Globally, flash floods are the most damaging natural hazards, because of its sudden nature and difficulty in forecasting that restrains emergency responses. Flash floods triggered by thunderstorms are frequent in the high mountainous area of Hindukush Himalaya in the north of Pakistan. The current study employed two widely used approaches for flash flood risk modeling, i.e., morphometric ranking approaches (MRAs) and El-Shamy’s approach to analyzing their effectiveness for flash flood susceptibility modeling in Swat river watershed, district Swat, Pakistan. The digital elevation model was utilized to delineate the watershed and drainage network using the ArcHydro tool of ArcGIS. A total of 15 morphometric parameters have been used for flash flood modeling. The analysis suggests that the Swat river watershed consists of 17 sub-basins. The MRA-based flash flood risk assessment suggests that sub-basins B1 and B2 (12% of total sub-basins) are highly susceptible to flash flooding. While sub-basins B4, B6, B11, B13, and B17 (59% of the total sub-basin) are moderately susceptible to flash flood risk. El-Shamy-based modeling suggests that sub-basins B12, B14, and B16 (18% of total sub-basins) have high flood susceptibility while sub-basin B5 has the lowest. The field observation and 2010 flood reports by WHO and NDMA suggest that the flash flood susceptibility modeling results by the MRA are more accurate as compared with El-Shamy’s approach. The results of the study perceived to help execute appropriate remedial measures to extenuate the potential flash floods in the study area.

Flash flood risk modeling of swat river sub-watershed: a comparative analysis of morphometric ranking approach and El-Shamy approach

Mechanical response and strain localization in coal under uniaxial loading, using digital volume correlation on X-ray tomography images

https://link.springer.com/content/pdf/10.1007/s40948-021-00300-2.pdf

Assessment of crack stress thresholds and development of a pre-failure indicator using Digital Image Correlation approach for coal specimen

Internal strain monitoring of coal samples based on fiber Bragg grating sensing

Internal Strain Monitoring of Coal Samples Based on Fiber Bragg Grating Sensing

Efficient execution of the underground coal extraction depends on the accuracy of deformation measurement of the pillars. The basic design information as stress-strain behavior is collected from the laboratory investigation. Contact-based deformation measurement approaches have limitations like data insufficiency, proneness to signal loss, physical damage, etc. In this investigation, a contactless technique like digital image correlation (DIC) has been evaluated for its applicability on coal specimen. Coal specimens from 100-m depth have been investigated for their stress-strain behavior through DIC as well as other conventional methods, i.e., strain gauge and linear variable differential transformer (LVDT). The deformation was found out from a set of images recorded and analyzed using the software StrainMaster. In the image analysis, the optimum subset size was found to be 99 × 99 pixels with a step size of 8 pixels. The average threshold stress levels of crack initiation and crack damage in uniaxial compression were observed to be 43.72% and 63.6%, respectively. DIC exhibits higher sensitivity to deformation of coal as compared to that by LVDT and strain gauges and proven to be a promising and dependable technique for coal pillar analysis.

Experimental evaluation of failure characteristics of coal using 2D digital image correlation approach

Strain measurement is vital in material and mechanical testing. The conventional contact based approaches as strain gauges, extensometers, acoustic emission, seismic waves etc. have limitations like sensitivity to contact areas, susceptible to external noise, vulnerable to breakage, influenced by surrounding environment etc. Recently, development of noncontact based methods has eliminated these challenges. Digital Image Correlation is an optical, noncontact based technique which is being widely used in measuring full-field displacement. The technique is based on acquisition of digital images taken before and during loading and developing a correlation between them with subpixel accuracy. In this paper, the behavior of equivalent coal specimens at varying depth from 92 to 126 m have been evaluated for static loading condition using non-contact based approach i.e. Reliability-guided Digital Image Correlation technique (RG-DIC). There exists a good agreement between the contact (strain gauge) and noncontact based approaches (DIC) for static loading condition. So, Digital Image Correlation (DIC) can also be a reliable strain measuring approach for investigating for earth materials.

Nutan Shukla

Papers

Experimental evaluation of failure characteristics of coal using 2D digital image correlation approach

Assessment of crack stress thresholds and development of a pre-failure indicator using Digital Image Correlation approach for coal specimen

An Investigation of Digital Image Correlation for Earth Materials