- June 11, 2018
- Data Visualization
Complementing Harvard’s Map of the Month series, each week, Map Monday highlights a data visualization that enhances understanding of or helps resolve a critical civic issue.
Temperatures and sea levels are rising. These trends should be of particular interest to cities, where dense populations, darker surfaces, and reduced green space lead to higher temperatures and lower water drainage capacity than in surrounding regions. Forward-thinking city administrations are taking action now to identify their most at-risk communities and bolster infrastructure to promote public safety.
One such initiative comes from the Trust for Public Land’s Climate-Smart Cities program, which partners with cities to create parks in areas lacking green space. Low-income neighborhoods are often hit hardest by climate changes, as insufficient green spaces combined with lower financial means leave their populations at greater risk of intense heat or flooding. In New Orleans, the Climate-Smart Cities program harnesses data from city hall, the federal government, and area non-profits to create detailed GIS maps that help decisionmakers develop effective and equitable park projects. Using this map, officials have aimed to improve New Orleans’ resistance to environmental stresses through four strategies: cool, connect, absorb, and protect.
New Orleans’ subtropical climate makes for hot summers, creating health risks from dehydration to heat stroke. Using GIS mapping, New Orleans city officials can track average temperatures across the city and identify daytime hotspots using data from landsat satellites. They can use this information to strategically situate parks and vegetation in priority areas, keeping residents cool by providing shade and reducing the urban heat island effect through carbon dioxide absorption.
The map also contains detailed transit information, ranging from bus stop data to pedestrian safety across the city. Among a host of other benefits, improvements to transportation infrastructure could reduce energy use, further mitigating high city temperatures. Understanding the modes by which New Orleanians connect to essential services and to one another—and placing this information within the context of crucial environmental indicators—may help spur improvements to public transit services and trail systems that improve local conditions as well as residents’ ability to cope with unsafe conditions.
The devastation of Hurricane Katrina served as a tragic and powerful illustration of New Orleans’ regional environmental dangers. Its proximity to the Gulf of Mexico makes Louisiana the site of the third most hurricanes of any U.S. state. Combined with the city’s low elevation and location along the shore of the Mississippi, New Orleans is susceptible to heavy flooding. Installing more water-smart parks, playgrounds, and other green spaces such as green alleys will help the city absorb stormwater. The Climate-Smart Cities map visualizes data on wetland buffers, FEMA floodzones, drainage basins, catch basins, and estimated runoff; it also categorizes hydrologic soil groups according to runoff potential, depicting areas of primary flooding concern. City officials can use flood and absorption analytics much like they use heat data, building parks in areas based on their degree of risk.
Users of the visualization can view the city’s overall green infrastructure priority areas, categorized from very high, to high, to medium. They can then alter the visualization by placing greater weight on six different factors: cool, absorb, connect, climate equity, critical infrastructure, and health. Adding consideration to absorption, for instance, generates more high priority areas in downtown New Orleans. Placing more weight on cooling or health increases the priority of many areas in Southeast and Northeast New Orleans.
The mapping tool also equips policymakers with the ability to design their own projects by defining the boundaries of a proposed park. The program automatically produces a report detailing the population served—broken down by age, income, and race/ethnicity. These metrics are informed by detailed knowledge of both neighborhood population demographics and the city’s walkable network. Understanding the particular characteristics of populations that projects would serve contributes to the city’s broader goal of boosting support for typically underserved residents, who are likely to bear a greater percentage of the cost of environmental stresses.
GIS mapping helps local leaders identify areas of concern, design solutions, and accrue project funding through superior public visualization of priorities and considerations. Using this approach, New Orleans is preparing for an unpredictable future, adapting its neighborhoods for a variety of possible weather events.