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Water supply and demand management (WSDM) is essential for developing sustainable cities and societies. WSDM is only effective when tackled from the perspective of a holistic system understanding that considers social, environmental, hydrological, and economic (SEHEc) sub-systems. System dynamics modeling (SDM) is recommended by water resource researchers as it models the biophysical and socio-economic systems simultaneously. This study presents a comprehensive literature review of SDM applications in sustainable WSDM. The reviewed articles were methodologically analyzed considering SEHEc sub-systems and the type of modeling approach used. This study revealed that problem conceptualization using the causal loop diagram (CLD) was performed in only 58% of the studies. Moreover, 70% of the reviewed articles used the stock flow diagram (SFD) to perform a quantitative system analysis. Furthermore, stakeholder engagement plays a significant role in understanding the core issues and divergent views and needs of users, but it was incorporated by only 36% of the studies. Although climate change significantly affects water management strategies, only 51% of the reviewed articles considered it. Although the scenario analysis is supported by simulation models, they further require the optimization models to yield optimal key parameter values. One noticeable finding is that only 12% of the articles used quantitative models to complement SDM for the decision-making process. The models included agent-based modeling (ABM), Bayesian networking (BN), analytical hierarchy approach (AHP), and simulation optimization multi-objective optimization (MOO). The solution approaches included the genetic algorithm (GA), particle swarm optimization (PSO), and the non-dominated sorting genetic algorithm (NSGA-II). The key findings for the sustainable development of water resources included the per capita water reduction, water conservation through public awareness campaigns, the use of treated wastewater, the adoption of efficient irrigation practices including drip irrigation, the cultivation of low-water-consuming crops in water-stressed regions, and regulations to control the overexploitation of groundwater. In conclusion, it is established that SDM is an effective tool for devising strategies that enable sustainable water supply and demand management.

The Soil and Water Assessment Tool (SWAT) is a well-established eco-hydrological model that has been extensively applied to watersheds across the globe. This work reviews over two decades (2002-2022) of SWAT studies conducted on Mediterranean watersheds. A total of 260 articles have been identified since the earliest documented use of the model in a Mediterranean catchment back in 2002; of which 62% were carried out in Greece, Italy, or Spain. SWAT applications increased significantly in recent years since 86% of the reviewed papers were published in the past decade. A major objective for most of the reviewed works was to check the applicability of SWAT to specific watersheds. A great number of publications included procedures of calibration and validation and reported performance results. SWAT applications in the Mediterranean region mainly cover water resources quantity and quality assessment and hydrologic and environmental impacts evaluation of land use and climate changes. Nevertheless, a tendency towards a multi-purpose use of SWAT is revealed. The numerous examples of SWAT combined with other tools and techniques outline the model's flexibility. Several studies performed constructive comparisons between Mediterranean watersheds' responses or compared SWAT to other models or methods. The effects of inputs on SWAT outputs and innovative model modifications and improvements were also the focus of some of the surveyed articles. However, a significant number of studies reported difficulties regarding data availability, as these are either scarce, have poor resolution or are not freely available. Therefore, it is highly recommended to identify and develop accurate model inputs and testing data to optimize the SWAT performance.

A growing number of studies has suggested potential impacts of meteorological variables on the spread of the COVID-19 pandemic. These impacts are supported by data from similar viral contagions, such as SARS and the 1918 Flu Pandemic, and corroborated by US influenza data relative to the last decade. However, there is still limited understanding about the extent to which meteorology affects COVID-19 transmission rates and how meteorology can be a relevant element to anticipate social and politic measures. This study demonstrates that such an understanding is attainable through the development of regression models that verify the contribution of meteorology to the modeling of COVID-19 transmission, and the use of feature importance techniques assessing the relative weight of meteorological variables compared to epidemiological, socioeconomic, environmental, and global health indicator factors. The study results show that meteorological factors play an important role in regression models of COVID-19 transmission that have low error rates (R2 0.964). These results are corroborated by a panel data fixed-effect model showing that meteorological coefficients are often significantly correlated with COVID-19 transmission rates (R2 0.691-0.746, p

We develop a water budget model that quantifies and forecasts water deficits and groundwater depletion of the main exploitable fresh fossil aquifer systems in North Africa and the Arabian Peninsula under different climatic and socio-economic scenarios from 2016 until 2050. Our results suggest that in the upcoming few decades, under the most plausible climatic and socio-economic scenario (SSP2-AVG), within North Africa, only Egypt and Libya will experience severe water deficits with respectively ∼ 45% and ∼ 90% of their current water budget in 2050. For the Arabian Peninsula, all countries will undergo water deficits, ranging from ∼ 20% for Saudi Arabia to almost double the supply for Yemen ( ∼ 190%). Under these alarming deficits, resulting from severe anthropogenic discharges, the majority of the small to mid-size exploitable fossil aquifer systems in the Arabian Peninsula could reach full depletion by 2050 and the total depletion of groundwater resources in all aquifer systems could be reached in ∼ 60–90 years. Over the same time span, North African fossil aquifers will lose 1–15% of their exploitable fresh water volume and may reach total depletion in ∼ 200–350 years with the projected increased extraction rates. We find that the major cause of the water budget deficit and groundwater depletion in the MENA area are anthropogenic drivers rather than climatic ones. Finally, we conclude that if current hydrologic, climatic and socio-economic trends continue, the nations with the lowest gross domestic product per capita, like Egypt, Yemen and Libya, will undergo the highest water deficit per capita, leading to a significant rise in food prices, potentially resulting in more socio-economic instabilities over the next three decades.

Eastern Arabian Peninsula represents the main natural groundwater discharge area of the Arabian platform fossil aquifer system. In such settings, connections between aquifers could strongly affect the flow dynamics, water quality and availability as well as karst formation and landscape evolution. Geological structures such as folds and faults are central to aquifer connectivity, yet their role on groundwater flow is poorly understood. Herein, we perform mapping of exposed and buried structural features in the Qatar Peninsula using Landsat, Sentinel-2 and ALOS-PalSAR scenes, correlated with field, GPR and isotopic data to assess their role in aquifer connections and groundwater dynamics. Our results suggest that ENE-WSW oriented fold-related faults act as vertical conduits along which artesian upward leakages from the deep Aruma aquifer take place into the shallower main aquifer unit (i.e. Umm er Radhuma and Rus) in southern Qatar Peninsula. On the other hand, downward leakage from the freshwater lens in the Dammam aquifer take place in northern Qatar Peninsula. The deep, brackish, and gaseous-rich waters ascending along faults in south Qatar Peninsula, in addition to degrading the water quality in the main aquifer unit, enhance dissolution of carbonates and evaporites leading to strong karstification that produces abundant collapse features. Our findings suggest that structure controls can add significant complexity to recharge mechanisms and groundwater dynamics in fossil aquifers. Future large-scale radar subsurface mapping will be essential to resolve the variability of the water heads in such areas and its correlation to structural discontinuities.

North Africa is classified as one of the Earth’s driest environments (UNESCO 1979), with an aridity index that falls below 0.2 (Penman in Proc Roy Soc A 193(1032):120–145, 1948).