Evaluation of integrating swat model into a multi-criteria decision analysis towards reliable rainwater harvesting systems

Rainwater harvesting (RWH) has been recognized as one of the most reliable and efficient methods for water supply, especially in arid and semi-arid regions (ASARs) facing freshwater scarcity. Nevertheless, due to the inherent uncertainty of input data and subjectivity involved in the selection of influential parameters, the identification of RWH potential areas is a challenging procedure. In this study, two approaches for locating potential RWH sites were implemented. In the first approach, a frequently-used method of the multi-criteria decision analysis and geographic information system (MCDA-GIS) was utilized, while, in the second approach, a novel strategy of integrating the soil and water assessment tool (SWAT) model as a hydrology model into an MCDA-GIS method was proposed to evaluate its performance in locating potential RWH sites. The Mashhad Plain Basin (MPB) was selected as a case study area. The developed potential RWH maps of the two approaches indicated similar patterns for potential RWH areas; in addition, the correlation coefficient (CC) between the two obtained maps were relatively high (i.e., CC = 0.914) revealing that integration of SWAT as a comprehensive hydrologic model does not necessarily result in very different outputs from the conventional method of MCDA-GIS for RWH evaluation. The overlap of developed maps of the two approaches indicated that 3394 km2 of the study area, mainly located in the northern parts, was identified as high-potential RWH areas. The performed sensitivity analysis indicated that rainfall and slope criteria, with weights of 0.329 and 0.243, respectively, had the greatest sensitivity on the model in the first approach while in the second approach, the criterion of runoff coefficient (with weights of 0.358) had the highest impact. Based on results from the identification of the potential locations for conventional RWH techniques, pond and pan techniques are the most proper options, covering high-potential areas of RWH more effectively than other techniques over MPB.Water Resource

Effect of SiC nanoparticle content and milling time on the microstructural characteristics and properties of Mg-SiC nanocomposites synthesized with powder metallurgy incorporating high-energy ball milling

The fabrication of magnesium nanocomposites with a homogeneous dispersion of nanoparticles has recently become an important issue. In the current study, micro-sized magnesium powders reinforced with 10, 20, and 30 wt% SiC nanoparticles were synthesized through high-energy ball milling using milling times ranging from 1 to 20 h to overcome the segregation and agglomeration of nanoparticles within the magnesium matrix. The milled nanocomposite powders were then consolidated using uniaxial cold pressing and sintering processes. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction were employed to investigate the effects of different milling times and contents of SiC nanoparticles on the evolution of the morphology of Mg–SiC milled powders and the microstructural characteristics of Mg–SiC sintered samples. In addition, once the consolidation process was complete, the relative densities and hardness values of the Mg–SiC nanocomposites were examined. The results indicated that as the content of SiC nanoparticles and the milling time increased, finer and equiaxed nanocomposite powders were obtained, and the average crystallite size of the milled magnesium powder significantly decreased. A homogeneous distribution of the SiC nanoparticles, including up to 30% of weight fraction, in the magnesium matrix was confirmed after 20 h of milling by elemental mapping generated by EDS. Additionally, the XRD analysis revealed that the diffraction peaks of the magnesium broadened while their maximum intensities decreased with increasing the milling time and SiC content. No undesirable phases were formed by interfacial reactions between magnesium and SiC nanoparticles in the milled nanocomposite powder during mechanical alloying. Furthermore, the results showed that both the relative density and hardness value of the Mg–SiC sintered sample improved as the milling time increased. However, the relative density of the Mg–SiC nanocomposite drastically decreased while the hardness significantly improved, as a result of increasing the content of SiC nanoparticles