OR/16/009 What information does the dataset provide
| Dearden, R. 2016. User guide for the infiltration SuDS map: detailed. British Geological Survey Internal Report, OR/16/009. |
Overview
This section describes in detail the subsurface property datasets included in each of the four questions discussed in About the dataset.
- Infiltration SuDS constraints focuses on question 1 in About the dataset
- Infiltration SuDS drainage potential focuses on question 2 in About the dataset
- Infiltration SuDS ground stability focuses on question 3 in About the dataset
- Infiltration SuDS groundwater protection focuses on question 4 in About the dataset
Infiltration SuDS constraints
Infiltration SuDS constraints summary layer
The Infiltration Constraints Summary layer highlights all areas where there is potential for a significant constraint. Constraints include those described in Soluble rocks constraints to Shallow groundwater constraints below. In these areas, infiltration SuDS should only be installed if the potential for, or the consequences of, the constraint are considered not to be significant. Table 2 shows the attributes used in this summary layer.
| Score | Short description | Detailed description |
| 4* | Very significant constraints are indicated | There is a very significant potential for one or more geohazards associated with infiltration |
* Polygons with the highest score (4) are shown independently in the ‘Infiltration Constraints Summary’
layer to provide an overview of where hazards may occur if water is infiltrated to the ground.
Soluble rocks constraints
Some types of ground contain layers of material that can dissolve in underground water. This can cause underground cavities to develop. Cavities created by dissolution of soluble rocks can collapse, resulting in subsidence of the land above. More commonly, changes in ground or surface water flow can flush away unconsolidated sediment, potentially leading to the collapse of overlying materials leading to subsidence at the surface. Infiltration may exacerbate this problem causing acute collapse around infiltration SuDS. Therefore the installation of infiltration SuDS should proceed only after a full appraisal of the ground conditions.
This component data layer is derived from the soluble rocks layer in the BGS GeoSure dataset. The dataset has been reclassified to show only those areas where collapse poses a significant hazard if water is infiltrated to the ground. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/geosure/soluble.html.
Landslide constraints
A landslide is a relatively rapid outward and downward movement of material on a slope, due to the force of gravity. A slope is under stress from gravity but will not move if its strength is greater than this stress. If the balance is altered so that the stress exceeds the strength, then movement will occur. In deposits that are highly susceptible to landslide, the infiltration of water to the ground may decrease the ‘strength’ of the deposit, resulting in slope instability. This may occur if water is infiltrated to the ground on or above the susceptible area. In such deposits, the installation of infiltration SuDS should proceed only following a full appraisal of the ground conditions.
This component data layer is derived from the landslide layer in the BGS GeoSure dataset. The dataset has been reclassified to show only those areas where landslide poses a significant hazard if water is infiltrated to the ground. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/geosure/landslides.html. Landslide hazards present along the coastline may be under-represented in this dataset. Where the installation of infiltration SuDS are considered on the coastline, the ground investigation should consider the potential for and the consequences of landslide.
Shallow mining (non-coal) constraints
In areas where current or past underground mining has resulted in cavities at shallow depths, the infiltration of water may destabilise material above or within a cavity potentially resulting in ground collapse in highly susceptible areas. In such areas, infiltration of water to the ground may initiate or exacerbate the instability of material leading to collapse around the infiltration system. This dataset considers only mining for commodities other than coal.
This component data layer is derived from the BGS Mining Hazards (not including coal) dataset. The dataset has been reclassified to show only those areas where shallow mining represents a potentially significant hazard if water is infiltrated to the ground. This dataset was created, or interpreted, from a wide variety of data sources. Hazards that may be under-represented in the 2012 version, include those present in geological units that would not typically be mined, for example hazards associated with archaeological workings, and those in deposits where artisan mining has occurred historically in urban areas, for example Norwich and Bury St Edmunds. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/geohazards/miningHazard.html.
Made ground constraints
Made ground, including ground that has been infilled or landscaped has an unknown composition and structure. Infiltration through such material may result in ground instability or in the remobilisation of contaminants from within that ground.
This component dataset is derived from DiGMapGB-50 which shows the occurrence of made ground where mapped and over 1 m in thickness. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/digitalmaps/digmapgb_art.html.
Shallow groundwater constraints
In areas where the water table is shallow either persistently or seasonally, the installation of infiltration SuDS requires further consideration for several reasons:
- At least 1 m of unsaturated zone thickness should exist between the base of the infiltration system and the groundwater to allow filtration and removal of surface water pollutants before they reach the groundwater. Where shallow groundwater occurs, this may not be possible
- Increased infiltration may result in a temporary rise in groundwater level, which may cause the inundation of subsurface storage chambers
- Increased infiltration may result in a rise in groundwater level, causing the emergence of groundwater at the ground surface (termed groundwater flooding)
This component dataset is derived from the BGS Susceptibility to Groundwater Flooding dataset. The susceptibility map seeks to identify areas where the geological conditions and water table level indicate that groundwater may be present at shallow depths and could rise at certain times of the year. A classification of high susceptibility in this dataset does not mean that groundwater flooding has occurred in the past, or will do so in the future, as susceptibility maps do not contain information on how often flooding may occur and to what depth. Very shallow groundwater and the potential for groundwater flooding is a relatively rare event and not easily distinguishable from other types of flooding. Therefore the susceptibility to groundwater flooding has been determined by a computer model, which uses: geological maps; information from boreholes and wells, and relationships between groundwater and surface water. Artificial lowering of the water table is not taken into account, so in places where groundwater is abstracted, the susceptibility to groundwater flooding may be less than that predicted by the model. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/hydrogeology/groundwaterFlooding.html.
The dataset has been reclassified to show only those areas where a shallow water table is likely to restrict the installation of infiltration SuDS.
Infiltration SuDS drainage potential
Drainage Summary
The Drainage Summary layer provides an overview of the extent to which the ground will drain. It is derived from the datasets described in Section 4.3.2 to 4.3.6 and is overlain with the Infiltration SuDS Constraints Summary layer discussed in Section 4.2.1. The summary layer indicates the likely design constraints associated with installing an infiltration system at a given location. Table 3 shows the four categories used in this summary layer.
| Score | Short description | Detailed description |
| 1 | Highly compatible for infiltration SuDS | The subsurface is likely to be suitable for free-draining infiltration SuDS. |
| 2 | Probably compatible for infiltration SuDS | The subsurface is probably suitable for infiltration SuDs although the design may be influenced by the ground conditions. |
| 3 | Opportunities for bespoke infiltration SuDS | The subsurface is potentially suitable for infiltration SuDS although the design will be influenced by the ground conditions. |
| 4 | Very significant constraints are indicated | There is a very significant potential for one or more geohazards associated with infiltration. |
If a site scores a value of 1, the subsurface is likely to be highly permeable, with a deep water table and not underlain by floodplain deposits that may respond rapidly to changes in river levels. In this environment, the installation of infiltration SuDS is likely to be straightforward. Sites that score a value of 2 may be characterised by a spatially variable permeability or a water table that may be within 1 m of the base of the infiltration system, or both. The design of infiltration SuDS in these areas should take account of the local ground conditions. Sites that score a value of 3 may be poorly draining, or have a shallow water table, or are located on floodplain deposits, or have some combination of these characters. In these areas, the subsurface may potentially be suitable for infiltration SuDS, but the design will be strongly dependent on the local ground conditions. Sites that score a value of 4 have a severe constraint that needs investigation to determine whether the potential for or the consequences of the constraint are likely to be significant.
Superficial deposit permeability
Superficial deposits mostly comprise unconsolidated gravel, sand, silt and clay in some combination. They are present beneath the pedological soil in patches or larger spreads over much of Britain. Infiltration systems are generally installed beneath the soil layer and hence the infiltration rate is dependent on the deposit that lies beneath. Where superficial deposits are present, the infiltration rate varies widely depending on the composition of the deposits.
This data layer reports the range of permeability predictions for the superficial deposits thereby indicating the type of infiltration system that might be suitable.
This component data layer is derived from the BGS Permeability Index dataset. The dataset has been reclassified to include a score field, but retains the original qualitative estimates of the predicted permeability range (minimum and maximum permeability). Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/hydrogeology/permeability.html.
Superficial deposit thickness
In some areas, the superficial deposits are thin or absent and hence the permeability of the subsurface may be controlled either by the superficial deposits and bedrock in combination or by the bedrock alone. To determine whether or not the bedrock permeability should be considered a model of the superficial thickness is provided.
This component data layer is derived from the BGS Basic Superficial Thickness Model (BSTM). The thickness model has been reclassified to denote areas where the superficial deposits are absent, less than 3 m thick, or more than 3 m thick. Where the superficial deposits are less than 3 m thick or absent, the bedrock permeability should also be taken into consideration. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/onshore/superficialThickness.html
Bedrock permeability
Bedrock forms the main mass of rock forming the subsurface. Where superficial deposits are thin or absent, the ease with which water will infiltrate into the ground depends on the permeability of the bedrock. The infiltration rate into the bedrock depends on its permeability, which is largely determined by the rock type.
This data layer provides a qualitative indication of the predicted permeability range, which may indicate the type of infiltration system that might be suitable.
This component data layer is derived from the BGS Permeability Index. The dataset has been reclassified to include a score field, but retains the original qualitative estimates of the predicted permeability range (minimum and maximum permeability). Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/hydrogeology/permeability.html.
Depth to water table
Guidance states that there should be a minimum unsaturated zone thickness of 1 m between the base of the infiltration system and the groundwater table. This ensures that there is sufficient space in the unsaturated zone to accommodate temporary rises in groundwater level resulting from infiltration. The depth to the water table is difficult to estimate, however by extrapolating river elevation levels, this dataset provides an estimate of the depth to water level. It is likely to be most accurate when applied at sites in close proximity to rivers. The dataset does not consider the presence of perched water tables, which may form above layers of low permeability material, causing a water strike above the level of the regional water table. The dataset provides an estimate of the natural water table not depressed by abstraction or dewatering. Prior to the installation of infiltration SuDS, the groundwater level should ideally be monitored for a period of one year to determine the likely seasonal variation. The infiltration SuDS system should be designed using the seasonal high groundwater level.
This component data layer has been derived specifically for the Infiltration SuDS Map. The dataset is classified into three zones; those where the water table is expected to be <3 m, between 3 and 5 m and >5 m deep.
Proximity to floodplains
On floodplains, the water table may respond rapidly to changes in river level. In times of high river level, a groundwater rise as a result of a rise in river stage may result in inundation of subsurface infiltration systems.
This component data layer is derived from the BGS Geological Indicators of Flooding dataset. The dataset has been subject to reclassification, such that the polygons highlighted in this component dataset represent those areas where floodplain deposits occur. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/hydrogeology/indicatorsOfFlooding.html.
Infiltration SuDS ground stability
Ground Stability Summary
The Ground Stability Summary layer provides an overview of ground stability issues that should be considered during the planning and design of infiltration SuDS. The summary layer is derived from the reclassified GeoSure datasets described in Soluble rocks to Collapsible ground below. These datasets have been reclassified, such that the polygons highlighted in each component dataset represent the hazards associated with infiltrating water to the ground.
To provide a spatial overview of the geological hazards associated with infiltration to the ground, polygons within the individual datasets are scored from 1 to 4 (Table 4). These scores indicate the potential for ground stability associated with installing infiltration SuDS at a given location. The summary layer reports the maximum score, thereby representing the potential for ground instability.
| Score | Short definition | Detailed definition |
| 1 | Geohazard unlikely | Increased infiltration is very unlikely to result in ground instability |
| 2 | Potential for geohazard | Ground instability problems may be present or anticipated. Increased infiltration is unlikely to result in ground instability |
| 3 | Significant potential for geohazard | Ground instability problems are probably present. Increased infiltration may result in ground instability |
| 4 | Very significant constraints are indicated | There is a very significant potential for one or more geohazards associated with infiltration |
The stability of an area with a score of 1 is not anticipated to be impacted as a result of infiltration. Areas with a score of 2 or 3 may need investigation prior to infiltration, however the hazards present should not prevent infiltration SuDS from being used. For areas with a score of 4, the potential for and consequences of the identified hazard should be fully appraised. The impacts of infiltration on ground stability may be influenced by the infiltration system design. Systems designed for high volume infiltration over small areas may have a greater impact on ground stability than those that are designed to infiltrate small volumes of water over more extensive surface areas. Where ground instability hazards are present, the infiltration system design should take such considerations into account.
The ground stability component data layers in this section are derived from the BGS GeoSure dataset. The dataset has been reclassified to show only those areas where the geohazard represents a significant hazard if water is infiltrated to the ground.
Soluble rocks
As discussed in Soluble rocks constraints, infiltration may result in ground collapse where the geological deposits are susceptible to dissolution.
This data layer provides an indication of the potential for a hazard to occur as a result of infiltration and suggests the relevant action. The presence of soluble rocks may prevent infiltration SuDS from being installed, however in many areas, infiltration systems can be used as long as the hazard from soluble rocks is taken into account during planning and design.
Landslide hazards
As discussed in Landslide constraints , the infiltration of water into deposits that are susceptible to landslide, may decrease the ‘strength’ of the deposit, resulting in slope instability.
This data layer provides an indication of the potential for a hazard to occur as a result of infiltration and suggests the relevant action. On some landslides the installation of infiltration SuDS is not recommended, but on many susceptible slopes, infiltration systems can be used as long as the hazards are taken into account during planning and design.
Compressible ground
Many geological deposits contain water-filled pores. When the ground is compressed by a building or other load, the water in the pore space can be squeezed out, causing the ground to compress. This may cause uniform or non-uniform settling, resulting in tilting, cracking or distortion to buildings. If water is added to the ground through an infiltration system, the compressibility may alter, possibly initiating settlement.
This data layer provides an indication of the potential for settlement to occur as a result of infiltration and provides relevant advice. Compressible ground is unlikely to prevent infiltration SuDS from being installed, but it should be considered during planning and design to ensure that the installation or nearby structures are not affected. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/geosure/compressible.html.
Swelling clays
Clays that are susceptible to shrink and swell change volume significantly according to how much water they contain. All clay deposits change volume as their water content varies, typically swelling in winter and shrinking in summer, but some do so to a greater extent than others. Contributory circumstances include the change in moisture content brought about by drought, leaking pipes, tree roots drying out the ground, or changes to local drainage patterns, such as the creation of soakaways. Shrinkage may remove the support from the foundations of buildings and structures, whereas clay expansion may lead to uplift or lateral stress on part or all of a structure; any such movement may cause cracking and distortion. If water is added to the ground through an infiltration system, susceptible clays may swell with the increase in moisture content, possibly introducing differential uplift.
Clay-rich deposits may be considered unsuitable for infiltration. This is likely to be true for systems that require rapid drainage such as soakaways, however infiltration systems that have an extensive infiltration area or that have provision for water storage may be appropriate. Such systems are often utilised for high-return period storm events and utilise land that has a different primary use (e.g. recreation).
This data layer provides an indication of the potential for ground movement to occur as a result of infiltration and provides relevant advice. Swelling clays are unlikely to prevent infiltration SuDS from being installed, but they should be considered during planning and design to ensure that the installation or nearby structures are not impacted. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/geosure/shrink_swell.html.
Running sands
Running sand conditions occur when loosely-packed sand, saturated with water, flows into an excavation or other type of void. The pressure of the water filling the spaces between the sand grains reduces the contact between the grains and they are carried along by the flow. This can lead to subsidence of the surrounding ground. Running sand is potentially hazardous during the installation of infiltration SuDS. The excavation of ground may create a space into which sand can flow, potentially causing subsidence of surrounding ground.
This data layer provides an indication of the potential for running sand. Running sand is unlikely to prevent infiltration SuDS from being installed, but it should be considered during planning and design to ensure that the installation or nearby structures are not impacted.
The dataset has been reclassified to show only those areas where running sand represents a significant hazard if water is infiltrated to the ground. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/geosure/running_sand.html.
Shallow mining hazards (non-coal)
As discussed in Shallow mining (non-coal) constraints, the infiltration of water may destabilise material bridging above or within a mined cavity, potentially resulting in ground collapse.
This data layer provides an indication of the potential for shallow mining collapse to occur as a result of infiltration. The installation of infiltration SuDS is possible in many areas that are affected by shallow mining as long as the potential for stability (and water quality) hazards are considered. The dataset considers only non-coal mining hazards. For information regarding underground and opencast coal mining and matters relating to subsidence or other ground movement induced by coal mining, please contact the Coal Authority, Mining Reports, 200 Lichfield Lane, Mansfield, Nottinghamshire, NG18 4RG; telephone 0845 762 6848 or at www.coal.gov.uk.
Collapsible ground
Collapsible ground comprises certain fine-grained materials with large pore spaces. Such deposits can collapse when they have been loaded and then become saturated by water. If the ground below a building collapses it may cause the building to sink. If the collapsible ground is variable in thickness or distribution, different parts of the building may sink by different amounts, possibly causing tilting, cracking or distortion. Infiltration will result in an increase in water content, which may affect the strength of the ground.
This data layer provides an indication of the potential for the ground to collapse. Collapsible ground is unlikely to prevent infiltration SuDS from being installed, but it should be considered during planning and design to ensure that the installation or nearby structures are not impacted.
The dataset has been reclassified to show only those areas where collapsible ground represents a significant hazard if water is infiltrated to the ground. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/geosure/collapsible.html.
Infiltration SuDS groundwater protection
Groundwater Protection Summary
The Groundwater Protection Summary layer provides an overview of subsurface factors that may impact the planning and design of infiltration SuDS in respect of protecting groundwater quality. The data will be useful when determining whether pre-treatment of surface water prior to infiltration is necessary. The summary layer is derived from the datasets described in the Predominant flow mechanism section. The site investigation should include a full risk-based assessment of the potential for groundwater quality deterioration. The data included in the Infiltration SuDS Map only provides preliminary data, for example it does not consider the presence of contaminated land, through which infiltration could result in the remobilisation of contaminants.
To provide a spatial overview of the extent to which precaution is required, polygons within the individual datasets are scored from 1 to 4 (Table 5). These scores indicate the extent to which the groundwater may be susceptible to contamination. The summary layer reports the maximum score, thereby representing the likely level of precaution required.
| Score | Short description | Detailed description |
| 1 | Low susceptibility | The groundwater is not expected to be especially vulnerable to contamination. Infiltrating water should be free of contaminants |
| 2 | Moderate susceptibility | The groundwater may be vulnerable to contamination. Infiltrating water should be free of contaminants |
| 3 | Considerable susceptibility | The groundwater is likely to be vulnerable to contaminants. Infiltrating water should be free of contaminants |
| 4 | Very significant constraints are indicated | Made ground is present at the surface. Infiltration may increase the possibility of remobilising pollutants |
Groundwater source protection zones
The source protection zone datasets sourced from the Environment Agency, and Natural Resources Wales, define zones around public water supply abstraction points where additional protection is required to safeguard drinking water quality. In these areas, activities that may affect the quality of the drinking water abstraction may be restricted. It is included here to show where restrictions on the installation of infiltration SuDS may apply.
Source protection zones are delineated only in England and Wales. Four source protection zone classifications are used, each defined by groundwater travel time to the abstraction point. Zone 1 areas are defined by a travel time of 50 days or less from any point within the zone, at or below the water table. Zone 2 is defined by a 400-day travel time from a point below the water table, with a minimum radius of 250 or 500 m. Zone 3 is defined as the whole of the area that supports the abstraction or discharge from the protected groundwater source. Zone 4 highlights areas (mainly on non-aquifers) where known local conditions mean that potentially polluting activities could impact a groundwater source. The source protection zone dataset provides only a partial indication of the sensitivity of the groundwater and should be used as the basis for risk-led decisions on the appropriateness of infiltration (for more information consult the Environment Agency publication, Groundwater Protection: Policy and Practice, Document GP3). It is important to prevent the transport of contaminants into the groundwater at all sites. This includes contaminants that are potentially introduced to the surface water and also contaminants that may be re-mobilised within the subsurface by infiltrating water.
Predominant flow mechanism
Some geological deposits will attenuate surface water pollutants more than others. The predominant flow mechanism in the unsaturated zone is one proxy for determining whether such attenuation is likely. There are three types of flow mechanism in the unsaturated zone: intergranular flow occurring through otherwise air-filled pore spaces, fracture flow occurring through cracks, or a combination of both. Where flow is intergranular, the residence time of the infiltrating water will be long and contact with the mineral surfaces large, so attenuation is likely to be maximised. Conversely, where flow is through fractures, the residence time will tend to be short and contact with surfaces low, and so attenuation will be minimised.
This component data layer is derived from the BGS’ Permeability Index dataset. The dataset has been re-attributed to include a score field, but retains the original descriptions of predominant flow mechanisms. Information about the original dataset can be viewed at: http://www.bgs.ac.uk/products/hydrogeology/permeability.html.
Made ground
As discussed in the Made ground constraints section, infiltration through made ground may impact groundwater quality as such anthropogenic deposits can contain contaminants that may be remobilised from the unsaturated zone into the groundwater. Made ground is shown on the geological maps only where it has been recorded, and it may be present elsewhere.
Data summary
The original datasets used in the creation of the Infiltration SuDS Map are detailed in Table 6.
| Data layer | Layer ID | Original dataset | Dataset owner | Scale |
| Infiltration SuDS constraints | ||||
| Infiltration constraints summary | SuDS_infiltrationconstraints_screen_2016 | N/A | BGS | |
| Soluble rock constraints | SuDS_infiltrationconstraints_solublerocks_2016 | GeoSure v7 | BGS | 1:50 000 |
| Landslide constraints | SuDS_infiltrationconstraints_landslides_2016 | GeoSure v7 | BGS | 1:50 000 |
| Shallow groundwater constraints | SuDS_infiltrationconstraints_shallowGW_2016 | Groundwater Flooding Susceptibility v6.1 | BGS | 1:50 000 |
| Made ground constraints | SuDS_infiltrationconstraints_madeground_2016 | DiGMapGB-50 v7 | BGS | 1:50 000 |
| Shallow mining constraints | SuDS_infiltrationconstraints_shallowmining(non-coal)_2016 | Mining hazard (non-coal) GB v7 | BGS | 1:50 000 |
| Infiltration SuDS drainage potential | ||||
| Drainage summary | SuDS_drain_screen_2016 | N/A | BGS | |
| Depth to water table | SuDS_drain_depthtowater_2016 | gwlevelgb (2016) | BGS | --- |
| Superficial deposit thickness | SuDS_drain_superficialthickness_2016 | Basic superficial thickness model, version 2.1, GI_SDTM v2.1 | BGS | 1:50 000 |
| Superficial deposit permeability | SuDS_drain_superficialpermeability_2016 | Permeability indices v7 | BGS | 1:50 000 |
| Bedrock permeability | SuDS_drain_bedrockpermeability_2016 | Permeability indices v7 | BGS | 1:50 000 |
| Floodplains | SuDS_drain_geologicalindicatorsofflooding_2016 | Geological indicators of flooding v6 | BGS | 1:50 000 |
| Infiltration SuDS ground stability | ||||
| Ground stability summary | SuDS_stability_screen_2016 | N/A | BGS | 1:50 000 |
| Soluble rocks | SuDS_stability_solublerocks_2016 | GeoSure v7 | BGS | 1:50 000 |
| Landslides | SuDS_stability_landslides_2016 | GeoSure v7 | BGS | 1:50 000 |
| Compressible ground | SuDS_stability_compressibles_2016 | GeoSure v7 | BGS | 1:50 000 |
| Swelling clay | SuDS_stability_swellingclay_2016 | GeoSure v7 | BGS | 1:50 000 |
| Running sand | SuDS_stability_runningsand_2016 | GeoSure v7 | BGS | 1:50 000 |
| Shallow mining | SuDS_stability_shallowmining_2016 | Mining hazard (non-coal) GB v7 | BGS | 1:50 000 |
| Collapsible ground | SuDS_stability_collapsibles_2016 | GeoSure v7 | BGS | 1:50 000 |
| Infiltration SuDS groundwater protection | ||||
| Groundwater protection summary | SuDS_waterquality_screen_2012 | N/A | BGS | |
| Source protection zones | SuDS_waterquality_sourceprotectionzone_2012 | Downloaded 2015 | EA | -- |
| Predominant flow mechanism | SuDS_waterquality_predominantflowmechanism_2012 | Permeability indices v7 | BGS | 1:50 000 |
| Made ground | SuDS_waterquality_madeground_2012 | DiGMapGB-50 v7 | BGS | 1:50 000 |