Irrigation of urban trees

Irrigation can directly ameliorate urban microclimate and thermal comfort and can reduce the 'urban heat island' effect. Irrigation alters surface heating, heat reflection, turbulent air mixing, and heat exchange between the air and the building, thus decreasing the external thermal load of buildings. Considering that urban areas account for 67–74 percent of global energy use, a city-wide wise irrigation program may effectively reduce urban heat island and energy use during summer. The choice of irrigation method is critical for efficient watering of urban trees. Common watering methods include: hand irrigation; sprinklers, sprays, and microsprays; surface drip; subsurface drip; watering wells and trenches; and water storage devices with controlled release of water. Estimating the irrigation needs of urban green areas with mixed vegetation is extremely challenging, but it is a key requirement for getting the most benefit from urban trees while saving water. Plant water needs can be accurately estimated with several methods accurately reviewed by Nouri and his team