The aquifer layer
What the rock is, where it is, and how much water it can hold.
What the rock is, where it is, and how much water it can hold.
Second layer of the pipeline. Sits on the area mapping and underneath the water layer.
AREA MAPPING --> [ GEOLOGY / AQUIFER ] --> WATER --> [SYSTEM MODEL] --> [OPTIMISATION]
Nothing here models a scheme. This layer answers: what rock is under this ground, where does each body sit, and what could it hold.
Chapters
| chapter | question |
|---|---|
| Mapping status | what do we know, from which source, at what confidence |
| Located inventory | every aquifer body within 40 km of the site box, with its location |
| Portfolio re-screen | which units have ANY role, not just the MAR role |
| Depths and volumes | thickness, storativity, drainable volume, and the confidence of each |
| Rock layers / layer model | the ordered column |
| Borehole data | the only direct observation of what is underground |
| Data gaps / next steps | what is missing and what is planned |
Headline
- 87% of the 50k map carries a formation confirmed by click
- 335 located bodies, 7,887 km2, within 40 km of the site-screen box
- 15,801 Mm3 drainable, range 2,033-92,140 - and 90% of that
rests on
inferredorguessinputs - 9 of 32 units have parameters of their own
The interface with the water layer
These two must match, and each side names the other. The
corresponding section in papers/water carries the same
table from its side.
| flux | direction | who owns it | value |
|---|---|---|---|
| recharge | water -> aquifer | water layer computes, aquifer layer consumes | 217 mm/yr |
| saturated thickness | water -> aquifer | water layer’s table sets it | removes 36% of rock |
| baseflow / leakage | aquifer -> water | signed exchange, k(h - h_river) |
net positive: aquifer feeds rivers |
specific yield Sy |
aquifer -> water | aquifer layer publishes, water layer uses | Chalk ~0.012 |
| storativity for volume | aquifer only | NOT the same number | Chalk ~0.0015 |
The one trap on this interface.
Syis not a single quantity. The value that governs how far a water table MOVES is the one AT the water table (Chalk 3-5e-2, top band of WD/97/34 Table 4.1.6). The value that governs how much a body HOLDS is averaged over the whole saturated column (Chalk ~1.5e-3, because most of the column sits below 30 m where storage collapses). They differ by more than an order of magnitude, and this project conflated them once already - making head 25x too responsive. Dynamics take the shallow value; volumes take the depth-averaged one.
The standing warning this layer exists to make
DRAINABLE IS A CEILING NOBODY CAN REACH. Water moves about 16 m
through the Sherwood in the 229-day surplus-to-deficit lag, so what can
be recovered is set by how many wells are drilled and where - not by
the size of a polygon. Every body in the inventory exceeds its own
advective reach by three orders of magnitude. build_aquifer_volumes.py
deliberately stops one step short of “accessible” so that the refusal
is visible rather than assumed away.