Expert Witness, Richard Allitt BSc FICE CEng CEnv of Richard Allitt Associates explains the importance of a methodical approach in identifying the root causes of flooding.
With heavy rainfall and storms seen across the UK atthe end of May, there will no doubt be a spate offlooding damage claims coming through in the nearfuture.
In most flooding cases that I am involved with, myinstructions are to investigate the cause of the flooddamage, considering all possible causes and wherepotential causes are excluded, to provide reasonswhy. In many cases, what is initially perceived to bethe cause of flooding is proven not to be the caseupon detailed investigation.
It’s imperative to approach each case in a methodicaland analytical way, with a site inspection being one ofthe first steps in data collection.
I often spend time with residents to discuss their experiences of how the flooding occurred, walkingaround the properties involved, the adjacent landand taking photographs. I also use RAA’s GPS surveyequipment to take site measurements and levels. Onlarger sites and harder to access areas I make use ofRAA’s own specialist Remote Aerial Survey servicewhich uses UAV’s (Drones) to carry out a range ofsurveys and inspections of flooded and other hard toreach areas. The advantages of using drones overregular survey equipment is that they are extremelyuseful in being able to identify things such as ‘urbancreep’ where hard landscaping has prevented watersoaking away leading to flooding, or identifyingditches and embankments which are not observablefrom ground level.
There is also a wealth of hydrology and rainfall datathat is readily accessible which I am able to draw on.For example, each month the “Centre for Ecologyand Hydrology” (CEH) in conjunction with the“British Geological Survey” (BGS) publish a 12 pageHydrological Summary which details what has happened in the preceding month in respect of rainfall,river flows, groundwater levels, reservoir levels andwater resources generally and compares them to longterm averages. I am also able to access storm analysisreports from the Met Office which can providevaluable insight into specific flooding events.
In some cases where the cause of flooding is not immediately obvious from initial investigations, hydraulicmodels can be used to test certain hypotheses.
Hydraulic Models look at flooding from a variety ofdifferent sources such as ponds, rivers, reservoirs aswell as from sewers and culverts. It is possible toobserve the implications of blockages in outlet pipesand explore a variety of ‘what if’ scenarios. Whatevercause the claimant thinks is at the root of the floodingincident can be fully tested and modelled to establishwhether this was the case. By using in depth knowledge of the industry and hydraulic modelling techniques, I am able to provide the legal team withobjective scientific information that can clearly determine what has occurred and who is responsible.
For further information please Tel: 01444 401 840
or visit: www.raaltd.co.uk