North Petherton Flood & Drainage Explorer

How to use this dashboard

Select local applications and any additional catchment conditions.
Adjust impermeable area, rainfall, climate allowance, drainage condition and pump/outfall status.
Read the headline status, key metrics and development breakdown.

Scenario controls

Inputs

Default impermeable area 200 m²

Used for selected housing sites unless a custom development uses its own area.

Design storm intensity

Climate change allowance

Drainage condition

Pump and outfall status

Include all local NP applicationsSeven applications, 1,080 dwellings

Local applications

Turn on/off

Catchment conditions

Stress factors

Scenario assumptions

Use these to test less favourable real-world drainage conditions. They are scenario assumptions, not forecasts.

Custom development

Optional

Specify custom impermeable areaUseful for larger hardstanding, care homes, schools or mixed-use schemes.

✅

Manageable indicative flood pressure

The selected scenario remains within indicative operating tolerances.

This is a public scenario tool. It is not a hydraulic model or formal flood-risk assessment.

Stress index0%

Dwellings tested0

Impermeable area0

Annual runoff0

Peak runoff0

Cumulative testReview

SuDS relianceConditional

Downstream receptorSensitive

Hydraulic stress index

This combines runoff, climate allowance, drainage condition, pump/outfall status and selected catchment conditions.

Catchment stress proxy

Plain-English interpretation

Green, amber and red signals are indicative public-understanding flags. They do not replace formal hydraulic modelling or statutory flood-risk assessment.

Scenario summary

Current selected assumptions and active conditions.

Evidence notes

Notes for catchment condition assumptions.

Development breakdown

Selected sites, homes, impermeable area, annual runoff and peak flow.

Site	Homes	Impermeable area	Annual runoff	Peak flow

Evidence, assumptions and limitations

Development names, planning references and dwelling counts are drawn from the North Petherton cumulative flood-risk report and publicly available planning information.
Default impermeable area is 200 m² per dwelling, runoff coefficient is 0.90, annual rainfall is 800 mm and central design storm intensity is 30 mm/hr.
Annual runoff is calculated as impermeable area × annual rainfall × runoff coefficient.
Peak runoff uses a simplified Rational Method proxy: C × rainfall intensity × area.
Stress index is an indicative public-understanding signal combining runoff, climate allowance, drainage condition, pump/outfall status and selected catchment conditions.
This tool does not represent approved discharge rates, attenuation performance, site-specific modelling, Environment Agency assessment or Lead Local Flood Authority assessment.