 122 Pruitt is at 4.18–4.47 ft / 246–334 cfs — above the ~3.7-ft low-stage-unreliable zone, values trustworthy.)
• Ponca rating-curve revision Day 76: 154 → 91 cfs step at 11:00 with smooth Boxley recession and zero QPE. Pre-Day-76 Ponca low-flow CFS over-reported by ~30–40%.
• Bear Cr rating-curve revision Day 45 (Apr 14): 3.2 → 21 cfs step at 15:30.
• Bear Cr second revision Day 96 (Jun 4): 60.0 → 71.7 cfs step ~18:30. Post-Day-96 CFS values are calibrated baseline. Days 102–122: Bear Cr cfs steps down smoothly in standard 0.7–1.4-cfs increments with no discrete jumps — revisions confirmed stabilized.
• High-stage rating curves performing well: Event 15 Pruitt 8.55 ft smooth; Event 19 Day 100 flood peaks clean; Event 20 Day-106 study-record stages tracked smoothly; Days 107–112 recession limbs clean with NO discrete cfs steps. Day-116–122 confirmation: still NO discrete cfs step at any gauge through ~17 days post-Event-20-record-peak — high-stage curves continue to perform; the historically-expected post-major-event field-revision artifact has not appeared. Active-weather field-calibration regime = highest-confidence cfs. NOTE: post-record-event USGS field visits historically produce visible step changes; KEEP watching Bear/Richland/Pruitt Days 123+ for revision artifacts.
• Height comparison across gauges is meaningless — each rating curve is location-specific. Event 20 Day-106: St. Joe 17.59 ft = 19,600 cfs vs Harriet 17.54 ft = 21,800 cfs vs Pruitt 10.23 ft = 4,290 cfs. Day-119/121 low-flow corollary: St. Joe 5.89 ft / 1430 cfs vs Harriet 5.52 ft / 1610 cfs — identical-stage/different-discharge effect persists at low flow and on fresh recession/rising limbs. Day-122 corollary: St. Joe 4.83 ft / 764 cfs vs Harriet 4.81 ft / 966 cfs — near-identical stage, Harriet ~200 cfs higher (limb-position effect).
• CFS accuracy improves during active weather. Later/storm-period cfs values higher-confidence.

Cross-Event Findings

Detection thresholds (Q1) — zone-averaged QPE required for measurable mainstem rise: - Boxley: ~0.5" wet/moist; ~1.0" dry (pool-fill barrier); sub-detection at 0.3" even wet, 0.5" even dry-moderate. Day 105: 0.753" on drying-moderate → +0.02 ft. Day 106: held + fresh 0.781" (wet) → +2.17 ft. Days 110–118: 0.216"/0.043"/0.005"/0.086" on draining pool → ZERO. Day 119: 0.851" on a PRE-FILLED wet pool (7-day 4.17") → +1.19 ft, ~5-hr lag — confirms ~0.5" wet threshold and pre-satisfied pool-fill. Days 120–122: 0.000" → pure recession. - Ponca/Pruitt: ~0.3" wet; ~0.5" dry; Pruitt response dominated by upstream routing — local-zone forcing produces small response even at 0.8–1.0" if no upstream signal. Event 20 exception (Day 105): 2.751" Cove → 4290-cfs local flood. Day 119: Ponca 0.864" → +562 cfs (registered strongly); Pruitt 0.609" local + upstream cascade → peaked 838 cfs / 5.81 ft @ day boundary Day 120. - St. Joe: ~0.5" zone-avg with concentrated cells; ~0.3" if spatially uniform with wet antecedent; sub-detection even at 0.45" if recession baseflow dominates. Day 119: own-zone 0.271" → no direct perturbation. Day 120: trunk rose +439 cfs to 1430 (18% of flood) by PROPAGATION from upstream, confirming own-zone 0.271" was sub-threshold and the response is routed. - Richland: ~0.25" with concentrated headwater bullseye on moist soil; ~0.5" otherwise; karst noise floor ±0.03–0.05 ft. Days 119–122: 0.056"/0.000"/0.000"/0.000" → no response (recession, new low 1.03 ft). - Bear Cr: dry-antecedent threshold >0.9–1.1" (Events 11–13); wet-antecedent threshold ~0.4" (Event 17). High structural absorption — but extreme forcing (3.77", Event 20) on low stage overruns even dry-ish damping (2.07 ft/in onset). Negative datapoints on actively-receding wet basin: 0.146" (Day 108), 0.059" (Day 110), 0.020" (Day 111), 0.001" (Day 112), 0.246"/0.083"/hr (Day 118), 0.145" (Day 119), 0.000" (Days 120–122) → all no response. - Harriet: direct-zone responses small unless concentrated >0.6"; dominated by upstream propagation. Event 20 Day 105: 2.532" → +2.61 ft. Event 21 Day 117: 1.12"-zone (Spring Cr 1.952") → +0.31 ft / +~320 cfs, ~5–6 hr lag (clean Harriet-zone-only pair). Day 118: 0.163" → no response. Day 119: 0.213" → no response. Days 120–121: 0.000" → rose to peak 1610 cfs @00:30 Day 121 (17% of flood) by PROPAGATION from St. Joe. Day 122: 0.000" → pure recession. - Flat/receding-basin absorbed-pulse floor (Q10): forcing-magnitude-gated (NOT antecedent-gated). ~0.10"–0.25" all fully absorbed across Days 104–118. The receding-basin floor is at least ~0.25" zone-average; minimum perturbing forcing is above ~0.25". Day 119 brackets the upper bound: 0.85"-class upper-zone forcing on very-wet antecedent DID register (Boxley/Ponca) — perturbing threshold for upper zones remains ~0.5".

Transfer ratios — Boxley (height ft/inch zone QPE): - Dry, low-intensity: ~0.40 (Event 5, 0.55") - Dry, high-intensity (>0.5"/hr): 0.62–0.82 (Events 7, 9, 11) - Moderate: 0.56–0.67 (Events 6, 10) - Wet/moist: 0.71–0.84 (Events 2, 3) - Very wet/wet, primed: 1.30 (Event 4); 1.42 (Event 20 Day 106, 2-day cumulative 1.53"); 1.40 (Event 22 Day 119, 0.851" on 7-day 4.17", ~5-hr lag) — wet/primed anchor now reproduced THREE times, tight cluster ~1.3–1.42 ft/in. Confidence HIGH. - Very wet + extreme intensity: 2.28 (Event 19 Day 100) — study high (requires >0.6"/hr) - Sub-detection on draining pool: 0.216"→0.0 (Day 110); 0.043"→0.0 (Day 111); 0.005"→0.0 (Day 112); 0.086"→0.0 (Day 118).

Transfer ratios — Ponca (cfs/inch zone QPE): - Wet, >1.0" forcing: ~1030 (Event 2); 1220 (Event 20 Day 106, 0.875") — wet Ponca range ~1000–1220 cfs/in. - Wet/moist but SUB-1.0" forcing: ~651 cfs/in (Event 22 Day 119, 0.864" on very-wet 7-day ~4") — NEW node, ~40% below the >1.0" wet node; consistent with Event-12 sub-1.0"-forcing-dilution finding (efficiency drops below ~1.0" regardless of antecedent). FLAGGED deviation; refine with more sub-1" data points.

Transfer ratios — Pruitt: - Antecedent-INDEPENDENT at ~1.4 ft/in when forcing is concentrated and routing contribution present. Dry (Event 9: 1.44) ≈ wet (Events 8, 15: 1.4–1.9) ≈ moist (Event 10: 1.6). - Distributed sub-1" forcing on dry zone with no upstream signal: <0.1 ft/in (Events 12, 17). Days 110–118: → no response. Event 22 (Day 119 local 0.609" + Day-119/120 Ponca cascade) → peak 5.81 ft / 838 cfs @ day boundary; height "transfer" 2.17 ft/in is ROUTING-DOMINATED (cascade stacked on local forcing, steep rise >9 hr after local QPE), NOT a clean local-zone value — do not compare 1:1 to the ~1.4 anchor. - Two-mode response (Events 12, 15, 20): surface peak at 4–7 hr lag + karst/subsurface secondary at 19–22 hr. Event 22: no distinct secondary observed (single integrated peak at day boundary, then clean recession Days 120–122). - Out-of-bank flood regime (Event 20): height transfer inflated by channel geometry once out-of-bank (10.23 ft / 4290 cfs); NOT comparable to the in-bank ~1.4 ft/in regime.

Transfer ratios — Richland: - Dry/recovering: 0.16–0.25 ft/in (Events 9, 11) - Dry, event-scale: 0.73 (Event 11, 1.32") - Moist: 0.90 (Event 13); ~0.67 (Event 19 Pulse 3, 0.40") - Moist + high intensity: 1.34 ft/in (Event 10, 1.43" with 0.83"/hr) - Moist + event-scale 3.8" (Event 20 onset): 1.92 ft/in at 8.35 ft, overnight culminating at study-record 9.25 ft - Wet/saturated, out-of-bank: 2.69 ft/in (Event 15, 8.89 ft) — channel-geometry nonlinearity - Recession-falling-limb: 0.5–0.6 ft/in (Event 8 secondary)

Transfer ratios — Bear Cr (most stage-and-antecedent-sensitive): - Dry (Event 11): 0.09–0.17 ft/in — extreme damping - Dry + intensity (Event 9): 0.35 ft/in - Moist (Events 7, 12): 0.22–0.25 ft/in - Moist + bimodal compound (Events 8, 15): 0.97–1.53 ft/in - Wet + low pre-event stage (Event 16): 2.08 ft/in — study high, CONFIRMED by Event 20 onset: 2.07 ft/in at low stage 2.13 ft from extreme 3.19" forcing — stage-on-rating-curve dominates antecedent when forcing is extreme and stage starts near baseflow. Overnight culmination 11.20 ft / 12,900 cfs (out-of-bank, study record). - Wet + mid-stage recession (Event 17): 0.51 ft/in - Bear Cr transfer is stage-AND-antecedent-dependent. Dry → ~0.1; moist → ~0.3; wet/low-stage OR extreme-forcing/low-stage → ~2.0; wet+mid-stage → ~0.5.

Transfer ratios — St. Joe / Harriet (cumulative event-scale, ft/in zone-avg): - St. Joe: dry 1.09 (Event 11), moist 1.3–2.1 (Events 8, 10, 19 secondary), wet ~4 (Event 15 flood scale), tributary-amplified ~6.1 ft/in (~8,800 cfs/in) (Event 20 Day 106, study-record). Wet-amplification factor ~4×; multi-tributary-concentration amplification ~6×. Upper-only-propagation (Event 22 Day 120): own-zone QPE sub-threshold; trunk rise is routed, NOT a per-inch own-zone transfer (+439 cfs to 18% of flood from a sub-1" upper pulse — attenuation analog of Event 19's 36%). - Harriet: dry 0.76 (Event 11), moist ~0.8–1.4 (Event 20 Day-105 direct: 1.03 ft/in; Event 21 Day-117 Harriet-zone-only ~0.28 ft/in for 1.12" on receding mid-Optimal baseflow), wet ~1.5–3.7 (Event 15), flood/tributary-amplified ~4.1 ft/in (~8,260 cfs/in) (Event 20 Day 106). Tracks St. Joe with slight attenuation. Event 22 Day 121: peaked 1610 cfs (17% of flood) by propagation from St. Joe — routed, NOT a per-inch own-zone transfer; the proportional analog of St. Joe's 18%.

Lag times — mainstem cascade peak-to-peak: - Boxley→Ponca: 1.75–5 hr (1.75 hr at flood/parallel-direct, 2.5 hr Event-22 parallel-forcing, 3–5 hr at moderate, 5 hr+ at low flow). - Ponca→Pruitt (velocity ∝ Q^0.35 confirmed): ~5.25 hr at high flow | ~5.75 hr at >1500 cfs (1.2 m/s) | 7.5 hr at ~500 cfs | 10.75 hr at ~300 cfs (dry) | 14–15 hr at ~150–180 cfs (0.46 m/s). Event-22 CONFIRMED: Ponca peak 16:30 Day 119 → Pruitt peak ~23:45 Day 119 = ~7.25 hr at ~500–840 cfs — matches the 7.5-hr/~500-cfs node. - Pruitt→St. Joe: 11–15 hr wet/flood | 17–23 hr dry/low-flow | Slow segment. Event-22 ADDS: ~16.25 hr at ~500–1400 cfs (~1.05 m/s assuming sinuosity 1.7 over 36.1 km straight-line) — intermediate moist-recession value, mid-band. - St. Joe→Harriet: ~6–13 hr — flow-dependent more than antecedent-dependent. 6–6.5 hr flood (Events 15 & 20 Day 106 — confirmed twice; ~1.24 m/s); 9 hr high flow (Event 8); 8.25 hr moderate (Events 2, 19); 10.25 hr (Event 9); ~13 hr dry (Event 11). Event-22 Day 121 CLOSED: St. Joe peak 16:00 Day 120 → Harriet peak 00:30 Day 121 = 8.5 hr at ~1400–1600 cfs (~0.99 m/s assuming sinuosity 1.7 over 17.9 km = ~30.4 km channel) — moderate-flow node, matching Events 2/19's ~8.25 hr. - Total Boxley→Harriet: ~29 hr at flood (Event 2) | 29–33.5 hr wet | 36 hr dry | 44.5–52 hr dry+low-flow. Event 22 CLOSED: Boxley peak 14:00 Day 119 → Harriet peak 00:30 Day 121 = ~34.5 hr (wet/moist band). - Direct in-zone response lags: Whiteley→Ponca 0.97 hr; Cove→Pruitt ≥5.47 hr; Water Cr→Harriet 5.97 hr (Event 20 Day 105); Spring Cr→Harriet ~5–6 hr (Event 21 Day 117); Headwaters Richland→Richland 0.47 hr (artifact, effective ~3 hr); Boxley pool-fill 5.97 hr (primed, Event 20) / ~5.0 hr (Event 22 Day 119, primed); Ponca 7.72 hr (wet, Event 20) / 7.47 hr in-zone (Event 22 Day 119); Richland→St. Joe tributary arrival 1.75 hr.

Wet/dry asymmetries: 1. Boxley pool-fill mechanism: dry forcing must fill pools first. Threshold ~0.5"; <0.5" sub-detection; >0.8" 8–11 hr delayed; ≥1.0" with primer/wet 2–4 hr. Confirmed AND extended (Event 20): sub-detection primer pulse (0.753" Day 105) fills pools silently, then next pulse rides through with shortened lag and elevated 1.42 ft/in. Days 110–118: sub-detection on draining pool. Event 22 Day 119: a wet antecedent (7-day 4.17") pre-satisfies pool storage → 0.851" rides through immediately at ~5-hr lag and 1.40 ft/in — the wet/primed end-member. 2. Pruitt's antecedent-independence at high concentrated forcing but extreme sensitivity to upstream routing presence — EXCEPT at extreme local forcing (Event 20, 2.75" Cove) where local-zone response alone drives flood. Event 22 reaffirms routing-dominance: the 838-cfs Pruitt peak was dominantly the Ponca cascade arriving >9 hr after local QPE. 3. Bear Cr structural damping under dry (0.09–0.17 ft/in) vs amplification under wet/extreme-forcing+low-stage (2.0+ ft/in) — 10–20× range. Stage matters as much as antecedent. 4. Richland intensity-dependence: moist + high-intensity bursts (>1"/hr) → 4–5 hr flash with 1.3+ ft/in, exceeding saturated-wet ratios at lower intensity. 5. St. Joe distributed-forcing dilution: same total QPE → lower per-inch transfer when distributed across all 14 HUC12s vs concentrated bullseyes. Corollary (Event 20): tributary forcing concentrated below the gauge's own-zone response time leaves the trunk lagging badly while tributaries flood — QPE pattern flags the trunk flood ~8–11 hr before trunk peak. Days 110–119 corollary: a single own-zone burst at low total, or trace own-zone, on receding baseflow does NOT register. Day 120 corollary: own-zone 0.271" sub-threshold → trunk rise is pure upstream propagation. 6. Ponca sub-1.0"-forcing dilution (Event 22): even on a very-wet antecedent (7-day ~4"), a sub-1.0" Ponca pulse transferred at only ~651 cfs/in vs ~1000–1220 for >1.0" wet forcing — reinforces the Event-12 finding that forcing-magnitude gates efficiency below ~1.0" regardless of antecedent.

Forcing-magnitude and spatial-coherence findings: - Event 12 paradox: Moist-antecedent transfer ratios LOWER than dry Event 11 when forcing was distributed sub-1.0". Below ~1.0" zone-average, response efficiency drops regardless of antecedent. Event 22 Ponca node (~651 cfs/in at 0.864") adds a wet-antecedent confirmation. - Spatial coherence matters: broad coherent pulses (Event 11) > spatially shifting distributions (Event 12) despite similar totals. Event 22 is a spatially-coherent upper-basin single pulse — clean direct responses at Boxley/Ponca and a clean propagated trunk bump.

Upstream-only vs lower-basin-only vs watershed-wide flood patterns (Events 19, 20, 15, 21, 22): - Event 19 (upper-only forcing, flood-scale): Pruitt/Ponca flood attenuated through routing to St. Joe 36% / Harriet 30% of flood thresholds — upper-basin-only flood-scale events do NOT propagate flood to mid/lower mainstem. - Event 20 (mid/lower-basin-only forcing): tributaries flooded Day 105 while St. Joe trunk barely moved same-evening; then the trunk surged overnight to STUDY-RECORD flood. REFINED CONCLUSION: lower/mid-basin-concentrated forcing (≈52% of basin area) DOES drive a study-record trunk flood, with an ~8–11 hr delay. Spatial COMPLEMENT of Event 19, OPPOSITE outcome. - Event 15 (watershed-wide, coherent): flood exceeded at three mainstem gauges simultaneously. - Event 21 (upper-only, FLOOD-scale, dry intervening basin): study-record upper flood (Ponca 5.4× flood) attenuated to St. Joe 99% / Harriet 73% of flood — just-below-flood. The flood-magnitude upper-only-attenuation archetype. - Event 22 (upper-only, sub-1" — FULLY CLOSED): small upper-basin analog of Event 19. CONFIRMED at sub-flood magnitude: St. Joe attenuated to 1430 cfs = 18% of flood; Harriet peaked 1610 cfs = 17% of flood (Day 121). The upper-only-attenuation rule holds proportionally across magnitudes — sub-1" → 17–18%, flood-scale (E19) → 30–36%, study-record upper flood (E21) → 73–99%. Open Q12a ANSWERED. - Implication: flood-warning logic must distinguish upper-only (attenuates) / lower-mid-only (delayed trunk flood) / watershed-wide (simultaneous) forcing patterns from QPE — each produces a distinct mainstem signature and timing. Lower-mid-only is the most dangerous "sleeper" pattern. - March-2024 reference REPRODUCED AND EXCEEDED (Event 20): St. Joe 17.59 ft / ~13 ft rise > 2024's ~15 ft / ~11 ft, from 3.4–3.9" multi-tributary concentration. Open Q4 answered. - Recession-tail corollary: a flood at the lower mainstem produces a sustained multi-day Optimal recreation window. Event 19 → ≥6 days; Event 20 → both St. Joe & Harriet re-entered Optimal Day 107, holding mid-Optimal through Day 112 (Day 7). Ponca (small drainage) first to exit Optimal in both events. Event 21 (Days ~114–118): a moderate event re-loaded a SECOND lower-mainstem Optimal window and reset Pruitt back into Optimal. Event 22 (Days 119–121): a third event re-elevated the upper basin, reset Ponca/Pruitt firmly into Optimal, and added a modest non-flood trunk bump (St. Joe to 1430 cfs / Harriet to 1610 cfs) — confirming that frequent summer events keep the lower mainstem floatable for extended near-continuous stretches. Ponca re-exited to Low-but-Floatable ~18:00 Day 121, then to Too Low ~16:00 Day 122; St. Joe (764) / Harriet (966) still mid-Optimal at Day-122 close.

Signal-separation logic — validated across multiple events: - Richland gauge as St. Joe-area discriminator: Events 10, 16, 19, 20, 22. Event 22 Days 119–122: Richland flat (0.056"/0.000"×3, new low 1.03 ft) while the upper cascade built and the trunk rose → confirms the event is upper-basin propagation, NOT Richland-sub-basin. Reliable diagnostic. - Bear Cr gauge as Harriet-area discriminator: Events 5, 16, 19 (Bear flat = mainstem propagation); Events 8, 20 (Bear surged + Harriet rose = compound source); Event 21 Day 117 (Bear flat while Harriet rose = Harriet-zone direct). Event 22 Days 120–122: Bear flat at new low (23.5 cfs) while Harriet rose to its 1610-cfs peak → Harriet rise = mainstem propagation, not Bear-confluence. Reliable diagnostic. - St. Joe double-peak structure observable when Richland flashes earlier than Pruitt mainstem signal arrives (Event 10), OR when a tributary arrival precedes the main integrated surge (Event 20). - Timing-discipline reminder (Days 108, 110, 111, 112, 118, 119, 120, 121, 122): a candidate "response" that PRECEDES or is sub-resolution relative to its candidate QPE peak cannot be attributed to that rain. Days 120–122: zero QPE everywhere — all rises (Days 120–121) are propagation from the Day-119 pulse, never attributed to those days' (nil) rain; Day 122 is pure recession with nothing to attribute.

Recreational threshold crossings observed in study: - Hailstone Low-Floatable (Boxley 3.7 ft): Events 4, 8, 19 (Day 100 5.50 ft Optimal+), 20 (Day 106 4.51 ft, crossed Hailstone OPTIMAL 4.4 briefly), 21 (Day 114 9.06 ft — STUDY RECORD, far above 5.9 Hailstone-Optimal), 22 (Day 119 3.93 ft, ~2 hr above 3.7) — window closed by Day 120 (Boxley back to 2.90 ft, 2.63 by Day 121, 2.44 by Day 122). - Boxley-Ponca section (3.2 ft): Events 2, 4, 8, 19, 20, 22 (Day 119 to 3.93 ft, above 3.2 from ~12:45; receded below 3.2 during Day 120). - Upper Richland Low-Floatable (Richland 3.2 ft): Events 4, 8, 15, 20 (study-record 9.25 ft) — 4 confirmed Upper-Richland-runnable events, consistent with "3–7 runs/year". - Pruitt flood-threshold (>2000 cfs): Events 2, 15, 19, 20 (4290 cfs), 21 (9,710 cfs — STUDY RECORD, Day 114 dry-antecedent upper flash). - St. Joe flood-threshold (>8000 cfs): Event 15 (14,500), 20 (19,600 — study record, held above flood ~22 hr). Event 21 (Day 115) reached 7,890 = 99%, JUST BELOW — the upper flood attenuated through the dry intervening basin (see Event 21). - Harriet flood-threshold (>9370 cfs): Event 15 (15,000), 20 (21,800 — study record, held above flood ~23.5 hr). Event 21 (Day 115) reached 6,870 = 73%, below. - Ponca Optimal→Low-but-Floatable exits (200 cfs): Event 19 Day 104; Event 20 Day 109. Ponca Low-but-Floatable→Too Low (150): Event 20 Day 110. Event 22 Day 119: Ponca dipped to 196 (<200) @07:15 — exit OCCURRED — then the event REVERSED it to 758 cfs; Day 121 RE-EXITED to Low-but-Floatable ~18:00 CDT (203→196), ending at 183 cfs; Day 122 crossed 150 → Too Low ~16:00 CDT (150 @15:15 → 147 @16:00), ending at 137 cfs. - Pruitt Optimal→Low-but-Floatable exit (200 cfs): Event 20 Day 112. Event 21 re-entry: Pruitt 784 cfs Day 116, 374 cfs Day 118; Event 22 Day 119–120 re-elevated to 838 cfs peak, receding to 337 cfs Day 121, 246 cfs Day 122 (still solidly Optimal). - Mainstem Optimal durations from major events: Events 4+5+6 → ~21 days; Event 15+16 → ~15+ days; Event 19 → ≥6 days; Event 20 → St. Joe/Harriet Day 107–112 (Day 7). Event 21 re-loaded a fresh window; Event 22 (Days 119–121) re-elevates the upper basin and adds a trunk bump while St. Joe/Harriet remain mid-Optimal (764/966 cfs at Day-122 close) — a near-continuous Optimal stretch through frequent summer events.

Open Questions / Next Watches

1. Spatial-coherence threshold quantification: Below what zone-aggregated coherence does forcing-magnitude dominance break down? Event 12 vs Event 11 qualitative; Event 22 Ponca sub-1" dilution adds a wet-antecedent point; need more data points.
2. Pruitt's local-zone forcing transfer in absence of upstream signal: Event 17 near-zero from 1.02" Cove; Event 20 high-forcing extreme: 2.75" Cove → local flood. Event 22 (0.609" local + upstream cascade): peaked 838 cfs / 5.81 ft @ day boundary, but ROUTING-DOMINATED (2.17 ft/in height is not a clean local value) — still no clean isolated local-zone Pruitt transfer at intermediate forcing without upstream signal. Keep watching.
3. Bear Cr stage-dependence function: <3.5 ft pre-event stage → 1.5–2.0 ft/in; 3.5–4.0 ft → 0.5–1.0 ft/in; >5.0 ft → <0.5 ft/in. Refine the floodplain breakout point with more events.
4. March 2024 reference event signature — ANSWERED (Event 20): full system EXCEEDED the 2024 St. Joe stage from 3.4–3.9" multi-tributary concentration. CLOSED — but watch whether a single-tributary 5–8" bullseye produces a comparable or larger trunk peak.
5. Bear Cr long-lag character: ~30.5 hr (Event 7, dry) vs ~14.2 hr (Event 9, dry) vs ~4.5 hr (Event 16, wet) — ~7× range, antecedent-driven. Confirm with more low-stage events.
6. Ungauged-watershed monitoring gap: Event 15 6.087" Long Cr; Event 20 Day 105 2.6–3.4" across ungauged HUCs; Event 21 Day 117 ungauged 1.335" (Hickory 2.176"). Recommend QPE-only watch criteria for ungauged tier.
7. St. Joe→Harriet lag structure: spans ~6–13 hr, shortens with flow; weak antecedent dependence. 6–6.5 hr at flood confirmed twice (Events 15, 20); 8.25 hr moderate (Events 2, 19); Event-22 Day-121 ADDS 8.5 hr at ~1400–1600 cfs (moderate node, confirms). Days 102–122: gauges converge to near-identical absolute recession rates at high flow, diverging modestly at lower flow; the persistent ~200–410-cfs offset is a flow-level/limb-position effect (Harriet sits higher on its limb because it peaks ~6–8.5 hr later). Day-122 offset ~200 cfs at near-identical stage (St. Joe 4.83/764 vs Harriet 4.81/966).
8. Long-term baseflow trajectory: Day 65 not a floor; subsequent days set new lows. Event 20 reset the system far upward; Events 21–22 reset it upward again before recession completed. No stable seasonal floor observed. Day 122 St. Joe 764 / Harriet 966 cfs (receding from the Event-22 bump, now approaching but still above the Event-20 Day-112 ~800/1110 slow-phase reference). Boxley (2.44 ft), Richland (1.03 ft) and Bear (23.5 cfs / 2.19 ft) at new post-event lows but not study lows. Watch whether St. Joe/Harriet set new study baseflow lows during the current dry stretch (3 dry days and counting).
9. Pruitt karst secondary peak quantification: Two-mode (Events 12, 15, 20). Event 22 did NOT show a distinct karst secondary — single integrated peak at the day boundary then clean recession Days 120–122. Continue watching future moderate events.
10. Detection-threshold lower bound under saturated-recession conditions: ~0.10"–0.25" absorbed (Days 104–118, all fully absorbed). Receding-basin floor is at least ~0.25" zone-average; forcing magnitude (not antecedent) gates detection. Day 119 brackets the upper bound: 0.5"-class upper-zone forcing DID register on a wet antecedent. Continue establishing the precise minimum per gauge.
11. High-flow recession-rate calibration — SUBSTANTIALLY ANSWERED (Days 106–122): dQ/dt-vs-Q curve bracketed across ~2.5 orders of magnitude. Event-21 Day 118 + Event-22 Days 119–122 add fresh-limb-through-baseflow-band points (St. Joe ~12 @1300, ~19 @1350, ~14 @1100, ~7.9 @850; Harriet ~14 @1750, ~16 @1400, ~11.6 @1100). Continue collecting slow-phase tail to anchor the baseflow-limited asymptote — the current dry stretch is ideal.
12. Event 20/21/22 recession & Optimal-window watch (Days 123+): Capture (a) Event-22 cascade — CLOSED (Day 121): Harriet peak 1610 cfs @00:30 = 17% of flood; St. Joe→Harriet final lag 8.5 hr; St. Joe 1430 cfs @16:00 = 18% of flood; upper-only-attenuation rule confirmed at sub-flood magnitude, Open Q12a ANSWERED; (b) Boxley pool drain from the 3.93-ft peak (Day 4, at 2.44 ft Day 122; ~4-day drain nearly complete); (c) any Pruitt karst tertiary (none seen Days 120–122); (d) total Optimal-window duration on the lower mainstem; (e) mainstem threshold cascade — Ponca re-exited to Low-but-Floatable ~18:00 Day 121, then Too Low ~16:00 Day 122 (137 cfs); Pruitt 246 cfs (still Optimal); St. Joe 764 / Harriet 966 cfs (mid-Optimal); watch whether the continuing dry stretch drops St. Joe/Harriet toward the Day-112 lows (~800/1110) and whether Pruitt exits Optimal; (f) any USGS rating-curve field-revision steps — NONE through Day 122 despite ~17 days post-record-peak; keep watching Bear/Richland/Pruitt Days 123+; (g) DATA-GAP RESOLVED 2026-06-29 — Days 113–115 summaries were present all along; Event 21's Day-114 flood is quantified from the truth card + Opus daily; (h) Event-22 transfer ratios — Boxley 1.40 confirmed; Ponca ~651 (flagged sub-1" node); Pruitt routing-dominated peak 838 cfs (no clean local transfer); St. Joe propagated +439 cfs (18% flood); Harriet propagated peak 1610 cfs (17% flood) — ALL CLOSED.

End of document.