The failure of earthen dams and levee structures are mostly caused by hydraulic erosion measures including overflow (surface) or piping (internal). Several research have attempted to control and mitigate surface and internal erosion of waterfront geotechnical engineering structures via seepage control and soil shear strength improvement. Meanwhile, microbial biopolymer-based soil treatment (BPST) is gaining attention as a new environmentally friendly method to amend the geotechnical engineering properties of soil in terms of: strength improvement, hydraulic conductivity reduction, erosion resistance enhancement, and surface vegetation growth. In this study, BPST has been attempted to improve the overall stability and erosion resistance of earthen levee structures, where severe overflow and internal piping conditions were simulated by a laboratory open-channel hydraulic flume apparatus. Small scale (50:1) levee models were prepared with different BPST (e.g., biopolymer contents) treatment conditions. Surface erosion has been simulated by allowing continuous overtopping, while internal erosion (piping) has been considered by initiating internal leakage through a pre-drilled hole along the bottom of the levee model. The erosion amount (volume and mass) with time has been monitored for all test conditions. The results show BPST having a significant effect on reducing both surface and internal erosion of an earthen levee structure with a small biopolymer quantity and treatment proportion compared to the entire volume of the levee model.
While the widespread nature of these discussions over the past year are welcome, the discussions themselves, about the overrepresentation of white men in STEM and attempts to increase diversity, are nothing new (for example: Bhatia, 1989) . In 1989, the National Science Foundation (NSF) sponsored a workshop of all fema le JHRWHFKQLFDO IDFXOW\ IRU GLVFXVVLRQV RQ VXSSRUWLQJ DQG LQFUHDVLQJ ZRPHQ¶V UHSUHVHQWDWLRQ LQ WKH field. There were seven women geotechnical faculty present. Through the 90s and 2000s, in line with general trends in the academy and society more broadly, t he number of women in the geotechnical field steadily increased. While the number of women in the field has certainly increased in the decades since, there is no central count of geotechnical faculty demographics. The American Society for Engineering Education (ASEE) publishes yearly snapshots assessing the demographics of engineering subfields, but geotechnical, as a specialty of the subfield civil engineering, is not among them. Three hundred and eight universities in the United States offer Civil Enginee ring degrees ( Dept. of Education, n.d.) , out of which we identified 181 that employ tenure or tenure -tracked faculty in the subfield of geotechnical engineering. U.S. institutions graduated 17,102 students in the year 2016 in the field of civil engineering, increasing to 20,056 just four years later in 2020. Of those 2016 graduates, 24.4% were female; LQ ZRPHQ¶V VKDUH KDG LQFUHDVHG WR MXVW RYHU D TXDUWHU DW 6LPLODU JURZWK ZDV SUHVHQW LQ ZRPHQ¶V UHSUHVHQWDWLRQ LQ FLYLO HQJLQHHULQJ DPRQJVW WHQXUHG RU WHQX-UtHrack faculty: from 18.4% in 2016 to 19.6% in 2020 ³(QJLQHHULQJ E\ WKH 1XPEHUV ´ ?
