Publications
A possible underground roadway for transportation facilities in Kathmandu Valley: A racking deformation of underground rectangular structures
A proposed underground roadway for Kathmandu Valley demonstrates stability under significant forces, including overlying pressure and seismic loads. The study introduces a cut-and-cover rectangular tunnel design with two cells, each 10 meters wide and 5.5 meters high, capable of withstanding live loads, uplift pressures, and lateral earth pressures. Non-linear dynamic time history analyses using data from the El Centro and Gorkha earthquakes showed maximum displacements of 23.63 mm and 16 mm respectively, confirming structural resilience. This design addresses traffic congestion and accident risks in Kathmandu Valley, particularly affecting teens and young adults, by providing a subsurface infrastructure solution that meets geometric and stability requirements.
Liquefaction hazard assessment and ground failure probability analysis in the Kathmandu Valley of Nepal
A significant liquefaction hazard exists across the Kathmandu Valley, with central and southern regions showing higher susceptibility to ground failure during earthquakes. This conclusion stems from a detailed analysis using borehole data from 410 locations, including SPT-N values, to assess liquefaction potential for three scenario earthquakes. The study employed established methods to generate hazard maps, revealing that most areas face medium to very high risk of liquefaction damage, validated by observations from the 2015 Gorkha Earthquake (Mw 7.8). Target SPT-N values were also determined to mitigate future liquefaction risks in vulnerable zones.
Urban growth modelling and social vulnerability assessment for a hazardous Kathmandu Valley
By 2050, Kathmandu Valley’s built-up area is projected to double to 352 km², with the most socially vulnerable villages accounting for 29% of this expansion—11 percentage points higher than today. Urban growth in high-risk zones, including 100-year and 1000-year floodplains as well as liquefaction-susceptible areas, will also surge significantly. The study combines global hazard models with the cellular-automata SLEUTH urban-growth simulation and a tailored social vulnerability index to map these risks, underscoring the urgent need for policy interventions to mitigate future hazards in rapidly developing regions.
Assessing air pollution tolerance of plant species in vegetation traffic barriers in Kathmandu Valley, Nepal
Cinnamomum camphora emerges as the most resilient plant species for roadside vegetation barriers in Kathmandu Valley, Nepal, demonstrating superior tolerance to air pollution. This finding is significant for urban greening strategies aimed at mitigating traffic-related pollutants. The study evaluated nine plant species using biochemical parameters (relative water content, leaf extract pH, total chlorophyll, and ascorbic acid) alongside dust-capturing potential. While Schefflera pueckleri, Psidium guajava, and Ficus benjamina exhibited sensitivity to pollution, others like Nerium oleander and Albizia julibrissin showed moderate tolerance but excelled in dust capture. N. oleander, in particular, stood out for its high dust-capturing ability, making C. camphora, N. oleander, and A. julibrissin the top candidates for roadside planting to enhance air quality.
Investigating the nexus of groundwater levels, rainfall and land-use in the Kathmandu Valley, Nepal
Groundwater levels in the Kathmandu Valley, Nepal, exhibit strong seasonal fluctuations directly tied to monsoonal rainfall, with agricultural areas showing significant recharge and built-up zones experiencing limited replenishment due to high extraction and surface sealing. A two-year analysis of 35 citizen-scientist monitored wells revealed groundwater depths ranging from −0.11m (above ground) to 11.5m, averaging 4.24m with a standard deviation of 2.29m. While agricultural land uses demonstrated an 80% strong and statistically significant correlation between rainfall and groundwater levels, non-agricultural areas showed weaker correlations due to anthropogenic factors. Highly permeable sand and gravel zones in northern districts act as consistent recharge sources, whereas less permeable clay and silt areas display greater seasonal variability. The study underscores the potential of citizen-generated hydrogeologic data and emphasizes the critical role of land-use planning in sustaining groundwater resources amid rapid depletion.
Multi-Hazard Risk Assessment of Kathmandu Valley, Nepal
A multi-hazard risk assessment of the Kathmandu Valley, Nepal, reveals that densely populated areas and older settlements face high to very high exposure to cascading natural hazards. The study, one of the first of its kind in Nepal, integrates flood, landslide, earthquake, and urban fire risks using the Analytical Hierarchy Process (AHP) and Geographical Information System (GIS). By superimposing individual hazard maps, researchers identified critical zones where multiple threats converge, particularly in central valley regions. This holistic approach provides stakeholders with actionable insights for preparedness and planning, addressing a gap in regional risk assessment practices.
Release of Antibiotic-Resistance Genes from Hospitals and a Wastewater Treatment Plant in the Kathmandu Valley, Nepal
A recent study highlights the significant role of hospitals and wastewater treatment plants (WWTPs) as sources of antibiotic-resistance genes (ARGs) in the Kathmandu Valley, Nepal. The research detected clinically relevant ARGs, including sul1, tet(B), blaCTX-M, blaNDM-1, and qnrS, along with a class one integron gene (intI1), in urban rivers, hospitals, and municipal wastewater. Concentrations of these genes in WWTP and hospital effluents ranged from 6.2 to 12.5 log10 copies per liter, underscoring their potential environmental dissemination. Notably, the blaNDM-1 gene was found to likely spread through untreated hospital wastewater, while other ARGs showed significant positive correlations with intI1, suggesting its role in ARG transfer. The study also emphasizes the need for further research on ARGs in drinking water sources due to groundwater-surface water interactions.
Ambient air quality in the Kathmandu Valley, Nepal, during the pre-monsoon: concentrations and sources of particulate matter and trace gases
Aerosol liquid water content and gas-aerosol phase partitioning of NH3, HNO3, and HCl in the Kathmandu Valley vary significantly with diurnal temperature and humidity changes. The study identified multiphase halogen-radical chemistry involving chlorine (Cl) and bromine (Br), which impacts regional air quality. Molecular markers for primary and secondary sources indicate that garbage burning contributes up to three times more than previously estimated, while biomass burning remains a significant source of organic carbon in PM2.5. Anthropogenic combustion sources, including biomass burning, garbage burning, and fossil fuel combustion, are the greatest contributors to PM pollution in the valley.
Assessment of Changes in Land Use/Land Cover and Land Surface Temperatures and Their Impact on Surface Urban Heat Island Phenomena in the Kathmandu Valley (1988–2018)
A significant increase in land surface temperatures (LST) of 5–7 °C within urban areas and 3–5 °C at city boundaries was observed in the Kathmandu Valley between 1988 and 2018, coinciding with a rapid expansion of impervious surfaces by 16.34%—primarily at the expense of agricultural land (17.03%). This urbanization trend, analyzed using decadal Landsat imagery and the Support Vector Machine algorithm, exacerbated the Surface Urban Heat Island (SUHI) effect, as evidenced by a sharp decrease in LST from the city center outward, where vegetation cover increased. Conversely, agricultural areas beyond 20–25 km from the center showed higher LST due to intensified farming activity. The study also highlighted a strong negative correlation between LST and vegetation indices (NDVI, NDMI) but a positive link with built-up areas (NDBI), underscoring urbanization's role in heat amplification. With Kathmandu's population projected to rise from 2.88 million (2016) to 3.85 million by 2035, the findings stress the urgent need for green urban planning to mitigate SUHI impacts.
Characterization of airborne dust samples collected from core areas of Kathmandu Valley
A study on airborne dust in Kathmandu Valley reveals the presence of asbestiform minerals, characterized by high aspect ratios, alongside clay, crystalline silicate, and carbonate minerals. Using Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy with Energy-Dispersive X-ray analysis (SEM-EDX), researchers identified quartz with high crystallinity and variable elemental distributions, including C, O, Mg, Ca, and Si. Notably, some minerals in the dust samples were also found in cement, suggesting construction materials as a potential source of airborne pollutants. This research provides critical insights into the mineralogical composition of particulate matter in one of the world's most polluted urban areas.
Trend of urban growth in Nepal with a focus in Kathmandu Valley: A review of processes and drivers of change
Nepal, one of the world's fastest urbanizing countries, has seen its urban population growth rate nearly double from 3.6% in 1991 to 6.5% in 2001, with the number of urban centers surging from 58 in 2013 to 293 in 2017. Kathmandu Valley, serving as the epicenter of this transformation, now hosts an estimated 2.54 million people and is expanding at a rapid 6.5% annually, making it one of South Asia's fastest-growing metropolitan areas. This study reveals that the shift from rural to urban dominance in Nepal is largely driven by governmental administrative decisions merging rural units into municipalities and significant rural-to-urban migration. However, this unplanned urbanization has led to environmental degradation, increased poverty, and heightened vulnerability to multi-hazard risks, particularly for the urban poor. While government initiatives aim to foster inclusive, equitable, and resilient urban development through smart city programs, their implementation faces challenges due to coordination gaps, financial constraints, and constitutional barriers that restrict property regulations, exacerbating disaster risks in urban areas like Kathmandu Valley.
Air quality trends of the Kathmandu Valley: A satellite, observation and modeling perspective
Air pollution in the Kathmandu Valley, Nepal, has increased by approximately 50–60% over the past two decades (2000–2015), with background pollution contributing an additional 20–25%. This finding was derived from satellite data (MODIS AOD) and supported by in-situ measurements and modeling. The study highlights the significant impact of background aerosol loading on local air quality, particularly during the dry season (November–June). Despite using advanced models like WRF-STEM and WRF-Chem, pollution levels were underestimated, suggesting gaps in current modeling approaches. Reduced visibility in Kathmandu is linked to this background pollution, emphasizing its role in urban air degradation.
Alteration of groundwater recharge areas due to land use/cover change in Kathmandu Valley, Nepal
A significant alteration of groundwater recharge areas is projected in the Kathmandu Valley, Nepal, due to rapid urbanization. Between 2020 and 2050, built-up areas are expected to increase by 21.4%, while agricultural land and forest areas will decrease by 20.5% and 0.9%, respectively. This shift is projected to reduce open land available for groundwater recharge by 6% per decade, potentially leading to a decline in groundwater levels and affecting urban water environments, including river base flows. The study utilized the CLUE-S model for future land use/cover (LULC) projections, GIS for spatial analysis, analytical hierarchy process (AHP) for weighting recharge-influencing factors, and field tests for infiltration rate analysis to assess these changes.
Integrated Assessment of Climate Change and Land Use Change Impacts on Hydrology in the Kathmandu Valley Watershed, Central Nepal
A significant increase in river runoff of up to 37% is projected for the Kathmandu Valley (KV) watershed by 2050 under climate change scenarios, with land use/cover changes exacerbating hydrological impacts. Unlike additive effects, integrated changes from both climate and LULC modifications do not simply superimpose; instead, they interact complexly to alter base-flow and annual flow dynamics. The study employed the CLUE-S model for future LULC projections and SWAT for hydrological simulations, incorporating three regional climate models and two RCP scenarios (RCP4.5 and RCP8.5). Findings underscore the need for integrated strategies to mitigate hydrological risks in rapidly urbanizing regions like KV.
Molecular characterization of organic aerosols in the Kathmandu Valley, Nepal: insights into primary and secondary sources
A year-long molecular characterization of organic aerosols in the Kathmandu Valley revealed that biomass burning (BB) is the dominant contributor to organic carbon (OC), accounting for 24.9% annually and peaking at 36.3% during the post-monsoon season. The study, conducted from April 2013 to April 2014, identified levoglucosan as the most abundant tracer, with significant seasonal variations in other tracers like isoprene-SOA (I-SOA), phenolic compounds, and resin acids. Anthropogenic and biogenic secondary organic aerosols also contributed notably, while fungal spores and plant debris had smaller but seasonally variable impacts. These findings highlight BB and anthropogenic activities as primary sources of air pollution in the region, offering critical insights for mitigation strategies.
Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal
Groundwater nitrogen contamination in the Kathmandu Valley exhibits significant seasonal and sediment-type variability. Research reveals that ammonium (NH4-N) concentrations decrease during the wet season in gravel-dominated areas, while nitrate (NO3-N) levels rise in both clay and gravel regions, with greater fluctuation observed in gravel-bearing zones over two years of monitoring. Iron (Fe2+) concentrations also drop during the wet season across sediment types. The study analyzed spatially distributed shallow dug well samples from 2016's dry and wet seasons, alongside long-term monitoring of two shallow dug wells and one deep tube well, providing critical insights into subsurface nitrogen dynamics affecting groundwater quality in this UNESCO World Heritage Site.
Vegetable Farming and Farmers’ Livelihood: Insights from Kathmandu Valley, Nepal
Vegetable farming significantly boosts the livelihood of peri-urban farmers in Kathmandu Valley (KV), Nepal, by generating cash and providing employment opportunities. A study involving 140 farm households found that most farmers are migrants cultivating an average area of 2551.5 m² for vegetables like tomatoes, carrots, and green leafy vegetables. Binary logistic regression revealed a strong positive relationship between vegetable farming and livelihood outcomes. However, challenges such as poor market management, lack of irrigation facilities, haphazard urban growth, price fluctuations, and vegetable diseases hinder sustainability. The research suggests that targeted interventions are needed to strengthen the vegetable sector and sustain this critical source of livelihood for peri-urban farmers.
Bringing the Community Back: A Case Study of the Post-Earthquake Heritage Restoration in Kathmandu Valley
Post-earthquake heritage restoration in Kathmandu Valley, Nepal, reveals that integrating traditional community practices with modern heritage management can foster inclusive and sustainable conservation. The study highlights how reinterpreted local traditions, rooted in the commons-based approach, offer a resilient framework for protecting vulnerable monuments while addressing the challenges of national heritage systems. By analyzing post-disaster case studies and reviewing existing literature, researchers demonstrate that such collaborative models enhance cultural identity, support tourism, and ensure long-term preservation. This emerging management system bridges gaps between top-down policies and grassroots participation, providing a scalable solution for UNESCO World Heritage Sites facing similar vulnerabilities.
Evaluation of Water Security in Kathmandu Valley before and after Water Transfer from another Basin
A severe water insecurity condition in Kathmandu Valley, Nepal, is expected to improve significantly following the completion of the Melamchi Water Supply Project (MWSP). The study assessed household water security index (WSI) before and after the MWSP, revealing that current infrastructure supplies only 19% of dry-season demand and 31% during the wet season. Post-MWSP, the project aims to supply up to 510 million liters per day (MLD), potentially serving an additional 1.21 million people. However, existing distribution networks may lead to inequality in water distribution, necessitating strategies for expansion and redistribution. The research used spatial mapping with ArcMap to analyze water demand and supply data, highlighting the need for long-term measures to optimize water loss, harness additional hillside water, and manage water resources within and outside Kathmandu Upatyaka Khanepani Limited (KUKL) service areas.
Nepal: A Guide to the Art and Architecture of the Kathmandu Valley
Kathmandu Valley's art and architecture, as explored by Michael Hutt, reveal a rich tapestry of cultural heritage. This guide provides a comprehensive overview of the valley's artistic traditions, architectural styles, and historical significance, offering insights into the intricate details that define its UNESCO World Heritage status. Hutt's work combines meticulous documentation with narrative depth, capturing the essence of Nepalese craftsmanship from ancient temples to modern interpretations. The approach involves thorough field research, archival analysis, and comparative study of architectural elements, making it a foundational resource for scholars and enthusiasts alike.
Quantifying the connections—linkages between land-use and water in the Kathmandu Valley, Nepal
A significant deterioration in water quality is observed from upstream to downstream areas of the Kathmandu Valley, Nepal, with built-up land uses having the most pronounced impact. The study, conducted across nine perennial watersheds during the 2016 monsoon and 2017 pre-monsoon periods, used a combination of Rapid Stream Assessment (RSA) protocols, water quality measurements, and streamflow data to quantify these linkages. Results indicated that upstream locations in six watersheds maintained near-natural status (RQC 1), suitable for all uses after standard treatment, while downstream areas across all nine watersheds exhibited the most impaired river quality (RQC 5). A pixel-based supervised classification method was employed to analyze land-use data from a 2015 Landsat 8 image. The findings underscore the critical need for integrated land and water management, particularly in addressing waste management challenges in the Kathmandu Valley.
WRF and WRF-Chem v3.5.1 simulations of meteorology and black carbon concentrations in the Kathmandu Valley
A study evaluating the Weather Research and Forecast (WRF) model for meteorological simulations in the Kathmandu Valley, Nepal, found that while the model effectively captures key parameters like wind speed, boundary layer height, and precipitation, it struggles with subgrid-scale processes in complex terrain. When extended to include chemistry and aerosols (WRF-Chem), the model significantly underestimated black carbon concentrations, even when using improved emission data for the valley. The findings highlight the challenges of accurately modeling air pollution in mountainous regions and underscore the need for further refinements in both models and emission databases before they can reliably assess mitigation scenarios.
Detection of Land Subsidence in Kathmandu Valley, Nepal, Using DInSAR Technique
A study applying Differential Synthetic Aperture Radar Interferometry (DInSAR) to ALOS PALSAR data detected significant land subsidence in Kathmandu Valley, Nepal, between 2007 and 2010. Subsidence areas, ranging from 1 km² to 9.9 km², exhibited velocities of up to 4.8 cm/year, with depths reaching 17 cm. The phenomenon was predominantly observed in old settlement zones with mixed land use, correlating with high concentrations of groundwater extraction wells. Geological formations, primarily unconsolidated fine-grained sediments, were identified as the primary factor contributing to subsidence due to groundwater extraction. This research highlights the vulnerability of urban areas built on such geological substrates to subsidence risks.
Impact of Urbanization and Climate Change on Urban Flooding: A case of the Kathmandu Valley
Future climate change combined with current urbanization levels will significantly increase pluvial flooding in the Kathmandu Valley, with potential for a 40% rise in flood volume under extreme rainfall events. This projection underscores the inadequacy of existing drainage infrastructure designed for present climatic conditions to handle future scenarios. The study employed a dual quantitative and qualitative approach, utilizing tools like RClimdex (a statistical downscaling model) and PCSWMM, alongside Intensity Duration Frequency (IDF) curve analysis based on Gumbel distribution. By examining the interplay between urban imperviousness and extreme rainfall, the research highlights critical vulnerabilities in urban drainage systems, offering a data-driven warning for infrastructure planning in rapidly developing regions.
Investigation of the mixing layer height derived from ceilometer measurements in the Kathmandu Valley and implications for local air quality
Black carbon emissions in the Kathmandu Valley have likely been significantly underestimated in previous modeling studies, according to a new analysis of ceilometer data. The study found that estimated black carbon emission fluxes during morning hours show a clear seasonal cycle, peaking from December to April, and are considerably higher than values reported in existing emission databases. Researchers analyzed one year of ceilometer measurements to investigate the diurnal variation of mixing layer height (MLH) and its impact on black carbon concentrations across seasons. The data revealed distinct seasonal patterns in MLH, with monsoon season characterized by the lowest daytime MLH and highest night-time MLH due to frequent cloud cover. These findings provide strong evidence that black carbon emissions in this region have been systematically underestimated, which has implications for air quality management and climate modeling.
Model-based estimation of land subsidence in Kathmandu Valley, Nepal
Land subsidence in the Kathmandu Valley, Nepal, is primarily driven by deep aquifer compaction due to excessive groundwater abstraction, with hotspots identified in the north and northeast peripheral areas. This study, the first of its kind, used a fully calibrated groundwater flow model coupled with surface-subsurface modeling to predict subsidence patterns. The findings indicate that changes in land cover within recharge areas significantly influence subsidence sensitivity, while the Melamchi water supply project demonstrates some mitigative effects. Although the analysis is preliminary and lacks field measurements, it provides critical insights for hazard prevention management, guiding future field investigations, monitoring networks, and groundwater data upgrades. However, a more comprehensive model incorporating clay subsidence is needed to fully assess the vulnerability of the densely populated central valley core.
Monitoring Urban Growth and the Nepal Earthquake 2015 for Sustainability of Kathmandu Valley, Nepal
Urban coverage in Kathmandu Valley has expanded dramatically from 20.19 km² in 1976 to 139.57 km² in 2015, with an average annual growth rate of 7.34% to 7.70%, driven by unplanned urbanization that has depleted cultivated lands and forests. This rapid expansion, analyzed using Landsat images from 1976 to 2015, shows significant urban concentration in the eastern part of the valley while exposing geological vulnerabilities that could threaten future sustainability if current trends persist. The study highlights the urgent need for strategic land-use planning and policies to mitigate environmental and cultural risks.
Near-road sampling of PM 2. 5 , BC, and fine-particle chemical components in Kathmandu Valley, Nepal
A significant contribution of vehicle-related emissions to air pollution in Kathmandu Valley, Nepal, persists throughout both the dry spring and monsoonal seasons. Despite lower overall PM2.5 concentrations during the monsoon, black carbon (BC) levels remained high, indicating strong vehicular influence year-round. The study, conducted using near-road sampling by volunteer traffic police officers at six major intersections in 2014, found that BC accounted for 39% of PM2.5 during the monsoon compared to 18% in spring, alongside increased contributions from crustal elements and heavy metals. Silica, calcium, aluminum, and iron were dominant elements in both seasons, with minimal spatial variation observed in PM2.5 and BC concentrations.
Particulate Matter and Risk of Hospital Admission in the Kathmandu Valley, Nepal: A Case-Crossover Study
A 10-μg/m³ increase in PM10 levels was associated with a 1.7% rise in respiratory hospitalizations and 2.29% in cardiovascular admissions, highlighting the severe health risks of air pollution in the Kathmandu Valley, where daily PM10 concentrations averaged 120 μg/m³, peaking at 403 μg/m³. This study, using time-stratified case-crossover analysis with data from six major hospitals (2004–2007), is among the first to quantify pollution-related hospitalization risks in South Asia, revealing a significant burden despite limited evidence in the region.
Rapid Urban Growth in the Kathmandu Valley, Nepal: Monitoring Land Use Land Cover Dynamics of a Himalayan City with Landsat Imageries
Between 1989 and 2016, the urban area of the Kathmandu Valley expanded by 412%, driven primarily by the conversion of agricultural land. This rapid urban growth, analyzed through a pixel-based hybrid classification of Landsat imagery, reveals a concentric expansion pattern along major roads, significantly altering the valley's cityscape. The study identifies rural-to-urban migration and the centrality of Kathmandu as key proximate causes behind this transformation. While most expansion occurred between 1989 and 2009, urban growth continues, underscoring the need for systematic monitoring of land use and land cover changes in this Himalayan metropolitan valley.
Screening of antibiotic residues in fresh milk of Kathmandu Valley, Nepal
A concerning prevalence of antibiotic residues, particularly amoxicillin and sulfadimethoxine, was detected in fresh milk from Kathmandu Valley, Nepal. High-performance liquid chromatography (HPLC) analysis revealed that 81% of samples contained amoxicillin (68–802 µg/kg), while 41% tested positive for sulfadimethoxine (31–69 µg/kg). These levels often exceeded maximum residue limits, posing significant risks to consumer health. The study, which analyzed 140 milk samples from various sources, demonstrated that HPLC detected more positives than rapid screening kits due to higher precision and accuracy. This highlights critical gaps in regulatory implementation and monitoring in developing countries.
Seasonal and diurnal variations in methane and carbon dioxide in the Kathmandu Valley in the foothills of the central Himalayas
Kathmandu Valley exhibits significantly higher levels of methane (CH4) and carbon dioxide (CO2) compared to global background sites. Annual averages measured at Bode, a semi-urban location in the valley, were 419.3 ppm for CO2 and 2.192 ppm for CH4—substantially above levels recorded in Mauna Loa (USA) and Waliguan (China). Seasonal variations showed that CO2 peaked during the pre-monsoon season due to forest fires and agro-residue burning, while CH4 exhibited minimal seasonal fluctuation. Diurnal patterns revealed pronounced morning peaks for all three gases (CO2, CH4, and CO), with a notable dip in the afternoon, attributed to local emissions such as residential cooking, vehicle exhaust, and brick kiln activities during winter. Simultaneous measurements at a rural site (Chanban) confirmed that urban areas like Bode experience 3.8–64% higher gas concentrations, underscoring the valley's unique geography and pollution dynamics.
Source apportionment of NMVOCs in the Kathmandu Valley during the SusKat-ABC international field campaign using positive matrix factorization
A study using positive matrix factorization identified eight major sources of non-methane volatile organic compounds (NMVOCs) in the Kathmandu Valley, with unresolved industrial emissions and traffic being the largest contributors. Notably, biomass co-fired brick kilns significantly elevated concentrations of health-relevant NMVOCs like benzene. Biogenic emissions dominated daytime ozone production potential, even in winter, while secondary organic aerosol (SOA) production was equally influenced by brick kilns and traffic. The research also found that existing emission inventories underestimate traffic contributions and omit brick kiln emissions entirely, highlighting gaps in current models. This quantitative source apportionment provides critical insights for refining NMVOC emission inventories and guiding mitigation strategies in the Kathmandu Valley.
A multi-model approach for analyzing water balance dynamics in Kathmandu Valley, Nepal
A multi-model hydrological analysis of the Kathmandu Valley, Nepal, reveals consistent water balance dynamics across three distinct models (SWAT, HBV, and BTOPMC), with annual runoff accounting for 55–59% of precipitation and evapotranspiration showing minimal inter-annual variation. While estimates of total water storage varied, all models agreed on long-term averages, providing a robust range for future water resource planning. The study demonstrates that multi-model approaches can effectively capture seasonal and temporal variations in water balance components, offering valuable insights for sustainable water management in the region.
Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley
Wintertime air pollution in the Kathmandu Valley, Nepal, is characterized by unusually high concentrations of volatile organic compounds (VOCs), with acetaldehyde (8.8 ppb), methanol (7.4 ppb), and acetone + propanal (4.2 ppb) dominating the chemical profile. The study, conducted during the SusKat-ABC campaign in 2012–2013 using a high-resolution proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS), identified 71 VOC species, including 'new' ambient compounds like formamide and acetamide, which can photochemically produce isocyanic acid—a known health hazard. Biomass burning and brick kilns emerged as major sources of toxic VOCs such as benzene and isocyanic acid, while isoprene and oxygenated VOCs significantly contributed to ozone production potential. This research highlights the critical need for mitigating biomass burning activities to reduce harmful emissions in South Asia.
Predictors of incompletion of immunization among children residing in the slums of Kathmandu valley, Nepal: a case-control study
A study in the slums of Kathmandu Valley, Nepal, reveals that 26% of children aged 12–23 months remained incompletely immunized, with measles vaccine coverage notably lower (80.5%) than BCG (95%). Key predictors of incomplete immunization included home delivery, rental housing, poor caretaker knowledge of vaccination schedules, negative perceptions about vaccinating sick children, and abscess formation post-vaccination. The research employed an unmatched case-control design, analyzing data from 236 children to identify independent risk factors using backward logistic regression. Findings suggest targeted interventions—such as reducing abscess rates, increasing follow-ups for home-born children or renters, and educating caretakers about immunization schedules and side effects—could significantly improve vaccination completion in slum settings.
Site amplification in the Kathmandu Valley during the 2015 M7.6 Gorkha, Nepal earthquake
The 2015 M7.6 Gorkha earthquake in Nepal caused significant damage and loss of life, particularly in the Kathmandu Valley, due to site amplification effects that exceeded design levels set by Nepalese building codes. A study using passive microtremor recordings identified clear site amplification in the Siddhitol Region, highlighting the need for site-specific hazard analysis and revisions to building codes to mitigate future risks. The research approach involved analyzing shear wave velocity profiles from severely damaged areas and the main seismic station in Kathmandu, converting these into spectral accelerations using earthquake input motion data.
Site effects and associated structural damage analysis in Kathmandu Valley, Nepal
Nonlinear seismic site response analysis more accurately predicts structural damage patterns in Kathmandu Valley compared to equivalent-linear analysis, as demonstrated by the 2015 Mw7.8 Gorkha earthquake. The study found that nonlinear models better capture soil amplification and peak ground acceleration (PGA) variations, with PGA ranging from 0.17 to 0.46 g—closely matching observed damage scenarios. While equivalent-linear analysis underestimated amplification (2.3–3.8), nonlinear analysis revealed higher values (8.9–18.2), aligning with severe damage in three sites and minimal damage in two others. The research also exposed inaccuracies in the USGS PGA map for southern Kathmandu, contrasting with northern regions. Soil fundamental periods of 0.4–0.5 seconds were consistent across both methods, providing critical data for seismic demand analysis.
Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake
The 2015 Gorkha earthquake (Mw 7.8) in Nepal revealed significant ground motion variations in the Kathmandu Valley, with sediment-filled sites experiencing prolonged, large-amplitude oscillations—up to 10 times greater than rock sites—due to basin response. While peak ground accelerations were lower than predicted, peak velocities exceeded predictions, particularly at sedimentary sites. These long-period oscillations (3–5 s) posed a destructive risk to high-rise buildings, highlighting the valley's complex structure and its role in amplifying seismic energy. The study analyzed strong ground motions from four observation sites, combining tectonic offset data with sediment-specific responses to assess earthquake hazards in urban areas.
The Status of Domestic Water Demand: Supply Deficit in the Kathmandu Valley, Nepal
A significant water supply deficit of 102 million liters per day (MLD) was identified in the Kathmandu Valley, Nepal, in 2016, despite the completion of the first phase of the Melamchi Water Supply Project (MWSP). The study estimated domestic water demand and available resources to assess the valley's water crisis. If the MWSP is fully completed by 2023–2025 with adequate treatment and distribution infrastructure, it could eliminate this deficit, substantially improving water security in one of Nepal's most developed and populated regions. However, the research highlights the need for efficient utilization of MWSP water through robust infrastructure development and complementary strategies such as rainwater harvesting, land-use planning for recharge, conjunctive use of surface and groundwater, and demand-side management to ensure sustainable water security.
Variability of Anthropogenic Gases: Nitrogen Oxides, Sulfur Dioxide, Ozone and Ammonia in Kathmandu Valley, Nepal
Ground-level ozone (O₃) poses significant air quality concerns in the Kathmandu Valley, frequently exceeding health guidelines. A 2013 study revealed higher O₃ concentrations in rural areas (108.5 ± 31.4 μg m⁻³) compared to urban sites (87.1 ± 9.2 μg m⁻³), highlighting the role of meteorology and precursor gases in its formation. Urban regions also exhibited elevated nitrogen dioxide (NO₂, 22.4 ± 8.1 μg m⁻³) and sulfur dioxide (SO₂, 14.5 ± 11.1 μg m⁻³) levels, with SO₂ peaking near brick factories (22.3 ± 14.7 μg m⁻³). Ammonia (NH₃) emerged as a critical pollutant near polluted rivers, while SO₂’s proximity to industrial sources underscored its role in particulate matter formation. The study employed passive sampling across 15 sites from March to May 2013, followed by targeted measurements in 2014, revealing spatial variability and the need for intensified monitoring.
Drinking Water Quality of Kathmandu Valley
A significant portion of drinking water sources in the Kathmandu Valley, including dug wells, deep borings, treated water, tap water, and other sources, exceeds World Health Organization (WHO) standards for key parameters. The study found that turbidity, iron, ammonia, and conductivity were common problematic factors across various water sources. Notably, 86% of groundwater samples (wells and borings) exceeded WHO standards for total Coliform bacteria, while 36% of treated water and 80% of tap water samples were contaminated with Coliform bacteria. Additionally, parameters such as pH, chloride, arsenic, and hardness frequently surpassed safe limits, particularly in untreated sources. The research analyzed 969 water samples collected from Kathmandu, Lalitpur, and Bhaktapur districts between March 2012 and March 2013, assessing physical, chemical, and microbiological parameters to assess compliance with WHO guidelines.
Seasonal variation of ozone and black carbon observed at Paknajol, an urban site in the Kathmandu Valley, Nepal
A first-of-its-kind year-long study (2013–2014) at Paknajol, Kathmandu, reveals persistent severe air pollution driven by local sources and regional open vegetation fires. The research found that ozone (O₃) and black carbon (BC) concentrations, particularly during pre-monsoon afternoons/evenings, are strongly influenced by photochemistry, planetary boundary layer dynamics, and westerly atmospheric circulations. High O₃ levels correlate with mixing processes between residual layers and the PBL, while BC spikes reflect local emissions. The study highlights dangerous air quality conditions for over 3 million residents, threatening health and ecosystems. These findings provide critical data to design mitigation strategies for acute pollution events in the Kathmandu Valley.
Seismic response of current RC buildings in Kathmandu Valley
Most existing reinforced concrete (RC) buildings in the earthquake-prone Kathmandu Valley exhibit inadequate seismic performance, with non-engineered structures showing significantly higher inter-storey drift demands and lower lateral resistance compared to engineered ones. The study analyzed four representative RC buildings using non-linear dynamic analysis under synthetic earthquakes applied at 0°, 45°, and 90° directions, revealing that geometric non-linearities (P-delta effects) reduce global lateral stiffness and structural strength. Engineered buildings demonstrated better performance but still faced challenges due to plan and vertical irregularities. The findings highlight the urgent need for seismic safety assessments and retrofitting of existing structures in Nepal.
Drawdown and Dynamics of Groundwater Table in Kathmandu Valley, Nepal
Groundwater drawdown in Kathmandu Valley, Nepal, averages 0.7249 meters annually, mirroring critical trends observed in Mexico City's alluvial deposits where subsidence is already a concern. This rapid depletion, driven by excessive groundwater extraction for domestic and industrial use, threatens water security and environmental stability, as nearly half the valley's population relies on these resources. The study employed linear regression modeling to analyze drawdown rates alongside standard deviation ranges, revealing a shift in drainage patterns toward the southwestern part of the valley. These findings underscore the urgent need for sustainable groundwater management to mitigate hydrological, hydrogeological, and environmental risks, including land subsidence and water scarcity.
Social capital in disaster risk management; a case study of social capital mobilization following the 1934 Kathmandu Valley earthquake in Nepal
A study on the Kathmandu Valley reveals that social capital—specifically bonding, bridging, and linking types—played a crucial role in disaster recovery following the 1934 earthquake. Survivors from Lalitpur demonstrated how close-knit community ties (bonding) provided immediate support, while broader networks (bridging and linking) facilitated long-term survival and neighborhood revitalization. The research suggests that integrating pre-disaster social capital into disaster planning could enhance response capacity, offering valuable insights for community-based disaster management strategies. This qualitative study used non-structured interviews and grounded theory to analyze survivor accounts, though memories from participants under ten at the time may have limited detail.
Access to improved water and its relationship with diarrhoea in Kathmandu Valley, Nepal: a cross-sectional study
In the Kathmandu Valley, Nepal, access to sufficient water—regardless of source—significantly reduces the risk of diarrhoea compared to inadequate water consumption. A study analyzing data from 2,282 households found that those consuming less than the WHO-recommended 100 liters per capita daily faced up to a 2.92-fold higher risk of diarrhoea. Additionally, households relying on alternative water sources alongside improved water had an 1.81-fold increased likelihood of illness. These findings held true even after accounting for socioeconomic factors, water treatment practices, and sanitation facilities, suggesting that ensuring adequate water quantity is critical in preventing diarrhoea, particularly in densely populated urban areas.
Microbial assessment of bottled drinking water of Kathmandu valley
A significant proportion of bottled water brands in Kathmandu Valley, Nepal, fail to meet international microbiological safety standards. The study found that 63.3% of samples exceeded acceptable heterotrophic bacterial counts (<50 CFU/ml), while 56.6% contained total coliforms (above WHO’s 0 CFU/ml threshold). Overall, 83.3% of brands were deemed unsafe for consumption due to microbial contamination. This research highlights a critical public health concern in the region, with potential implications for waterborne disease transmission. The study employed cross-sectional sampling of 30 commercial brands using membrane filtration and spread plate techniques to enumerate bacterial contaminants.
Seasonal variation in the microbial quality of shallow groundwater in the Kathmandu Valley, Nepal
Groundwater microbial quality in the Kathmandu Valley, Nepal, deteriorates significantly during the wet season compared to the dry season. This seasonal variation is attributed to increased infiltration of fecal material and rising groundwater levels, which likely introduce contaminants into shallow aquifers. The study, conducted from 2009 to 2012, analyzed Escherichia coli and total coliform concentrations in dug wells monthly for a year, revealing a moderate to strong correlation between microbial contamination and groundwater levels. These findings highlight the need for targeted pollution control strategies to mitigate seasonal fluctuations in water quality, particularly during monsoon periods.
Seroprevalence of Zoonotic Parasites in Pigs Slaughtered in the Kathmandu Valley of Nepal
A study conducted between 2007 and 2010 in the Kathmandu Valley, Nepal, revealed low but notable seroprevalence of zoonotic parasites in slaughtered pigs. Only 0.1% of the 742 pigs tested positive for Trichinella infection, while 13.8% were found to have T. solium cysticercosis and 11.7% showed signs of Toxoplasma infection. The research highlights the potential risk of pork as a carrier of zoonotic agents, emphasizing the need for enhanced food safety protocols throughout the pork production chain in Nepal. This cross-sectional study used serological methods to assess the infection status of pigs, providing critical data on the prevalence of these parasites and their implications for public health.
Seismic Microzonation of Densely Populated Area of Kathmandu Valley of Nepal using Microtremor Observations
Seismic microzonation of the Kathmandu Valley reveals that areas with thick lake sediments, particularly near the valley's center, experience dominant amplification periods approaching 2 seconds. This finding indicates a heightened risk for long-period shaking during future earthquakes in densely populated urban zones, where tall structures and bridges with similar natural periods are prevalent. The study employed horizontal-to-vertical spectral ratio analysis of ambient noise recordings to map seismic site response variability, providing critical insights for earthquake hazard assessment in this historically vulnerable region.
Prevalence of protozoa, viruses, coliphages and indicator bacteria in groundwater and river water in the Kathmandu Valley, Nepal
A significant prevalence of waterborne pathogens was found in groundwater and river water samples from the Kathmandu Valley, Nepal, during the rainy season of 2009. The study detected at least one type of pathogen—including Cryptosporidium, Giardia, human adenoviruses, and noroviruses—in 56% of shallow well samples tested. River water exhibited notably higher concentrations of these pathogens compared to groundwater, with Cryptosporidium and Giardia levels reaching 140 oocysts/l and 8500 cysts/l, respectively. The research also demonstrated that E. coli-positive groundwater samples were more likely to contain protozoa and viruses, suggesting its potential as an indicator for pathogen contamination in valley groundwater. Additionally, genotyping of F-RNA coliphages was successfully used to differentiate between human and animal fecal sources.
Characteristics and Sources of Carbonaceous, Ionic, and Isotopic Species of Wintertime Atmospheric Aerosols in Kathmandu Valley, Nepal
Aerosol pollution in Kathmandu Valley during winter is dominated by local emissions, with secondary organic carbon (SOC) contributing 31% to organic carbon (OC). The study, using bulk aerosol samples collected from 2007–2008, found that elemental carbon (EC) and OC were correlated, suggesting common sources. Water-soluble organic carbon (WSOC) accounted for half of OC, with SOC strongly correlating with WSOC, indicating water solubility in both primary and secondary forms. Carbon isotope analysis confirmed anthropogenic fossil fuel combustion as a consistent source, while nitrogen isotopes suggested limited biomass burning influence. Principal component analysis identified four major particle sources: local/vehicular emissions (39%), secondary gas-to-particle conversion (23%), aqueous processing (11%), and dust transport (9%).
Urban Vulnerabilities in the Kathmandu Valley, Nepal: Visualizations of Human/Hazard Interactions
Rapid, unplanned urbanization in the Kathmandu Valley, Nepal, exposes residents to significant vulnerabilities, particularly related to environmental degradation and seismic risks. Unlike previous studies that primarily focus on socioeconomic factors, this research highlights the spatial and physical dimensions of these vulnerabilities—such as population density, road networks, vehicular traffic, garbage management, and open spaces—using three-dimensional visualizations to differentiate between high-risk and relatively safer urban areas. The study contributes a methodological framework for understanding human-hazard interactions in rapidly urbanizing cities of the Global South, offering insights applicable to similar socioeconomic and environmental contexts.
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