Saudi Arabia (SA) faces a water shortage, and it further challenges sustainable agriculture, industrial development and the well-being of people. SA uses more than 80% of its water resources for agricultural purposes. Groundwater extractions account for most of this demand, which is not sustainable. Hence, this study aims to analyze water management practices used in SA to propose viable and workable solutions to achieve sustainable management of scarce water resources. This study is based on a critical evaluation of information available on the water sector in SA. About 89% of the water demand in the Kingdom is non-sustainably met through over-pumping from groundwater resources and 9.3% by energy-intensive desalination. SA invested in dams and developed rainwater harvesting to enhance surface water availability and increase the recharge capacity of renewable aquifers. As there is a huge demand–supply gap, water demand management tools are the viable solutions leading to sustainability compared to supply enhancement that is capital intensive. A national agricultural policy, together with a water policy, can make agricultural systems more input efficient with higher productivity. Region-specific sustainable water resources management plans need to be implemented to match the demand–supply gap. Conjunctive water uses utilizing and prioritizing different water sources viz. harvested rainwater, treated wastewater, desalinized water, and groundwater, is vital in sustainable water resources management. In addition, climate change has exerted pressure on the available water resources and water uses as well as users, leading to adaptation for measures that are more sustainable in terms of water management. The most pressing problem SA faces in water resources management is the depletion and degradation of surface and subsurface water sources. SA has to implement many technological and legislative changes in addition to service management, conservation measures, paying a reasonable and justifiable price for water, and strengthening state agencies that will make water resources management in SA sustainable.

Global food security challenges have been burdened by a rapidly expanding population and its attendant food demands. Safer and higher-quality agriculture is one of the most essential solutions for addressing the growing problem. In agriculture that is safer, the quality of irrigation from a safer water source will boost food security. Groundwater is one of the most widely utilized water sources for agriculture. Safeguarding groundwater against contamination and preserving water resources is a rising global concern. Herein, previous literature studies were analyzed to determine the groundwater potential for food production of the various continents around the globe, as well as the various types of groundwater contamination, the sources of groundwater contamination, and the best methods for combating groundwater contamination in order to guarantee safe irrigation for agriculture and thus achieve food security. Consequently, the natural and anthropogenic activities that degrade the quality of the groundwater and transform it into contaminated water from harmful organisms, residues of organic and inorganic soluble and non-soluble salts of the groundwater from chemical, leachate from landfills, sewage systems, and biological contamination, are the major issues in safer agriculture, causing a number of problems in the growth of agricultural crops and leading to a negative impact on food production as well as on the health of the population. Proper identification of different sources of contamination and proper methods to prevent contamination from reaching groundwater, as well as governmental and institutional frameworks to combat contamination and treatment methods to treat contaminated groundwater, will contribute to the future achievement of food security by ensuring a safer irrigation method and agriculture.

The assessment of pesticide residues in agricultural soils is an essential prerogative in maintaining environmental health standards. Intensive vegetable cultivation is practiced in the Al-Kharj area of the eastern Najd region of Saudi Arabia, where excessive applications of agrochemicals are reported to pollute vegetable-growing soils, challenging the sustainable management of soils and groundwater resources. This study aimed to monitor the levels of thirty-two types of pesticide residues in the soils of vegetable fields and the estimated potential health risk for humans due to non-dietary exposure to pesticides in soils in the Al-Kharj region. Pesticide residues were evaluated at 0–10 cm and 10–20 cm depths at 20 sampling sites from Al-Kharj. Gas chromatograph-mass spectrometry, coupled with a quadrupole mass spectrometer with a GC column, was used in the analysis. The results indicated that agrochemical residues show prolonged soil pollution that may cause adverse impacts on human and environment. Herbicides Atrazine, Isoproturpon, and Linuron have been detected in the soils, and these pose many problematic environmental threats. Bromoxynil, Pendimetholin, and Diclofop-methyl could be used as per the recommendations to sustainably manage soil and water resources in the Al-Kharj area. Resmethrin, Methidathion, Ethoprophos, Tetramethrin, Bromophis-methyl, Bifenthion, Permethrin, Fenoxycarb, Cyfluthrin, Phosmet, and Azinophos-methyl can be used safely in the Al-Kharj agricultural area, maintaining sustainable soils and water resources. Applications of Carbaryl require sufficient care, while Endosulfan, Deltamethrin, Lindane, Chlorpyrifos, Chlorpyrifos-methly, Dimethoate, Heptachlor, and Mevinphos, which are detected in soils, require policy guidelines to limit the use to ensure sustainability. Policy interventions need to be formulated to increase the sustainability of soil management and groundwater resources in the Al-Kharj region to ensure the safety of people who are in direct contact with the agrochemicals used and to ensure the safety of agricultural products generated in this region.

Larval indices such as Premise Index (PI), Breteau Index (BI) and Container Index (CI) are widely used to interpret the density of dengue vectors in surveillance programmes. These indices may be useful for forecasting disease outbreaks in an area. However, use of the values of these indices as alarm signals is rarely considered in control programmes. Therefore, the current study aims to propose threshold values for vector indices based on an empirical modeling approach for the Kandy District of Sri Lanka. Monthly vector indices, viz PI, BI and CI, for Aedes aegypti and Aedes albopictus, of four selected dengue high risk Medical Officer of Health (MOH) areas in the Kandy District from January 2010 to August 2017, were used in the study. Gumbel frequency analysis was used to calculate the exceedance probability of quantitative values for each individual larval index within the relevant MOH area, individually and to set up the threshold values for the entomological management of dengue vectors. Among the study MOH areas, Akurana indicated a relatively high density of both Ae. aegypti and Ae. albopictus, while Gangawata Korale MOH area had the lowest. Based on Ae. aegypti, threshold values were defined for Kandy as low risk (BI_agp > 1.77), risk (BI_agp > 3.23), moderate risk (BI_agp > 4.47) and high risk (BI_agp > 6.23). In addition, PI > 6.75 was defined as low risk, while PI > 9.43 and PI>12.82 were defined as moderate and high risk, respectively as an average. Threshold values recommended for Ae. aegypti (primary vector for dengue) along with cut-off values for PI (for Ae. aegypti and Ae. albopictus), could be suggested as indicators for decision making in vector control efforts. This may also facilitate the rational use of financial allocations, technical and human resources for vector control approaches in Sri Lanka in a fruitful manner.

A comprehensive study incorporating results from different findings related to heavy metal removals from wastewater using sludge as an absorbent will assist researchers and practitioners in planning wastewater treatment processes. This study aims to provide a comprehensive foundation on the potential of using sludge-based materials to remove heavy metals from wastewater based on recent studies. The physicochemical properties of sludge and the nature of metal ions have significantly contributed to the adsorption of heavy metals into sludge-based materials. Many researchers found the effects of pH, temperature, initial heavy metal concentrations, contact time, and adsorbent dose on the adsorption characteristics of heavy metals into sludge-based materials. Isotherm, kinetic, and thermodynamic studies have explained the mechanism of heavy metal adsorption by sludge-based materials. The effectiveness of regeneration of sludge-based adsorbents has been investigated by some researchers, providing an environmentally friendly solution to remove heavy metals from wastewater. It was found that less attention has been paid to metal recovery and recycling of sludge-based adsorbents, which indicates the need for future studies to enhance the reusability of sludge in wastewater treatment. Moreover, many studies have been conducted as lab-scale experiments on heavy metal adsorption from aqueous solutions using sludge-based adsorbents, leaving a research gap for future studies to focus on the removal of heavy metals from actual wastewater at field scale.