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Realistic 3D replay: imagery, modelled dams, five cameras; live-mode results
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Sources: the Cumberland River record (January-June 2025)

All sources are works of the U.S. federal government (public domain). envs/flood_ops/tools/curate_cumberland.py fetches them, caches the raw responses in raw/ (git-ignored), and writes basin.json and record.csv.gz.

Real (the record)

what where series
dam release, cfs (hourly mean) USACE CWMS Data API, office LRN <dam>.Flow.Ave.1Hour.1Hour.man-rev
dam storage, acre-feet (hourly) same <dam>.Stor.Inst.1Hour.0.man-rev
pool elevation, ft (hourly) same <dam>.Elev-Pool.Inst.1Hour.0.man-rev
top and bottom of the flood pool, top of the inactive pool CWMS location levels <loc>.Stor.Inst.0.Top of Flood etc. J. Percy Priest's bottom of flood pool is seasonal: 483 ft to 21 March, 490.5 ft from 21 April to 9 October
flow at Burkesville KY USGS 03414100 (Water Data OGC API) discharge, 00060
flow at Nashville TN USGS 03431500 discharge, 00060
stage at Celina TN USGS 03417500 gage height, 00065 (no discharge is published)
flood categories, stage-flow ratings NOAA NWPS, gauges BRKK2, CLAT1, NAST1 action / minor / moderate / major

Dams: WLCK2-WOLF_CREEK, DLHT1-DALE_HOLLOW, CEHT1-CENTER_HILL, JPHT1-J_PERCY_PRIEST.

Flood thresholds used (flow, cfs):

gauge action minor moderate major from
Burkesville (BRK) 32,500 40,000 57,500 90,000 NWS published flows
Celina (CEL) 52,006 76,030 91,010 110,011 NWS stages 30/40/45/50 ft through the NWS rating
Nashville (NAS) 70,072 119,465 128,065 154,611 NWS stages 30/40/42/45 ft through the NWS rating

Gaps: the hourly series are complete except Celina (85 hours) and Nashville (3 hours), filled by linear interpolation (basin.json, gap_hours_filled).

| river forecasts NWS issued, Jan-Jun 2025 (live mode) | Ohio River Forecast Center products RVFCMU and RVFCML, from the Iowa Environmental Mesonet's NWS text archive (mesonet.agron.iastate.edu/cgi-bin/afos/retrieve.py) | SHEF .ER ... HGIFF stage forecasts, 6-hourly to about 5 days, at BRKK2 (30 issues), CLAT1 (219), NAST1 (228); turned into flow through the NWS ratings; forecasts.csv.gz (tools/curate_forecasts.py) |

| the 3D replay's map: imagery, terrain, rivers, reservoirs | USGS The National Map orthoimagery (USGSImageryOnly, USDA NAIP; the Kentucky side colour-matched to Tennessee's at the state-line seam); USGS 3D Elevation Program (3DEPElevation ImageServer); USGS National Hydrography Dataset (NHDPlus small-scale flowlines and waterbodies); dam locations from CWMS, gauge locations from NWPS | openenv/flood_openenv/web/twin/basin.json.gz (tools/twin/build_basin.py); display only, never in a cost |

Derived

  • 6-hour steps (UTC): mean release and flow over the step; storage and elevation at its start.

  • Dam inflow I[t] = R[t] + (S[t+1] − S[t]) / 0.49587, from the record's own mass balance. It is noisy where the storage record is (it can be negative for a step).

  • Local runoff at a gauge L[t] = Q[t] − Σ routed record releases. With these two definitions the Corps' own releases reproduce the record's storage and gauge flows exactly (core/tests/test_core.py).

  • Travel times (hours), from cross-correlating 24-hour-smoothed hourly changes in the 2025 record, reach by reach:

    reach lag
    Wolf Creek → Burkesville 10
    Burkesville → Celina 8
    Celina → Cordell Hull (pool) 0
    Cordell Hull → Old Hickory 6
    Old Hickory → Nashville 2
    Center Hill → Old Hickory 16
    J. Percy Priest → Nashville 2

    Dale Hollow's releases are too steady to identify. Its 7.3 miles to the Cumberland use the 3.5 mph measured below Wolf Creek (2 h). The sums give the dam-to-gauge lags in basin.json. A fractional lag is split linearly between two 6-hour steps.

  • Maximum release: the largest hourly release in the 2018-2025 record. WC 59,900, DH 10,100 and CH 25,300 (all February 2019), JPP 14,900 (February 2020).

  • Ramp: the 99.9th percentile of the change between consecutive 6-hour mean releases, 2018-2025, rounded: WC 18,000, DH 4,500, CH 10,000 and JPP 5,000 cfs per step.

  • Storage → elevation tables: from the hourly record plus the official levels. Used for display only.

  • Forecast errors (live mode): for each issued forecast, the log ratio of forecast to observed flow, lead by lead (observed = the mean of the two 6-hour steps around the valid time). 214 Celina and 222 Nashville forecasts reach 5 days. The spread grows from 0.09 (Celina) and 0.13 (Nashville) at 0-12 h to 0.38 and 0.36 at 108-120 h. The bias falls to -0.26 and -0.19 at 108-120 h.

  • Forecast scenarios (live mode): each of the 8 members replays one issued forecast's whole error path, multiplied into the true series (positive values only).

    • Upper-basin series take Celina's path: Wolf Creek and Dale Hollow inflow, Burkesville and Celina local flow.
    • Lower-basin series take the Nashville path from the product issued closest in time.
    • There are no forecasts at the four storage lakes, so their inflows borrow the nearest gauge's error.
    • Leads beyond 5 days keep the 5-day error.
    • Members are seeded by task and decision.

Assumed (modelling choices)

  • Cordell Hull and Old Hickory are run-of-river: their pool changes are part of the local runoff.
  • Minimum release 0 cfs. In April 2025 Wolf Creek released 20 cfs for three days.
  • The cost weights (README) and the 6-hour decision step.
  • Drawn tiers, labelled in the task text:
    • storm: runoff above the week-before baseflow multiplied by 1.5, at the dams and at the gauges;
    • full: every lake starts with half its flood pool in use.
  • Plan mode: the agent knows the window's inflows and runoff exactly (hindsight). Live mode replaces that with the forecast scenarios above.
  • Live mode: the spill penalty (100 per 1,000 acre-feet per step above the top of the flood pool or below the inactive pool), 24-hour decision blocks, 8 scenarios.