In prehistoric times the
Walter Kollmorgen: Settlement control beats flood control 
“A friend of mine remarked that before the flood he valued his land at $300 per acre, but after the flood he valued it at $400 per acre because fill of proper textured material had solved all drainage problems and removed all waste land. Flooded floodplains are in no way to be compared to an enemy, although our attack on flood problems suggests the lavish expenditures of money and resources thrown into a military campaign. Geographic engineering directed at settlement control can resolve many of the flood-loss problems”.
Smith and Tobin: Human adjustment to the Flood Hazard. 
“As a result of inadequate planning policies and partial alleviation strategies, the responsible authorities have failed to contain the flood hazard. In essence, flood losses continue to rise because, in an increasingly crowded world, man has put a progressively higher premium on a floodplain location and the attendant risks of such development have been disregarded… Having failed to control floodplain settlement, the authorities have sought to control the rivers. Typically, this form of adjustment has relied on a structural approach with limited engineering work invariably undertaken after a flood event in response to pressure from floodplain dwellers… More recently, the authoritarian adjustment in many areas has included… flood forecasting and warning systems… Unfortunately, the mistakes associated with the structural adjustments have been repeated in that these schemes have been installed with comparatively little regard for social feasibility”.
Environment Agency: Living with the risk 
“It’s not possible to accurately forecast flooding in some areas such as parts of north Cornwall, where steep valleys mean that rivers can rise so rapidly after heavy rain that, with current technology, there’s not enough time to issue warnings”.
Paul Samuels: .
“Absolute protection from flooding cannot be achieved and the societal goal is for the management of flood risks at an “acceptable” level. Flood risk management therefore has the character of a “wicked problem”  in that flood risk is part of a broader environmental and social system, there are many potential solutions with no “true” or “false” answers and different stakeholders have differing (and potentially conflicting) views of the problem”.
Interview with a Councillor at
“the hydrologists, the scientists are all going a very straight, linear route that is almost like purely theoretical. That would be ok if they were 100% right. Now they may be significantly correct, in terms of the proportions of what works, and what doesn’t work, in terms of flood management. But I still feel even though I understand where they are coming from… there is a lot of historical evidence that they have just completely discounted in a very offhand way. And that there is a kind of myopia there that is again born of confidence, but confidence is moving into arrogance.”
Interview with a second Councillor at
“Don’t trust the Environment Agency…if they get their experts on it, they will pay them a fortune, and they will come up with a massive system. The Environment Agency cannot be trusted.”
National Flood Resilience Review .
“This is the first time that fluvial flood risk has been based on realistic rainfall scenarios and considered extreme events that are meteorologically plausible but lie outside existing observational records. Previous assessments have used peak river flows based on historical records. This means that this study is breaking new ground on how flood risk is assessed; however it is important to be clear about the scope of the study…. (Historic flood information) can have an impact on flood estimates but it is rarely used in the UK. Using data from historic sources, for example newspaper reports, photographs and sedimentary records, will supplement the observed record of flooding. Making greater use of this information would improve planning and management of extreme events in the future. Collating, storing and accessing this information in a way that enables it to be accessed by a wider range of users will be a key consideration…. It is estimated that without effective planning controls, pressure to build more homes could add up to 16% to the cost of optimal flood protection. In 2014/15, 8% of new homes were built in flood zone 3, which has 1% annual chance of flooding from rivers or a 0.5% annual chance of flooding from the sea, if defences are not taken into account. Where the environment agency is aware of a planning decision notice, 97.8% of residential units in those planning decisions were in line with Environment Agency advice”.
DEFRA Select Committee on Future flood prevention .
“Current flood risk management structures are fragmented, inefficient and ineffective… current arrangements do not encourage widespread use of catchment scale approaches. The Government’s National Flood Resilience Review’s limited solutions will not rectify fundamental structural problems: we propose a new governance model which the Government must consider as part of a root and branch review of how it manages England’s flood risk…. current descriptions of a ‘1 in x year’ flood risk are confusing to the public. The Environment Agency and the Met Office must develop clearer methods by the end of this year, including maps showing all sources of flooding in one place”. There are two areas of concern regarding these extracts which span a 60 year period. The first is knowledge the second, understanding
The effects of floods are not all bad . Controlling where houses are built would help to avoid many floods. The belief of the Environment Agency  that it is not technically feasible to give a flood warning to people at Boscastle is completely wrong because they had already adopted a real time flood warning system for the upper Brue, which is in the same Region of the Agency . A warning of 1 hour as could be provided by a flood warning system for Boscastle produced by the author  would have saved the destruction of about 40 cars and other property. The suggestion of Samuels  that floods are a “wicked problem” does not accord with Rittel & Webber’s  criteria of such problems in that they are clearly defined, the solution can be tested with the passage of time and the solution can be modified in the future in the light of new knowledge. Furthermore Conklin, 2006  notes that these “wicked problems” do not have an alternative solution which is clearly not applicable to flooding problems. Wicked problems are those where the solution requires people to change their mindsets and behaviour. Good examples are climate change and nuclear weapons.
The historical knowledge that seems to be missing in the opinion of the Councillor at
The National Flood Resilience Review shows that their knowledge is far from complete. The use of rainfall estimates  which fall outside the measured values was described for the river Brue by
The Report from the DEFRA Select Committee shows a lack of knowledge of what exists to deal with problems of flooding. There is no alternative suggestion to describing the chances of a flood taking place, and while a new Body to oversee flooding was proposed, the additional knowledge that the Body should possess was not specified either implicitly or explicitly.
That floods are a problem caused by the ecological imbalance of Man and the environment was well understood by Kollmorgen . Smith and Tobin  added their analysis of the situation with the problem of lack of space and by implication wrong choice of sites for building. Samuels  misses the point that some flood problems have become worse through the provision of poor road drainage and the significant raising of Highway surfaces: this point is described later in this paper.
The level of understanding of flood wave generation, and translation down the watercourse has eluded the Environment Agency . The use of telemetered rainfall has been in use for decades , and it is significant that some staff of the Agency at
The Councillor at
The two Government Reports published in 2016 show a lack of understanding by what is not stated as much as the content. This can best be improved by those who have had direct experience of floods over a long period of time. Unless hydrologists are better trained in the field, the level of uncertainty, which may be an excuse for the lack of more accurate forecasts, slows down future progress.
For Kollmorgen  the control of where houses are built is vital. Smith & Tobin , suggested five ways of improvement: General education, Flood wardens, development controls on housing, a National Flood Policy made by Government, and further research into how people respond to floods. Samuels  concludes by stating: “Past research on flood risk management has brought real advances in knowledge and understanding which have been taken up into practice and have shaped changes in policy. However, looking to the future indicates that flood risks are set to increase driven by changes in climate, population, demographics and patterns of land use and settlement. Our management of floods and flood risks must respond to these pressures in a sustainable way which does not prejudice the ability of future generations to meet their own needs; again this points to adaptation as a key strategy”.
For several sites in
Government based solutions focus on spending on flood mitigation £2.3bn for the five year period 2016-2020 . At the same time houses continue to be built in flood prone areas: as fast as money is spent on alleviating floods in one area, new problems are being produced. The suggestion of a new regulatory body to deal with floods seems perverse: successive Authorities such as the Water Boards constituted in the 1930’s, the Water Authorities of the 1970’s, the National Rivers Authority in 1990, and finally the Environment Agency which replaced the NRA in 1996, have failed to deal with the flooding problem in a comprehensive way.
2. Interaction with the Public as an Impediment to Progress
Perhaps it was the ground breaking paper by Callon  who highlighted the likely mistrust of the Public of technocrats and the growing divide between specialists and non-specialists. This is inevitable in a rapidly changing technological world, but it can lead to decisions that are later found to be wrong, which leads to further mistrust in the Authorities. He describes three models of interaction of the public and decision makers: first, the Public Education (PEM) model in which the authorities tell the public what is good for them and the latter accept the facts as given. Second, the Public Debate Model (PDM) wherein people are allowed to express an opinion. For example the planning process in the
As an example of the CKM model in practice, Lane et al.  described the evolution of a solution to the flooding problem at Pickerng in Yorkshire UK. The situation started with great mistrust between local people and the Environment Agency which is contrary to their own guidelines . At
However, there is a wide variety of practice across the
3. The Nature of Hydrological Models
A model can be described as a formal description of an opinion of how a system works. In the case of river floods in the
The problem with models is that their greatest asset is also their greatest weakness. They are easy to apply, the input data can be obtained from maps or from the FEH CDROM of catchment descriptors, and there is no need for time consuming fieldwork. Computer graphics make the results look even more convincing. Several different models can produce a range of answers. They are the consultant’s paradise. There are assumptions regarding extreme value theory, multicollinearity, cumulative errors due to parameter specification, and the ever increasing mistake of simply believing the machine rather than the patient! Like any set of results or hypothesis, they are only scientific if they can be falsified . The results of a flood frequency analysis should be tested with independent observations. If not then we are left with an unscientific theory. Buyer beware!
4. The Upper Brue,
The author’s involvement with the river Brue goes back nearly 60 years. Two letters about the floods at Bruton published in the Western Gazette resulted in a letter from the Wessex Water Authority in 1978 asking for details of the studies made which focused on the flood history of the area. This resulted in a report . What follows is a summary of events during the following 38 years.
1) May 1979 Bruton badly flooded.
2) September 1979. Meeting with WWA to discuss estimates of the peak flow of flood in May.
3) October 1979. WWA revised estimate of peak discharge.
4) Memorandum of Agreement between WWA and Rendle Palmer & Tritton (RPT) to report on possible flood alleviation scheme.
5) February 1982. Reassessment of flood frequency of the Brue by the author based on a photograph of the aftermath of 1917 flood.
6) Progress report from RPT with estimate of Q100 35% below author’s revised flood frequency estimate. Senior Land Drainage Engineer, James Green- land endorses author’s results.
7) 12th July 1982, major flood.
8) 13th July report from RPT . Main recommendations not affected by the flood. Comparing the historical results with their own, RPT stated: “However, in drawing a curve through the plotting positions of only 6 events in the historical sequence of more than 130 years total weighting is given to these big events whose plotting position is most in doubt”.
9) Publication of new plotting equation based on probability and
10) 1984 flood detention dam completed. Design spillway discharge 240 cumecs.
11) Publication of rainfall frequency analysis of 44 sites in
12) 1995 Publication of new estimates of probable maximum precipitation  which showed that 24 hour PMP should be about 500 mm instead of 300 mm.
13) May 1996 Report to Environment Agency regarding dam safety and design at Bruton. The storage volume had been overestimated by 26% and the PMF about 500 instead of 240 cumecs.
14) August 1996. Report by Babtie on Bruton dam  concluded: “No recommendations are made with respect to reassessing the PMP or PMF for the Bruton dam as a result of Clark’s report… With respect to the reservoir storage volume it is recommended that a desk study is made using the largest scale contoured maps available to determine the depth-storage curve and check against the RPT and Clark data. A walked field survey would highlight any discrepancies. if considered necessary, a topographic survey of the reservoir basin could then be carried out”.
15) Inclusion of the flood of 1768 in the authors flood frequency analysis . Estimate of the 100-year flood increased to 90 cumecs.
16) 1996-2002. Protracted correspondence between the author and the Environment Agency.
17) 2003 Inspecting Engineer for Bruton dam, John Beaver, asks for a design standard assessment.
18) 2004 Environment Agency ask Black & Veatch Consulting to report on author’s paper: Bruton dam-a cause for concern .
19) November 2005 Report from Black and Veatch  concluded: that the PMF for Bruton dam site is 500 cumecs or higher, that the time to peak at the site is about 2 hours, that the percentage runoff could be up to 92%, and a design rainfall of 245 mm in 4.25 hours should be used. The PMF would overtop the dam crest by 0.6 m and the dam spillway, which was armoured with petriflex blockwork with a density of 135 km・m−2 would be destroyed in about 30 minutes.
20) 2007: Author raises concerns that the crest should be protected with material stronger than Geotextile. Answers to questions not forthcoming over a period of several months.
21) 2007 the Bruton dam was raised by 2 m and the petrifex armouring was overlain by concrete tiles each weighing in excess of 100 kg, with drainage holes that would tend to provide suction and therefore maintain their integrity during a major flood.
22) 2015. Remedial work on Bruton dam to install cellweb™ protective material on the dam crest.
In conclusion the use of models was shown to be seriously flawed. Thankfully, with the supporting evidence of the historic floods, evidence from the Martinstown storm , and the soil survey data , a dam safe from being breached by extreme floods has been produced.
5. The Valency at Boscastle in
The implications of the upper Brue study ought to have been propagated into other rivers at least in
The present author also made a study of the event starting in October 2004. The archives of several newspapers, and archive material of Anne and Rodney Knight were used as source material. A summary of events from January 2005:
1) Environment Agency announces findings of report into flooding at Boscastle.
2) January 2005, Author visits Agency office in
3) Visits HR
4) May 2005 HR Wallingford report finished  but not made available for several months.
5) Long correspondence with Environment Agency regarding the inappropriate flood estimates.
6) June 2006, author publishes revised flood estimates  which prove that HRW estimates are too low at the more frequent end and far too high at the rare, +100 year flood. For example HRW estimated that the 2004 flood had a return period of about 400 years, while the flood producing rainfall had a rarity of several thousand years. The floods of 1882, 1894, 1903, 1911, and 1926 were not included in their report.
7) On site planning meeting in September 2006 to agree channel improvements to a design standard  of 70 years, as compared with a return period of 40 years .
8) The growth rate of floods in EX5160  is far greater than any river in the whole of
9) The expected 1 in 1000 year flood in EX5160 is about 300 cumecs while the 1 in 5000 year flood is about 1000 cumecs. This has a rate of runoff of 50 cumecs per km2 which is 2.5 times greater than the Extreme catastrophic flood of Allard, Glasspoole & Wolf .
10) If the flood estimates in EX5160 are correct then flooding in Boscastle should take place on average about once every 30 years. However, in the 20th century there were floods in 1903, 1911, 1926, 1932, 1940’s-exact date unknown, 1950, 1958, 1963, and 1993. This gives an average time interval between floods of 12 years. For noticeable flooding to take place the author’s estimate suggests a frequency of about 10 years. Table 1 shows the results of both studies.
It is clear that the Environment Agency has adopted the PEM of Callon . In spite of serious and significant errors and omissions being pointed out, the report of May 2005 remained unchanged. As a result Boscastle has a flood alleviation scheme whose design standard will probably be exceeded in the next 30 years. What is even more alarming is that an alternative scheme to protect the area from fluvial flooding and costing about half of the cost of the channel improvements was not investigated thoroughly. Clearly the PKM was not considered by the Environment Agency.
The situation is made even worse since the Agency declined to use the author’s flood warning flow model  which would have given at least one hour’s warning for the 2004 flood.
6. The Upper Stour at Bourton, Dorset
In 2013 another application was made to build a lower number of houses with the addition of light industrial units, a Village Hall, and two low cost houses for
Table 1. Comparison of flood frequency estimates (cumecs).
local people. The developer employed engineering consultants  who used the models as described in the Flood Estimation Handbook . This approach is for use when there are no riverflow data. However, the FEH does advocate the use of historical flood information. This can include photographs, eye witness accounts, newspaper reports and other archival material. There is a small but growing body of literature which suggests that when historic flood information is used, the estimated discharges are often higher than those predicted by using models. The disadvantage of using more direct hydrological analysis is that searching out and the interpretation of historic flood information can take considerable time, especially in the case of small rivers which tend not to have towns with good news coverage, or many people who have old photographs of floods that they and others have seen.
The response of both Planning Authority and the Environment Agency can be placed in the PEM. There was no opportunity to meet and discuss with the Developer’s Consulting Engineer  and JBA, , who were asked to review the hydraulic modelling and dam break scenarios, but they failed to consider the reliability of the flood hydrology. The central problem was that the models had so much in common that they could not really represent independent assessments. Furthermore, there was no local or historic data used. While a report by Black & Veatch for the 2004 application considered estimates of the peak flow of the July 1982 flood during which Bourton Mill was badly flooded, the 2011 consultants report ignored this and other events. The author’s 2004 estimate of the flooding was extended to include 247 years’ events, , which is the second longest record of a small catchment in the whole
In mid 2016 after more questions were raised about the size of a downstream road bridge, it was admitted that the consultants had used the wrong sized section. Even a site visit by JBA, independent assessors in August 2011  failed to check this important control of upstream water levels at Bourton Mill. Further questioning has shown that the use of bankfull discharge as a measure of the 1.1 - 2.0 year flood has been misunderstood by the Agency. Since bankfull discharge has been measured in the field  it is now certain that the Consultant’s report is in serious error. This also means that the growth factor Q100/Q2 is much greater than their report suggests. It is well known that the model formulations of the FEH often overestimate the 2-year flood. This is because of the big scatter in the HOST  indices and standard percentage runoff, and the use of model I regression rather than model II which gives higher HOST percentage runoff rates at low values of observed percentage runoff, and vice versa.
7. Surface Water or Pluvial Flooding
The occurrence of flooding from sources other than rivers has been well known for decades : the problem is growing . While some lessons have been learnt from the summer 2007 floods   there is hardly any mention of the effect of road levels being raised as much as 0.5 m above their historic level. This
Figure 1. Two estimates of the flood frequency of the
problem is widespread in rural areas, which again have been neglected in nearly all previous studies of pluvial flooding.
Two examples are worthy of note. The first is at Hadspen in
There has been a tendency for the use of models as opposed to local data to assess flood frequency. In the case of the upper Brue it was the Wessex Water Authority that asked the author for information about historic floods. This led to more research and collaboration with WWA and also enabled the flood detention dam to be built . By the time more recent research showed that the dam was in fact underdesigned and unsafe the organisation of the Water Industry had changed. Staff at
In the future there will be even more pressure on building land, some of which may be at risk of serious flooding. Past experience of floods has not influenced National Policy anything like the extent that is needed in order to prevent widespread damage to property and death from drowning. While an allowance for climate change has been included in flood risk assessments, there is not enough knowledge about the natural variability of the system to make such allowances effective. When a flood scheme with a design standard of 1 in 100 is badly exceeded during a flood, will the confidence in other schemes be undermined? Models can also give a false sense of the accuracy of the results. Talking about the uncertainty of any result does not appear to change the final design. For example, at Bourton the consultants took the highest of several flood estimates, but at the same time ignored actual events for which evidence exists. Another problem with models is that they do not encourage the user to test the resulting hypotheses. For example, at Boscastle the results in EX5160  could not match the observed frequency of flooding over a hundred year period. The FEH methods are based on riverflow records which are often much shorter than 50 years, while the rainfall estimates used in the FEH do not use data gathered before 1960. How this narrow data set can produce sensible estimates of rare flood events whose rarity is often in excess of 100 years is difficult to imagine.
Flood hydrology is essentially a field based science. Considerable fieldwork is needed to assess and produce solutions to surface water flooding that are caused by raised road levels. The answers to the questions that are badly needed will eventually be found in the field and not at the keyboard of the latest personal computer. The CKM needs to be fully embraced by all branches of the Establishment.
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 Coulthard, T.J. and Frostick, L.E. (2010) The Hull Floods of 2007: Implications for the Governance and Management of Urban Drainage Systems. J. Flood Risk Mangt, 3, 1-19. https://doi.org/10.1111/j.1753-318x.2010.01072.x
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