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This paper investigates the possible relationship between solar activity and monthly rainfall in Pokhara and Kathmandu cities in Nepal from the year 1968 to 2023. The study uses Cross Correlation Analysis (CCA) and wavelet analysis, the Cross-Wavelet Transform (XWT) and Wavelet Transform Coherence (WTC), to analyze the time series data. The CCA shows a strong positive correlation between the solar cycle and rainfall trend, with correlation coefficients of 0.77 and 0.76 and time lags of 18 months and 14 months at Pokhara and Kathmandu, respectively. The p-values, calculated to be < 0.0001 through the t-test, indicate that the observed correlations are statistically significant. The XWT results show a long-term ∼ 11-year common periodicity in solar cycle and rainfall. The WTC analysis confirms the local correlation between these two time series in time–frequency domain at a common periodicity. The results indicate that the monthly rainfall pattern in Nepal is closely related to the solar cycle pattern. Thus, solar activity likely plays a role in influencing rainfall trends in Nepal. This study shows that solar-climate interaction on a regional scale is complex and emphasizes the importance of understanding these relationships for predicting and managing climate change. [ABSTRACT FROM AUTHOR]

In Nepal, historic earthquakes have shown extensive liquefaction in different areas of the country, including its capital, Kathmandu Valley. The 1833 and 1934 earthquakes caused significant harm due to liquefaction. An earthquake of moment Mw7.8 struck on 25 April, 2015, keeping the epicentre at the central part of Nepal. Although damages due to liquefaction were limited, several surface manifestations were observed at various places in the valley. This paper summarises the field reconnaissance concerning the liquefaction cases in Kathmandu after the mainshock. The field observations, alongside results from liquefaction evaluation, contrasts with the previous liquefaction studies conducted before the 2015 Earthquake for the valley. To evaluate the irregularity of existing maps with the ground manifestations caused by the 2015 Gorkha earthquake, we utilised the geotechnical database gathered from 400 locations before the quake and 10 boreholes drilled before the 2015 Gorkha earthquake to conduct quantitative analyses and modelling using simplified procedure by Idriss and Boulanger (2008). Likewise, the susceptibility of affected zones to liquefaction during the 2015 Gorkha earthquake is depicted, and utilized standard technique is validated to estimate liquefaction hazard in Kathmandu Valley. [ABSTRACT FROM AUTHOR]

The 25th April 2015 Nepal earthquake was the first major event in the Himalayan orogeny to provide a relatively well-recorded dataset. This paper presents a comprehensive analysis of the mainshock and its five major aftershocks through 21 well-established ground motion parameters. The analysis is presented for near-field stations of the Kathmandu basin and far-field stations of the Indo-Ganga Plains, including the site response behavior with varying sediment depths. Moreover, Hilbert–Huang Transform is used to study site amplifications associated with sediment depth and soil class, especially at long periods. In addition, a new ground motion model (GMM) is derived for all 21 parameters using moment magnitude, source-to-site distance, site class and sediment depth as predictor variables. Further, to ensure that the developed GMM is not biased, an inter-event and intra-event residual analysis is performed. Furthermore, the GMM is compared with other well-established prediction models applicable to the study region. The efficacy of the current model is further addressed by the evaluation of ranking indices. [ABSTRACT FROM AUTHOR]

Nepal possesses a good solar resource, and there has been increasing interest in the use of photovoltaic systems. About 1.1 million solar home systems, rated at nearly 30 MWp, have been installed across Nepal. With the introduction of net metering by the Nepal Electricity Authority, an increase in rooftop photovoltaics (RPV) is expected. However, to inform any policy developments around increased electricity generation, and the uptake of RPV, there is a need to quantify the potential of such systems (a situation mirrored in many developing countries). To this end, this study utilized a hierarchical geospatial technique based on open-source data to estimate the potential output from RPV in several cities in Nepal (Kathmandu, Pokhara, Butwal, Nepalgunj, and Biratnagar). It was found that the potential theoretical output of RPV ranged from 637 GWh per annum, in Kathmandu, to 50 GWh per annum in Butwal. Moreover, the total RPV potential from urban households of Nepal was estimated to be in the order 6.5 TWh per annum. As such, the findings of this paper can be used to make informed policy decisions about the future of Nepal's energy mix. [ABSTRACT FROM AUTHOR]

This paper investigates how variations in sediment supply, grain size distribution and climate change affect channel morphology and flood inundation in the Nakkhu River, Kathmandu, Nepal. Climate change‐induced extreme rainfall is expected to increase flood intensity and frequency, causing severe flooding in the Kathmandu basin. The upper reaches of the Nakkhu River are susceptible to landslides and have been impacted by large‐scale sand mining. We simulate potential erosion and deposition scenarios along a 14 km reach of the Nakkhu River using the landscape evolution model CAESAR‐Lisflood with a 10 m digital elevation model, field‐derived sediment grain size data, daily discharge records and flood forecast models. In a series of numerical experiments, we compare riverbed profiles, cross‐sections, flood extent and flow depths for three scenarios (1.2‐, 85‐ and 1000‐year return period floods). For each scenario, the model is first run without sediment transport and then with sediment transport for three grain size distributions (GSDs) (observed average, finer and coarser). In all cases, the inclusion of sediment led to predicted floods of a larger extent than estimated without sediment. The sediment grain size distribution was found to have a significant influence on predicted river morphology and flood inundation, especially for lower magnitude, higher probability flood events. The results emphasise the importance of including sediment transport in hydrological models when predicting flood inundation in sediment‐rich rivers such as those in and around the Himalaya. [ABSTRACT FROM AUTHOR]

The 2015 Gorkha earthquake damaged many unreinforced masonry buildings in the UNESCO World Heritage Sites of Kathmandu Valley, such as Kathmandu, Patan, and Bhaktapur. But there were a few multi-tiered temples, with high plinths, that survived the recent earthquake. The temples with a massive high plinth have shown better seismic performance both in past historical earthquakes as well as in the recent 2015 earthquake. In this paper, the results of a reconnaissance survey conducted to assess the seismic effect on the high plinth caused by the 2015 Gorkha earthquake is presented first. Extensive field investigation of excavation works indicates the bulky volume of the traditional construction materials were used to build the high plinth with distinct construction techniques. Second, the dynamic properties of high plinths of nine Nepalese temples measured from microtremor data are presented. The damage assessment shows that the 2015 Gorkha earthquake had minor effects on the plinths. The predominant frequencies obtained at the ground points nearby the temples vary from 0.44–1.32 Hz and predominant frequencies obtained from the H/V spectral ratio ranged 2.88–12.70 Hz. Damping ratios obtained vary from 2.01–8.50%. 1-D wave propagation shows that the plinth act as damping agent. [ABSTRACT FROM AUTHOR]

The aim of this paper is to identify, also through micro tremor analysis and numerical analysis, the collapse's mechanisms of the Nepalese wood-masonry monuments damaged by the 2015 seismic event that struck Kathmandu and its valley. The research analyses two case studies: The Radha Krishna and the Bhimsen Temples. After a careful anamnesis based on visual inspection and hypotheses on the temple's structural behaviour, a global dynamic ambient test (micro tremor) was carried out for qualitative characterisation of the structural system, residual stiffness and strengths. First, numerical models have been calibrated on mechanical parameters present in literature. The difference between experimental results and numerical model values is higher than 100% in the Radha Krishna temple and 70% in the case of Bhimsen temple. Considering this results, the models were calibrated on the experimental results. The modal analysis shows important mixed effect of torsional and flectional mode in the case of the Radha Krishna temple while in the Bhimsen temple local effects prevail. The capacity curve of Radha Krishna temple shows behavior close to collapse at 0.26 g, while the Bhimsen temple presents important damage at 0.3 in Z direction and 0.23 in X direction. [ABSTRACT FROM AUTHOR]

Land transport is a major contributor to the human-caused climate change; knowing the total number and composition of the vehicle fleet is key for estimating its emissions. Especially for countries of the Global South, emission inventories are associated with high uncertainties because fleet data are often unknown or outdated – classifying vehicles on remote sensing has the potential to change this. We present the XWHEEL dataset based on annotated vehicles in aerial images with six classes depending on the number of wheels, size and motorization. The dataset consists of 73 annotated aerial images of the city of Dar es Salaam (Tanzania) with 15,973 vehicles. To analyze the performance of the dataset, a convolutional neural network, ReDet, and a transformer-based neural network, DINOOBB, are trained with different configurations and validated on the validation and test split, but also on aerial images from other regions. The transformer-based DINO architecture has been adapted to the remote sensing domain and modified to predict Oriented Bounding Boxes. Results show a good performance on the test split from Dar es Salaam, when the two-wheeled classes are merged and the non-motorized three-wheeled vehicles are excluded due to their rare occurrence. The best performing algorithm configurations with four classes were then tested on aerial images of Kathmandu (Nepal) and Kampala (Uganda). The performance drops for cycles and three-wheeled vehicles, as their appearance varies between countries. A main finding is that we can reliably detect the different vehicle classes in Dar es Salaam. When algorithms trained on XWHEEL are generalized to other regions of the Global South, performance decreases for the more difficult classes (bicycles and tricycles). To obtain results that are comparable across the board, we therefore recommend expanding the dataset with additional annotations from other regions of the Global South. [ABSTRACT FROM AUTHOR]

We use Visible Infrared Imaging Radiometer Suite (VIIRS) nightlight data to model the impact of the 2015 Nepal earthquakes. More specifically, the data—showing nightlight emissions—are used to examine the extent to which there is a difference in nightlight intensity between cells damaged in the earthquake versus undamaged cells based on (1) mean comparisons; and (2) fixed effect regression models akin to the double difference method. The analysis is carried out for the entire country as well as smaller regions in and around the Central area and Kathmandu, which were the hardest hit areas. Overall, the regressions find a significant and negative effect from the initial shock, followed by a positive net effect from aid and relief efforts, which is consistent with what one would expect to find. However, the mean analysis results are inconclusive and there is substantial noise in the nightlight measurements due to how the values are produced and persistent cloud cover over Nepal. [ABSTRACT FROM AUTHOR]

In this study, wavelet analysis and traditional cross-correlation analysis (TCA) have been employed to explore the temporal characteristics of the Air Quality Index (AQI) (PM2.5) and its relationships with meteorological factors, air temperature, and rainfall in the capital city of Nepal, Kathmandu, during 2017 - 2020. The temporal variation of monthly averaged (AQI) (PM2.5) revealed that the air quality was unhealthy in winter, improved in summer, and subsequently became unhealthy again in autumn and spring. We also noticed that the lowest AQI (PM2.5) was recorded in 2020, which is due to the COVID-19 pandemic lockdown. By analyzing the time-frequency relationship of (AQI) (PM2.5) with air temperature and rainfall, using Cross Wavelet Transform (XWT), we observed the interannual, seasonal, and monthly common periodicity between them. The coherency of XWT is then tested by using Wavelet Transform Coherence (WTC), which showed a negative correlation of AQI (PM2.5) with rainfall and air temperature, while an anomaly was seen among AQI (PM2.5) and temperature as they were positively associated for a few months in 2017, 2018, and 2020. Moreover, the results of cross-correlation and multiresolution analysis (MRA) are consistent with wavelet analysis, indicating the driving effect of air temperature and rainfall on (AQI) (PM2.5). [ABSTRACT FROM AUTHOR]

This research aims at characterizing the deep sedimentary basin of Kathmandu (Nepal) from microtremor measurements, by using two surveys carried out in November 2015 and November 2018. The data collected are sufficient for a qualitative investigation of the seismic response of such a complex basin. The measurements were undertaken in the framework of a collaboration between the NSET (National Society for Earthquake Technology, Nepal) and the OGS (National Institute of Oceanography and Applied Geophysics, Italy). During the two campaigns, a series of passive seismic surveys were made, taking into consideration both single broad-band sensors and arrays. The 2015 study initially focused on the Lalitpur area (southern part of Kathmandu) and was later extended to the northern and more urbanized area of the capital city of Nepal. The 2018 survey focused on estimating the S -wave velocity field of the entire stratigraphic sequence by array and a repetition of some Horizontal to Vertical Spectral Ratio (HVSR) measurements close to two boreholes with reliable stratigraphy. Two inversion methods, using the data from the seismic arrays, were useful to infer the S -wave velocity profiles of the shallower layers and to interpret some HVSRs. The outcome is a map of the periods of single station data representing the seismic response of the basin. Comparing these results with the strong motion data of the Gorkha 2015 main shock, we confirm that the longer periods are not only the effects of the earthquake source, but also of the local response of the basin itself. [ABSTRACT FROM AUTHOR]

A monumental tetrastyle canopy (four columns topped by a hollow cap overlaying a statue), built in 1948 at the centre of Kathmandu, Nepal, has suffered full collapse during the April 25, 2015 Mw7.8 earthquake. Two video camera recordings let us recover the most important movements of the structure. At a distance of 2.9 km from the monument, an accelerometric station (KATNP) recorded the motion which we used as input of a model structure made with DEM. Geometry and dimensions of main elements were mostly obtained from satellite images. Concrete and steel in columns were considered as the common practice at that time. We performed some sensitivity analyses varying the mechanical properties due to the possibility of aging alterations in concrete and steel and to incorporate uncertainties on the geometric characteristics. Albeit the response has a significant variability, results show that it is possible to reproduce well the video images, attesting the importance of video cameras to capture the dynamic performance of structures, providing insight into their behaviour and data to support numerical investigations. [ABSTRACT FROM AUTHOR]

Most studies on air pollution have focused on source apportionment aspect but very few have considered meteorological factors responsible for variation in air pollution levels including studies in Nepal. Consequently, the effects of meteorological parameters including effects of seasonality and lag effects are investigated and quantified for Kathmandu valley, Nepal. Daily temporal data of air pollution for 2017–early 2020 monitored by the Department of Environment and US Embassy, Kathmandu, Nepal, and meteorological data monitored by the Department of Hydrology and Meteorology, Kathmandu, Nepal, are used. Regression models namely exponential, Box-Cox transformed and Gamma generalized linear models are used to quantify the effects supported by regression diagnostics. Results depict high proportions of observed air pollution variations (79–85%) explained by the fitted models with varied effects of meteorological parameters. Around 5% reduction in PM10 (96% CI: 0.034–0.069) and PM1 (95% CI:.0.029–0.063) levels per 1 °C increase in average temperature and significant increase in surface O3 level (0.177, 95% CI: 0.126–0.228 Box-Cox transformed value) per 1 °C increase in average temperature are detected. Similarly, around 0.7% (95% CI: 0.1–1.3) and 2% (96% CI:1.3–2.5) decrease in PM1 and PM10, respectively per 1% increase in relative humidity, 0.032 (95% CI: 0.024–0.040) decrease in transformed value of PM2.5 per 1 mm increase in rainfall, and 7.3% (95% CI: 1.3–15.9) decrease in PM10 per 1 m/s increase in wind speed are also detected. In conclusion, meteorological conditions are found significant contributing factors in determining air pollution levels in Kathmandu valley. On the long run, atmospheric conditions can play vital roles in air pollution situation shifts mainly due to climate change characterized by changes in meteorological values. [ABSTRACT FROM AUTHOR]

Boulder movement can be observed not only in rockfall activity, but also in association with other landslide types such as rockslides, soil slides in colluvium originating from previous rockslides, and debris flows. Large boulders pose a direct threat to life and key infrastructure in terms of amplifying landslide and flood hazards as they move from the slopes to the river network. Despite the hazard they pose, boulders have not been directly targeted as a mean to detect landslide movement or used in dedicated early warning systems. We use an innovative monitoring system to observe boulder movement occurring in different geomorphological settings before reaching the river system. Our study focuses on an area in the upper Bhote Koshi catchment northeast of Kathmandu, where the Araniko highway is subjected to periodic landsliding and floods during the monsoons and was heavily affected by coseismic landslides during the 2015 Gorkha earthquake. In the area, damage by boulders to properties, roads, and other key infrastructure, such as hydropower plants, is observed every year. We embedded trackers in 23 boulders spread between a landslide body and two debris flow channels before the monsoon season of 2019. The trackers, equipped with accelerometers, can detect small angular changes in the orientation of boulders and large forces acting on them. The data can be transmitted in real time via a long-range wide-area network (LoRaWAN®) gateway to a server. Nine of the tagged boulders registered patterns in the accelerometer data compatible with downslope movements. Of these, six lying within the landslide body show small angular changes, indicating a reactivation during the rainfall period and a movement of the landslide mass. Three boulders located in a debris flow channel show sharp changes in orientation, likely corresponding to larger free movements and sudden rotations. This study highlights the fact that this innovative, cost-effective technology can be used to monitor boulders in hazard-prone sites by identifying the onset of potentially hazardous movement in real time and may thus establish the basis for early warning systems, particularly in developing countries where expensive hazard mitigation strategies may be unfeasible. [ABSTRACT FROM AUTHOR]

Background: Despite direct-acting antivirals (DAA), aims to "eradicate" viral hepatitis by 2030 remain unlikely. In Nepal, an expert consortium was established to treat HCV through Nepal earthquakes aftermath offering a model for HCV treatment expansion in a resource-poor setting. Methodology/Principal findings: In 2015, we established a network of hepatologists, laboratory experts, and community-based leaders at 6 Opioid Substitution Treatment (OST) sites from 4 cities in Nepal screening 838 patients for a treatment cohort of 600 individuals with HCV infection and past or current drug use. During phase 1, patients were treated with interferon-based regimens (n = 46). During phase 2, 135 patients with optimal predictors (HIV controlled, without cirrhosis, low baseline HCV viral load) were treated with DAA-based regimens. During phase 3, IFN-free DAA treatment was expanded, regardless of HCV disease severity, HIV viremia or drug use. Sustained virologic response (SVR) was assessed at 12 weeks. Median age was 37 years and 95.5% were males. HCV genotype was 3 (53.2%) or 1a (40.7%) and 32% had cirrhosis; 42.5% were HIV-HCV coinfected. The ITT SVR rates in phase 2 and 3 were 97% and 81%, respectively. The overall per-protocol and ITT SVR rates were 97% and 85%, respectively. By multivariable analysis, treatment at the Kathmandu site was protective and substance use, treatment during phase 3 were associated with failure to achieve SVR. Conclusions/Significance: Very high SVR rates may be achieved in a difficult-to-treat, low-income population whatever the patient's profile and disease severity. The excellent treatment outcomes observed in this real-life community study should prompt further HCV treatment initiatives in Nepal. Author summary: Despite very effective antiviral therapies, Hepatitis C virus (HCV) eradication remains a major challenge, especially in resource-limited countries. In Nepal, which ranks among the poorest countries in the world an expert consortium was established to treat HCV patients in six centers throughout the country. A cohort of 600 individuals with HCV infection and past or current drug use were treated using different treatment strategies over time. Very high treatment response rates were achieved in a difficult-to-treat, low-income population whatever the patient's profile and disease severity and despite the severe 2015 earthquakes in Nepal. The excellent treatment outcomes observed in this real-life community study should prompt further HCV treatment initiatives in Nepal. [ABSTRACT FROM AUTHOR]

Safe flights over the Tribhuvan International Airport (TIA), Kathmandu, Nepal, remain a considerable challenge. Since the airport opened, there have been 13 aircraft accidents during landings and takeoffs that have claimed 392 lives. A detailed understanding and dependable forecast of atmospheric conditions that may develop over the complex terrain of the mid hills of central Nepal Himalaya are yet to be achieved. The present study discusses the near-surface atmospheric conditions possibly associated with the most recent fatal crash at TIA on 12 March 2018 as revealed by the Advanced Research version of the Weather Research and Forecasting(WRF-ARW) Model routine forecast. At the time of the accident, two prominent gap winds were converging in the valley, thereby, forming a crosswind and a mix of strong up- and downdrafts over the airfield. As a result, the near-surface atmosphere was significantly turbulent. Unexpected encounters with such turbulent winds are a likely contributor to the fatal crash. This indicates that the knowledge of near surface atmospheric conditions, critically needed by pilots in advance, for safe operations over the airfield may be generated with WRF-ARW forecasts. [ABSTRACT FROM AUTHOR]

Catastrophic natural disasters often require rapid community mobilization to meet local needs. . This study uses social capital to explore how indigenous Newar communities in Kathmandu responded to the 2015 Nepal earthquake. Data from thirty-three semi-structured interviews with local Newar inhabitants, and secondary sources, form the basis of analysis. Newari prosocial behaviors learned through living in communal neighborhoods, experiences of working for community welfare through cultural Guthi systems, spiritual strength drawn from ancestors and their proud heritage, and the community's high level of equanimity facilitated disaster responses in a positive way. The study provides insights on how social capital among ethnic groups like the Newar influence community responses to natural disasters. [ABSTRACT FROM AUTHOR]

A review of articles published in 2015 issues of "Nature Geoscience," "Geophysical Research Letters," and "Science" examining why the April 25, 2015 7.8 magnitude earthquake in Nepal was so damaging to tall buildings in Kathmandu, including the discovery the greatest fault movement occurred 50 kilometers east of the epicentre near Kathmandu.

Disaster-related internal displacement is on the rise in many countries and is increasingly becoming an urban phenomenon. For many people, as in the case of the earthquake disaster 2015 in Nepal, protracted or multiple disaster displacements are a lived reality. While the drivers of displacement are relatively well understood, significant uncertainties remain regarding the factors that trigger prolonged or secondary displacement and impede ending of displacement or achieving durable solutions. The purpose of this article is to illustrate and theorise the discourse of reconstruction and return that shapes experiences, strategies, and policies in order to gain a better understanding of the obstacles to pursuing durable solutions that are still shaping the reality of life for urban internally displaced people (IDPs) in Kathmandu Valley. I use the concepts of 'fields of practice' and 'disaster justice' to provide insights into the theorisation of the links between social inequality, structural forms of governance, and the reconstruction process itself. Findings demonstrate that the application of these concepts has great potential to expand our understanding of 'realities of life' and practices of IDPs, and thus contribute to a more differentiated evidence base for the development and implementation of appropriate disaster risk reduction policies and practices. [ABSTRACT FROM AUTHOR]