ABSTRACT

A majority of Earth's population now lives in urban areas. In cities, humans have intensively reconfigured the landscape and extensively concentrated resources. These urban environs are expected to host almost all future global population growth. If and how cities will remain livable in the future, however, is a critical question. Key factors of livability include a comfortable environment, access to and efficient use of water, and resilience to extremes of drought, flood, cold, and heat. Natural science suggests that these factors are strongly related to the vegetation cover, soils, and heat and water balances of a place, but it is an open question how precisely lessons from natural science conducted in rural, natural areas might apply to cities. Among the most prominent, unique characteristics of cities are their extreme spatial variations in land cover (e.g., grass, pavement, trees, gardens, and bare ground juxtaposed over short distances) and the phenomenon called the urban heat island (UHI). An UHI occurs where an urban area is substantially warmer than nearby rural areas due to factors such as greater absorption of solar energy by paved surfaces and less evaporative cooling from dry urban surfaces than rural fields or forests. This project will determine (1) how urban landscape variations, heat, and water balances interact as cause and consequence of local hot or cool microclimates within the city, (2) how microclimates and their vegetative and hydrologic influences relate to urban human health and comfort, and (3) how the overall UHI climate and hydrologic regime of cities may be made more resilient to weather extremes for the benefit of urban infrastructure, urban environmental quality, and urban human safety. To the extent that the linked surface water and energy balances of a city might be controlled by is landscape composition and configuration, with sufficient knowledge of urban heterogeneity-heat-water relations, cities could be engineered for greater health and sustainability, even in the face of global change.

The dual goals of this project are to (1) quantify the links and feedbacks between urban landscape heterogeneity, urban heat, and the urban water cycle and (2) to forge a strong pipeline between science, education, and management to help empower people of all abilities and positions to develop practices to enhance the comfort and resilience of urban landscapes in the face of global change. The research will address how the distributed surface water and energy balances of the urban environment function, whether they function differently in urban heat or cool islands, how they are governed by various types of land cover, and how they in turn affect water resource demands and human comfort. Research approaches will include in situ quantitative monitoring of the heat and water balances of the most common urban land covers subject to the same microclimate island and compared among different microclimates; field, remote sensing, and modeling investigation of urban soil moisture's controls on urban warming; physics-based numerical modeling of urban landscape composition and configuration controls on microclimate, surface energy balance, and surface water balance; and remote sensing and modelling assessments of how progressive urbanization and warming and the scale of data considered may influence the quantifications of urban heat and water cycles. This project will also foster research-education-management synergy with multiple open-access innovations. Urban environmental science field course modules will be developed for a variety of age levels (pre-school to graduate) to foster place-based, experiential, and life-long STEM learning. The modules will also be explicitly designed to make field science accessible to students with mobility needs. Research-management collaboration will occur among a consortium of western US cities and universities and public outreach on "urban backyard science" will freely distribute educational urban-environment activities for all ages.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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