The baseline section of a landscape and visual impact assessment

The baseline of a Landscape and Visual Impact Assessment is two separate exercises that get run together and then confused. The landscape baseline describes the landscape itself as a resource: its character, its elements, its condition and the value attached to it. The visual baseline describes people and what they can see: who the receptors are, where they are, and how visible the site is from where they stand. Effects on the landscape and effects on views are assessed separately in the third edition of the Guidelines for Landscape and Visual Impact Assessment, and a baseline that merges them produces an assessment nobody can follow.

For a farm diversification scheme in a designated landscape, this section is where the cost sits and where the objections are won or lost. Get the study area and the receptor list agreed early and the rest of the work follows.

Landscape baseline and visual baseline as two exercises

Keep them in separate sub sections with separate figures.

The landscape baseline answers what is here. Landform, field pattern, boundary type, tree cover, water, settlement pattern, roads and tracks, land use, condition of the elements, and the designations and policy that attach value to it. Its receptors are the landscape character areas and the individual elements and features that could be changed.

The visual baseline answers who sees it. Residential properties, users of public rights of way, road and rail travellers, users of recreational assets and viewpoints, and people at work. Its receptors are people, grouped by the activity they are engaged in when they see the view.

The same physical fact appears in both, described differently. A hedgerow is an element of landscape character in one and a screening feature in the other.

Published character assessments and how to use them

Start with what exists and cite it precisely. In England the hierarchy usually runs from the national character areas published by Natural England, through county or district landscape character assessments, to any landscape sensitivity or capacity study the authority has commissioned, plus historic landscape characterisation where it exists.

Three rules for using them well.

Check the date and the scale. A national character area covers hundreds of square kilometres and tells you almost nothing about a 4 hectare site. A district assessment at 1:25,000 is more useful but may predate significant change on the ground.

Do not paraphrase them as your own analysis. Quote the character type, name the document and the year, then say what is and is not true of your site within that type. Inspectors notice when a description could apply to any field in the county.

Then add site level characterisation where the published work is too coarse. That means defining a local landscape character area for the site and its immediate context, described from fieldwork, and explaining how it relates to the published units. That step is what makes the baseline specific.

Defining the study area defensibly

The study area has to come from a method, not from a circle.

The normal approach is a zone of theoretical visibility generated from terrain data, showing where the proposed development could in principle be seen based on landform alone. It is then refined by fieldwork, because a bare earth terrain model ignores hedges, woodland and buildings, and over states visibility substantially in lowland England.

State four things about it: the terrain data used and whether it is a bare earth or a surface model, the height and extent of the development modelled, the receptor height assumed, and the outer limit chosen with the reason. A single storey agricultural building might justify a study area of one to two kilometres. A tall structure justifies much more.

Then sanity check it on the ground. Drive and walk the edges of the zone. If you cannot see the site from a point the model says is visible, record why, and show that refinement on the figure. An unrefined zone of theoretical visibility presented as the study area is the most common weakness in a rural assessment.

Identifying visual receptors and their sensitivity

The guidelines separate two things that are often collapsed into one word. Susceptibility to change is about the receptor's activity and attention: someone sitting in a garden or walking a recreational route is more susceptible than someone driving to work. Value attached to the view is about recognition: a view from a promoted trail, a designated landscape, a heritage asset or a viewpoint identified in a local plan carries more value than an incidental one.

Sensitivity is the combination, and it should be reasoned rather than asserted. Set it out in a table, receptor by receptor, with a column for susceptibility, a column for value and a short justification for each.

Receptor groups worth checking on a rural site:

• residents of individual properties and hamlets, identified by property or group rather than as "nearby residents"
• users of public rights of way, with the footpath numbers taken from the definitive map
• users of promoted or long distance routes, and of open access land
• road users on routes where the view is part of the experience rather than incidental
• visitors to heritage assets where setting matters
• users of nearby recreational facilities

Residential visual amenity is a separate assessment for a small number of dwellings where effects may be severe, and it is worth saying explicitly whether one is needed rather than leaving it implied.

Fieldwork records and what to keep

Keep enough that someone else could repeat the visit.

For every viewpoint: a grid reference to the metre, the bearing, the date, the time, the weather and visibility conditions, the camera body and the focal length used, the tripod height, and notes on what screens the view and in which season. Photography for a formal assessment follows the Landscape Institute's technical guidance on visual representation of development proposals, which sets expectations for focal length, stitching, print size and viewing distance.

Classify viewpoints by purpose, as the guidelines do: representative viewpoints standing for a wider group, specific viewpoints chosen because of a particular receptor or a named view, and illustrative viewpoints included to show something clearly. Agree the list with the local planning authority before fieldwork, in writing, and record the agreement in the report.

Photograph more viewpoints than you will use. Returning to a site in the right conditions is expensive, and a case officer asking for one more view from a lane you did not record costs a day.

Seasonal variation in the baseline

Deciduous screening is the issue. A baseline taken in July, with hedges and woodland in full leaf, understates winter visibility, and an objector with a phone camera in January will point that out.

The defensible approach is to survey in winter for the worst case, or to survey in summer and commit to a winter verification visit, saying so in the report. Where only summer photography exists, state the limitation plainly and describe the likely winter position from the structure of the vegetation.

Two related points. Note the condition and management of the screening vegetation, because a hedge maintained at 1.5 m screens nothing at eye level and a hedge that is allowed to grow out changes the baseline within a few years. And note whether the screening is in your control, because mitigation that relies on a neighbour's trees is not mitigation.

Setting the baseline up so the assessment follows

The baseline should contain no conclusions about effects. Its job is to define the receptors and their sensitivity so that magnitude of change can be assessed against them in the next chapter.

A structure that works: the landscape baseline with character description, elements and value, then the visual baseline with the zone of theoretical visibility, receptor identification and the viewpoint schedule, then a sensitivity table for each set of receptors, then a statement of the scoping agreement and its date, and finally a limitations section covering season, access and any receptor that could not be reached.

Where the scheme is urban, the same logic applies through a Townscape and Visual Impact Assessment instead, with townscape character replacing landscape character. Where mitigation planting is proposed, the baseline vegetation description has to match what the Landscape Strategy assumes, and the visual material has to follow the photomontage methodology if it is to carry weight.

Draft the structure of your Landscape and Visual Impact Assessment on PlanScope, then hand it to a chartered landscape architect with the viewpoint photography and the terrain analysis to complete and sign off.

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