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Urban flooding problem has been exacerbated in recent times, especially in developing nations, due to haphazard changes in land use and land cover (LULC) resulting from rapid urban expansion, coupled with river encroachments and inadequately engineered river management structures. Kathmandu Valley Watershed (KVW), encompassing Kathmandu, Bhaktapur and Lalitur districts, the fastest growing cities in South Asia, is constantly growing, with a significant increase in urban areas. Due to urbanization, the watershed's water storage capacity is diminishing, while surface runoff volume and rate are accelerating. We evaluated the isolated as well as the integrated impact of multiple scenarios of LULC change and river encroachment on flood inundation characteristics in KVW. LULC prediction revealed an increase in built-up areas by 113% between 1990 and 2020, which are further projected to increase by 29% by 2050. Inundation modeling using Rainfall-Runoff Inundation (RRI) model showed that rather than the increase in inundation extent, the depth of inundation is projected to increase in future as a result of increasing urban areas. Furthermore, our research highlighted that the impact of river width encroachment had a more substantial effect on flooding compared to changes in LULC alone. Similarly, integrated impact of LULC change and river encroachment was more pronounced than the impact of change in LULC alone. The aggregate of observations leads to the conclusion that the encroachment of rivers is the predominant factor contributing to the flooding issue within the KVW. The findings of the study is anticipated to assist policymakers in effective land use planning and in proposing appropriate development initiatives concerning the river environment. [ABSTRACT FROM AUTHOR]

Studies on concrete dam breach are limited compared to earthen and other types of dams. With an increase in the construction of concrete dams, particularly in the developing world, it is imperative to have a better understanding of the dam breach phenomena and the identification of the most influential breach parameters. This study aims to contribute to this gap by taking the case of the concrete arch dam proposed for the 1200 MW Budhigandaki Hydropower Project located in central Nepal. This study carries special significance for Nepal, primarily because of the increasing number of under construction and proposed large dams for water resources development in the country. We carry out dam breach analysis of the Budhigandaki dam using HEC-RAS 2D model to calculate the flood discharge peaks, time to peak, water surface elevation and the extent of inundation for two scenarios (with and without probable maximum flood) to estimate the damage on four downstream settlements. We carry out sensitivity analysis of the breach parameters on the flood magnitudes and severity. Results show that all the study locations lie in the high flood hazard zone. Flood peaks can reach as high as 286,000 m3s− 1 to 511,000 m3s− 1 in the considered settlements. The time to peak ranges from 11.3 to 17 h after the breach at these locations. We estimate that if a breach should happen, it would most likely inundate around 150,000 buildings, impact nearly 672,000 lives and flood 3,500 km of road downstream. Furthermore, dam breach elevation is found to be the most sensitive parameter to downstream floods. Hence, rather than structural measures, it is recommended that non-structural measures are implemented for minimizing the impacts of flood disasters at the study locations. The findings could be a useful reference for future dam projects in Nepal and other areas with similar hydrological and topographical conditions. [ABSTRACT FROM AUTHOR]

Climate variability, climate change, and anthropogenic disturbances increase the likelihood and intensity of heatwaves. Urban centers, characterized by dense populations, are experiencing a growing impact from these heatwaves. A comprehensive understanding of the spatiotemporal characteristics of heatwaves is essential for proposing effective mitigation strategies. This study utilizes land surface temperature datasets from 2003 to 2020 to characterize spatial and temporal variability of heatwaves across the Kathmandu Valley, Nepal, and identify regions and periods with high heat hazards, exposure, and risks. Regions with high heatwave hazards are identified based on frequency, duration, and magnitude of heatwaves for daytime, nighttime, average of daytime and nighttime, and a combination of both conditions. Additionally, vulnerability is assessed based on demographic distribution. Heatwave Risk Index is computed by superimposing composite heatwave index and vulnerability. Through geospatial analysis, our study identifies distinct regions and time periods characterized by varying levels of heatwave severity and associated risks to diverse population distributions. In recent years, there has been a notable increase in the prevalence of extreme heatwave conditions, particularly after 2010 and especially from 2012 onwards. Importantly, this trend is more pronounced in nighttime temperature data, highlighting discomfort during the night when the body requires rest and recovery. Our findings emphasize the crucial need for policies tailored to urban environments, addressing factors related to the built environment factors, societal stresses, and vulnerabilities. These policies are essential for enhancing systematic preparedness in response to the challenges posed by a changing climate. [ABSTRACT FROM AUTHOR]

Hydro-climatic extremes, such as floods and droughts, are influenced by climate change and climate variability, significantly affecting natural ecosystems, human lives, and livelihood. It is crucial to advance the understanding of long-term trends of hydro-climatic extremes for effective water resource planning and management. We analyzed 25 climatic extremes-related indices and 33 hydrologic extremes-related indices in a medium-range river basin in western Nepal, the Babai River Basin. We used RClimDex and Indicators for Hydrologic Alterations to analyze extreme climatic and hydrologic parameters. We computed monotonic trends to evaluate temporal changes in extreme events. The results show a positive trend of total precipitation at Kusum (+ 2.2 mm/year) and Bargadaha (+ 17.7 mm/year) stations and a negative trend at Gulariya (− 5.7 mm/year), Nayabasti (− 7.0 mm/year), Luwamjula (− 5.9 mm/year), and Ghorai (− 18.5 mm/year) stations. Similarly, we observe that almost all temperature extreme indices have a rising trend except the percentage of the days when the maximum temperature is less than the 10th percentile index at Rani Jaruwa station, located at a low elevation. Notably, the cold day temperature index falls at 0.13 days per year. Overall, the hydrologic alteration value shows moderate variability and reduction in the median flow for the second half. The findings of this study indicate that the study area is subjected to a reduced flow regime with a medium degree of variability. [ABSTRACT FROM AUTHOR]

Quantifying the extent of change in climatic and hydrological variables in the past and the future is essential for climate change-resilient development, especially in the climate change sensitive region of Nepal. This paper analyzed future climatic trends and extremes, historical hydrological extremes and their linkage with historical precipitation extremes, and discussed the impacts of climate change on various sectors in the less-studied Small and Medium-sized Eastern River Basins (SMERB) of Nepal. Applying an ensemble of five Coupled Model Intercomparison Project phase 6 (CMIP6) global climate models (GCMs), we evaluated 10 precipitation and 13 temperature extreme indices using Climpact2 for the historical (1979–2020), near-future (2021–2045), mid-future (2046–2070) and far-future (2071–2100) under two Shared Socioeconomic Pathway (SSP), SSP245 and SSP585. Hydrological extreme indices were assessed using Indicators of Hydrologic Alteration tool. Projected climate revealed significant increase (9–73%) in annual and seasonal rainfall except winter; frequent intense rainfall extremes but prolonged dry spells; significant increasing minimum and maximum temperature trends (0.4–5 °C); rise in extreme heat events; increasing minimum and maximum discharge extreme trends in most hydrological stations; as well as strong association between maximum 1 day precipitation (Rx1day) and 1 day max flow for all stations. Growing dry periods but intense rainfall in few wet days, coupled with warming pattern all-over SMERB with frequent extreme events indicate high risk for future climate-related disasters. The harsher climate will potentially have damaging implications, especially in climate-induced disasters, food security, and water and sanitation infrastructure. [ABSTRACT FROM AUTHOR]

Floods pose significant risk to riparian buildings as evidenced during many historical events. Although structural resilience to tsunami flooding is well studied in the literature, high-velocity and debris-laden floods in steep terrains are not considered adequately so far. Historical floods in steep terrains necessitate the need for flood vulnerability analysis of buildings. To this end, we report vulnerability of riparian-reinforced concrete buildings using forensic damage interpretations and empirical/analytical vulnerability analyses. Furthermore, we propose the concept and implications of functionality loss due to flooding in residential reinforced concrete (RC) buildings using empirical data. Fragility functions using inundation depth and momentum flux are presented for RC buildings considering a recent flooding event in Nepal. The results show that flow velocity and sediment load, rather than hydrostatic load, govern the damages in riparian RC buildings. However, at larger inundation depth, hydrostatic force alone may collapse some of the RC buildings. [ABSTRACT FROM AUTHOR]

Climate change has increased the intensity and frequency of hydro-climatic extremes in many parts of the world and they are projected to continue in the future too, thus, posing a major threat to agriculture, biodiversity, ecosystems, and water systems. This study characterized the historical as well as projected future hydro-climatic extremes in the eleven rain-fed watersheds in western Nepal (i.e., south-western watersheds, SWWs). Sixteen climate extreme indices were analyzed using ClimPACT2 tool and nine hydrological extremes using IHA tool. Five CMIP6-based climate models driven by SSP245 and SSP585 scenarios were used to project the future climate. Results showed that the SWWs have experienced progressive warming and increased rainfall during the historical period (1980–2014), and this rising trend is projected to be more prominent in the future (2021–2100), posing risks to the socio-environmental equilibrium. Establishing a positive correlation between the occurrences of climatic and hydrologic extremes, this study also points towards more prevalence of hydrological extremes in the future as well, and therefore, suggests policy and technology recommendations to reduce and adapt to climate change, intending to alert relevant authorities to promptly enact climate-related policies. [ABSTRACT FROM AUTHOR]

Recurring floods have devastating consequences on the East Rapti Watershed (ERW), but effective mitigation/adaptation measures are lacking. This article aims at establishing a rainfall‐runoff (RR) relationship; estimating depth and extent of inundation under climate change scenarios; assessing impacts on the socio‐economy; and identifying and evaluating adaptation strategies in the ERW. Artificial Neural Network (ANN) was used to generate peak flows which were then entered into a hydraulic model to simulate inundation. Results were validated with field survey. The calibrated and validated RR and hydraulic models were fed with projected future climate (2021–2050) derived from multiple regional‐climate‐models to assess the changes in inundation. Results showed the peak discharge likely exceeds 10,500 m3/s at the ERW outlet in the extreme future flood scenario with corresponding inundation of 80 km2 and up to a depth of 11 m sweeping away over 1000 houses and 19 km2 of agricultural land in the critical areas. Constructing a 17 km long embankment in the critical areas along the right bank of the East Rapti River could reduce the flood spread by 35%, safeguarding 78% of the houses and saving 51% agricultural land compared with the scenarios without the embankment. [ABSTRACT FROM AUTHOR]

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Successful community institutions in the global South, which are contributing to livelihoods' improvement while conserving water and other natural resources, can sustainably build the resilience that policy makers at different tiers are seeking. This article assesses different models of community institutions in Nepal in governing water resources from various lenses, based on Ostrom's and others' design principles, including bricolage. Illustrated by three empirical cases, it analyses key features of community institutions in integrated water governance, their contributions to health, nutrition, food security, and environmental conservation, and ways for empowering these institutions as viable and sustainable solutions to address various livelihood challenges. However, inequalities along gender, caste, and ethnicity lines persist. We argue that the recently established local governments under the federal system in Nepal provide new opportunities for gender and social inclusion. [ABSTRACT FROM AUTHOR]

An accurate estimation of precipitation amount is crucial for various studies and planning related to water resource management, effective flood prediction and warning systems, agriculture, climatic research, and disaster risk management. However, due to the sparse and uneven distribution of ground-based precipitation gauges over rugged terrain, accurate and consistent measurement is inadequate in many developing and mountainous countries like Nepal. Therefore, satellite-based precipitation products (SPPs) and interpolation-based gridded data are considered as a vital source of precipitation estimation, which may serve as crucial inputs for a wide range of hydrological applications. However, in the absence of quality assessment, applications of these products pose uncertainty. This study evaluated the performance of three SPPs, i.e., CHIRPS V2.0, PERSIANN CDR, and MSWEP V2.8, and a ground-based gridded precipitation product APHRODITE on daily, monthly, and annual scales at ten rain gauges over the Arun River Basin. The performance of the precipitation products was evaluated from 1983 to 2014 using several statistical categorical and continuous indices. Our results show APHRODITE and MSWEP V2.8 are comparatively better than CHIRPS V2.0 and PERSIANN CDR in the study area. We finally applied the bias correction of the selected products using a linear scaling method, where daily precipitation data were corrected using a monthly correction factor. We find all SPPs have improved after the bias correction. The method is scalable and applicable in other river basins across the country and beyond Nepal. [ABSTRACT FROM AUTHOR]

Despite subtle variations in soil moisture (SM) across a paddock, irrigation scheduling in New Zealand dairy farms is solely based on the SM monitored at a single location, primarily using an Aquaflex soil moisture sensor at a specified root depth. This study aimed to address this issue by assessing the "effective" root depth of a pasture, calibrating the Aquaflex soil moisture sensor and evaluating the spatial and temporal variability of SM. Twenty non-weighing lysimeters and 1 Aquaflex with 2 sensors installed 125-m away from the lysimeters on the same paddock were utilized for the study. TDR probes with 200-, 500- and 900-mm lengths were installed vertically adjacent to the Aquaflex and the lysimeters for monitoring spatio-temporal variability in SM, and calibrating the Aquaflex. A dry down experiment was performed for investigating the root depth of the pasture. All TDR probes responded to wetting and drying events, with varying SM measurements both vertically and horizontally, due to variations in soil type at different locations, indicating a need of SM monitoring at different locations in the paddock for irrigation scheduling. There was a strong linear relationship between the Aquaflex and TDR probes readings, which can be used to calibrate the Aquflex and improve its reliability for measuring soil moisture and in turn irrigation needs. Over the dry down period, out of the total moisture change in the 0–900-mm soil profile, 96% was contributed by 0–500 mm, indicating that the significant root depth of the pasture lies on the top 500-mm soil profile. Findings of the study can contribute to better irrigation scheduling and to conserve water. [ABSTRACT FROM AUTHOR]

Springs supply water for drinking and livelihood for a vast majority of rural population in Nepal. Haphazard development activities are affecting springs adversely in hills and mountains of Nepal. This study aims to map springs, characterize their status from visual inspection and local/indigenous knowledge, characterize water quality, and then evaluate their suitability for drinking and irrigation in the Thuligaad watershed, western Nepal. Analysis of 160 springs mapped within four Wards (Ward is the smallest (fourth level) Administrative Unit in Nepal) in the Jorayal Rural Municipality in the Thuligaad watershed indicated that most of the springs are perennial (95%), located in less than 1,200 or within 1400–1600 m above the sea level elevation (70.6%), and have discharge less than five liters per minutes (80% during pre-monsoon season). Multiple tools such as Gibb's diagram, Piper's diagram, and principal component analysis were used to characterize water quality. Forty springs selected for spring water quality analysis indicated that it is dominated by Ca2+ > Mg2+ > Na+ > K+ and HCO3− > Cl− > SO42− water types, thus revealing rock–water interaction as dominant process controlling the spring water quality. Furthermore, water chemistry is dominantly Ca–HCO3 (52% in pre-monsoon) and Mixed Ca–Mg–Cl (28% in pre-monsoon) types. Finally, suitability analysis revealed that spring water quality is of excellent quality for drinking and concentration of various parameters comply with national and World Health Organization's standard for drinking water quality. Similarly, the water is sage against various hazards for use in irrigation. Results of this first study in the study area provided valuable baseline information for spring water source protection and management. [ABSTRACT FROM AUTHOR]

The COVID‐19 pandemic has impacted social, economic, and environmental systems worldwide, slowing down and reversing the progress made in achieving the Sustainable Development Goals (SDGs). SDGs belong to the 2030 Agenda to transform our world by tackling humankind's challenges to ensure well‐being, economic prosperity, and environmental protection. We explore the potential impacts of the pandemic on SDGs for Nepal. We followed a knowledge co‐creation process with experts from various professional backgrounds, involving five steps: online survey, online workshop, assessment of expert's opinions, review and validation, and revision and synthesis. The pandemic has negatively impacted most SDGs in the short term. Particularly, the targets of SDG 1, 4, 5, 8, 9, 10, 11, and 13 have and will continue to have weakly to moderately restricting impacts. However, a few targets of SDG 2, 3, 6, and 11 could also have weakly promoting impacts. The negative impacts have resulted from impeding factors linked to the pandemic. Many of the negative impacts may subside in the medium and long terms. The key five impeding factors are lockdowns, underemployment and unemployment, closure of institutions and facilities, diluted focus and funds for non‐COVID‐19‐related issues, and anticipated reduction in support from development partners. The pandemic has also opened a window of opportunity for sustainable transformation, which is short‐lived and narrow. These opportunities are lessons learned for planning and action, socio‐economic recovery plan, use of information and communication technologies and the digital economy, reverse migration and "brain gain," and local governments' exercising authorities. Plain Language Summary: The current pandemic has impacts on social, economic, and environmental systems, including Sustainable Development Goals (SDGs). SDGs consist of 17 interlinked goals that aim to achieve a better and more sustainable future for all. We studied the pandemic's impacts on SDGs for Nepal by following a knowledge co‐creation process. For this, we conducted online surveys and workshops with experts from various professional backgrounds and assessed expert's opinions articulated in the surveys and workshops. The experts reviewed and validated our assessment. Then, we revised and synthesized the assessment. Our study highlights that the pandemic has negatively impacted most SDGs, particularly the targets of SDG 1, 4, 5, 8, 9, 10, 11, and 13. These negative impacts may subside in the medium and long terms. The key factors behind the negative impacts are: lockdowns, underemployment and unemployment, closure of facilities, diluted focus and funds for non‐pandemic issues, and anticipated reduction in development support. The pandemic has also opened a short‐lived and narrow window of opportunity for sustainable transformation. The transformative opportunities consist of lessons learned for planning and actions, socio‐economic recovery plan, use of information and communication technologies and the digital economy, reverse migration and "brain gain," and local governments' exercising authorities. Key Points: The COVID‐19 pandemic has negative impacts on most Sustainable Development Goals, which may subside in the medium and long termsKey impeding factors causing the negative impacts include lockdowns, unemployment, and diluted focus on non‐COVID‐19‐related issuesThe COVID‐19 pandemic has also opened a short‐lived and narrow window of opportunity for sustainable transformation [ABSTRACT FROM AUTHOR]

Water resources can play significant roles in development pathways for water-endowed, low-income countries like Nepal. This article describes three visions for water resource development in the Karnali and Mahakali Basins of Western Nepal: state-led development, demand-driven development and preservation of ecosystem integrity. The analysis calls attention to water use trade-offs, including those resulting from national priorities such as infrastructure-based hydropower and irrigation, from local drinking water demand, and from environmental conservation concerns. While these visions of water resources development do diverge, common trends appear, including acknowledgment of water management's role in expanding energy access and increasing agricultural productivity. [ABSTRACT FROM AUTHOR]

Climate change/variability and subsequent exacerbation of extremes are affecting human and ecological health across the globe. This study aims at unpacking hydro-climatic extremes in a snow-fed Marshyangdi watershed, which has a potential for water infrastructure development, located in Central Nepal. Bias-corrected projected future climate for near (2014–2033) and mid-future (2034–2053) under moderate and pessimistic scenarios were developed based on multiple regional climate models. Historical (1983–2013) and future trends of selected climatic extreme indices were calculated using RClimDex and hydrological extremes using Indicators of Hydrologic Alteration tool. Results show that historical trends in precipitation extremes such as number of heavy and very heavy precipitation days and maximum 1-day precipitation are decreasing while the temperature-related extremes have both increasing and decreasing trends (e.g., warm spell duration index, warm days and summer days are increasing whereas cold spell duration index, cool days and warm nights are decreasing). These results indicate drier and hotter conditions over the historical period. The projected future temperature indices (hot nights, warm days) reveal increasing trend for both the scenarios in contrast with decreasing trends in some of the extreme precipitation indices such as consecutive dry and wet days and maximum 5-day precipitation. Furthermore, the watershed has low mean hydrological alterations (27.9%) in the natural flow regime. These results indicate continuation of wetter and hotter future in the Marshyangdi watershed with likely impacts on future water availability and associated conflicts for water allocation, and therefore affect the river health conditions. [ABSTRACT FROM AUTHOR]

This article investigates water security in Nepal from the perspective of the water-energy-agriculture (food) nexus, focusing on pathways to water security that originate in actions and policies related to other sectors. It identifies promoting development of Nepal's hydropower potential to provide energy for pumping as way to improve water security in agriculture. Renewable groundwater reserves of 1.4 billion cubic meters (BCM), from an estimated available balance of 6.9 BCM, could be pumped to irrigate 613,000 ha of rainfed agricultural land in the Terai plains, with a potential direct economic gain of USD 1.1 billion annually and associated benefits including promotion of energy-based industry, food security and local employment. Governance also plays an important role in addressing water security. We conclude that a nexus-based approach is required for effective water management and governance. [ABSTRACT FROM AUTHOR]

Kathmandu Upatyaka Khanepani Limited (KUKL) has planned to harness water from outside the valley from Melamchi as an inter-basin project to supply water inside the ring road (core valley area) of the Kathmandu Valley (KV). The project, called the "Melamchi Water Supply Project (MWSP)", is expected to have its first phase completed by the end of September 2018 and its second phase completed by the end of 2023 to supply 170 MLD (million liters a day) through the first phase and an additional 340 MLD through the second phase. The area has recently faced a severe water deficit and KUKL's existing infrastructure has had a limited capability, supplying only 19% of the water that is demanded in its service areas during the dry season and 31% during the wet season. In this context, this study aims to assess the temporal trends and spatial distribution of household water security index (WSI), defined as a ratio of supply to demand for domestic water use for basic human water requirements (50 L per capita per day (lpcd)) and economic growth (135 lpcd) as demand in preand post-MWSP scenarios. For this purpose, data on water demand and supply with infrastructure were used to map the spatial distribution of WSI and per capita water supply using ArcMap. Results show a severe water insecurity condition in the year 2017 in all KUKL service areas (SAs), which is likely to improve after completion of the MWSP. It is likely that recent distribution network and strategies may lead to inequality in water distribution within the SAs. This can possibly be addressed by expanding existing distribution networks and redistributing potable water, which can serve an additional 1.21 million people in the area. Service providers may have to develop strategies to strengthen a set of measures including improving water supply infrastructures, optimizing water loss, harnessing additional water from hills, and managing water within and outside the KUKL SAs in the long run to cover the entire KV. [ABSTRACT FROM AUTHOR]

This study is the first to assess land subsidence in the Kathmandu Valley, Nepal. Land subsidence simulations were based on a fully calibrated groundwater (GW) flow model developed using a coupled surface–subsurface modelling system. Subsidence is predicted to occur as a result of deep aquifer compaction due to excessive GW abstraction. The north and north-east areas at the periphery of the GW basin are hotspots for this subsidence. The estimated subsidence is most sensitive to changes in land cover within the recharge areas. The model shows the Melamchi water supply project assists in the control of subsidence to some extent. In the absence of land subsidence measurements, this paper highlights the location and the potential levels of the subsidence hazard which will be useful for hazard prevention management. Additionally, this work provides a basis to design field investigations, monitoring networks for land subsidence and upgrading the present GW monitoring network. Although the study has presented a preliminary analysis, a more comprehensive model inclusive of clay subsidence is required to address the subsidence vulnerability of the central densely populated core of the valley, which reflects the need for a comprehensive database of the hydrogeology in the valley. [ABSTRACT FROM AUTHOR]

A physically based distributed hydrological model developed at the University of Yamanashi based on block-wise use of TOPMODEL and the Muskingum-Cunge method (YHyM/BTOPMC), integrated with a simple degree-day-based snow accumulation/melt sub-model, was applied to evaluate hydrological responses under changing climatic conditions in the snow-fed Kali Gandaki River Basin (KGRB) in Western Nepal. Rainy season precipitation (June to September) in the basin takes up about 80% of the annual precipitation, and dry season runoff is largely contributed by snowmelt. Climate change is likely to increase the probability of extreme events and problems related to water availability. Therefore, the study aimed to simulate runoff pattern under changing climatic conditions, which will be helpful in the management of water resources in the basin. Public domain global data were widely used in this study. The model was calibrated and validated with an acceptable degree of accuracy. The results predicted that the annual average discharge will increase by 2.4%, 3.7%, and 5.7% when temperature increases by 1, 2, and 3 °C compared with the reference scenario. Similarly, maximum, minimum, and seasonal discharges in the monsoon and pre-monsoon seasons will also increase with rising temperature. Snowmelt runoff is found sensitive to temperature changes in the KGRB. Increasing temperature will cause a faster snowmelt, but precipitation will increase the snowpack and also shed a positive effect on the total annual and monsoonal discharge. For the combined scenarios of increasing temperature and precipitation, the annual average discharge will increase. In contrast, discharge during the increasing temperature and decreasing precipitation will tend to decrease. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper reviews, compiles and comprehensively analyzes spatial variations in hydrogeologic characteristics of shallow and deep groundwater aquifers in Kathmandu Valley. To estimate transmissivity ( T) (and then hydraulic conductivity) as a function of specific capacity (SC), an empirical relationship between T and SC is developed for shallow and deep aquifer. The results show that T and SC are log linearly related by an equation T = 0.8857(SC) [ R = 0.79] in shallow and T = 1.1402(SC) [ R = 0.85] in deep aquifer. The estimated T ranges from 163 to 1,056 m/day in shallow aquifer and 22.5 to 737 m/day in deep aquifer. Finally, mapping of spatial distribution in hydrogeologic characteristics (thickness, T, hydraulic conductivity and storage coefficient) in shallow and deep aquifers are accomplished using ArcGIS9.2 and such maps would be useful in delineating potential areas for groundwater development and simulating groundwater flow in the aquifer system. [ABSTRACT FROM AUTHOR]

Natural hazards are complex phenomena that can occur independently, simultaneously, or in a series as cascading events. For any particular region, numerous single hazard maps may not necessarily provide all information regarding impending hazards to the stakeholders for preparedness and planning. A multi-hazard map furnishes composite illustration of the natural hazards of varying magnitude, frequency, and spatial distribution. Thus, multi-hazard risk assessment is performed to depict the holistic natural hazards scenario of any particular region. To the best of the authors' knowledge, multi-hazard risk assessments are rarely conducted in Nepal although multiple natural hazards strike the country almost every year. In this study, floods, landslides, earthquakes, and urban fire hazards are used to assess multi-hazard risk in Kathmandu Valley, Nepal, using the Analytical Hierarchy Process (AHP), which is then integrated with the Geographical Information System (GIS). First, flood, landslide, earthquake, and urban fire hazard assessments are performed individually and then superimposed to obtain multi-hazard risk. Multi-hazard risk assessment of Kathmandu Valley is performed by pair-wise comparison of the four natural hazards. The sum of observations concludes that densely populated areas, old settlements, and the central valley have high to very high level of multi-hazard risk. [ABSTRACT FROM AUTHOR]

The impacts of multihazards have become more pronounced over the past few decades globally. Multiple hazards and their cascading impacts claim enormous losses of lives, livelihoods, and built environment. This paradigm prompts integrated and multidisciplinary perspectives to identify, characterize, and assess the occurrence of multihazards and subsequently design countermeasures considering impending multihazard scenarios at the local level. To this end, we considered one of the most egregious transboundary watersheds, which is regarded as a multihazard hotspot of Nepal, to analyze the underlying causes and cascade scenarios of multihazards, and their associated impacts. In this paper, geophysical, hydrometeorological, and socioeconomic perspectives are formulated to characterize the watershed from the dimension of susceptibility to multihazard occurrence. To characterize the complex dynamics of transboundary multihazard occurrence, insights have been presented from both the Nepali and the Chinese sides. Individual case studies and the interrelation matrix between various natural hazards are also presented so as to depict multihazard consequences in the transboundary region. The sum of the observations highlights that the watershed is highly vulnerable to a single as well as multiple natural hazards that often switch to disasters. [ABSTRACT FROM AUTHOR]

Streamflow alteration and subsequent change in long-term average, seasonality, and extremes (e.g., floods and droughts) may affect water security, which is a major concern in many watersheds across the globe. Both climatic and anthropogenic activities may contribute to such changes. Therefore, this study assesses: (i) Streamflow and precipitation trends to identify streamflow alterations in the Extended East Rapti (EER) watershed in central-southern Nepal; (ii) relationship of the alterations to climatic and anthropogenic sources; and (iii) implications of streamflow changes to the socio-environmental system. The trends in streamflow were analyzed for pre-and post-1990 periods considering the abrupt shift in temperature trend in 1990. Results showed a general decreasing trends in discharge post-1990 in the EER watershed. Human activities have significantly contributed in altering streamflow in the EER. Human-induced streamflow alterations have affected the water availability, food security, river health, aquatic biodiversity, and groundwater abstraction in the EER watershed. [ABSTRACT FROM AUTHOR]

The Himalayas are highly susceptible to the impacts of climate change, as it consequently increases the vulnerability of downstream communities, livelihoods and ecosystems. Western Nepal currently holds significant potential as multiple opportunities for water development within the country are underway. However, it is also identified as one of the most vulnerable regions to climate change, with both an increase in the occurrence of natural disasters and exacerbated severity and impacts levels. Regional climate model (RCM) projections indicate warmer weather with higher variability in rainfall for this region. This paper combines bio-physical and social approaches to further study and understand the current climate shocks and responses present in Western Nepal. Data was collected from 3660 households across 122 primary sampling units across the Karnali, Mahakali and Mohana River basins along with focus group discussions, which provided a rich understanding of the currently perceived climatic shocks and related events. Further analysis of climatology was carried out through nine indices of precipitation and temperature that were found to be relevant to the discussed climate shocks. Results show that 79% of households reported experiencing at least one type of climate shock in the five-year period and the most common occurrence was droughts, which is also supported by the climate data. Disaggregated results show that perception varies with the region and among the basins. Analysis of climatic trends further show that irregular weather is most common in the hill region, although average reported frequency of irregular weather is higher in the mountain. Further analysis into the severity and response to climatic shocks suggest an imminent need for better adaptation strategies. This study's results show that a vast majority of respondents lack proper access to knowledge and that successful adaptation strategies must be adapted to specific regions to meet communities' local needs. [ABSTRACT FROM AUTHOR]