Climate change and population growth play crucial roles in the planning of future water resources management strategies. In this paper, a balancing between projected water resources and water demands in the Iraqi Part of the Tigris River Basin (TRB) was evaluated till the year 2080 based on RCPs 2.6, 4.5 and 8.5 and population growth. This paper examined a sustainable adaptation plan of water resources in the TRB considering three scenarios; (S1) as no change in the current strategy, (S2) as improved irrigation efficiency and (S3) as improved irrigation and municipal water use efficiency. The results showed a decline in streamflow will occur in the range from 5 to 18.4% under RCP 2.6 and RCP 8.5, respectively. The minimum increase in water demand is expected for RCP 2.6 (maximum increase for RCP 8.5) by 51.8 (208.2), 9.9 (42) and 1.2 (7)% for the municipal–industrial, irrigation and environmental water demands, respectively, compared with the RP. The main finding indicated that S1 is the worst scenario, with water stress in four provinces, especially on the warmest RCP. Whereas, under S2 and S3 conditions, water stress can be eliminated. Increasing ambition towards adaptation becomes obligatory for developing sustainable water sources, supporting water food securities and increasing resilience towards climate change.

Accumulation of trace elements, including heavy metals, were evaluated in soil and fruits of chilli plants (Capsicum annuum L.) grown under both laboratory-controlled and semi-controlled greenhouse location conditions. Chilli plant biomass growth in different development stages and fruit productivity were evaluated and compared with each other for the impact of growth boundary conditions and water quality effects. Treated synthetic greywaters by different operational design set-ups of floating treatment wetland systems were recycled for watering chillies in both locations. Effluents of each individual group of treatment set-up systems were labelled to feed sets of three replicates of chilli plants in both locations. Results revealed that the treated synthetic greywater (SGW) complied with thresholds for irrigation water, except for high concentrations (HC) of phosphates, total suspended soils, and some trace elements, such as cadmium. Chilli plants grew in both locations with different growth patterns in each development stage. First blooming and high counts of flowers were observed in the laboratory. Higher fruit production was noted for greenhouse plants: 2266 chilli fruits with a total weight of 16.824 kg with an expected market value of GBP 176.22 compared to 858 chilli fruits from the laboratory with a weight of 3.869 kg and an estimated price of GBP 17.61. However, trace element concentrations were detected in chilli fruits with the ranking order of occurrence as: Mg > Ca > Na > Fe > Zn > Al > Mn > Cu > Cd > Cr > Ni > B. The highest concentrations of accumulated Cd (3.82 mg/kg), Cu (0.56 mg/kg), and Na (0.56 mg/kg) were recorded in chilli fruits from the laboratory, while greater accumulations of Ca, Cd, Cu, Mn, and Ni with concentrations of 4.73, 1.30, 0.20, 0.21, and 0.24 mg/kg, respectively, were linked to fruits from the greenhouse. Trace elements in chilli plant soils followed the trend: Mg > Fe > Al > Cr > Mn > Cd > Cu > B. The accumulated concentrations in either chilli fruits or the soil were above the maximum permissible thresholds, indicating the need for water quality improvements.

This paper reports a research work on assessing clay content effect on the water retention capacity of clayey sandy soils. At first, experimental tests were conducted to measure the soil water retention curves (SWRCs) of clayey sandy soils. A total of four different soil samples, which have clay content of 0, 15, 30 and 50%, respectively, by total soil sample weight, were measured. Secondly, a revision of a physical–chemical (PC) analytical model previously proposed has been reviewed and adopted to represent the SWRC measurements and compared for its predictive performance against the classic van Genuchten model and the original PC model. The experimental results demonstrated that clay content has a significant influence on soil water retention capacity, showing that a positive correlation generally exists between them. The modelling results showed that the revised analytical model not only produced a good representation for the soil water retention curves over whole range of soil water content, particularly at low water content side, but also provided advanced insight into the fundamental physics underlying soil water retention mechanisms. The analysis of its parametric data highlights the functions of the involved physics and their roles shaping the SWRCs, which intrinsically relate to specific surface area, pore size distribution, and particle size and shape. At last, the model was used to describe the pore size distribution from a revised concept against conventional approach. However, the revised concept and approach needs further wide verification and is open for discussion.