The Environment Agency (EA) warns of flooding at Frilsham, Stanford Dingley and Bradfield when the level at the Frilsham gauge goes above 62 cm. The EA has no gauge at Stanford Dingley; the Pang Valley Flood Forum (PVFF) runs its own. This page asks a simple question: of the EA gauges on the Pang, which is the best to use to trigger a Flood Warning for Stanford Dingley?
Short answer: the gauge below Bucklebury village (the EA's "Bucklebury gauge", station 2150TH, which the PVFF calls the Bucklebury "Below Village" gauge). It is the only gauge that measures all the water that reaches Stanford Dingley. The Frilsham gauge is upstream of the streams that carry rain runoff from the clay ridge to the south, from Cold Ash to Bradfield, and so is not impacted by large rain events and the EA's new gauge within Bucklebury village is bypassed by the flood channel when the river is high (it's for that reason that this new gauge was implemented specifically to trigger Flood Warnings in Bucklebury itself).
The level of the river Pang is driven by chalk base flow, combined with runoff following rainfall from the clay ridge running from Cold Ash to Bradfield along the south of the valley. That runoff joins the river as stream, from downstream of Frilsham. There are no streams flowing into the river upstream of Frilsham.
The Environment Agency operates gauges at:
The PVFF operates its own automated level gauges:
There are two relevant flood warning areas: 061FWF21FrSDBrad (River Pang for Frilsham, Stanford Dingley and Bradfield) and 061FWF21Buklebry (River Pang at Bucklebury). The Bucklebury area sits between two parts of 061FWF21FrSDBrad and splits it in two. Warnings for 061FWF21FrSDBrad are triggered at the moment on the basis of the level at the Frilsham gauge.
The only EA gauge before Stanford Dingley that includes the main runoff flow from the clay ridge, is the gauge Bucklebury gauge station 2150TH.
Using data from the EA's Bucklebury and Frilsham gauges and the PVFF's Stanford Dingley gauge, we have plotted in the charts below: Below Village v Stanford Dingley and Frilsham v Stanford Dingley.
Each dot on the two charts below is a Stanford Dingley reading plotted against the level at the other gauge a few hours earlier. The level in Stanford Dingley is impacted by whether the mill sluice boards are in or out (and there is no formal record of their position) - so we have filtered only on occasions when the Bucklebury Below Village gauge is above 55cm for both charts (as the boards would not be in in such as circumstance). This is an indicator, not a record of the position of the boards. For each we show also correlation r which runs from 0 (no relationship) to 1 (a perfect match); R² is r squared.
Note that initial flooding in Stanford Dingley can begin when the level at the mill is 90cm.
The best way for the EA to know the level in Stanford Dingley, and to have the best gauge to trigger Stanford Dingley flood warnings, would be to have a level gauge in Stanford Dingley itself. Until then, the Bucklebury gauge is the only existing EA gauge that measures the flow reaching Stanford Dingley.
EA gauge levels (15 minute values), the PVFF's Stanford Dingley gauge (hourly, from 27 January 2024) and readings of the Stanford Dingley gauge board (2013 to 2024), all held by the PVFF. The data behind each chart can be downloaded with its download icon.