A review of modelling methodologies for flood source area (FSA) identification

Flooding is an important global hazard that causes an average annual loss of over 40 billion USD and affects a population of over 250 million globally. The complex process of flooding depends on spatial and temporal factors such as weather patterns, topography, and geomorphology. In urban environments where the landscape is ever-changing, spatial factors such as ground cover, green spaces, and drainage systems have a significant impact. Understanding source areas that have a major impact on flooding is, therefore, crucial for strategic flood risk management (FRM). Although flood source area (FSA) identification is not a new concept, its application is only recently being applied in flood modelling research. Continuous improvements in the technology and methodology related to flood models have enabled this research to move beyond traditional methods, such that, in recent years, modelling projects have looked beyond affected areas and recognised the need to address flooding at its source, to study its influence on overall flood risk. These modelling approaches are emerging in the field of FRM and propose innovative methodologies for flood risk mitigation and design implementation; however, they are relatively under-examined. In this paper, we present a review of the modelling approaches currently used to identify FSAs, i.e. unit flood response (UFR) and adaptation-driven approaches (ADA). We highlight their potential for use in adaptive decision making and outline the key challenges for the adoption of such approaches in FRM practises

Assessment the flood hazard arising from land use change in a forested catchment in northern Iran

The provinces of northern Iran that border the Caspian Sea are forested and may be prone to increased risks of flooding due to deforestation and other land use changes, in addition to climate change effects. This research investigated changes in runoff from a small forested catchment in northern Iran for several land use change scenarios and the effects of higher rainfall and high antecedent soil moisture. Peak discharges and total runoff volumes from the catchment were estimated using the US Soil Conservation Service 'Curve Number' (SCS-CN) method and the SCS dimensionless unit hydrograph. This method was selected for reasons of data availability and operational simplicity for flood managers. A GIS was used to manipulate spatial data for use in the catchment runoff modelling. The results show that runoff is predicted to increase as a result of deforestation, which is dependent on the proportion of the catchment area affected. However, climate change presents a significant flood hazard even in the absence of deforestation. Other land use changes may reduce the peak discharges of all return period floods. Therefore a future ban on timber extraction, combined with agricultural utilisation of rangeland, could prove effective as 'nature-based' flood reduction measures throughout northern Iran

Spatial patterns and temporal variability of drought in Western Iran

An analysis of drought in western Iran from 1966 to 2000 is presented using monthly precipitation data observed at 140 gauges uniformly distributed over the area. Drought conditions have been assessed by means of the Standardized Precipitation Index (SPI). To study the long-term drought variability the principal component analysis was applied to the SPI field computed on 12-month time scale. The analysis shows that applying an orthogonal rotation to the first two principal component patterns, two distinct sub-regions having different climatic variability may be identified. Results have been compared to those obtained for the largescale using re-analysis data suggesting a satisfactory agreement. Furthermore, the extension of the large-scale analysis to a longer period (1948–2007) shows that the spatial patterns and the associated time variability of drought are subjected to noticeable changes. Finally, the relationship between hydrological droughts in the two sub-regions and El Niño Southern Oscillation events has been investigated finding that there is not clear evidence for a link between the two phenomen

The Microstructural Study of in Situ Al Alloy 319 Based Composite Reinforced by Iron-Based Intermetallic Produced by Stir Casting Process

The effect of stir casting process on the modification of the Fe-containing intermetallics formed in a cast in-situ composite based on Al-319 matrix alloy was studied in the present work. Microstructural observations using optical and scanning electron microscopes showed that the undesirable needle-like shape of the Fe-containing intermetallics (β) and also the coarse star-like α compounds were modified into the disc and spheroid shape particles with much less length to width ratio. The effect of parameters such as stirring temperature, cooling rate and Fe contents on the shape, size and distribution of intermetallic particles and eutectic Si blades were also studied. Results showed that the best condition to improve the shape, size and distribution of  intermetallic particles can be achieved at a stirring speed of 1200 rpm for 5 minutes at the vicinity of β needles nucleation temperature followed by casting into a metallic mold. Based on the results obtained from the current work, it can be concluded that the harmful morphology of the β intermetallic needles can be properly modified by applying a shearing force during stirring the molten alloy in the semi-solid state

Thermochemical synthesis of nanostructured Cu-Al2O3 composite powder

Synthesis of Cu-Al2O3 nanocomposite powder through a thermochemical method from the water solution of copper nitrate (Cu (NO3)2.3H2O) and aluminum nitrate (Al (NO3)6.9H2O) is studied in this research. X-ray diffraction (XRD) technique, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to characterize the synthesized powder. XRD results show that γ-Al2O3 phase begins to form at the temperature ≈800°C during the heat treatment process. Studying SEM micrographs proves that the nano sized Al2O3 particles are homogenously dispersed in the copper matrix. XRD results also show that disappearing the reflects of CuO peaks after performing a reduction chemical reaction at the temperatures above 800°C in hydrogen atmosphere indicates that such chemical reaction at the temperatures above 800°C is required in order to achieve Cu-Al2O3 nanocomposite powder

Eutectic Nucleation in 7xxx Series Aluminum Alloys from a Non-classical Viewpoint

The early stages of eutectic solidification in a copper-containing 7xxx series aluminum alloy (AA 7068 or AMS 4331) were studied using the two-thermocouple computer-aided thermal analysis (CATA) technique. A feature was detected on the cooling rate curve at the equilibrium solidus temperature of the alloy which persists until the peak of the subsequent final eutectic solidification. Detailed analysis of the temperature difference between the wall and the center of the thermal analysis sample, together with examination of the eutectic solidified on the walls of porosities and a study of the eutectic nucleation on the basis of the non-classical theory of adsorption heterogeneous nucleation, indicated how the feature can be related to the faceting of the atomic structure of the solid/liquid (S/L) interface. The solidification of the remnant liquid after the faceting transition at the equilibrium solidus point depends on the interfacial undercooling and proceeds via either primary phase re-nucleation or secondary phase nucleation by adsorption. The eutectic solidification is affected by the presence of the primary phase which acts like an adsorbent