Curbridge Preservation Society

Working to Protect Our Natural and Built Environment

Whiteley Area 2

That Is Curbridge To You And Me!

 

The Horse and Jockey Curbridge
Roll your mouse over to see what it will probably look like
after the floods come from North of Whiteley...

See the image in greater detail here

See The Expected Flood Slideshow!!

"Is it Safe?"

Hampshire Ornithological Society Describe the River at Curbridge as follows: -

"Curbridge lies on the upper reaches of the Hamble estuary. Here, where the Hamble and Cur rivers meet, mudflats punctuate the river, small areas of reeds and saltmarsh have formed near the shore and ancient woodland lines the banks.

The estuary provides Curbridge with an abundance of river and shore life. This area is the most fragile part of the reserve. The action of tides and river flow contribute to this constant change. Mudflat, saltmarsh, woodland - each habitat illustrates the transitional nature of the reserve.

 This wooded estuary is a delightful reminder of what rivers in southern England must have looked like hundreds of years ago."

 

Come on Winchester - it is not just about the floodplains - it is about fluvial flooding and Spring Tides along with the Time of Concentration - just think about Boscastle in 2004!

WCC have invited comments on the Draft Infrastructure Plan by the 7th January

We obviously will accept this invitation...
as per below our comments on flood management/SUDS...
and PPS25 that they seem to be ignoring...

Flooding/SUDS

Tidal and Fluvial flood combined (including water run-off management) is one of the most significant issues facing Curbridge as several of the properties are in a 3a floodplain. These homeowners are not able to have flood insurance and are at significant current and increased future risk due to climate change; let alone due to fluvial flood water, from hard surfaced land, having a small time of concentration before entering the river.

Draft Plan...Page 128Flood Defences:  Strategy yet to be devised (dependant on master plan) so costs unknown… Flood defences not required. Development will be restricted to flood zone 1 areas.

This is wholly inadequate and high risk and we believe against PPS 25 – it is not just about houses yet to be developed; but also existing properties that are in the floodplain. Significant mitigation of these risks must be achieved especially with consideration to climate change.

Topography: The centre of Curbridge, bordering the river, is situated at the bottom of a valley and has a height of 3m (OS) with the raised ground to the north, east and south of it rising to 20m giving a maximum 17m drop over approximately 300m. With storm water/significant rainfall events (0.1m or more) there are significant flood risk issues. It is not believed that SUDS would be able to cope with the time of concentration of water accelerating down such slopes to the river.

Curbridge is already experiencing significantly increased levels of water run-off coming down the Whiteley Stream, through higher low tide water levels before the bridge, since Bluebell Way has been developed, so the SUDS in Whiteley isn’t obviously not fit for purpose.

We believe that the following aspects of PPS25 have not been taken into consideration in the draft infrastructure report and that these significantly affect the sustainability of the proposed development and its ability to be integrated with any existing community.

PPS25:

Appendix B

“B5. Global sea level will continue to rise, depending on greenhouse gas emissions and the sensitivity of the climate system. The relative sea level rise in England also depends on the local vertical movement of the land, which is generally falling in the south-east and rising in the north and west. Allowances for the regional rates of relative sea level rise shown in Table B.1 should be used as a starting point for considering flooding from the sea, along with the sensitivity ranges for wave height and wind speed in Table B.2, in preparing flood risk assessments.

B9. In making an assessment of the impacts of climate change on flooding from the land, rivers and sea as part of a flood risk assessment, the sensitivity ranges in Table B.2 may provide an appropriate precautionary response to the uncertainty about climate change impacts on rainfall intensities, river flow, wave height and wind speed.

B11. Flooding in estuaries may result from the combined effects of high river flows and high sea surges. When taking account of impacts of climate change in flood risk assessments covering tidal estuaries, it will be necessary for the allowances for sea level rise in Table B.1 (see para. B5) and the allowances for peak flow, wave height and wind speed in Table B.2 (see para. B9) should be combined.

B12. Indirect impacts of climate change on land use and land management may change future flood risk. For example, changes in crop type, methods of cultivation and harvesting could affect the porosity and surface of the ground and hence the volume, speed and direction of storm run-off.”

Appendix C

“Flooding from Rivers

C4. Rivers flood when the amount of water in them exceeds the flow capacity of the river channel. Most rivers have a natural floodplain into which the water spills in times of flood. Flooding can either develop gradually or rapidly according to how steeply the ground rises in the catchment and how fast water runs off into surface watercourses. In a large, relatively flat catchment, flood levels will rise slowly and natural floodplains may remain flooded for several days, acting as the natural regulator of the flow. This is a function that the planning system should promote and enhance. In small, steep catchments, local intense rainfall can result in the rapid onset of deep and fast-flowing flooding with little warning. Such “flash” flooding, which may only last a few hours, can cause considerable damage and possible threat to life. Land use, topography and the form of local development can have a strong influence on the velocity and volume of water and its direction of flow at particular points. Flooding can occur when culverts and bridges are blocked by debris.

Flooding from the Sea

C5. Flooding to low-lying land from the sea and tidal estuaries is caused by storm surges and high tides. Where tidal defences exist, they can be overtopped or breached during a severe storm, which may be more likely with climate change. The onset of flooding from the sea can be extremely rapid. Deep, fast-flowing water can create an extreme hazard. The severity of such flooding will depend on a number of factors, often in combination: the height of tides; weather systems; wind and wave conditions; topography; the effectiveness of drainage systems; and the condition of flood defences. The consequences and impacts of flooding from the sea and tidal waters are more severe than flooding from rivers. It is for this reason that Flood Zone 3a (see Table D.1, Annex D) has a 0.5 per cent annual probability boundary for flooding from the sea and tidal waters while from rivers it has a 1.0 per cent annual probability boundary.

Flooding from Land

C6. Intense rainfall, often of short duration, that is unable to soak into the ground or enter drainage systems can run quickly off land and result in local flooding. In developed areas, this flood water can be polluted with domestic sewage where foul sewers surcharge and overflow. Local topography and built form can have a strong influence on the direction and depth of flow. The design of development down to a micro-level can influence or exacerbate this. Overland flow paths should be taken into account in spatial planning for urban developments. Flooding can be exacerbated if development increases the percentage of impervious area.