Today saw the first spatially significant rainfall of the study period, concentrated in the upper watershed (headwaters through Pruitt zone) with a strong west-to-east gradient.
Highest totals (gauged zones): - Cove Creek (Pruitt zone, 110100050204): 0.365" — the day's maximum in the gauged watershed. Peak 1hr intensity: 0.161"/hr at 14:06 CST (20:06 UTC). This is the highest hourly intensity recorded in the study to date. - Boxley (110100050201): 0.194", peak 0.069"/hr - Whiteley Creek-Buffalo River (Ponca zone, 110100050205): 0.186", peak 0.102"/hr - Flatrock Creek (St. Joe zone, 110100050206): 0.179", peak 0.068"/hr - Beech Creek (Ponca zone, 110100050202): 0.173", peak 0.073"/hr - Smith Creek (Ponca zone, 110100050203): 0.140", peak 0.074"/hr - Hoskin Creek (Pruitt zone, 110100050207): 0.132", peak 0.069"/hr
Timing: Rainfall occurred in two pulses — an early pulse around 14:06 UTC (08:06 CST) concentrated in Cove Creek, and a later pulse around 23:06 UTC (17:06 CST) / 05:06 UTC Mar 5 (23:06 CST) across the headwaters and Ponca zone. Many peak 1hr values are timestamped at 05:06 UTC March 5 (23:06 CST March 4), meaning the rainfall was ongoing at end of day.
Lower watershed was essentially dry: Bear Creek zone received only 0.017", Harriet zone 0.017", and most St. Joe sub-basins received <0.06". The ungauged zone below Harriet received only 0.021" (zone average), though Clabber Creek (0503) got 0.109" in a localized cell.
Richland Creek zone: Only 0.091" (zone average), with Headwaters Richland (0306) getting 0.110".
Antecedent conditions: 7-day antecedent precipitation is unchanged from yesterday (no rain fell on 3/03). Cove Creek's 7-day antecedent is 0.61" — the highest in the Pruitt zone. With today's 0.365" addition, the 8-day cumulative for Cove Creek is now ~0.975".
No significant rises detected at any gauge. All gauges continue their baseflow recession.
Boxley (07055646): 1.89–1.91 ft. Dropped to new study low of 1.89 ft around 19:00 CST, then ticked back to 1.90 ft by end of day. The rainfall in the Boxley HUC12 (0.194") was still arriving at end of day — the late-day bump from 1.89 to 1.90 ft is within noise (±0.01 ft) but worth monitoring tomorrow. No detectable response yet.
Ponca (07055660): 82.4 cfs all day with occasional 83.7 spikes. The slight increase in 83.7 readings in the afternoon/evening (16:00-17:00, 18:30-18:45, 20:30, 21:00, 22:45-23:30) compared to the morning (all 82.4) is suggestive but within normal quantization noise. End-of-day reading 83.7 cfs. No detectable response yet, but end-of-day trend needs monitoring.
Pruitt (07055680): Height range 3.41-3.44 ft, discharge 59.6-63.7 cfs. The diurnal minimum hit 59.6 cfs (3.41 ft) around 12:00-13:15 — matching the previous day's minimums. The diurnal range has compressed: only 0.03 ft today vs. 0.07 ft on 3/02 and 3/03. Nighttime discharge bounced between 62.3 and 63.7, settling at 63.7 at end of day. Despite 0.365" in Cove Creek (its direct tributary zone) with 0.161"/hr peak intensity, no response is visible at Pruitt. This is a critical non-detection data point.
St. Joe (07056000): Height range expanded to 0.08 ft (3.37-3.45), and new study low values appeared: 144 cfs / 3.37 ft at 15:15. The increased noise/variability (CFS ranging 144-171 today vs. 158-180 yesterday) is notable. However, this appears to be increasing measurement noise at very low flows rather than a rainfall response — the pattern shows no sustained directional change, and the lowest values occurred in the afternoon, consistent with the diurnal pattern seen at Pruitt. Mean discharge clearly dropped: early morning ~166 cfs, late afternoon/evening ~160 cfs. Continued recession, no rainfall response, but increased noise floor at these very low levels.
Harriet (07056700): Height dropped from 3.55 ft to 3.53 ft through the day, with a clear step-down around 17:00. Discharge went from 180 cfs to 172 cfs — a new study low. This is consistent with continued recession. No rainfall response — expected given virtually no rain in the Harriet local zone.
Richland Creek (07055875): Range 0.90-0.94 ft. The pattern is consistent with previous days' noise — spikes to 0.93-0.94 ft interspersed with dips to 0.90 ft, especially late in the day. Only 78 readings received (vs. typical 92-95), suggesting some data gaps. No response to the 0.091" zone average.
Bear Creek (07056515): Height 2.31-2.33 ft, discharge mostly 6.58 cfs with a single 6.02 cfs reading at 20:00 (new study low) that appears to be a spike/quantization artifact. Continued deep baseflow recession.
Critical non-detection at Pruitt — strongest test case to date: - Cove Creek (HUC12 0204): 0.365" in 24 hours, peak 1hr intensity 0.161"/hr - 7-day antecedent: 0.61" - Cumulative 8-day: ~0.975" in Cove Creek - Pruitt gauge: No response through end of day - However: Much of the rainfall arrived late — peak at 14:06 CST, with additional rain through the evening. A response could appear on 3/05. This is a provisional non-detection that needs to be confirmed tomorrow.
Non-detection at Boxley: - Boxley HUC12: 0.194" with peak 0.069"/hr, much of it arriving late (peak at 23:06 CST) - Response possible tomorrow. The 1.89→1.90 ft uptick at end of day is ambiguous.
Updated detection threshold context: The Cove Creek case is our strongest test yet. If no response appears at Pruitt by end of 3/05 (giving ~24+ hours since the rain), this would push the detection threshold for Pruitt to >0.97" cumulative (8-day) or >0.365" single-day at ≤0.161"/hr peak intensity under dry antecedent conditions.
No propagation to observe — no rises detected.
The rainfall today adds to the 3/01-3/02 precipitation. Cove Creek's cumulative is now ~0.975" over the study period (3/01-3/04). This is approaching the 1.0" threshold I previously hypothesized as potentially needed for detection under dry conditions. Watch Pruitt carefully on 3/05.
St. Joe increased noise: The height range at St. Joe expanded to 0.08 ft today (from 0.07 ft yesterday) and the minimum dropped to 3.37 ft (new study low). The discharge minimum of 144 cfs is a significant new low. Importantly, the 144 cfs reading at 15:15 corresponds to height 3.37 ft — this is approaching a regime where the rating curve may become less reliable. The gauge noise is increasing as flow drops, which will make future event detection harder at St. Joe.
Ponca recession appears to have stalled: Ponca has been locked at 82.4 cfs for essentially 3 days (since ~3/03 04:30), with only occasional 83.7 spikes. This could indicate: (1) Ponca has reached a quantization floor where the true discharge is between 82.4 and 83.7 but the rating curve can't resolve it; (2) Ponca is approaching a true baseflow asymptote supported by karst springs. The slight increase in 83.7 readings at end of day on 3/04 could be the very first hint of a response to headwater rainfall, or noise.
Pruitt diurnal cycling compressed: The height range at Pruitt dropped from 0.07 ft (3/02, 3/03) to 0.03 ft today. The diurnal minimum remained at 59.6 cfs / 3.41 ft, same as yesterday. This compression could mean: (1) the diurnal driver is weakening as flow drops further; (2) incoming rainfall is partially masking the afternoon decline; or (3) random variation. Need more data to distinguish.
Cove Creek peak intensity is the study's first above 0.1"/hr: At 0.161"/hr, this is nearly double our previous maximum (0.109"/hr in the ungauged zone on 3/02). If this still produces no response, it significantly constrains our infiltration capacity estimates.