User:Teddieursa/Oasis effect

Urban Planning

The oasis effect plays a role in urban development because plants and bodies of water result in cooler cities. Accordingly, cities with parks will have lower temperatures because plants have higher albedo than bare ground or roads. Areas with higher albedo reflect more light than they absorb, leading to cooler temperatures. Normally, cities are hotter than their suburbs due to dense population, dark buildings and roads, and pollution; this is known as the urban heat island effect. However, by careful placement of trees, parks, and plant life, cities can create their own oasis effect. By maintaining plant life throughout a city, urban planners can produce an oasis effect to offer the urban heat island effect; even a small scattering of trees can significantly reduce local temperatures. However, concerns can arise in arid regions with limited water sources where city planners may not want to leave water sources out in the open to evaporate, and may not want to sacrifice water for upkeep of plants. Urban oases have also had additional benefits of improving biodiversity. For example, green roofs in the Netherlands have been observed to stimulate plant diversity.

Chicago City Hall pilot green roof project

Green roofs have been growing increasingly popular in dense cities as a space-saving way to cool down urban areas. They have been found to be effective at creating oases in both temperate and tropical climates, suggesting their effectiveness and benefits in urban planning. Urban planners have to decide on which plants are best suited for the environment, growth medium, filter layer, insulation, water proofing, and many other factors. There are also very high initial costs associated with green roofs, but in the long-run they can help save money.

Concerns

The creation of an artificial effect can result in issues in arid regions with limited water sources where city planners may not want to leave water sources out in the open to evaporate, and may not want to sacrifice water for upkeep of plants. There are concerns that the oasis effect may result in increased carbon emissions and water loss if irrigation occurs at night. Instead, switching to irrigation during the day could potentially decrease the water loss and decrease carbon emissions. One potential way to counteract freshwater loss is to instead switch to saltwater. The Sahara Forest Project Foundation has been creating seawater greenhouses in the middle of the desert, in order to achieve these oases while conserving freshwater.