1. PRECIPITATION SUMMARY
Negligible rainfall across the watershed. No gauge zone received more than 0.1" total. The upper watershed (Boxley, Ponca, Pruitt zones) received exactly 0.0". Minor trace amounts fell in the lower/eastern watershed:
None of these are hydrologically significant. This is effectively Day 3 of zero meaningful rainfall — excellent for continued recession analysis.
2. GAUGE RESPONSES
All gauges continued monotonic recession with no new event signal. Summary of Day 10 recession:
| Gauge | Start of Day | End of Day | Daily Decline | Daily Rate (cfs/hr or ft/hr) |
|---|---|---|---|---|
| Boxley | 2.74 ft | 2.63 ft | -0.11 ft | 0.0046 ft/hr |
| Ponca | 226 cfs | 200 cfs | -26 cfs | -1.1 cfs/hr |
| Pruitt | 402 cfs / 4.79 ft | 324 cfs / 4.56 ft | -78 cfs / -0.23 ft | -3.3 cfs/hr |
| St. Joe | 1,180 cfs / 5.67 ft | 902 cfs / 5.22 ft | -278 cfs / -0.45 ft | -11.6 cfs/hr |
| Harriet | 1,490 cfs / 5.40 ft | 1,140 cfs / 5.02 ft | -350 cfs / -0.38 ft | -14.6 cfs/hr |
| Richland | 1.84 ft | 1.71 ft | -0.13 ft | 0.0054 ft/hr |
| Bear Creek | 24.2 cfs / 2.64 ft | 20.4 cfs / 2.58 ft | -3.8 cfs / -0.06 ft | -0.16 cfs/hr |
Key recession observations:
Ponca crossed the Optimal/Low-but-Floatable boundary (200 cfs) during the day. At EOD it's flickering around 200 cfs — essentially at the threshold. By tomorrow it will clearly be in "Low but Floatable" (150-200 cfs) territory.
Pruitt remains well in Optimal (324 cfs, threshold 200 cfs) but the recession rate has continued to decelerate. Day 2 recession was ~6.5 cfs/hr; Day 3 is ~3.3 cfs/hr — a 0.51x ratio, confirming the exponential decay pattern.
St. Joe remains firmly in Optimal (902 cfs, threshold 200 cfs). Day 2 recession was ~28 cfs/hr; Day 3 is ~11.6 cfs/hr — a 0.41x ratio, nearly identical to yesterday's deceleration ratio. Very consistent exponential behavior.
Harriet remains in Optimal (1,140 cfs, threshold 200 cfs). Day 2 recession was ~34 cfs/hr; Day 3 is ~14.6 cfs/hr — a 0.43x ratio.
Boxley recession continues decelerating: 0.0054 ft/hr on Day 2, 0.0046 ft/hr on Day 3. At 2.63 ft, still +0.73 ft above pre-study baseflow (1.90 ft). At current rate, return to baseflow would take ~7 more days (around March 17), considerably longer than my Day 9 estimate of March 11-12. The pool drainage is slower than initially projected.
Richland Creek at 1.71 ft is approaching its pre-event baseflow of 0.93 ft but still +0.78 ft above it. The rate of decline has slowed considerably.
Recession comparison — Ponca-Pruitt discharge relationship: Ponca at 200 cfs, Pruitt at 324 cfs — Pruitt now exceeds Ponca by 62%. This relationship continues to be normal at these flow levels, consistent with our finding that the Ponca>Pruitt inversion is a low-flow-only phenomenon.
3. RAINFALL-RESPONSE PAIRS
None. No meaningful rainfall to correlate.
4. DOWNSTREAM PROPAGATION
No new event to track. The recession continues to show the expected upstream-first pattern: Ponca is nearest to baseflow, Pruitt next, then St. Joe, then Harriet — reflecting increasing drainage area and storage.
5. MULTI-DAY EVENTS
This is Day 3 of the Event 2 recession (post-peak). Three full days of essentially zero rainfall provide an excellent dataset for recession curve characterization.
Refined recession half-life estimates (updated with 3 days of data):
Using the exponential model Q(t) = Q_base + (Q_peak - Q_base) × e^(-t/τ), I can now better constrain the time constants:
| Gauge | Excess at Peak | Excess Day 1 EOD | Excess Day 2 EOD | Excess Day 3 EOD | Implied τ (hr) | Half-life (hr) |
|---|---|---|---|---|---|---|
| Ponca (base ~84) | 2,036 | 193 | 142 | 116 | ~10 hr (fast phase done) | ~7 hr early, now in slow baseflow recession |
| Pruitt (base ~64) | 2,546 | 338 | 338 | 260 | — | ~18 hr for late recession |
| St. Joe (base ~165) | 3,065 | 1,635 | 1,025 | 737 | ~34 hr | ~24 hr |
| Harriet (base ~172) | 2,878 | 2,158 | 1,348 | 968 | ~40 hr | ~28 hr |
The upstream gauges (Ponca, Pruitt) have essentially completed their event recession — the remaining flow is dominated by slow groundwater/interflow recession, not event stormflow. The downstream gauges (St. Joe, Harriet) are still in recognizable event recession but transitioning.
6. ANOMALIES OR SURPRISES
Boxley pool drainage much slower than projected: I previously estimated baseflow return by March 11-12. At current deceleration, it's looking more like March 15-17. The exponential deceleration is stronger than initially modeled — the pools are releasing water much more slowly as they approach equilibrium. This refines the local knowledge finding: the pool-and-drop system not only delays initial response to rainfall but also dramatically extends recession, acting as distributed storage that drains on a multi-week timescale.
Ponca approaching a key threshold: At 200 cfs, Ponca is at the boundary between Optimal and Low-but-Floatable. This provides a useful calibration point — we can estimate that ~3 days after a 2,120 cfs peak, Ponca returns to the low-floatable boundary under dry conditions. This is consistent with the ~7 hr early half-life (the peak excess of ~2,000 cfs above base was reduced to ~200 cfs excess in ~3 days = ~72 hr, which would require ~3.3 half-lives, giving ~22 hr half-life on average for the full recession curve. The two-phase nature — fast early, slow late — means a single half-life doesn't capture the full behavior well.)
Richland Creek data quality: Still showing gaps — 87 of ~96 expected readings. Persistent issue, though not critical during recession.