A flood risk assessment concludes that the development is safe for its lifetime, and it is correct, subject to a return period. What the document rarely says with any force is what the place will be like on the day the design event is exceeded — which will happen, somewhere, to somebody, and which the assessment has usually treated as beyond its scope. The residents who move in have read the word "safe" and nothing else.

We edit what water resources and flood risk engineers produce — flood risk assessments and sequential test documentation, hydraulic modelling reports and their assumptions, hydrology and design flow estimation reports, drainage strategies and sustainable drainage design documentation, reservoir and impoundment safety reports, flood defence design and appraisal documentation, catchment and river basin studies, water resource availability and abstraction documentation, flood warning and evacuation plan documentation, culvert, bridge and structure hydraulic assessments, climate change allowance justifications, and consultation and public information material. Our editors work on the section that describes what happens when the design event is exceeded.

The residual risk section is where a flood risk assessment either protects people or protects a planning application, and it is routinely reduced to a sentence about a flood warning service. Every scheme has an event beyond which it does not work, and describing that event is not an admission of failure; it is the entire basis on which people can plan. We write these so the exceedance behaviour is described physically — where the water goes, how deep, how fast, and in what order the parts of the site are affected, because a site that floods gradually from one corner is a different proposition from one where the access road goes first; so the time available is stated, since the interval between the trigger and the water arriving determines whether evacuation means anything or whether the answer is to go upstairs; so the safe refuge and the escape route are named and tested against the same event rather than assumed, given that an escape route that floods before the building does is a common and serious error; so what the occupants must do, and who tells them, is written as a plan with an owner rather than as a reference to a national warning service; so the climate allowance used is stated with what happens if it proves low; and so the assessment says plainly which parts of its conclusion depend on maintenance that somebody must actually perform for a hundred years. Assessments written this way are useful to the people who live there.

Everything you send is treated in confidence, including modelling, site data and client information. We are editors rather than hydrologists or flood risk engineers, and we offer no view on modelling, risk or design. What we can do is make the exceedance case as clearly written as the design case.