Browsing by Author "Ao, Yufei"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Alleviating Water Scarcity by Optimizing Crop Mixes
    Richter, Brian D.; Ao, Yufei; Lamsal, Gambhir; Wei, Dongyang; Amaya, Maria; Marston, Landon T.; Davis, Kyle F. (Nature Portfolio, 2023-11)
    Irrigated agriculture dominates freshwater consumption globally, but crop production and farm revenues suffer when water supplies are insufficient to meet irrigation needs. In the United States, the mismatch between irrigation demand and freshwater availability has been exacerbated in recent decades due to recurrent droughts, climate change and over extraction that dries rivers and depletes aquifers. Yet, there has been no spatially detailed assessment of the potential for shifting to new crop mixes to reduce crop water demands and alleviate water shortage risks. In this study, we combined modelled crop water requirements and detailed agricultural statistics within a national hydrological model to quantify sub-basin-level river depletion, finding high-to-severe levels of irrigation scarcity in 30% of sub-basins in the western United States, with cattle-feed crops—alfalfa and other hay—being the largest water consumers in 57% of the region’s sub-basins. We also assessed recent trends in irrigation water consumption, crop production and revenue generation in six high-profile farming areas and found that in recent decades, water consumption has decreased in four of our study areas—a result of a reduction in the irrigated area and shifts in the production of the most water-consumptive crops—even while farm revenues increased. To examine the opportunities for crop shifting and fallowing to realize further reductions in water consumption, we performed optimizations on realistic scenarios for modifying crop mixes while sustaining or improving net farm profits, finding that additional water savings of 28–57% are possible across our study areas. These findings demonstrate strong opportunities for economic, food security and environmental co-benefits in irrigated agriculture and provide both hope and direction to regions struggling with water scarcity around the world.
  • Thumbnail Image
    Quantifying The Linkages Between US' Water Resources And Its Production Of Food, Energy, And Water
    Ao, Yufei (Virginia Tech, 2023-05-25)
    Water is a critical resource that is essential for human well-being and economic development. Many regions around the world face ongoing water scarcity and competition over water resources. Climate change, other drastic social changes, and population and economic growth can significantly impact the supply and consumption of water. There has been an increasing body of research focusing on the Food-Energy-Water (FEW) nexus. There is a mismatch between the spatial resolution of data availability and the resolution that water resources follow. Lack of quality sub-county water data also makes the research of micro-level food-water dynamics difficult if not impossible. These challenges pose obstacles to the further understanding of water scarcity in the context of the FEW nexus and leaves critical gaps in the research of the nexus. In this dissertation I asked and answered the question: how do socio-economic forces shape localized groundwater depletion and surface water scarcity within the United States at the field and basin scale? Specifically, I tested whether irrigated farm size leads to reduction in groundwater application per unit area and whether an increase in the annual depletion in the underlying aquifer storage increases the probability of an irrigated land transfer, with a Kansas field level dataset and an econometrics approach. I estimated the FEW production and the water footprint of FEW production in every US watershed and compare the water footprint of production against their water scarcity. Then the groundwater reserves and dam storage in watersheds were examined as the buffers for the watersheds' FEW production against water shortages. I mapped the transfers of FEW goods and services and both the virtual and physical water flows from watersheds to US cities. The transportation infrastructure and other infrastructure that supports the FEW transfers are analyzed in terms of their contributions to the movement of FEW goods. This dissertation improves our understanding of how broad structural changes within the agricultural industry are interconnected with the overexploitation of groundwater resources. It is the first study of water footprint accounting with the most recent input data for the whole US food-energy-water system at the watershed level and includes an analysis of cities' infrastructure reliance for food-energy-water transfers and infrastructure as buffers. The transfers of virtual water and physical water were compared. The resulting data and findings from the novel data synthesis will provide insights for consumers, food companies, and other decision-makers at various levels on their connection to water resources in non-local areas. The outcomes of this dissertation will also improve our ability to analyze drivers and solutions to local small-scale watershed water scarcity challenges and allow a quantifiable basis for policy support in the water resources management domain and beyond.