proposed solar park development at cave farm, nr pitney, somerset ...

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J-3999.7-FM Flood Risk Assessment & SUDS Design, Cave Farm, Nr Pitney, Somerset V2
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4.0 FLOODING MECHANISMS
A number of possible flooding mechanisms have been considered at the site, and are
discussed below.
4.1 Groundwater Flooding
Investigation of ground water flooding has been undertaken within the South Somerset SFRA.
Springs showing the emergence of ground water at the surface have been identified and are
shown in Appendix D. Several springs are located north of the site near Bramwell, however,
no springs are located within the region of the site. A large area to the north of the River
Cary is low-lying (around 5m AOD) and requires significant land drainage in the form of
rhynes, and ditches etc. The site is located between 35m AOD and 50m AOD, which suggests
it should not suffer from similar ground water issues
The SFRA does report on suspected ground water flooding events around Langport, however,
this was recorded in 1954. Ground water as a source of flooding is particularly difficult to
identify. Areas are typically assessed with respect to their geological properties and historic
events , The SFRA continues with:
“The available records appear to indicate emerging groundwater (i.e. in excess of the norm)
in response to extreme rainfall. These appear to be localised and may in part relate to poor
“land” drainage. None of the recorded occurrences appear to be widespread and do not
therefore appear to be a reflection of regional rises in groundwater level.”
Given that the development is non-residential, the site topography is high/steep relative to the
surrounding area, and, that the solar panels are supported on frames which give limited
resistance to the flow of water, ground water flooding will not be considered further within
this report.
4.2 Overland Sheet Flow
The site is set in a rural environment with fields surrounding the entire site. Due to the sites
elevation relative to the surrounding topography, and the location of the nearby watercourses
which can intercept overland flows, the risk of any significant overland flows being generated
that can effect the site are considered to be small and will not be considered further within
this report.
Surface water runoff generated by the development of the site is considered further in section
6 of this report.
4.3 Fluvial (River) Flooding
The EA’s Indicative Flood Map illustrates that the entire site is located within Fluvial Flood
Zone 1. This implies the site has greater than a 1 in 1000 year chance of being affected by
fluvial flooding.
As discussed in Section 3.0, the closest watercourse/drainage ditch to the site has a very
small catchment of less than 1km 2 and will therefore, have limited capacity to generate
significant flows.
As such the fluvial flooding will not be considered further within this report.
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