Using the WEI+ index to evaluate water scarcity at highly regulated river basins with conjunctive uses of surface and groundwater resources

An artificial intelligence-based model for optimal conjunctive operation of surface and groundwater resources

A hybrid simulation-optimization model is proposed for the optimal conjunctive operation of surface and groundwater resources. This second-level model is created by finding and combining the best aspects of two resilient metaheuristics, the moth swarm algorithm and the symbiotic organization search algorithm, and then connecting the resulting algorithm to an artificial neural network simulator. For assessment of the developed model efficiency, its results are compared with two first-level simulation-optimization models. The comparisons reveal that the operation policies obtained by the developed second-level model can reliably supply more than 99% of the total demands in the study regions, indicating its superior efficiency compared to the two other first-level models. In addition, the highest sustainability index in the study regions belongs to the proposed model. Comparing the results of this research with those of other recent studies confirm the supremacy of the developed second-level model over several previously developed models.

Groundwater security indicators and their drivers: An assessment made in a region of tropical climate (Paraopeba River basin, Brazil)

Groundwater helps overcoming periods of drought buffering their effects on water supply to people, natural ecosystems and the economy. Following the latest Conference of the Parties (COP27), groundwater research gained renewed impulse because the Parties committed themselves to invest on environmental dimensions of water security related with aquifer characterization and protection. In that context, the purpose of this study was to help providing an integrated assessment to some fundamental issues about groundwater security, summarized as the three "how"s: how much, how ready and for how long can groundwater be delivered from watersheds? A complementary goal was to identify and quantify the role of watershed characteristics controlling these "how"s. The methodology combined hydrologic modeling and GIS and the results for the test site (Paraopeba River basin, Brazil) were: (1) the studied river tributaries mostly drain regolith aquifers with short hydrologic turnover times (1.3-23.7 yr) and small aquifer mobile storages (0.1-1.3 m), but high specific yields (0.2-8.2 m/yr), being generally prone to hydrologic droughts; (2) the specific discharge is primarily elevation controlled (via precipitation increases with altitude), but relates positively with drainage density as well; (3) the mobile storage in the Quadrilátero-Ferrífero mountain is larger than elsewhere, being influenced by a local geomorphologic setting (higher coverage with concave hillslopes); (4) the groundwater contribution to streamflow discharge is high (> 50 %, on average), being improved with the coverage of argisols; (5) vulnerability to droughts could be alleviated through expansion of water-retention infrastructure in specific regions, as well as through land use conversions targeting reduced evapotranspiration or sustainable land management of argisol and concave surface landscapes. Although applied to a specific catchment, our results stand on a site-independent methodological framework. Thus, the understanding about groundwater security gained with this study can be inspiring to other workers dealing with tropical climate landscapes.

The COP27 screened through the lens of global water security

Water security is an expression of resilience. In the recent past, scientists and public organizations have built considerable work around this concept launched in 2013 by the United Nations as "the capacity of a population to safeguard sustainable access to adequate quantities of acceptable quality water for sustaining livelihoods, human well-being, and socio-economic development, for ensuring protection against water-borne pollution and water-related disasters, and for preserving ecosystems in a climate of peace and political stability". In the 27th Conference of the Parties (COP27), held in Sharm El-Sheikh (Egypt) in last November, water security was considered a priority in the climate agenda, especially in the adaption and loss and damage axes. This discussion paper represents the authors' opinion about how the conference coped with water security and what challenges remain to attend. As discussion paper, it had the purpose to stimulate further discussion in a broader scientific forum.