A Basin's Water Story
This is where the course converges. You've traced the water cycle, delineated a watershed, read a hydrograph, separated baseflow, fetched real USGS data, and computed TWI. Now you put it all together — characterise one basin end-to-end and tell its water story.
Seven-step capstone — click to jump
1 · Choose your basin
Select the basin you explored in Module 5, or pick a different one. The same four teaching gauges are available — each with a distinct hydrological character. All three kernel cells below will update when you change your selection.
2 · The streamflow record
This cell synthesises 10 years of daily discharge shaped to your basin's hydrological character and computes key statistics. Run it first — the signatures cell below builds on these results.
3 · Hydrological signatures & flow duration curve
The Lyne–Hollick BFI and flashiness index compress the whole record into two numbers. The Flow Duration Curve (FDC) shows what fraction of time any given discharge is exceeded — a steep FDC means flashy; a flat one means steady. Run the cell, then compare the FDC shape to the client-side plot rendered below.
Flow Duration Curve — interactive (client-side)
Updates instantly when you change basin — no kernel needed. Uses aihydro.plot (Plotly).
Steep slope = flashy basin · Flat slope = steady groundwater-dominated basin
4 · The shape of the land
TWI tells you where the landscape stays wet. Each basin type has a characteristic wetness distribution. Run the cell to see the synthetic TWI grid for your basin and interpret where saturation-excess runoff is most likely to occur.
5 · Your basin's water story
Step through the six modules — each arrow from Module 1's water cycle appears here, annotated with what your basin's numbers say about it. Use the timeline controls or click the dots.
A water molecule evaporates from the ocean, condenses in clouds, falls as precipitation over your basin, and begins its journey.
For Fish River, ME, much of the annual precipitation (~1 000 mm/yr) arrives as rain and snow. The six-flux budget: P ≈ ET + R + ΔS constrains everything that follows.
Every drop that falls inside the Fish River drainage divide eventually passes through gauge 01013500. Topography routes it there via D8 flow paths.
The watershed boundary is an invisible wall drawn by elevation — the continental divide concept applied at sub-basin scale. Flow paths converge in valleys; ridges are the divides.
The multi-year record you just plotted is a sequence of storm hydrographs. In Fish River, ME you'll see steep rising limbs in spring (snowmelt) and scattered winter peaks (rain-on-snow events).
The flashiness of the rising limb depends on catchment storage. A high BFI basin (like Bogue Chitto) barely shows individual storm peaks — groundwater smooths them out.
The Lyne–Hollick filter extracted the slow groundwater component from your record. Your basin's BFI is ≈ 0.55 — meaning roughly 55% of all discharge comes from stored groundwater, not direct storm runoff.
A BFI above 0.7 indicates a basin where soil or aquifer storage dominates (e.g. Bogue Chitto, LA). A BFI below 0.2 signals rapid direct runoff with minimal storage (e.g. Rillito Creek, AZ).
In Module 5 you found gauge 01013500 on the USGS NWIS map. Here you've extended that record to 10 years to see inter-annual variability — wet and dry years, flood years and drought years.
The annual regime (bar chart in §2) is the most compact summary of how your basin behaves across seasons — a fingerprint unique to its climate and landscape.
The TWI grid from §4 tells you where saturation-excess runoff is most likely. Your basin's mean TWI of ≈ 8.2 places it in the moderately wet class.
This completes the spatial picture: the hydrograph tells you when flow is high; the TWI tells you where the landscape was already saturated when it happened.
export_session and returns a JSON artefact you
can share or reload in a future session.
6 · Capstone checkpoint
These three questions draw on the full course — Modules 1 through 6. Answer all correctly to complete the course.
Rillito Creek (AZ) has a BFI of about 0.08. Bogue Chitto (LA) has a BFI of about 0.82. Which basin would show a steeper Flow Duration Curve (FDC)?
The water balance equation is P ≈ ET + R + ΔS. If a basin receives 900 mm/yr of precipitation, evapotranspires 450 mm/yr, and has negligible long-term storage change (ΔS ≈ 0), what is the expected mean annual runoff R?
You compute TWI for two basins: Basin A (forested humid Appalachian; mean TWI = 9.1) and Basin B (semi-arid desert wash; mean TWI = 5.3). Which basin would you expect to have more saturation-excess overland flow during a moderate storm?
7 · Where to go next
You've completed the AI-Hydro flagship course — the six flux arrows, seven modules, and every interactive primitive in the platform. Here's what you can do from here:
window.aihydro primitives you used here power every community module. If you can
author HTML + Python, you can build a module that teaches hydrological science — and share it
with every student who has AI-Hydro installed.
References
- Addor, N., Newman, A.J., Mizukami, N. & Clark, M.P. (2017). The CAMELS data set: catchment attributes and meteorology for large-sample studies. Hydrology and Earth System Sciences, 21, 5293–5313. DOI: 10.5194/hess-21-5293-2017
- Lyne, V. & Hollick, M. (1979). Stochastic time-variable rainfall-runoff modelling. Institute of Engineers Australia National Conference, Publ. 79/10, 89–93.
- Beven, K.J. & Kirkby, M.J. (1979). A physically based, variable contributing area model of basin hydrology. Hydrological Sciences Bulletin, 24(1), 43–69. DOI: 10.1080/02626667909491834
- Dingman, S.L. (2015). Physical Hydrology, 3rd ed. Waveland Press.