Date: 2026-02-28 (Day 0 of 90)
Trace precipitation only — negligible across the entire watershed. The QPE data shows the first non-zero readings of the study, but amounts are hydrologically insignificant:
Highest totals by HUC12 (24-hr): - Boxley (0201): 0.033" — highest in watershed - Beech Creek (0202): 0.031" - Smith Creek (0203): 0.029" - Headwaters Little Buffalo (0102): 0.027" - Falling Water Creek (0307): 0.024" - Shop Creek (0101): 0.023" - Headwaters Richland (0306): 0.021" - Henson Creek (0103): 0.020" - Whiteley Creek (0205): 0.019"
Spatial pattern: A very light west-to-east gradient. The western/upper watershed (Boxley, Ponca, Little Buffalo) received the most — up to 0.033". The eastern/lower watershed (Bear Creek 0404: 0.000", Calf Creek 0401: 0.003") was essentially dry. Peak 1-hr intensities were all under 0.031" — well below any conceivable detection threshold.
Timing: All peak 1-hr accumulations occurred between 23:06 UTC Feb 28 and 01:06 UTC Mar 1 (5-7 PM CST Feb 28), suggesting a brief, very light precipitation event moving through in the evening.
Gauge-zone aggregates: Boxley 0.033", Ponca 0.026", Pruitt 0.006", St. Joe 0.009", Richland 0.022", Bear Creek 0.006", Harriet 0.004".
7-day antecedent precipitation: 0.00" across all 37 HUC12s. The watershed is extremely dry.
No significant rises at any gauge. All gauges continued their baseflow recession from yesterday. The trace precipitation produced no detectable response anywhere.
Baseflow recession trends (comparing 2/27 → 2/28 end-of-day values):
| Gauge | 2/27 EOD | 2/28 EOD | Change | Rate |
|---|---|---|---|---|
| Boxley | 2.01 ft | 1.97 ft | -0.04 ft | -0.02 ft/day |
| Ponca | 92.0 cfs | 89.2 cfs | -2.8 cfs | -1.4 cfs/day (~1.5%/day) |
| Pruitt | 81.4 cfs / 3.56 ft | 75.3 cfs / 3.52 ft | -6.1 cfs / -0.04 ft | -3 cfs/day (~4%/day) |
| St. Joe | 197.0 cfs / 3.53 ft | 187.0 cfs / 3.50 ft | -10 cfs / -0.03 ft | -5 cfs/day (~2.5%/day) |
| Harriet | 215.0 cfs / 3.63 ft | 201.0 cfs / 3.60 ft | -14 cfs / -0.03 ft | -7 cfs/day (~3.3%/day) |
| Richland | 1.0 ft | 0.96 ft | -0.04 ft | -0.02 ft/day |
| Bear Creek | 8.5 cfs / 2.35 ft | 8.2 cfs / 2.35 ft | -0.3 cfs / 0.00 ft | -0.15 cfs/day (~1.8%/day) |
Observations on recession: - All gauges are declining. This is classic baseflow recession under dry conditions. - Pruitt is receding fastest in percentage terms (~4%/day), which is notable. Pruitt dropped from ~81 to ~75 cfs while Ponca dropped from ~92 to ~89 cfs. The Pruitt-below-Ponca anomaly is now more pronounced: Pruitt is 75.3 cfs vs. Ponca at 89.2 cfs. This is a 14 cfs deficit despite Pruitt being downstream with 123 km² additional drainage. - St. Joe dropped to 187 cfs, now clearly in the "Low but Floatable" range (40-200 cfs). - Harriet dropped to 201 cfs — barely above the Optimal floor (200 cfs), will likely cross into "Low but Floatable" tomorrow. - Richland Creek dropped from ~1.0 to ~0.96 ft. The late-day readings (20:30-23:15) clustered at 0.95-0.97 ft, lower than any reading on 2/27. This represents a new low baseline.
Pruitt intra-day pattern: An interesting feature visible in the Pruitt discharge time series — it declined from ~83 cfs at midnight to a low of ~70.8 cfs around 13:45-15:00, then partially recovered to ~75-76.8 cfs by late afternoon. This ~13 cfs swing (83→71→76) within a single day with zero precipitation is notable. It may reflect a diurnal evapotranspiration cycle affecting shallow groundwater, or possibly a daily pumping/regulation pattern. The minimum occurs during mid-afternoon, consistent with ET effects. Pruitt has the highest apparent noise range of any gauge today (height range 0.09 ft vs. yesterday's 0.04 ft).
None. The trace precipitation (max 0.033") produced no detectable gauge response. This establishes that 0.03" of rainfall on a bone-dry watershed (0.0" antecedent) does not produce a measurable rise at any gauge in the network. This is expected but worth recording as a lower bound on detection thresholds.
No event to track. The synchronized recession across all gauges is consistent with baseflow decline, not pulse propagation.
No events. Two consecutive dry days establishing baseflow recession curves.
Pruitt-Ponca deficit widening: The discharge inversion is now 14 cfs (Ponca 89.2, Pruitt 75.3) and has increased from yesterday's ~11 cfs difference. This strengthens the hypothesis that there are real karst losses in the Ponca-to-Pruitt reach, as the deficit grows during recession (consistent with a losing reach where losses are relatively constant while surface flow declines). Confidence upgraded from Low to Medium.
Pruitt diurnal cycling: The ~13 cfs intra-day swing at Pruitt (high at night, low mid-afternoon) without precipitation is larger than the gauge noise floor established yesterday (±3 cfs). This may be a real diurnal signal — possibly ET-driven baseflow variation or a water use pattern. If it persists, it will need to be accounted for when assessing small rainfall responses at Pruitt.
Recession rate hierarchy: Pruitt is receding fastest (4%/day), while Ponca and Bear Creek are slowest (~1.5-1.8%/day). This is consistent with the karst loss hypothesis at Pruitt — it's losing water both downstream AND to the subsurface.