Estimating Urban Greenspace Irrigation for 400 Cities in China: Implications for Urban Land Use and Water Management

Estimating Urban Greenspace Irrigation for 400 Cities in China: Implications for Urban Land Use and Water Management Lianlian Pan1, Tingju Zhu1,2, Ci Li1,2 1ZJU-UIUC Institute, International Campus, Zhejiang University, China 2College of Civil Engineering and Architecture, Zhejiang University, China Abstract Urban greenspace has increased significantly in many Chinese cities along with the rapid urbanization in China where total urban population and built-up areas have reached 0.9 billion and 146 thousand km2 by 2021, respectively. Despite various important environmental and societal benefits of urban greenspace, water uses for urban greenspace irrigation have become an important yet under-researched area in urban water management. Using daily meteorological data in 1986-2015 and the spatial distribution and areas of grassland, shrubs and trees in urban greenspace taken from the 30-meter resolution EULUC database and the 10-meter resolution GLC database, we estimated irrigation water demand of urban greenspace for 400 cities at prefecture level or above in China using a newly developed evapotranspiration and soil water budgeting model coded in Python. Such water demand results were then compared with water uses of those cities in recent years to approximate the shares of urban greenspace irrigation in total urban water uses for each city, thus revealing water stress imposed by urban greenspace where this is concerned. Additionally, a clustering algorithm was used to classify those cities based on location, climatic condition, economic development, and population to explore the drivers of urban greenspace and associated water uses. This study provides the first set of results of urban greenspace irrigation for major cities across the entire country of China, to the best of our knowledge, thus offering useful insights for greenspace development and urban water management in an era of rapid urbanization.