Managing flood risks

“A challenge for Dorset will be the significant effect on local flood risks as a result of increases in rainfall.  As Lead Local Flood Authority and Coastal Management Authority, Dorset Council will have a significant role to play in flood risk management, alleviation and mitigation work” (Food Risk Manager). 

The red triangle shows the proposed North Dary Farm Solar Site would be at the constricted neck of the 40 square kilometre ‘funnel’ rainfall catchment area formed by the downs, escarpments and high ground that almost surround the Farm. The critical effect on downstream residents of placing some 55 acres of impervious PV panels immediately in front of the catchment “bottleneck” would have on the speed, timing and intensity of the surface runoff from the site have not been calculated by the developer. Flooding downstream is a major, and life-threatening matter.

The Council’s Flood Risk Management Officers note that: “Solar farms have the potential to reduce the amount of rainfall absorbed into the ground, increase the rate and volume of surface water runoff”, and that “development, through the introduction of impermeable areas, has the potential to exacerbate flood risk“

AONB UNIT – SOLAR STATEMENT

“The experience of this AONB is that although assertions are made that the field surfaces will be largely unchanged that does not turn out to be the case. Frequently the quantity of rainfall on the hard and impervious surfaces of the panels leads to increased surface runoff. To control and manage stormwater runoff, swales are created, along with connecting channels. The impact of that extra activity, along with the impacts of concentrated volumes of runoff water, do need to be fully assessed.”

(Richard Burden BSc DipCons MSc MCMI (rtd) MCIPD FLI PPLI Chartered Landscape Architect Principal Landscape and Planning Officer For and on behalf of the Cranborne Chase AONB)

Dorset Council

There is no single body responsible for managing local flood risks in the UK. In many cases, flooding may be caused by a number of different sources which are managed by different Flood Risk Management Authorities.

The following Flood Risk Management Authorities and stakeholders are integral to flood risk management in Dorset.

• Dorset Council as the Lead Local Flood Authority
• Town and Parish Council
• Environment Agency
• Water Authorities – Wessex Water / South West Water
• Highway Authorities – Dorset Council, Highways England
• riparian owners
• private drainage assets owners
• property owners and residents

As a Lead Local Flood Authority, Dorset Council is responsible for managing flood risk from local sources such as ordinary watercourses (not main rivers), surface water and groundwater. We also ensure local flood incidents are investigated by the appropriate risk management authorities and regulate work on ordinary watercourses/culverts.

Our responsibilities in this area are set out in the Flood and Water Management Act 2010 and Flood Risk Regulations 2009.  The Flood Risk Management team who undertake these duties on behalf of Dorset Council can be contacted by emailing FloodRiskManagement@dorsetcouncil.gov.uk 

Local Flood Risk Management Strategy

An important duty for a LLFA is to produce and maintain a Local Flood Risk Management Strategy. These include flooding from surface water, groundwater, ‘ordinary watercourses’ (for example, ditches and streams), lakes and small reservoirs.

The Strategy sets out the vision for managing local flood risk across the County, and how we will seek to work with communities and partner organisations. The vision is “working together to manage local flood risk in Dorset so communities are resilient and prepared for flooding”. This vision will be met through the following objectives:

• understand flood risk across Dorset
• manage the likelihood and impacts of flooding
• help Dorset’s communities to manage their own flood risk
• ensure flood risk is considered in local land development proposals
• improve flood prediction, warning, response and flood recovery 

The Local Flood Risk Management Strategy is available in two forms:

• Local Flood Risk Management Strategy for Dorset (summary)
• Local Flood Risk Management Strategy for Dorset (Technical Report)

Preliminary Flood Risk Assessment

The Preliminary Flood Risk Assessment is an initial screening exercise required under the Flood Risk Regulations 2009. It aims to review historical flooding and future (potential) flood risk and determine Flood Risk Areas in accordance with nationally specified criteria.

A  Preliminary flood risk assessment for Dorset has been prepared which assesses the local flood risk. Flood risk from main rivers, the sea and large reservoirs is the responsibility of the Environment Agency and is not considered in this report. 

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