The EA do KNOW about the option of not putting in the channel. But they only modelled this option at the prompting of Dr King in February 2017. However the report is only in Appendix Q of the Planning Application but no proper conclusions have been drawn. Our petition is simply asking for the current streams and ditches to be properly dredged about which NO modelling has been done. Dr King has been told “We do not do dredging any more.” However, at the Somerset Levels, public pressure led to proper dredging being carried out which reduced the flood level by two metres.
WHY NOT LEAVE OUT THE CHANNEL ALTOGETHER? By Tim King (28 August)
(1) The computer modellers modelled this possibility of removing the channel in the winter/spring of 2017. It is an obvious comparison to make. So I was surprised that the only comparisons economically assessed hitherto had been between the current situation (2016) on the one hand and the preferred scheme (bunds, bridges, culverts and the channels (primary and secondary)) on the other. Nothing in-between.
(2) Their conclusions were set out in the:
Oxford FAS – Western Conveyance Channel Review
PREPARED FOR: | Environment Agency | |
PREPARED BY: | Chris Weeks | |
DATE: | June 15, 2017 – Revision 5 | |
APPROVED BY: | Phil Marsh | |
and in Appendix Q of the Planning Application.
Dr King continues:
(3) The way in which this document ended has always seemed unsatisfactory. After an excellent first eight pages, clearly explained, we reach what should be the nub of the argument, since the scheme is ultimately considered in economic terms. The section is entitled ‘Economics’. We have TABLE 4 and TABLE 5, and there the argument ends, abruptly. Either the author ran out of time, or the rest of the document was censored, or perhaps the author found that the case for the channel could not be made in economic terms. This is a highly unsatisfactory ending to one of the most important documents of all. We have no explanation of why the ‘preferred’ option is better than the option without the channel. I reproduce modified Tables 4 and 5 overleaf.
(4) The relevant comparison is between the ‘preferred option’ (bunds, bridges, culverts, channel) and Scenario A, which is what I asked the modellers to model. This is :
Scenario A – Western conveyance channel removed from 200m downstream of Botley Road to Old Abingdon Road (outline design channel modifications d/s of Old Abingdon Road to Mundays Bridge are retained).
(5) In Table 4 (‘High Level Economic Review’) we do not even have a comparison between Scenario A and the Preferred Option. The Preferred option is omitted altogether. Furthermore, at the base, how can the IBCRs for Scenario B and Scenario A be so different (89.91 vs 0.60) when all the other figures in Table 4 are virtually the same?
(6) Let us do some (crude) calculations of our own, based on the 1/100 peak flood event, in Table 5, imagining that there are, say, 1,600 houses and 600 businesses at risk of flooding. The preferred option (£120 million) saves 2026 properties (1492 houses and 534 businesses) and Scenario A (£37 million) saves 1585 properties (1124 houses and 459 businesses). The benefit/cost ratio of the preferred option is 16.9 properties per million pounds and that of Scenario A is 42.8 properties per million pounds, two and a half times greater. Notice that this is an economic argument. and takes no account of the environmental disadvantages of not building the channel, on biodiversity, public amenity, views, archaeology and channel maintenance.
(7) Furthermore, the money saved by not building the channel would allow us to spend some of it to incorporate some extra, imaginative measures to protect those houses and businesses most at risk, particularly in Botley and Osney.
(8) The report and Appendix Q quantify in detail the levels of flood water expected during a peak flood event expected in 1/100 years at 51 points down the whole route, comparing the preferred option with Scenario A (without the channel). At fourteen points the water level is 1-10cm lower without the channel. At ten points the level is the same. At twenty-one points it is 1-9 cm higher. Only at six points in the whole watercourse are the levels more than 19 cm higher without the channel.
(9) These points are: Seacourt Stream – upstream of Botley Road bridge (15 cm); Seacourt stream – downstream of Botley Road bridge (23 cm); Seacourt Stream – new bridge (23 cm); upstream of Seacourt stream spilway (35 cm); New Willow Walk bridge (21 cm); Willow walk bridge (15 cm).
(10) Remember that these levels only occur once in a lifetime (1/100 years) and are not in built up areas. Are they worth building and maintaining a channel for? Surely alternative ways of spending £83 million can be devised, to improve flood protection, targeting these areas and causing less environmental damage downstream?
(11) In any case, it does not make sense to rely so heavily on a computer model. It would make better sense to carry out the scheme in two stages, even if they have to be 30 years apart. First, install the bunds, culverts and bridges. Assess their value; see what happens. Only if major problems remain is there any need to build the channel itself.