For managing the freshwater in the worldwide coastal aquifers, it is imperative to understand the hydrogeochemical processes and flow patterns in the mixing freshwater/saltwater zone. The Egyptian Nile Delta aquifer is a typical example. The management of seawater intrusion (SWI) requires detailed investigations of the intrusion wedge and the dynamic processes in the mixing zone. Thus, a multidisciplinary approach was applied based on holistic hydrogeochemical, statistical analysis, and DC resistivity measurements to investigate the lateral and vertical changes in groundwater characteristics undergoing salinization stressor. The results of cross plots and ionic deviations of major ions, hydrochemical facies evolution diagram (HFE-D), and seawater mixing index (SMI) were integrated with the resistivity results to show the status of the SWI where the intrusion phase predominates in ~2/3 of the study are (~70 km radius) and the compositional thresholds of Na, Mg, Cl, and SO₄ are 600, 145, 1200, and 600 mg/L, respectively, indicating that the wells with higher concentrations than these thresholds are affected by SWI. Moreover, the results demonstrate the efficiency of combining hydrogeochemical facies from heatmap and resistivity investigations to provide a large-scale characterization of natural and anthropogenic activities controlling aquifer salinization to support decision-makers for the long-term management of coastal groundwater.

Sediment, often considered a by-product of various activities within river basin management to be disposed of, or a pollutant to be controlled, is increasingly being acknowledged as a resource in need of management. The paper deals with the possibility of reusing sediment from two Slovak reservoirs (Klusov and Ruzin) as an alternative raw material in concrete production. Concrete specimens were prepared by a combination of original reservoir sediment, reservoir sediment mechanically activated by dry milling, reservoir sediment mechanically activated by dry milling together with biomass incinerator fly-ash as a binder. To improve the strength properties of specimens, sodium hydroxide (NaOH) was used as a sediment activator. Mixtures containing 40% of binder replacement by the above-mentioned combinations of original and treated sediments were tested for flexural and compressive strengths after 28, 90 and 365 days of curing. The results showed that the mixtures prepared from sediments milled without and with addition of fly ash as cement replacement satisfied the strength requirements for the compressive strength class C16/20 according to the European standard except the composites prepared with NaOH as the sediment activator. Addition of NaOH into composites in the concentration of 5 M as an activator of sediment indicated the negative impact on compressive and flexural strengths and thus NaOH was not an effective pozzolanic activator for sediments. This study reveals that the sediment may be considered as 40% cement substitution in building materials.

Climate change could cause changes in temperature and precipitation patterns that may increase the probability of drought. Climate change could enormously affect arid regions, and many countries may suffer from drought. This study aims to monitor the historical drought in Syria. Monthly data was collected from 71 land stations for the period (1991–2009). After 2010, the field data were not available due to the civil war in Syria. The satellite images for monthly precipitation were collected for the period (1983–2020). Remote Sensing (RS) and Geographic Information System (GIS) were used to correct the satellite images using the land station data for the period (1991–2009), and a correction equation was developed for each station that was used to correct the data for the period (1983–2020). Drought risk analysis was carried out utilizing the Standardized Precipitation Index (SPI) in the period (1983–2020). Three main types of droughts have been detected: meteorological, agricultural and hydrological drought. The results showed that significant drought struck Syria, where, the long-term drought (hydrological) occurred in 1988–1989 and 2013–2014. From the assessment of months for the period 1983–2020 in Syria, it is obvious that the driest year was 2013, and extremely dry and very dry were repeated in the years 1988, 1993, 1999, 2003, 2008, 2013 and 2017. This reveals that the dry season is repeated between 4 and 6 years with an average of 5 years. The results of the SPI trend analysis showed increasing trends at all the stations. This highlights the impact of climate change on Syria, which may suffer from more droughts in the future, which in turn affect the availability of water resources. The results of this research could help to manage water resources and adapt to climate change risks in Syria. The results proved that SPI is a useful tool to monitor drought that could help decision-makers put efficient plans for drought risk management. Graphical Abstract The current study aims to monitor the historical drought in Syria using remote sensing data. Monthly data was collected from 71 land stations for the period (1991–2009). Then satellite images for monthly precipitation were collected for the period (1983–2020). RS and GIS were used to correct the satellite images using the land station data for the period (1991–2009), and a correction equation was developed for each station that was used to correct the data for the period (1983–2020). Drought risk analysis was carried out utilizing SPI in the period (1983–2020). Three main types of droughts have been detected: meteorological, agricultural and hydrological drought. The findings indicated that Syria experienced significant drought conditions, with the long-term drought index (SPI-12) identifying periods of extreme dryness during 1988–1989 and 2013–2014. The results show that 2013 was the driest year, while extremely dry and very dry conditions recurred in the years 1988, 1993, 1999, 2003, 2008, 2013, and 2017. This pattern reveals that dry seasons tend to occur every 4 to 6 years, averaging 5 years. The trend analysis of the SPI revealed an increasing trend across all monitoring stations, underscoring the influence of climate change on Syria, which may face an increased frequency of droughts in the future, thereby impacting water resource availability. The insights gained from this research could be instrumental in managing water resources and addressing the risks associated with climate change.