This is the study's first significant rainfall event. A widespread storm system moved across the entire watershed on March 5, with dramatically higher intensities than anything observed in the previous 4 days.
Upper watershed (heaviest rainfall): - Boxley HUC12 (0201): 1.038" total, peak 1hr 0.751" at ~04:06 CST (10:06 UTC), max 3hr 0.949". This is by far the most intense rainfall observed in the study — nearly 5x the previous maximum intensity of 0.161"/hr. - Ponca zone: 0.587" zone average. Beech Creek (0202) 0.635", Smith Creek (0203) 0.643", Whiteley (0205) 0.484". Peak 1hr 0.379" (Smith Creek). - Pruitt zone: 0.431" zone average. Cove Creek (0204) 0.477", Hoskin Creek (0207) 0.386". Peak 1hr 0.106" (Cove Creek) — notably lower intensity than upstream.
Mid-watershed: - Richland Creek zone: 0.677" zone average. Headwaters Richland (0306) 0.745" with peak 1hr 0.383", Falling Water (0307) 0.610". - St. Joe zone: 0.526" zone average across 14 HUC12s. Highest: Headwaters Little Buffalo (0102) 0.696", Headwaters Big Creek (0302) 0.666", Calf Creek (0401) 0.625". Peak 1hr 0.44" in Headwaters LB.
Lower watershed: - Bear Creek zone: 0.522" zone average. Headwaters Bear (0403) 0.532", Outlet Bear (0404) 0.512". Peak 1hr 0.303". - Harriet zone: 0.435" zone average. Brush Creek (0405) 0.489", Water Creek (0408) 0.432". Peak 1hr 0.266".
Key spatial pattern: The storm was concentrated heavily in the Boxley headwaters (1.038" with 0.751"/hr peak) with a strong northwest-to-southeast gradient. The Richland Creek sub-basin also received intense rainfall (0.745" with 0.383"/hr peak). The lower watershed received moderate amounts at lower intensity.
Timing: Most rainfall arrived in two pulses — an early morning pulse peaking around 04:00-05:00 CST (based on QPE peak times at 10:06-11:06 UTC) and continued accumulation through midday.
Boxley (07055646) — FIRST CONFIRMED RISE IN THE STUDY
This is the headline event. Boxley went from 1.90 ft at midnight to a peak of 2.77 ft at 15:15-16:00 CST — a rise of 0.87 ft.
Detailed timeline: - 00:00-02:00: Flat at 1.90 ft (pre-event baseline) - 02:15: First detectable uptick to 1.91 ft - 03:15-03:30: Clear rise to 1.92 ft - 03:45-04:00: 1.94 ft — sustained above noise - 04:00-10:15: Plateau at 1.93-1.95 ft (~7 hours of very slow rise while rain continues) - 10:30: Acceleration begins — 1.95 → 1.96 → 1.97... - 11:15-13:00: Rapid rise phase: 1.99 → 2.31 ft (+0.32 ft in 1.75 hours) - 13:00-14:00: Steepest rise: 2.31 → 2.69 ft (+0.38 ft in 1 hour; peak rate 0.46 ft/hr at 13:45) - 14:00-16:00: Approaching peak: 2.69 → 2.77 ft - 16:00-23:30: Slow recession: 2.77 → 2.65 ft (-0.12 ft in 7.5 hours, ~0.016 ft/hr)
This is a textbook flashy headwater response with a biphasic pattern. The initial rise (1.90 → 1.94 ft) was modest and slow, consistent with the local knowledge about "filling the pools" before water reaches the gauge. The major pulse arrived ~8-10 hours after peak rainfall intensity, suggesting significant storage/translation delay in the "pool and drop" upstream reach.
Ponca (07055660) — FIRST CONFIRMED RISE
Ponca rose from 83.7 cfs at midnight to 179 cfs at 19:45 CST — more than doubling.
Timeline: - 00:00-03:00: Flat at 83.7 cfs (baseflow) - 03:30: First uptick to 85.1 cfs - 04:15: 86.4 cfs — sustained above previous range - 05:30: 87.8 cfs - 09:15: 89.2 cfs — gradual staircase rise - 11:00: 90.6 cfs - 14:30-15:45: 90.6-92.0 cfs — still gradual - 16:30-17:45: Rapid acceleration: 94.9 → 129 cfs - 18:00-19:00: 145 → 175 cfs - 19:15-23:30: Peak plateau at 177-179 cfs
This has two distinct phases: (1) A gradual 83.7 → 92 cfs rise from ~03:30 to 16:00 (12.5 hours, +8.3 cfs) likely from direct tributary contributions in the Ponca zone, and (2) a sharp 92 → 179 cfs surge from 16:30 to 19:15 (+87 cfs in 2.75 hours) which is almost certainly the Boxley headwater pulse propagating downstream.
Ponca crossed from "Too Low" (<150) to "Low but Floatable" (150-200) at ~18:00 CST, a recreationally significant threshold.
Pruitt (07055680) — COMPLEX RESPONSE
Pruitt shows two distinct phases: - Phase 1 (early morning rise): Height rose from 3.44 ft at midnight to 3.47 ft by ~05:00, holding at 3.46-3.47 through ~15:00. Discharge rose from 63.7 to 67.9 cfs. This is a modest but real response from Cove Creek/Hoskin Creek rainfall (0.431" zone average). - Phase 2 (afternoon CFS anomaly): At 15:00, discharge suddenly dropped from 67.9 to 59.6 cfs, then further to 50.9 cfs at 17:00, while height remained at 3.44-3.47 ft or even rose slightly. This is a rating curve shift, not a real flow decrease. The USGS appears to have updated the rating curve mid-day. - Phase 3 (evening rise): From 19:00 onward, clear height rise: 3.47 → 3.53 ft by 23:30. This is the upstream Ponca pulse arriving. Discharge under the new rating reads 55.1 → 64.2 cfs.
The mid-day CFS drop at Pruitt while height was stable is strong evidence of a rating curve adjustment. This is consistent with local knowledge about rating curve reliability. The new CFS values (50.9-64.2) are systematically lower than old values at the same heights, confirming the curve shifted downward.
St. Joe (07056000) — NO CLEAR RESPONSE YET
Height range 3.39-3.45 ft (0.06 ft range — actually tighter than yesterday's 0.08 ft). CFS 150-171, similar to recent days. The widespread 0.526" of rain across the 14 HUC12s has not yet produced a detectable rise at St. Joe. The Pruitt pulse has only just begun (evening) and won't reach St. Joe for 4-8 hours. Tributary inputs from the St. Joe zone's own rainfall may appear on 3/06.
Richland Creek (07055875) — FIRST CONFIRMED RISE
Clear, steady rise from 0.92 ft at midnight to 1.18 ft at 21:00 — a 0.26 ft rise.
Timeline: - 00:00-02:45: Baseline 0.92-0.93 ft - 03:15-03:45: First rise to 0.94-0.95 ft - 04:00-04:45: 0.96-0.98 ft - 05:00: 1.02 ft — clear breakaway from noise - 05:30-06:00: 1.03 ft - 07:00-09:15: Gradual rise 1.03 → 1.10 ft - [Data gap 09:15-13:00] - 13:00: 1.12 ft - 14:00-16:00: 1.13-1.14 ft - 17:00-21:00: 1.14 → 1.18 ft (continued slow rise) - 21:15-23:15: Slight decline to 1.16 ft
This is a sustained, moderate response — 0.26 ft over ~18 hours with no sharp spike. Richland received 0.677" zone average with 0.383"/hr peak intensity. The response is gradual enough to suggest significant subsurface/karst buffering even in this flashy watershed.
Harriet (07056700) — MODEST RISE
Harriet reversed its recession trend: - 00:00-04:15: 3.53-3.54 ft (continued baseflow) - 05:00-06:00: Rise to 3.55-3.57 ft - 07:45: Brief spike to 3.58 ft - 08:00-23:00: Stable at 3.56-3.57 ft (mostly 3.56)
CFS: 172 → 185-189, then settling at 185 cfs. This is a ~0.03-0.04 ft rise, barely above the noise floor. Source: likely a combination of direct rainfall in the Harriet zone (0.435") and some early tributary contribution.
Bear Creek (07056515) — BRIEF SPIKE THEN RECESSION
Brief rise to 2.35 ft / 8.19 cfs at 05:15-05:45, then recession back to 2.32 ft / 6.58 cfs by 09:00. Total rise: 0.03 ft / ~1.6 cfs. This is barely above noise but the timing matches the QPE pulse (~05:00 CST). The response was extremely transient — Bear Creek absorbed almost all of its 0.522" rainfall, producing only a brief blip.
Pair 1: Boxley headwaters → Boxley gauge - Rainfall: 1.038" total, 0.751"/hr peak at ~04:06 CST, 0.949" in 3 hours - Response: 0.87 ft rise (1.90 → 2.77 ft) - First detectable rise: ~02:15 CST (1.91 ft) — but QPE shows rainfall beginning well before this. Using the peak rain at 04:06 and the clear sustained rise at 03:45 (1.94 ft), the initial lag is approximately 1.5-2 hours from onset of significant rain to first gauge response. - Peak lag: Peak rainfall ~04:06 CST, peak gauge ~15:15-16:00 CST → ~11-12 hours from peak rain to peak gauge. This is remarkably long for a 92 km² watershed and strongly validates the local knowledge about "pool and drop" upstream storage. - Transfer ratio: 1.038" rainfall → 0.87 ft rise. Under current dry antecedent conditions with 0.384" 7-day antecedent. - Biphasic pattern: Initial slow fill (0.04 ft in first 8 hours), then rapid pulse (0.83 ft in next 5 hours). The pools filled first, then the connected water released as a pulse. - Local knowledge validation: The "pool and drop" nature and "filling the pools" behavior described by the 20-year local resident is strongly confirmed. The ~8-hour delay between initial rain arrival and the start of the rapid rise phase is exactly what pool-filling dynamics would produce.
Pair 2: Ponca zone + Boxley propagation → Ponca gauge - Ponca zone rainfall: 0.587" average, 0.379"/hr peak - Direct response (Phase 1): 83.7 → 92 cfs over ~12 hours. Modest — 8.3 cfs from 0.587" over 298 km². - Propagated response (Phase 2): 92 → 179 cfs starting ~16:30. The Boxley peak was ~15:15-16:00, suggesting a 0.5-1.5 hour lag from Boxley to Ponca for the leading edge of the surge. - Boxley → Ponca propagation velocity: ~15 river miles in 1-2 hours → approximately 7.5-15 mph (very fast). This is faster than expected, but the pulse was large and the channel was already wetted from direct rainfall.
Pair 3: Pruitt zone rainfall → Pruitt gauge - Pruitt zone rainfall: 0.431" average (Cove Creek 0.477", Hoskin 0.386"), peak 0.106"/hr - Response: 3.44 → 3.47 ft rise (0.03 ft) starting ~04:00. Very modest. - Transfer ratio: 0.431" → 0.03 ft under dry antecedent conditions. Barely above detection threshold. - Important: The much larger rise starting at 19:00 (3.47 → 3.53 ft, +0.06 ft) is NOT from Pruitt zone rainfall — it's the upstream propagated pulse from Boxley/Ponca.
Pair 4: Richland zone rainfall → Richland Creek gauge - Rainfall: 0.677" average (0.745" in Headwaters Richland, 0.610" in Falling Water). Peak 0.383"/hr. - Response: 0.26 ft rise (0.92 → 1.18 ft) over ~18 hours - Lag to first detectable rise: Rain peaked around 05:06 CST. First clear rise above noise was ~03:45 (0.95 ft), suggesting lag of ~1-2 hours from rain onset (rain likely started before peak). - Transfer ratio: 0.677" → 0.26 ft under dry conditions (0.224-0.252" 7-day antecedent)
Pair 5: Bear Creek zone → Bear Creek gauge - Rainfall: 0.522" average, 0.303"/hr peak - Response: Transient 0.03 ft / ~1.6 cfs spike lasting ~4 hours, then back to baseline - This is effectively a non-detection for sustained response. The watershed absorbed virtually all rainfall. This is notable because Bear Creek received more total rain (0.522") than produced a response at Pruitt (0.431" → 0.03 ft). Bear Creek's specific discharge (0.028 cfs/km²) is the lowest in the network, consistent with deep groundwater losses.
First measured propagation: Boxley → Ponca → Pruitt
Boxley peak → Ponca surge onset: ~0.5-1.5 hours (~15 river miles) Ponca peak → Pruitt rise onset: ~0 hours (concurrent) — but this seems too fast for 10 river miles. More likely, Pruitt's evening rise is a combination of Ponca propagation AND continuing direct Cove Creek input, and the leading edge of the Ponca pulse reached Pruitt before Ponca peaked.
Ponca surge onset → Pruitt rise onset: ~2.5 hours (16:30 → 19:00). This is more consistent with 10 river miles at moderate flow.
St. Joe has not responded yet. Given Pruitt → St. Joe is ~30 river miles and current low flow conditions, expect a response at St. Joe late on 3/06 or 3/07, potentially combined with St. Joe zone's direct tributary responses.
The Cove Creek cumulative test from yesterday can now be evaluated: - Cove Creek received 0.365" on 3/04 + 0.477" on 3/05 = 0.842" cumulative with 0.975" 7-day total - Pruitt response to Cove Creek (direct, excluding upstream propagation): The early morning rise of 0.03 ft (3.44 → 3.47) represents the combined Cove Creek + Hoskin Creek direct input - Conclusion: ~0.43" at moderate intensity (0.106"/hr peak) on top of 0.61" antecedent produced a barely detectable 0.03 ft direct rise at Pruitt. This confirms that the detection threshold at Pruitt for local tributary input is very high under current conditions.
Pruitt rating curve shift: The mid-day CFS drop from 67.9 to 50.9 while height remained stable is a clear rating curve update. This affects all CFS comparisons at Pruitt going forward. The Ponca-Pruitt discharge inversion hypothesis needs to be re-evaluated under the new rating curve. At the new curve, Pruitt's 3.53 ft reads 64.2 cfs while Ponca is at 177 cfs — but this comparison is meaningless during an active event. Need to wait for post-event baseflow to reassess.
Boxley's biphasic response is more extreme than expected. An 8-hour delay between initial rain arrival and the rapid rise phase for a 92 km² watershed is very unusual. This is a powerful confirmation of the "pool and drop" local knowledge and suggests that detection threshold estimates based on total rainfall depth are misleading for Boxley — it's the sustained duration and total volume that matters, not just peak intensity. The pools need a threshold volume before they connect and release.
Ponca's peak (179 cfs) is still below "Low but Floatable" threshold (200 cfs). Even doubling from 83.7 to 179 cfs from a 1"+ headwater event wasn't enough to reach recreational optimal (200 cfs). This calibrates expectations: it takes more than 1" in Boxley + 0.6" in Ponca zone to reach paddling levels from dry baseflow.
St. Joe's lack of response despite 0.526" zone average is surprising but may simply reflect lag time — the rain fell in the morning and the massive tributary drainage area (1,342 km²) takes longer to concentrate. Monitor closely on 3/06.
Harriet reversed its recession. After declining from 215 → 172 cfs over 8 days, Harriet bounced to 185 cfs. This 13 cfs increase from 0.435" of moderate-intensity rain establishes a rough detection threshold: ~0.4" at 0.1-0.27"/hr is sufficient to halt recession and produce a modest rise at Harriet (but only +0.03-0.04 ft in height terms).