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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]

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]

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]

Climate variability and insufficient irrigation are primary constraints to stable and higher agricultural productivity and food security in Nepal. Agriculture is the largest global freshwater user, and integration of surface- and ground-water use is frequently presented as an strategy for increasing efficiency as well as climate change adaptation. However, conjunctive management (CM) planning often ignores demand-side requirements and a broader set of sustainable development considerations, including ecosystem health and economics of different development strategies. While there is generic understanding of conjunctive use, detailed technical knowhow to realize the CM is lacking in Nepal. This article presents a holistic framework through literature reviews, stakeholders consultations and expert interviews for assessing CM and implementation prospects from a systems-level perspective. We demonstrate the framework through a case study in Western Nepal, where climatic variability and a lack of irrigation are key impediments to increased agricultural productivity and sustainable development. Results show that knowledge of water resources availability is good and that of water demand low in the Western Terai. Additional and coordinated investments are required to improve knowledge gaps as well as access to irrigation. There is therefore a need to assess water resources availability, water access, use and productivity, to fill the knowledge gaps in order to pave pathways for CM. This paper also discusses some strategies to translate prospects of conjunctive management into implementation. • Customized framework development for assessing prospects for conjunctive management. • Conjunctive management status in western Nepal assessed by applying the framework. • Knowledge on water availability and demand are moderate and low, respectively. • Additional and coordinated investments required to improve access to irrigation. [ABSTRACT FROM AUTHOR]

An understanding of water sufficiency provides a basis for informed-planning, development and management of water resources. This study assessed spatio-temporal distribution in water sufficiency in the Extended East Rapti watershed in Nepal. The "Palika" (local government unit) is considered as a spatial-scale and seasons and future periods as temporal-scale. The water sufficiency was evaluated based on water sufficiency ratio (WSR) and water stress index (WSI). A hydrological model was developed to simulate water availability. An ensemble of multiple Regional Climate Models was used for assessing climate change impacts. Results showed water sufficiency by mid-century is projected to decrease; WSR by 40% and WSI by 61%. Despite projected decrease in water sufficiency, annually available water resources are projected as sufficient for the demands until the mid-century, however, seasonal variability and scarcity in future is projected in most Palikas. Such results are useful for water security planning in the Palikas. • Water sufficiency is assessed based on WSR and WSI for present and future. • Palika and seasons are taken as spatial and temporal scales for water sufficiency. • Water availability across the Palikas were assessed based on SWAT model outputs. • Multiple RCMs were used to assess climate change impacts on water sufficiency. • Water sufficiency is projected to decrease by the mid-century. [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]

Abstract: This paper discusses an indicator-based framework – consisting of seven indicators, four parameters, and an index – to assess adaptive capacity of the water resources system in the Nepalese context and applies this framework to the Bagmati River Basin (BRB) in Nepal. With respect to the BRB, and Nepal in general, the study results show variations in adaptive capacity of the water resources system across the river basin (eight districts within the BRB), at different geographical (district, river basin and national level) as well as temporal (over decades) scale. Such variations suggest a need of differential policy interventions at different spatial scale to achieve adaptive management of the water resources. The adaptive capacity index can be used to prioritize basins, the adaptive capacity parameters can be used to identify the broader areas of intervention in the selected basin, and adaptive capacity indicators reveal the degree of attention required to strengthen adaptive capacity of the water resources system. [ABSTRACT FROM AUTHOR]

• Rainfall and temperature extremes are projected to increase in rain-fed watershed. • Hydrological alterations are visible in terms of increasing hydrological extremes. • Visible linkages are established between hydrological and climatic extremes. Extreme climatic and hydrological events result in water-induced disasters and associated loss and damage of lives, livelihoods, and properties. It is related with various climatic, topographical, and anthropogenic factors, and therefore, expected to vary widely across the watersheds. This study characterized historical and projected future trends in climatic extremes, their spatial variations, hydrological extremes, and linkage between hydro-climatic extremes for a rain-fed Extended East Rapti (EER) watershed in Central-Southern Nepal. The watershed feeds into the Ganges in the South Asia through the Gandaki river. A set of 14 climate extreme indices, seven related to precipitation and seven to temperature, and eight hydrological indices were selected to characterize the extremes. Climatic and hydrological extreme indices were computed using RClimDex and IHA (Indicators for Hydrological Alteration) tools, respectively. Trends were calculated using the Modified Mann-Kendall test and Sens's slope estimator. Relationship between hydrological and climatic extremes was evaluated by checking dates for rainfall extreme, hydrological extreme, and reported cases of flooding during that period. Results showed increasing trends in both precipitation and temperature extremes for the historical period (1980–2005) with a rate of 10–35% increase in RX1day (monthly maximum 1-day precipitation), 10–50% increase in R95p (very wet days precipitation amount) and 15–60% increase in warm nights from the base period until the mid-century. Hydrological alterations in terms of increasing extremes are also clearly visible in maximum flows, minimum flows as well as the shift in the day of maximum flow. Since, hydro-climatic extremes bear a direct relationship, future hydrological extremes, primarily floods, are expected to increase in future. [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]

Climate change alters the river flow regimes causing significant changes in the structure and function of an aquatic ecosystem, ultimately affecting river health. This study applied a customized framework consisting of 1-index, 4-components, 6-indicators, and 43-metrics, to assess river health for two seasons and future periods, in the Marshyangdi Watershed, Nepal. Hydrological, water quality, biological and physical conditions were assessed using simulated results from a hydrological model, physiochemical analysis of water samples, macroinvertebrates assemblages analysis, and physical habitat condition assessment, respectively. Climate change impact on river health was assessed based on projected climate (precipitation and temperature) based on regional climate models under representative concentration pathways (RCP) 4.5 and 8.5 scenarios until the mid-century. Results showed moderate river health condition in both the seasons and it's deterioration for future scenarios and periods. It reveals the need to formulate appropriate measures for the conservation of the river health. [ABSTRACT FROM AUTHOR]

With economies heavily dependent on agriculture, South Asia is the world's most poverty-dense region. Nepal--a country of considerable geographic variability ranging from population-dense low-elevation Terai region to the sparsely inhabited, poorly accessible Himalayan hills and mountains--has enormous environmental and socio-economic challenges to agricultural development. Runoff from the hills and mountains feed networks of rivers that are crucial for supply of surface and groundwater for the Terai and northern India and Bangladesh, benefitting approximately one-fifth of the world's population. Nepal's farming systems are complex, with insufficient documentation of research evidence on the challenges and opportunities facing them. This review documents the key environmental, socio-economic and agronomic issues affecting cereal-based farming systems in Nepal. Evidences suggest farmers in the hills and mountains primarily practice integrated crop-livestock-tree based agroforestry systems with local varieties of crop and livestock species, and use farm-derived organic amendments and limited external inputs, resulting in low but stable yields. The Terai's cropping systems are predominantly rice-based, with wheat, maize and pulses grown in rotation with low to moderate use of inputs, although high yielding varieties are increasingly common. Major environmental challenges in the high and mid-hills include erosion and soil degradation, while in the Terai, reduced soil fertility and sub-optimal management of water resources are important constraints. Climate variability and extremes are cross-regional challenges. Socioeconomic issues include land use policy, labor out-migration and agricultural feminization. Large gaps between potential and farmers' yields are consistent concerns. While summarizing past and current agronomic research findings, this review suggests new research needs and agricultural development pathways that could address these environmental, socioeconomic and agronomic issues and challenges. [ABSTRACT FROM AUTHOR]