Arabian Journal of Geosciences最新文献

Flood damage assessment is essential for the economic analysis of flood risk management in municipal and agricultural areas. In order to develop effective flood risk management plans, it is essential to have reliable flood damage models. This study aims to assess the economic losses caused by flood in the Shoor watershed, Esfahan, Iran, in April 2019. A digital elevation model (DEM) with a resolution of 1:1000 has been used to generate the river geometric cross-sections in HEC-GeoRAS software, and the inundation maps and vulnerable areas were specified by HEC-RAS software. Based on the results of this step, the HEC-FDA software has been employed to assess agricultural and municipal financial damage. The Monte-Carlo method was utilized to estimate Expected Annual Damage (EAD) based on vulnerability curves. Although HEC-FDA is primarily developed for estimating municipal damage, it was used to assess damage to agriculture indirectly by incorporating agricultural characteristics into the software. Results indicate that in the Shoor watershed, total losses were estimated about $517.800 in April 2019, mainly in agricultural classes. In this regard, the Damage-Reach No. 7 (D.R.7) experienced the highest economic losses with approximately about $317.000, while D.R.6 had the lowest amount of economic losses, with only about $16.900. These results show 84% compliance and correctness of our study results with the amount of damage caused by this flood in April 2019, which was about $440,000. Also, the results showed that discharge estimation with different return periods by HEC-FDA has high accuracy and is within the range of 5 to 95% confidence interval. Therefore, this watershed is relatively affected by floods and has noticeable economic losses. This study also could be beneficial for decision-makers in making decisions in flood management and reducing flood economic losses.

This research paper has presented Unified Soil Classification System (USCS)–based soil type and Standard Penetration Test (SPT) N₆₀–based zonation maps in the Dhaka Metropolitan Development Plan (DMDP) area of Bangladesh. For this purpose, 360 borehole data have been collected from different parts of the DMDP area. The data were analyzed in ArcGIS 10.5 using Ordinary Kriging and Inverse Distance Weighting (IDW) interpolation techniques. The spatial Analyst, Ordinary Kriging method, has demonstrated better results for SPT-N₆₀-based, and IDW has provided superior outcomes of the USCS-based soil type zonation maps. This study has developed 13 SPT-N₆₀-based and USCS soil-type zonation maps for the DMDP area at 1.5 to 19.5 m depth. To assess the reliability of the zonation map, SPT-N₆₀ values and USCS soil classification, acquired through field tests at 10 locations (depths: 1.5 to 19.5 m), were compared with anticipated SPT-N₆₀ values and USCS soil type at exact coordinates in the developed zonation maps. The root mean square error (RMSE) for the SPT-N₆₀ zonation maps was 8.29 blows, and the coefficient of determination (R²) was 0.688. The comparison shows a correlation coefficient of 0.82. For USCS soil-type zonation maps, 55.81% of the field-validated data fully matched the model-anticipated USCS zonation maps data. The generated zonation maps in this research will help to understand the subsurface condition and geotechnical characteristics of soils in the DMDP area. This data will also help engineers to create an initial foundation layout for a new site using the existing data from the nearby locations.

Access to groundwater for use in semi-arid regions is costly due to consistent failures in borehole drilling programs attributable to either a survey not carried out before drilling or incorrectly interpreted geophysical results. Thus, this study aims at delineating the geometry of the shallow weathered crystalline basement aquifer of the Vea catchment, northern Ghana, to aid in the assessment of its groundwater storage potential. Integrated electromagnetic and electrical resistivity surveys within the study area and borehole logs were integrated to delineate the aquifer zones of the study area. The study results revealed the interface between the bedrock and the overlying weathered subsurface as the most transmissive aquifer zone, with the saturated weathered subsurface making up 90% of the total volume of aquifers in the subsurface. The aquifer material in this zone predominantly includes varying proportions of sandy clay and weathered granite, with apparent resistivity ranging from 100 to 500 Ωm in the subsurface. Also, the results indicated that the weathered bedrock interface is irregular, and the water strike zone of the shallow aquifer in the weathered zone mimics the water table and the landscape of the area. Therefore, the study findings could improve the success rate of borehole drilling within the catchment and similar geological terrains.