Accessibility to greenspaces: GIS based indicators for sustainable planning in a dense urban context

摘要

The issue of accessibility to urban greenspaces is raising as one of the most debated in sustainable urban planning, especially in topics such as environmental justice and health inequalities. This is mainly due to the growing attention that is recognised today to health and well-being benefits from greenspaces. Different people interpret accessibility based on their individual needs and priorities, but it is generally acknowledged that access to greenspaces may be particularly beneficial for children, lower socioeconomic groups and for people with other mental/psychological illness. However, if accessibility is the measure of the ease of reaching valued destinations, clarifying its definition is an important pre-requisite for further analysis aimed at supporting urban planning choices on greenspaces. The following paper presents a set of accessibility indicators aimed at quantifying different measures of accessibility to existing open spaces for the city of Catania, south Italy, an urban context characterised by a general lack of greenspaces and high density of urban settlements. Proposed indicators are divided into two main categories: simple distance indicators (SIs) and proximity indicators (PIs). The first accounts for the number of people or users that can have access to a particular open space, while the second weights these people or users with the distance from their location to the open spaces. Indicators are calculated using different thresholds of Euclidean and network distances. Results show different scenarios in terms of rank of greenspaces accessibility, strongly influenced by chosen distance metric (Euclidean vs network) and thus emphasise a careful use of these indicators as planning support tools. Some practical implications of measuring accessibility for urban planning can be highlighted: for instance, specific land uses might be chosen for highly accessible open spaces, especially those characterised by a high proximity to residential settlements. Examples include allotment gardens, playgrounds and other informal green areas.