Visual Impact Prediction

Sixth Section in Litton's Article: Descriptive Approaches to Landscape Analysis
 

Visual Impact Prediction:

According to Litton, there are four criteria used in determining aesthetic values, visual values, and relationships in a landscape. 

•  vividness (memorability),
• intactness (relative apparent naturalness),
• encroachment (presence of degradation), and 
• uniqueness (relative scarcity)

A report of these criteria also serves as an indicator of the landscape’s environmental aesthetics which can be clearly and tangibly established through visual landscape analysis.  The author explains that visual impact predictions address the landscape’s visual vulnerability or sensitivity to change.  Visual simulations identify special landscape compositions, expose surrounding influences, conditions, and reveal the unit’s context and location in a larger environment  and possible impacts to the adjacent landscapes, both positive and negative (“red flags”).  These impact predictions can also be valuable tools for landscape architects to use to show the proposed changes to the public and become review material for resource management.  Litton argues that since these representations are developed by professionals that the results should be reasonably accurate.  He goes on to explain that several alternatives must be prepared to display a difference in changes and impacts.

A visual absorption capability study by Jacobs and Way (1969) describes an alternative way of considering relative visual impacts.  Similar to visual vulnerability, visual absorption is the “potential for developmental changes to be absorbed or screened by vegetation or topography” (pg. 84).

Visual Impact Prediction applied to Vista Management:

Numerous vistas within Great Smoky Mountains National Park exhibit all of the aesthetic value criteria listed by Litton.  Many of the most memorable, unique views can be seen from Newfound Gap Road.  Visual impact predictions were developed for Campbell Overlook and Newfound Gap Parking Area, because they demonstration two considerably different management methods, topography, and vegetation.  Even though both vistas have not been formally managed in decades, Campbell Overlook is significantly more obstructed by encroaching vegetation. 

   

Visual simulations revealed the pros and cons of three clearing alternatives for Campbell Overlook.  Positive impacts include removing encroaching vegetation to reveal the opposing peaks and valley, view of the river, increased sunlight for lower growing flowering shrubs, and an increased food supply for animals by encouraging fruiting plants.  Negative impacts include the disturbance of a natural ecosystem and temporary unpleasant appearance of the clearing until a new ecosystem could be established.  Potential impacts could be erosion, accidental release of chemicals into waterways (herbicide, gas, geological disturbance), and more invasive plants with the increase of sunlight.

Newfound Gap Parking Area requires significantly less clearing, and visual simulations only revealed one practical alternative.  By selectively removing trees that are obstructing the view and treating the stump with herbicide, the view should be preserved for years to come.  Minimal work will be needed cyclically to maintain this clearing.  Positive impacts include a panoramic view of mountain ranges to the horizon.  Negative impacts include loss of possible flying squirrel habitat, although the amount of possible habitat to be removed is so small, this impact is negligible.  Since the clearing will be done at the top of Newfound Gap and herbicide will be used in such small amounts, it doubtful chemicals will enter the waterways.