The increase in food demand and limited opportunities to expand agricultural land pose a threat to local and global food security. Producing food in urban areas such as green roofs can help satisfy... Show moreThe increase in food demand and limited opportunities to expand agricultural land pose a threat to local and global food security. Producing food in urban areas such as green roofs can help satisfy urban food demand and thus alleviate pressure on agricultural land. However, a modeling framework that simulates crop growth and production potential on green roofs at a city scale is missing. Here, we adapt the Aquacrop model to explore the growth potential of various types of crops on green roofs and apply it to suitable roof areas in the city of Amsterdam. Our modeling framework includes irrigation methods for water use on green roofs that are optimized according to various climate-driven scenarios of water availability. We find that cabbage has the maximum achievable crop yields ranging from 30.8 to 75.9 t ha-1 yr-1, while pea has the minimum achievable crop yields ranging from 1.7 to 6.4 t ha-1 yr-1. The potential suitable green roof area (i.e., roofs with a certain slope and bearing capacity) for Amsterdam is roughly 400 ha for crop production. This represents 16 % of the total rooftop areas of Amsterdam and can produce up to a total of 28 kt of crops on an annual basis. Our modeling framework can be easily applied to other cities to identify the crop growth potential of green roofs. Our results can help policymakers and urban planners find optimal planting strategies and contribute to shorter food supply chains. Show less
Cropping pattern determines the agricultural water use requirement and efficiency, as well as economic benefits of crop production. Agricultural water resources include blue water (irrigation water... Show moreCropping pattern determines the agricultural water use requirement and efficiency, as well as economic benefits of crop production. Agricultural water resources include blue water (irrigation water) and green water (soil moisture from precipitation), which have different shadow prices. The virtual water (VW) flow embedded in the interregional food trade causes burden shifts of water resources pressures in space. However, these intertwined economic and social effects have been neglected in regional cropping structure management. Using the case of the Yellow River Basin in China, here, we propose a two-stage multi-objective cropping pattern optimization scheme to maximize crop economic output, while minimize blue water scarcities (the first stage), and considered the criteria of maximum economic benefits of the interprovincial crop-related VW flows based on the shadow prices of crop green and blue water use (the second stage). Results show considerable differences in shadow prices of crop water use by colures, crops and location. With the optimized cropping pattern, which appropriately expands the planting scale of vegetables with higher water shadow price and comparative advantage and reduces the crop planting with lower water shadow price and intensive blue water consumption (e.g., soybean and wheat), blue water scarcity can be alleviated by ∼20%, combined with a ∼5% increase in crop economic output and up to ∼3% (800 million USD) higher benefits of VW flows. The premise to achieve above goals is to improve crop water resources utilization efficiency and break down the barriers of dietary preferences and trade policy. Show less
