Review on assessing climate-change-induced risks to run-of-river hydropower infrastructure in Nepal

Nepal annually invests millions of dollars in hydropower development, with a substantial portion of these funds allocated to civil infrastructure. Climate change, which impacts geological and hydrological conditions, poses a threat to civil components throughout hydropower project construction and operation. This causes budget overruns, project delays, and adverse consequences for society and the environment, ultimately resulting in multimillion-dollar losses. The identification of risk factors and their underlying causes, stemming from the impacts of climate change, constitutes a fundamental aspect of this study. This critical analysis primarily draws upon extensive literature reviews to pinpoint these factors (risk factors arising from climate change), emphasizing their economic and human impacts. This paper highlights the risks to run-of-river hydropower infrastructures in Nepal. The findings of the study can be used to develop and implement adaptation strategies to mitigate the risks posed by climate change to Nepal's vital hydropower sector.</p

Backwater effect in lowland regions due to bridge structure: a case study of Shreekhandapur, Kavre, Nepal

The backwater effect can be caused by a number of factors, including the bridge's pier width and deck level. In lowland regions, the backwater effect can be particularly problematic, as it can lead to flooding and inundation of farmlands and houses. This study examines the impact of bridge structure on the backwater effect in the lowland region of Shreekhandapur, Kavre, Nepal. The study area is characterized by a hill slope and inner river valley, with a gentle river profile that results in low flow velocity and increased deposition. The study compares the backwater effect of an old demolished bridge with four piers of 1.2 m width and abutments on both sides to a new bridge with a single pier of 0.4 m width and a deck level that is 1 m higher. HEC-RAS software was used to analyse the steady flow and create a flood hazard map. The results show that the new bridge with a reduced pier width and increased deck level significantly reduces the backwater effect. The flood hazard map shows that the new bridge along with floodwalls reduces the potential hazard-prone areas by up to 50 %. The findings of this study can be applied to disaster mitigation and bridge design in lowland regions. By reducing pier width and increasing deck level, bridges can be designed to minimize the backwater effect and reduce the risk of flooding.</p

Flowchart of DEM Modeling Stability Analysis of Large Underground Powerhouse Caverns

The power of the Distinct Element Method (DEM) in solving the stability of underground powerhouse caverns (UPC) is discovered, but when does the DEM need to be adopted? What problems can be solved? The flowchart is provided and applied to analyze the stability of UPC in this paper. With the guide of the flowchart, the damage index (Di) is used as a failure type (gravity-controlled or stress-induced) judgment indicator. Through the calculation of three typical engineering, the problems of random blocks stability, dynamic calculation, and support system evaluation are studied, respectively, with the help of the DEM code 3DEC. The method and results of this paper can give reference to engineering projects of its category

The Estimation of Shear Wave Velocity for Shallow Underground Structures in the Central Himalaya Region of Nepal

A subsurface investigation was conducted to assess the suitability of a site for potential tunnel construction, focusing on the determination of shear wave velocities (Vs) in subsurface materials. This study employed three distinct methods to analyze Vs in weathered soft rock: drilling mechanism, multichannel analysis of surface waves (MASW), and microtremor array measurement (MAM). Through the utilization of MASW and MAM, empirical relationships were established, enabling the determination of Vs based solely on soil type and depth, offering a practical alternative to the limitations of SPT N-Value, particularly when exceeding 50 blows. The comparison of Vs values obtained from these methods revealed a close alignment between empirical techniques and MASW/MAM, which proved to be cost-effective and an efficient alternative to drilling for comprehensive underground structure assessments. The reliability of MASW was further underscored through its comparison with existing empirical methods. Moreover, the empirical approach demonstrated its efficacy in predicting velocities in weathered soft rock within the Central Himalayan region of Nepal, thus enhancing the feasibility study of underground structures. Lastly, this study proposed a Vs-Depth correlation specifically tailored for highly weathered meta-sandstone bedrock resulting in clay and sandy soils

A possible underground roadway for transportation facilities in Kathmandu Valley: A racking deformation of underground rectangular structures

Abstract The increasing number of private cars, public transportation vehicles, and pedestrians, as well as the absence of adequate space for these ground amenities, are one of the primary causes of traffic congestion and accidents in the Kathmandu Valley. Investigations have indicated that the Kathmandu Valley has the greatest traffic accidents despite the heavy presence of the government and its agencies there. Most teens and young adults suffer injuries while using motor vehicles. The study's primary objective is to foresee and prevent such complications by planning for sufficient subsurface infrastructure (a cut‐and‐cover rectangular tunnel) for the Kathmandu Valley's transportation network. The overlying pressure, lateral earth pressure, live load, uplift pressure, and live surcharge are some of the forces acting on the tunnel, creating unique stress and moment zones. The tunnel meets the following geometric requirements: (a) Each of the tunnel's two cells has a clear span of 10 m and a clear height of 5.5 m. The side walls, inner walls, top slab, and bottom slab are all 700 mm thick. Soil has built up to a height of 4 m over the tunnel's roof. The analytical method is used in the tunnel segment's analysis. Furthermore, the designed tunnel has been evaluated for stability, considering the deflection and shear resistance. The analysis indicates that the tunnel meets the stability requirements. This implies that the structure is capable of withstanding the applied forces without excessive deflection. Non‐linear dynamic time history analyses of the El Centro earthquake and the Gorkha earthquake were computed. From the El Centro earthquake, the maximum displacement was 23.63 mm at 10.59 s, and from the Gorkha earthquake, the maximum displacement was 16 mm at 0.19 s for the modeled structures

Clinicomycological Characterization of Superficial Mycoses from a Tertiary Care Hospital in Nepal

Background. Superficial mycosis is a common fungal infection worldwide, mainly caused by dermatophytes. However, the prevalence of species varies geographically. In addition, fungal treatment is best guided according to species isolated. This study was carried out to determine the clinical as well as mycological profile of superficial mycoses in a tertiary care hospital, Nepal. Methods. This was a prospective case-control laboratory based study conducted over a period of six months from January to June 2014 at Tribhuvan University Teaching Hospital, Nepal. A total of 200 specimens were collected from the patients suspected of superficial mycoses. The specimens were macroscopically as well as microscopically examined. The growth was observed up to 4 weeks. Results. Out of total 200 specimens from the patients suspected of superficial mycoses, tinea corporis 50 (25%) was most common clinical types. KOH mount was positive in 89 (44.5%) and culture was positive in 111 (55.5%). Trichophyton mentagrophytes 44 (39.6%) was the most common isolate. Conclusions. The diagnostic yields of KOH mount and culture were found to be complementary to each other. Thus both the methods added with clinical findings are equally important to establish superficial mycosis

Antimicrobial susceptibility pattern of Shigella spp. isolated from children under 5 years of age attending tertiary care hospitals, Nepal along with first finding of ESBL-production

Abstract Background Shigella is an important cause of bacterial gastroenteritis in resource-poor countries. The treatment of shigellosis mostly requires antibiotics. However, the increase of multidrug resistance along with emergence of extended-spectrum β-lactamase and ciprofloxacin resistance among Shigella spp. has challenged the situation. This study was conducted to determine the distribution of species and antibiotic susceptibility pattern of Shigella species isolated from stool specimen among children less than 5 years of age in Nepal. Results Out of total 717 stool samples collected, 15 cases of Shigella spp. was isolated which includes 12 S. flexneri and 3 S. sonnei. Multidrug resistance was found among 13(86%) of the isolates. One of the isolates of S. flexneri was found to be ESBL-producer with MIC >256 mg/L for cefixime. Conclusion The high occurrence of multidrug resistance among Shigella spp. along with a case of ESBL-production for the first time in Nepal alarms the concerns about dissemination of the resistant isolates. So, systemic monitoring of the antimicrobial susceptibility pattern of Shigella spp. is becoming crucial to guide therapy

Molecular epidemiology of Rotavirus causing diarrhea among children less than five years of age visiting national level children hospitals, Nepal

Abstract Background Rotaviruses are the major cause of diarrhea among the infants and young children all over the world causing over 500,000 deaths and 2.4 million hospitalizations each year. In Nepal Rotavirus infection positivity rates ranges from 17.0 to 39.0% among children less than 5 years. However, little is known about the molecular genotypes of Rotavirus prevailing. The objective of this study was to estimate the burden of Rotavirus gastroenteritis and determine the genotypes of Rotavirus among children less than 5 years. Methods The cross sectional study was conducted from January to November 2014 among children less than 5 years old visiting Kanti Children’s Hospital and Tribhuvan University Teaching Hospital. Rotavirus antigen detection was performed by Enzyme Linked Immunosorbent Assay (ELISA) using ProSpecT Rotavirus Microplate Assay. Among the Rotavirus antigen positive samples, 59 samples were used for Rotavirus RNA extraction. Multiplex PCR was performed to identify G type comprising G1-G4, G8-G10 and G12 and P type comprising P[4], P[6], P[8], P[9], P[10], and P[11]. Results A total of 717 diarrheal stool samples were collected from patients ranging from 10 days to 59 months of age. Rotavirus antigen positive was found among (N = 164)22.9% of patients. The highest number of the diarrhea was seen in January. Molecular analysis of Rotavirus genotypes revealed that the predominant G-Type was G12 (36%) followed by G9 (31%), G1 (21%), G2 (8.6%). The predominant P- type was P6 (32.8%) followed by P8 (31%), P10 (14.8%), P4 (14.8%). A total of seven G/P type combinations were identified the most common being G12P [6] (35.8%), G1P [8] (15.1%), G9P [8] (15.1%). Conclusion Rotavirus diarrhea is, mostly affecting children from 7 to 24 months in Nepal, mostly occurring in winter. The circulating genotypes in the country are found to be primarily unusual genotypes and predominance of G12P[6]. It is recommended to conduct genotyping of Rotavirus on large samples before starting vaccination in the country

Isolation, speciation and antifungal susceptibility testing of Candida isolates from various clinical specimens at a tertiary care hospital, Nepal

Abstract Background Candida species are responsible for various clinical infections ranging from mucocutaneous infection to life threatening invasive diseases along with increased resistance to antifungal drugs has made a serious concern. Resistance to antifungal agents has increased during the last decade. Thus, identification of Candida up to species level and its antifungal susceptibility testing has a paramount significance in the management of Candidal infections. The aim of the study was to speciate Candida species and to determine antifungal susceptibility pattern of Candida species to antifungal agents. Methods A total of 100 consecutive Candida species were isolated from 1248 clinical specimens over 7 months period. Growths on Sabouraud dextrose agar were evaluated for colony appearance, macroscopic examination, Gram staining, germ tube test and urea hydrolysis test. Further, they were processed for Candida speciation on CHROMagar. Antifungal susceptibility testing was performed as recommended by Clinical and Laboratory Standards Institute (CLSI) M44-A document. Results Out of 100 Candida isolates, Candida albicans (56%) was the most common species. Among the non-albicans Candida species, Candida tropicalis (20%) was the predominant isolate followed by Candida glabrata (14%). Regarding antifungal susceptibility pattern, Candida species were more susceptible to clotrimazole (82%) followed by fluconazole (64%) and miconazole (44%). Conclusions Candida albicans was the predominant species responsible for various Candidal infections. Among commonly used antifungal drugs clotrimazole, miconazole and fluconazole were most effective