Gross rainfall by pilot watershed

Beta · flood peak timing screen

Harvey at Rosharon: when could an upstream intake change flow?

USGS approved 15-minute discharge and gauge-height readings let us compare Harvey's observed hydrograph with an idealized upstream diversion. The blue line assumes the entered rate was removed before the gauge with immediate effect, no return flow or added runoff. There is no selected intake or built conveyance. This is a flow screen, not a predicted flood level or damage result.

The flow floor and comparison threshold are user assumptions. Neither is a legal protected-flow value or a flood-stage threshold. The modeled removal is capped by both assumed intake capacity and observed flow above the floor.

Orange: observed discharge · Blue: assumed residual discharge · vertical scale: thousands of cfs. Gaps are not drawn across missing readings.

At the assumed 100,000 cfs comparison line, observed flow spent about 105.7 hours above it; the idealized residual spends about 100.0 hours. This is an illustrative flow metric, not hours of flooding. 406.75 of 408 event-window hours have adjacent valid discharge samples; 75 minutes across two gaps are excluded from integration.

Evidence still needed for actual flood relief: an upstream intake location and travel time; sub-hourly hydraulics with cross sections, tributary inflows and backwater; a surveyed elevation datum and stage-to-inundation mapping; exposed buildings and assets; downstream safety checks. The recorded 52.65-foot gauge peak cannot be lowered by simply subtracting cfs from feet. The USGS Harvey inundation data show the historical extent, while the Lower Brazos hydraulic study provides a starting point for a calibrated project comparison. Neither dataset alone predicts a diversion's effect. USGS discharge readings · USGS gauge-height readings · Download observations and provenance.

Beta · upstream intake shortlist

Where should a floodwater intake be investigated first?

Choose the threatened reach. The table checks how much water passed each upstream USGS gauge before that reach's observed Harvey crest, using the same assumed rate cap and flow floor at every gauge. An upstream gauge is a measurement point, not an approved intake site. The named reach is a screening proxy; a real population and floodplain must be mapped before siting.

Target gauge 08114000 peaked at 122,000 cfs on Aug 31, 10:45 PM CDT. The table ends each source calculation at that timestamp. Gauges are ordered along the main stem; local tributary inflows and floodplain storage make their hydrographs different.

How to read this: the displayed acre-feet are independent arithmetic screens at different points on the same river. Do not add the rows. A larger number at a gauge does not identify a buildable intake or prove earlier flood relief: the water may arrive too late at the protected population, a tributary may add flooding downstream, and the removal may shift risk elsewhere. Stage, diversion rights, sediment, pump startup, pipe capacity, energy, land access and downstream environmental flows remain untested. The next engineering comparison must pair candidate parcels and threatened neighborhoods with a calibrated lower-Brazos hydraulic model.

Beta · Harvey scale and response timing

How quickly would a flood diversion need to scale?

Harvey's seven-day rainfall over the five pilot watersheds totaled 8,377,874 acre-feet (8.38 million AF). That is rainfall over land, not water passing one intake or a full-storm total. The timeline below replays a separate 17-day USGS river record at Rosharon to compare no diversion with a system that starts when the observed gauge height crosses a selected trigger and ramps up over time.

Trigger height is a retrospective demonstration, not an operating rule. Flood stage at this gauge is 43 ft under current NWS markers. Earlier upstream warning and real-time forecast data would be needed for advance activation. The flow floor is an assumption, not an environmental-flow or water-right decision.

Daily flow passing the gauge and idealized removal

Daily bins use UTC. Orange is observed gauge throughput; blue is the assumed amount removed from that same flow. These bars do not represent rainfall totals.

Calculation: at each adjacent 15-minute sample, assumed removal is min(installed capacity × availability × elapsed ramp fraction, max(0, observed cfs − flow floor)). Trapezoids convert that rate to acre-feet. 406.75 hours of adjacent readings are included; 75 minutes of gaps are excluded. Removal is assumed to affect Rosharon immediately and perfectly; no travel delay, local runoff, backwater, treatment, losses, cost, power, receiving-site limit or operating outage beyond the entered availability is simulated. Observed and assumed flows are two scenarios for the same water, never additive. Actual life safety, flood-damage reduction, delivery and aquifer recharge require site-specific engineering and approvals.

NOAA rainfall ledger · USGS 15-minute observations · NOAA forecasts

Harvey retrospective · proposed corridor

What could a prebuilt route move?

This beta stress test applies hypothetical, continuous equipment to the observed 17-day Rosharon daily-flow record. The intermediate stop and Ogallala endpoint are unnamed planning placeholders, with no surveyed alignment or accepted receiving site. Enter route assumptions to see the scale of transport and energy. A forecast can trigger operations; it cannot create a corridor before landfall.

Decision order: protect people and avoid transferring risk downstream; test whether an intake lowers flood peaks and damage at the places that matter; then maximize movement of eligible excess water within intake, route, storage and receiving-site limits. This calculator has no flood-inundation or damage model, so its volume output is not a flood-safety result.

For an approaching storm, use official NOAA river forecasts for planning and update the modeled input as observations arrive. This page replays 2017 observations; it does not predict a future hurricane or issue an operating order.

Method and limits: Each day's screened rate is min(built cfs, max(0, daily mean cfs − assumed floor)). One cfs-day equals 1.98347 AF. Allocated volumes assume eventual passage and draining with no losses; they are not the amounts delivered by September 10. Pump energy uses ρgH × volume / efficiency for entered elevation lift only. Friction, surge protection, treatment, intermediate demand, reservoir operations, rights, actual route capacity, storage and recharge acceptance are absent. Daily mean flow cannot establish peak flood relief, life safety or damage avoided; those require time-resolved hydraulic and inundation analysis. No project cost or aquifer gain is inferred. USGS source and daily flags.