Drought limits maize production in regions exposed to climate variability; however, estimates of agricultural and economic impacts depend on the precipitation data used to characterize drought. This study evaluates the relationship between growing-season drought and historical maize yields and estimates corresponding losses in production and gross income in the Colombian Caribbean. Municipal-level data from 191 municipalities across different agricultural cycles were analyzed using the Standardized Precipitation Evapotranspiration Index (SPEI) at 3- and 6-month accumulation scales, derived from the CHIRPS v3.0, GPCC v2025, and MSWEP v2.8 precipitation products. Fixed-effects panel models estimated yield responses, accounting for municipality, cycle, year, and department-specific temporal trends. Drought severity, derived from SPEI03 during the growing season, was negatively associated with maize yield in the CHIRPS and GPCC models (estimated coefficients of −0.042 and −0.039, respectively), while the MSWEP estimate was close to zero. The corresponding cumulative production losses, calculated using the models, were 76.2 thousand metric tons for CHIRPS and 71.6 thousand metric tons for GPCC, equating to estimated gross revenue losses of 115,550 million COP and 106,500 million COP, respectively, at constant 2024 prices. In contrast, the MSWEP model yielded much lower estimates: 2400 metric tons and 3.76 billion COP, with confidence intervals that included zero for both results. The negative associations between yield and precipitation under the CHIRPS and GPCC frameworks generally persisted across several alternative drought definitions, although they weakened when the growing season was shifted one month later. These results show how sensitive estimated drought-related agricultural losses are to crop choice and precipitation data, and support presenting crop-specific estimates and uncertainty when assessing climate-related risks to traditional maize production.
Highly stratified microtidal estuaries are governed by nonlinear baroclinic processes and delayed responses of estuarine circulation and salt-wedge propagation to transient river discharge. This study applies a two-layer numerical model to the lower 21.2 km of the Neretva River Estuary (Croatia), using 3456 hourly time steps and 93 cross-sections. Model calibration and validation draw on 2004 field observations comprising 30 CTD profiles collected over eight survey days and seven ADCP transects. The simulated salt-wedge toe exhibits a peak cross-correlation lag of 38 h relative to the flash-flood response; this lag is specific to the simulated event and 2004 boundary conditions. Bulk Richardson-number diagnostics identify the most persistent low-Rib conditions (Rib < 0.25) within a 4.2 km transition zone during modelled discharges of 180–280 m3/s, although intermittent low-Rib conditions also occur elsewhere. Baroclinic pressure gradients support landward intrusion at low flow (QA < 80 m3/s), while higher upper-layer momentum and interfacial shear promote downstream wedge displacement above 280 m3/s. Complete flushing of the modelled 21.2 km reach requires approximately 487 m3/s under the simulated 2004 geometry and forcing. The results provide a process-based interpretation of salt-wedge variability while identifying the limitations that must be addressed before operational application.
This review addresses a key research gap: palm oil milling’s water, energy, Palm Oil Mill Effluent (POME), and solid-residue flows are typically managed independently, while AI applications remain fragmented and rarely support integrated resource-allocation decisions. To address this gap, the review synthesises 109 sources retrieved under a PRISMA-reported protocol and classifies every reported capability as demonstrated in palm oil (A), demonstrated in analogous systems only (B), or proposed as an integration by this review (C), each class being given an operational definition and a validation scale. The term artificial intelligence is used here in the restricted sense of data-driven predictive modelling, model-based optimisation and closed-loop control, and these three functions are kept distinct throughout. The review states the nexus as a formal coupled decision problem with declared variables, objectives, constraints and time scales; specifies the dynamic material flow analysis and in-loop life cycle assessment that existing reviews identify as missing, including reconciliation, functional unit and allocation rules; and specifies how calibrated predictive uncertainty enters resource allocation. These are assembled into an AI-enabled resource-nexus digital twin operated under human oversight. The review finds that current palm-oil AI applications are concentrated in plantation sensing, single-unit treatment modelling, and response-surface optimisation, with validated industrial applications mainly involving anaerobic digestion, membrane separation, and selected biomass-conversion processes. It further identifies limited integration of Material Flow Analysis (MFA) and Life Cycle Assessment (LCA) into real-time operational decisions and inadequate propagation of feedstock and POME variability into resource allocation. Practically, the proposed framework provides a pathway for mills to coordinate water, energy, wastewater and residue management. The framework is a conceptual architecture accompanied by a stated evaluation protocol covering mass-balance closure, predictive accuracy and interval coverage, allocation performance against an incumbent policy, life-cycle consistency, robustness to effluent variability and computational feasibility.
This case study uses data from Greece, specifically the Region of Eastern Macedonia and Thrace, to examine the trade-offs of siting ground-mounted photovoltaic (PV) systems on agricultural land. Although PV siting is often guided primarily by solar yield, relatively small differences in solar resource may conceal substantial agricultural and environmental opportunity costs. The study applies an integrated screening framework that combines estimates from the Photovoltaic Geographical Information System (PVGIS) using the SARAH-3 database, parcel-level agricultural revenue data, and foregone carbon sequestration. Annual PV yield ranged from 1437 to 1516 kWh/kWp (coefficient of variation = 2.19%). Historical cumulative differential gross revenue over 2009–2021 reached €338.91 million, of which 90.52% was associated with arable parcels; Evros and Xanthi accounted for approximately 77% of this component, while Xanthi contributed 71% of the tree-crop component. Correlations between capacity factor and benefit share were 0.10 for arable parcels and −0.70 for tree crops, indicating that solar and economic rankings may diverge substantially. In 2021, differential gross revenue amounted to €10.884 million. Valuing the foregone carbon sink of 28,650 t CO2 yr−1 at approximately €380/t CO2 would close this gap, whereas at €200/t CO2, €5.154 million would remain. The findings indicate that PV siting should consider, beyond solar resource and grid adequacy, agricultural value and land capability, perennial investment, environmental factors such as carbon, biodiversity, water and landscape, distributional effects, and the feasibility of agrivoltaic or non-farmland alternatives. Excluding investment costs, discounting, grid constraints and lifecycle emissions, the proposed framework functions as a screening rather than a project-appraisal tool, supporting the identification of lower-opportunity-cost locations and the assessment of agrivoltaic options on high-value farmland.
Brazil holds a large rare-earth endowment and, since 2024, a commercial upstream operation, yet geological abundance has not translated into secure access to separated oxides, metals and magnets. This study examines how far Brazilian rare-earth capability extends along the value chain and why. We combine official mineral and trade statistics, facility disclosures, policy documents and peer-reviewed literature to score seven stages annually from 2015 to 2026 against explicit decision rules, distinguishing technological from commercial maturity and measuring how many consecutive stages from extraction operate at each level. Commercial capability now covers mining, beneficiation and the production of a mixed chemical intermediate, while separation, metallisation, magnet manufacture and circular recovery remain at research or pilot level. The record also reveals a discontinuity: pilot separation capacity documented in the mid-2010s was not sustained. Part of the recent downstream progress is disconnected from domestic feed, and the main commercial operation has been integrated into a foreign mine-to-magnet chain. We describe this configuration as a downstreaming paradox. For resource-rich economies, the findings indicate that resilience depends on connecting conversion stages in sequence, selectively and subject to explicit environmental safeguards that should be independently assessed before scale-up, rather than on extraction alone.
