Frances Haigh: Water, water everywhere!

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Winter has officially arrived, bringing with it the threat of more rain. Every time we have a heavy downpour, parts of Horsham Town flood. Lib Dem Councillors have been taking action to clear the flood issues. Thanks to Cllr Morwen Millson, the flooding problems at the rear of Horsham Station and the flood in North Street by Horsham Gates offices have been resolved. We continue to press WSCC to deal with other minor floods around the area caused by blocked drains. But what about major flooding incidents?

Last year parts of Horsham close to the River Arun and Boldings Brook saw high water levels. Homes in Riverside were under water, and homes in Tanbridge Park and River Walk were threatened. Local residents are trying to find solutions and answers as to why their homes have suddenly come under threat. They brought their case to Denne Neighbourhood Council last week and are planning to form a residents’ action group to tackle flooding issues and to apply for funds from WSCC’s Operation Watershed. Meanwhile Forest Neighbourhood Council are also considering applying to Operation Watershed.

To understand the problem, it is important to look at the network of main streams. In the north west of the town is Boldings Brook. This collects water from across the area south of Capel, flows through a floodplain near Warnham Station, through Warnham Nature Reserve and West of the town, joining the River Arun near Hills Farm Lane. On the north east side is Chennells Brook, which collects water from the area between Rusper Road and Faygate, flows though the north of the town and joins with Boldings Brook at Warnham Mill Pond. To the south of the Town is the River Arun, which gathers water from all the various streams and ponds, such as Hammerponds and the areas up to Mannings Heath. The River Arun then heads west towards Broadbridge Heath before weaving in the meadows between the villages of Slinfold, Rudgwick and then heading south to Wisborough Green, the floodplains between Pulborough and Arundel, and down to the coast at Littlehampton.

Downstream of the homes which flooded is the West of Horsham development. When this was being considered, HDC investigated and assessed the possible risk of flooding and insisted on sustainable drainage systems known as “SuDS”. These are designed to cope with “one in a thousand year” flood events. However, what is happening is that flood events are becoming more frequent. Last winter, the water in the River Arun backed up, causing flooding within existing built up areas and threatening the new developments.

What then has to be considered is what would be the effect of building North of Horsham in the Chennells Brook catchment area? Would this add to the problem by reducing the amount of water that is held to the north of the town, sending it down to the town more quickly and flooding wider areas? The submission from Peter Brett Associates on behalf of Liberty Property Trust as part of the HDPF Examination states that “the Environment Agency has advised that they have no detailed flood risk information or modelling of the Chennells Brook through the site.” The Environment Agency’s on-line map shows Chennells Brook as a Category three flood risk area, the highest. No one has any idea how water flows through the area at present, how development could affect the flow, or the impact that it could have on the water flow within the existing built up area of the town. Yet this site has been proposed as the main strategic site in the HDPF. This is completely unacceptable.

Following last year’s floods, there were many articles about what caused flooding and how we should prevent further incidents. But the essential science is that rivers need to wind and meander through the countryside. As George Monbiot said, “A river can, at any moment, carry very little of the water that falls on its catchment: the great majority must be stored in the soils and on the floodplains.” We also need to ensure that there are plenty of trees to help absorb and soak up the water, to reduce the amount which goes downstream. In our rush to build homes, we ignore the science at our peril.

Which brings us round to who pays to stop the flooding? Last week it was reported that Liberty Property Trust expects to make £120m profit from developing North of Horsham, most of which will go back to the USA. They are required to contribute a certain amount for S106 which is specific to the site, but the CIL, which should pay for local infrastructure has been reduced to nil. So not only does Liberty not pay for highway related impacts of the development, they do not pay to offset the flooding. Which means that we the community will pay for this ill-considered project. Is that what we want? The answer has to be no.


Flood Maps:

Frances Haigh is leader of the Lib Dem group on Horsham District Council.