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Purpose: This paper presents the regionalized water scarcity characterization factors (CFs) of the available water remaining (AWARE) model, which was found by a previous study, on the water scarcity in Brazil, to be the most indicative characterization model for the water-scarce regions in Brazil. We used the national database and hydrographic delimitations defined by the National Water Agency (Agência Nacional de Águas — ANA) to generate the regionalized AWARE BR CFs. Methods: The CFs were regionalized by hydrographic delimitations used by ANA: (i) State Hydrographic Units (SHU) and (ii) Hydrographic Regions (HR). These AWARE BR CFs were compared with the factors originally proposed by WULCA (2018) and with the Scarcity Index used by ANA to identify the scarcest regions in the country. Finally, the AWARE and AWARE BR factors were applied to a case study of Brazilian melons, evaluating the regionalization effects on the results of water scarcity analysis. Results and discussion: The AWARE BR CFs demonstrate most consistency with the regions recognized by ANA to have water scarcity problems, such as the semiarid region. Approximately 12% of the SHUs exhibited maximum water scarcity (CF = 100) during the entire year, while 11% presented minimum scarcity factors (CF = 0.1). The comparison of hydrologic data from ANA with those from WaterGAP indicated that water availability was overestimated in WaterGAP, while demand was underestimated in different basins. The comparison of AWARE BR CFs with ANA Scarcity Index values indicated more similarity (smaller residual error) than the comparison of AWARE BR CFs with AWARE. The case study regarding the impact of water scarcity on melons showed a significant difference between characterization factors and, consequently, in the values of impact. Conclusions: AWARE BR factors generated with national characterization data are adapted to the different regions of Brazil, exhibiting higher sensitivity to the semiarid region. This regionalization provided a more accurate representation of the scarcity in smaller basins located in larger basins, characterized by large climate variation. [ABSTRACT FROM AUTHOR]

Purpose: Fate factors, for freshwater eutrophication, represent the route of a limiting-nutrient, phosphorus or nitrogen, and their degradation in the environment. Their value may vary according to the location and emission season; that is, they are site and temporal dependent. In this study, phosphorus fate factors for the freshwater eutrophication impact category were estimated in a native scale of state hydrographic units (SHU), considering its variability and applied in a case study for one hydrographic basin in the state of Bahia, Brazil. Methods: The fate model considered the phosphorus removal processes of advection, retention, and agricultural and domestic water use, based on national databases (Geonetwork, HidroWeb, SAR, and SNIS). Heat maps and correlation networks allowed the assessment of fate factors' spatiotemporal variability. The new generated fate factors were qualitatively and quantitatively assessed, then further applied in a case study of buffalo milk production at Leste SHU to determine the regionalization effects on the freshwater eutrophication potential impact. Results and discussion: This study reconfirmed the spatial and temporal variability of the fate factors. The fate factor values found, in this study, for Pardo SHU are similar to those estimated with the non-regionalized data used by the adopted model, being within the range of 0 to 20 days. However, the fate factors for De Contas and, mainly, for Leste were underestimated, reaching a value up to five times higher, indicating that the model's proposed changes impacted the final result. The temporal differentiation was mainly determined by periods of higher and lower water availability. Advection processes inversely determined the fate factors, and the phosphorus removal by retention processes became more prominent when the water availability was lower. On the other hand, the role of phosphorus removal through water use was minimum. Water availability was the largest contributor to the sensitivity analysis, followed by the total freshwater volume. Conclusion: The fate modeling adopted in this study, with the use of data from national databases and native resolution, gave a more precise and detailed analysis perspective of the phosphorus fate in Brazilian SHUs, setting up site- and temporal-specific fate factors. Besides, this study provides a further understanding of the fate factors establishment by analyzing their relationship with the respective input parameters and highlighting one of the used model's weaknesses: the estimation of phosphorus removals instead of phosphorus load underestimates the true freshwater eutrophication potential. [ABSTRACT FROM AUTHOR]