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1. Integrated Water Management at the Peri-Urban Interface: A Case Study of Monterey, California

   https://doi.org/10.3390/w12123585  

   Gile, Bridget C. ; Sciuto, Paul A. ; Ashoori, Negin ; Luthy, Richard G. ( December 2020 , Water)

   null (Ed.)

   Climate change, drought, and chronic overdraft represent growing threats to the sustainability of water supplies in dry environments. The Monterey/Salinas region in California exemplifies a new era of integrated or “one water” management that is using all of the water it can get to achieve more sustainable supplies to benefit cities, agriculture, and the environment. This program is the first of its kind to reuse a variety of waters including wastewater, stormwater, food industry processing water, and agricultural drainage water. This study investigates the partnerships, projects, and innovations that shape Monterey’s integrated water network in order to better understand the challenges and opportunities facing California communities as they seek to sustainably manage peri-urban water supplies. Water reuse in the Monterey region produces substantial economic and environmental benefits, from tourism and irrigation of high-value crops to protection of groundwater and increases in environmental flows and water quality. Water resource managers in other communities can learn from Monterey’s success leveraging local needs and regional partnerships to develop effective integrated water solutions. However, key challenges remain in resolving mismatched timing between water availability and demand, funding alternative water supplies, and planning effectively under uncertainty. Opportunities exist to increase Monterey’s recycled water supply by up to 50%, but this requires investment in seasonal storage and depends on whether desalination or additional recycling forms the next chapter in the region’s water supply story. Regulatory guidance is needed on seasonal subsurface storage of tertiary-treated recycled water as distinct from potable recharge. By increasing the supply of recycled water to Monterey’s indirect potable use system, the region’s potential need for seawater desalination may be delayed as much as 30 years, resulting in cost and energy savings, and giving the opportunity to resolve present planning concerns. 

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2. Life cycle greenhouse gas emissions for irrigated corn production in the U.S. great plains

   https://doi.org/10.1016/j.envc.2023.100750  

   Koushki, Raana ; Sharma, Sumit ; Warren, Jason ; Foltz, Mary E. ( December 2023 , Environmental Challenges)

   Agricultural management practices improve crop yields to satisfy food demand of the growing population. However, these activities can have negative consequences, including the release of greenhouse gas (GHG) emissions that contribute to global climate change. To mitigate this global environmental problem, the management practices that contribute the most to system GHG emissions should be identified and targeted to mitigate emissions. Accordingly, we estimated the cradle-to-product GHG emissions of irrigated corn production under various farmer-selected scenarios at an experimental testing field in the semi-arid U.S. Great Plains. We applied a carbon footprint approach to quantify life cycle GHG emissions associated with pre-field (e.g., energy production, fertilizer production) and in-field (e.g., groundwater pumping, fertilizer application) activities within fourteen scenarios in the 2020 Oklahoma Testing Ag Performance Solutions (TAPS) sprinkler corn competition. We determined that 63% of the total GHG emission from corn production was associated with in- field activities and that agricultural soil emissions were the overall driving factor. Soil biochemical processes within agricultural soils were expected to contribute an average of 89 ± 18 g CO2-eq kg− 1 corn of the total 271 ± 46 g CO2-eq kg− 1 corn estimated from these systems. On-site natural gas combustion for agricultural groundwater pumping, pre-field fertilizer production, and pre-field energy production for groundwater pumping were the next most influential parameters on total GHG emissions. Diesel fuel, seed, and herbicide production had insignificant contributions to total GHG emissions from corn production. The model was most sensitive to the modeled GHG emissions from agricultural soil, which had significant uncertainty in the emission factor. Therefore, future efforts should target field measurements to better predict the contribution of direct soil emissions to total GHG emissions, particularly under different managements. In addition, identifying the optimal application rate of irrigation water and fertilizer will help to decrease GHG emissions from groundwater irrigated crops. 

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3. Water shortage risks from perennial crop expansion in California’s Central Valley

   https://doi.org/10.1088/1748-9326/ab4035  

   Mall, Natalie K. ; Herman, Jonathan D. ( October 2019 , Environmental Research Letters)

   California’s Central Valley is one of the world’s most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from a vast network of reservoirs and canals as well as groundwater, which has been substantially overdrafted to support irrigation. The region has undergone a shift to perennial (tree and vine) crops in recent decades, which has increased water demand amid a series of severe droughts and emerging regulations on groundwater pumping. This study quantifies the expansion of perennial crops in the Tulare Lake Basin, the southern region of the Central Valley with limited natural water availability. A gridded crop type dataset is compiled on a 1 mi²spatial resolution from a historical database of pesticide permits over the period 1974–2016 and validated against aggregated county-level data. This spatial dataset is then analyzed by irrigation district, the primary spatial scale at which surface water supplies are determined, to identify trends in planting decisions and agricultural water demand over time. Perennial crop acreage has nearly tripled over this period, and currently accounts for roughly 60% of planted area and 80% of annual revenue. These trends show little relationship with water availability and have been driven primarily by market demand. From this data, we focus on the increasing minimum irrigation needs each year to sustain perennial crops. Results indicate that under a range of plausible future regulations on groundwater pumping ranging from 10% to 50%, water supplies may fail to consistently meet demands, increasing losses by up to 30% of annual revenues. More broadly, the datasets developed in this work will support the development of dynamic models of the integrated water-agriculture system under uncertain climate and regulatory changes to understand the combined impacts of water supply shortages and intensifying irrigation demand.

    

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4. The adaptive benefits of agricultural water markets in California

   https://doi.org/10.1088/1748-9326/abde5b  

   Arellano-Gonzalez, Jesus ; AghaKouchak, Amir ; Levy, Morgan C. ; Qin, Yue ; Burney, Jennifer ; Davis, Steven J. ; Moore, Frances C. ( March 2021 , Environmental Research Letters)

   Climate change is expected to increase the scarcity and variability of fresh water supplies in some regions with important implications for irrigated agriculture. By allowing for increased flexibility in response to scarcity and by incentivizing the allocation of water to higher value use, markets can play an important role in limiting the economic losses associated with droughts. Using data on water demand, the seniority of water rights, county agricultural reports, high-resolution data on cropping patterns, and agronomic estimates of crop water requirements, we estimate the benefits of market-based allocations of surface water for California’s Central Valley. Specifically, we estimate the value of irrigation water and compare the agricultural costs of water shortages under the existing legal framework and under an alternate system that allows for trading of water. We find that a more efficient allocation of curtailments could reduce the costs of water shortages by as much as $362 million dollars per year or 4.4% of the net agricultural revenue in California in expectation, implying that institutional and market reform may offer important opportunities for adaptation.

    

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5. Diets, Food Miles, and Environmental Sustainability of Urban Food Systems: Analysis of Nine Indian Cities

   https://doi.org/10.1029/2018EF001048  

   Boyer, D. ; Sarkar, J. ; Ramaswami, A. ( August 2019 , Earth's Future)

   With ever‐growing populations, cities are increasingly interested in ensuring a well‐functioning food system. However, knowledge of variation between individual city food systems is limited. This is particularly true in countries such as India, experiencing significant issues related to food security and sustainability. This paper advances the understanding of urban food systems, by analyzing the unique food systems of nine cities within India, through the integration of multiple city‐specific data sources including demand of residents, visitors and industries, and commodity‐specific supply chains to assess nutrition, environmental impact, and supply risk. This work finds a large degree of intercity food system variability across multiple food system characteristics. Specifically, levels of undernutrition vary, with the percentage of city populations who are underconsuming protein ranging from 0% to 70%, and for calories 0% to 90%. Environmental impacts (consumptive water loss, land use, and greenhouse gas emissions) of urban food demand also show variation, largely influenced by differing composition of residential diet. Greenhouse gas emissions are also largely influenced by location of production and spatially informed energy intensity of irrigation. Supply chain distance (“food‐miles”) also vary by city, with the range of 196 (Pondicherry) to 1,137 (Chennai) km/Mg—shorter than more industrialized nations such as the United States. Evaluating supply chain risk in terms of water scarcity in food‐producing regions that serve city demand finds production locations, on average, to be less water‐scarce than the watersheds local to the urban environments. This suggests water‐intensive agriculture may at times be best located at a distance from urban centers and competing demands.

    

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