The Loughton SWMP is within the administrative area of Epping Forest District Council and is ranked fourth within the county in terms of properties at risk of surface water flooding.

Loughton is situated approximately 21km North-east of central London and is bounded by Epping Forest to the West, and the River Roding Valley to the East. The contributing catchment area includes the urban regions of Theydon Bois to the North, Buckhurst Hill and Woodford Wells to the South.

The area is susceptible to main river flooding from the River Roding to the East, and from Loughton Brook and Loughton Hall Farm Ditch that drain from the Epping Forest to the West, and flow South-east through Loughton joining the River Roding. Loughton Brook is classified as ordinary watercourse upstream of Loughton Hall Road, whilst Loughton Hall Farm Ditch is classified as ordinary watercourse upstream of the Davenant Foundation School.

9 CDA’s have been identified within the study area and around 1,100 residential properties identified as being at risk of surface water flooding during a 1 in 100 year storm, or 1% Annual Exceedance Probability (AEP). This has potential to increase to around 1,620 residential properties should the upper limit of 40% be considered to account be considered to account for future climate change. There is a history of surface water flooding within the area that reinforces the LLFA’s decision to conduct a more detailed study here.

Map of Loughton Study Area

1) The SWMP Study Area represents the extent of the LLFA’s hydraulic modelling and detailed modelling data can be made available within this area. The Risk of Flooding from Surface Water (RoFfSW) mapping should continue to be referenced for an indication of surface water flood risk outside of the SWMP Study Area boundary.

2) A Critical Drainage Area (CDA) is a discrete geographic area (usually a hydrological catchment), within the SWMP Study Area where multiple or interlinked sources of flood risk cause flooding during a severe rainfall event thereby affecting people, property, or local infrastructure.

Summary of Flood Risk across the Study Area

Table 1

AEP*	Residential †	Non-Residential ‡	Critical Service §	Total
10%	326	65	0	391
5%	544	93	1	638
3.33%	668	105	2	775
1.33%	997	144	6	1147
1%	1108	154	6	1268
0.50%	1404	178	9	1591
1% CCL**	1340	173	7	1520
1% CCU***	1625	193	10	1828

* Annual Exceedance Probability (AEP) = Chance of a rainfall event occuring, or being exceeded in any one year.
** Climate Change Lower (CCL) = Lower Climate Change increase, taken as 20% additional rainfall.
*** Climate Change Upper (CCU) = Upper Climate Change increase, taken as 40% additional rainfall.

† Residential Property = a building used, or is suitable for use as, a dwelling.
‡ Non-Residential Property = property other than residential, such as office buildings, shopping centres, businesses, churches, hotels, hospitals, schools or government buildings.
§ Critical Service = includes services such as power, water, sewer, wastewater treatment, communications, education and emergency medical care.

Table 2

			Residential Properties
No.	CDA Ref.	CDA Name.	1% AEP	1% AEP+CCU
1	LGH_001	Theydon Bois	145	169
2	LGH_002	Pyrles Lane	236	324
3	LGH_003	Loughton Brook	188	335
4	LGH_004	The Avenue	87	114
5	LGH_005	Kings Avenue	69	97
6	LGH_006	The Meadway	60	87
7	LGH_007	Lower Park Road	19	28
8	LGH_008	Valley Hill	29	44
9	LGH_009	Chequers Road	61	89