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Mountain springs are the only water source for most of the communities in the Kashmir Himalayas. However, over the past two decades, the discharge of these springs has decreased, and some springs have dried up. The current study mapped springs from the Sindh basin of the Kashmir Himalaya via a GPS-based Field survey. The dynamics of spring discharge were evaluated vis-à-vis climatic variability, land use changes, snow cover area, and any major developmental projects in the catchment. The observed temperature and precipitation data were subjected to trend analysis using the Mann Kendall's tau test and Sen's slope estimator. MODIS data were used to understand the dynamics of the Snow Cover Area (SCA) from 2010 to 2021. Landsat satellite imagery was processed to quantify the changes in Land use/cover (LULC). The study found that 13% of the springs below 1600 masl, 22% from 1600 to 2500 masl, and 28.9% above 2500 masl have witnessed a high decrease in discharge. The seasonality of the spring discharge implies snowmelt is the predominant source. The time series analysis shows a weak decreasing trend in the precipitation during the growing season (Spring and Summer). However, both minimum and maximum temperatures show a statistically significant upward trend and result in the early melting of the snow, also confirmed by the analysis of SCA. The study reveals that climate change and LULC change are responsible for the drying of the springs. [ABSTRACT FROM AUTHOR]

The Western Himalayan Region (WHR) is under constant threat from Land Use and Land Cover Change (LULCC) brought on by various socioeconomic activities such as urbanization, agricultural expansion, and population growth. Detailed research into the scope of these changes is necessary to comprehend the challenges they represent. This study aimed at (1) examining and quantifying spatiotemporal patterns of LULCC from 1975 to 2015, (2) mapping the hotspots of forest loss, and (3) modelling future LULCC for the year 2055 using medium spatial resolution multispectral satellite imagery (MSS, TM, LISS-I, LISS-III, AWiFS), field data, visual interpretation and logistic regression model in the WHR. Logistic regression integrated various drivers of LULCC, including climatic, topographic, and socio-economic factors and past LULCC trends to forecast potential LULC in the WHR by 2055. The results highlight an outrageous 184% increase in regional urbanization. Expansion of urban and cropland (12%) led to deforestation which reduced the area of natural habitats, specifically forests (−11%), water bodies (−8%) and scrubland (−6%). A significant rise in barren land by 30% was noted, while there was a decrease of 20% in glacier/snow melt. The future projection for 2055 anticipates continuing current trends, emphasizing an intensified urban expansion of 63% and an approximate 9% reduction in overall forest coverage. The accuracy of the predicted 2015 LULC map was assessed using ROC/AUC (Receiver Operating Characteristic/Area under Curve) which was found to be 0.79. [ABSTRACT FROM AUTHOR]

The Third Pole (TP) is the world's largest highland and has one of the biggest reservoirs of glacier ice mass and snow cover on the Earth. Three major Asian rivers (the Indus, Ganga and Brahmaputra) are nourished by the melting of glaciers and snow in Central Himalaya, which are inevitable for the socioeconomic sustainability and water security of South Asia. Here, we investigate the long-term (1980–2020) changes in snow depth and precipitation in TP, where major precipitation occurs in the form of rainfall in summer, and snowfall in winter and spring. The seasonal mean snow depth is deep (≥1 m) in winter and shallow (≤0.2 m) in summer. The average snowmelt and snow water equivalent are higher in the central and western Himalaya and Karakoram ranges in spring, which are the regions with most glaciers in TP. There is a significant positive trend in total precipitation, about 0.01–0.03 mm d−1 yr−1 in the central and eastern TP during the South Asian Summer Monsoon for the 1980–2020 period. Snowmelt is also increasing (>0.5 × 10−3 mm yr−1) in the western Himalaya during spring, which is consistent with the temperature rise (0.04–0.06 °C yr−1) there. In addition, there is a notable increase in the annual mean glacier melt (here, the water equivalent thickness) in TP (−1 to −5 cm w.e. yr−1), with its highest values in the eastern and central Himalaya (−3 to −5 cm w.e. yr−1), as estimated for the period 2003–2020. On top of these, by the end of the 21st century, the Coupled Model Intercomparison Project Phase 6 (CMIP6) projections show that there would be a significant decrease in snow depth and an increase in temperature of TP in all shared socioeconomic pathways (SSPs). Henceforth, the increasing trend in temperature and melting of snow/glaciers in TP would be a serious threat to the regional climate, water security and livelihood of the people of South Asia. [ABSTRACT FROM AUTHOR]

The prevalent climate warming across the mountain regions worldwide has exacerbated the snow melt, glacier recession and permafrost thawing that is impacting the hydrological cycle. The rock glaciers, a manifestation of ice-rich permafrost, could be regionally important for sustaining the streamflow, especially in the lean season in the Himalaya. Several rock glacier inventories have been developed for high-mountain areas worldwide. However, there are sporadic studies that have characterized rock glaciers in the Himalaya. In this study, a comprehensive rock glacier inventory has been generated for the western Himalayan regions of Jammu-Kashmir and trans-Himalayan Ladakh spread over six mountain ranges utilizing optical satellite images from Google Earth and Sentinel 2A. The inventory has characterized each rock glacier with 22 attributes following the guidelines of the International Permafrost Association (IPA). The inventory contains 5492 rock glaciers (4973 intact and 519 relict) with a total area of 573 km² and an average area of 0.1 km². The highest number of rock glaciers (n=1772) were found in the Zanskar range and the lowest (n=311) were found in the Pir Panjal range. The majority of rock glaciers (~83%) have a talus origin, and the remaining ~17% have a glacier origin. The inventory reports 4756 tongue-shaped and 736 lobate rock glaciers. The average Potential Incoming Solar Radiation (PISR) was observed to be 511 (kWH m-2). The rock glaciers are located between the elevation range of 3301 m asl and 5605 m asl with 63% of these having a north- or northeastor northwest-facing aspect. The Mean Annual Air Temperature (MAAT) and precipitation of the rock glaciers range from -8 °C to 8 °C (mean -4°C) and 71 mm to 1135 mm (mean 328 mm), respectively. The rock glacier inventory provides direct evidence of the presence of permafrost in this ecologically sensitive region and provides a lower bound on the elevation of the permafrost. This inventory shall serve as a baseline for the future hydrological impacts of permafrost and its response to regional climate change. The rock glacier inventory is publicly available at https://doi.org/10.5281/zenodo.10559297 (Bhat et al., 2024). [ABSTRACT FROM AUTHOR]

Snow and glacier melt are significant contributors to streamflow in Himalayan catchments, and their increasing contributions serve as key indicators of climate change. Consequently, the quantification of these streamflow components holds significant importance for effective water resource management. In this study, we utilized the spatio‐temporal variability of isotopic signatures in stream water, rainfall, winter fresh snow, snowpack, glaciers, springs, and wells, in conjunction with hydrometeorological observations and Snow Cover Area (SCA) data, to identify water sources and develop a conceptual understanding of streamflow dynamics in three catchments (Lidder, Sindh, and Vishow) within the western Himalayas. The following results were obtained: (a) endmember contributions to the streamflow exhibit significant spatial and seasonal variability across the three catchments during 2018–2020; (b) snowmelt dominates streamflow, with average contributions across the entire catchment varying: 59% ± 9%, 55% ± 4%, 56% ± 6%, and 55% ± 9% in Lidder, 43% ± 6%, 38% ± 6%, 32% ± 4%, and 33% ± 5% in Sindh and 45% ± 8%, 40% ± 6%, 39% ± 6%, and 32% ± 5% in Vishow during spring, summer, autumn, and winter seasons, respectively; (c) glacier melt contributions can reach ~30% to streamflow near the source regions during peak summer; (d) The primary uncertainties in streamflow components are attributed to the spatiotemporal variability of tracer signatures of winter fresh snow/snowpack (±1.9% to ±20%); (e)regarding future streamflow components, if the glacier contribution were to disappear completely, the annual average streamflow in Lidder and Sindh could decrease up to ~20%. The depletion of the cryosphere in the region has led to a rapid increase in runoff (1980–1900), but it has also resulted in a significant streamflow reduction due to glacier mass loss and changes in peak streamflow over the past three decades (1990–2020). The findings highlight the significance of environmental isotope analysis, which provides insights into water resources and offers a critical indication of the streamflow response to glacier loss under a changing climate. [ABSTRACT FROM AUTHOR]

Numerous environmental issues are being faced by the world today as a result of unfavorable climate changes brought on by global warming and other man-made factors, as well as natural earth imbalances. Consequently, the temperature is rising every day, and as a result of the melting of land, snow, or ice sheets, the world's sea levels are rising. One of the largest difficulties we have is the rising rates of melting of land-based snow and ice sheets, which we must regulate or address as soon as feasible. So, utilizing a few digital image processing techniques and a few other geospatial techniques applied to high resolution snow-covered satellite photos, an effort is made in this work to research and build a system that can extract the snow-covered area using K-means clustering. Using temporal satellite imageries, this work went further to investigate and comprehend changes in snow-covered Himalayan ranges from the years 1984 to 2022. [ABSTRACT FROM AUTHOR]

Himalayas hydroclimate is a lifeline for South Asia's most densely populated region. Every year, flooding in the Himalayan rivers is usual during summer monsoon, which impacts millions of inhabitants of the Himalayas and downstream regions. Recent studies demonstrate the role of melting glaciers and snow in the context of global warming, along with monsoonal rain causing recurrent floods. Here, we highlight the natural variability in the eastern Himalayan hydroclimate over the last 43 years (1979–2021). We found extreme monsoonal rainy years with six dry years and seven wet years after removing the climate change signal. Monsoon rainfall is a significant contributor, and melting snow is not a potential contributor to these anomalous extreme years. The variability of Himalayan monsoonal rainfall is strongly regulated by local monsoonal Hadley circulation associated with tropical sea surface temperature. Our findings demonstrate mechanisms associated with Himalayan wet and dry monsoon. Atmospheric dynamics are attributed as the primary modulating factor, influencing local thermodynamics through moist processes. The insights provided in this study underscore the impact of natural variability‐driven challenging events that could be predictable. Thus, this mechanism could improve the predictability of the Himalayas floods. Plain Language Summary: The monsoon rainfall in the Himalayan region is very important for the people living in South Asia. Every year, heavy rainfall during the monsoon season causes floods in the region. We found the strong Himalayan rainfall variability in the eastern side of the Himalayas during the monsoon season and examined the natural rainfall cycle over the past few decades. As a result, we have characterized that there are extreme rainy monsoons and dry monsoons. We also found that the main cause of the extreme flooding is the heavy rain during the monsoon as a part of natural variability rather than the melting snow. Our study supports atmospheric bridge as the primary driver for extreme monsoons over the Eastern Himalayan region. We looked at different factors that influence monsoon rainfall, such as the local landscape, the conditions in the atmosphere, and large‐scale features. The eastern Himalayas region includes Bhutan, Nepal, India, and China. Understanding these rainfall patterns can help us predict floods in these countries and better prepare for their impact. Furthermore, as climate change continues to affect the climate system, there is growing concern about how it may influence the natural variability of the Himalayan monsoon. Key Points: The study highlights the natural variability in the eastern Himalayan hydroclimate over the past 43 years, emphasizing its significance as a recurring natural hazard that affects the regionThe research identifies extreme monsoonal rainy years, with monsoon rainfall as a major contributor to river discharge. Notably, the study rules out the role of melting snow in these extreme eventsThis research underscores the dominant influence of atmospheric dynamics as the primary modulating factor in the Eastern Himalayan monsoon [ABSTRACT FROM AUTHOR]

Recent evidence shows a noticeable reduction in the glacier mass in the Himalaya due to increasing temperatures, and therefore the downstream water availability is becoming uncertain. This study analyse the effect of changes in the Gangotri glaciers (i.e. thickness), including Raktavaran and Chaturangi regions, on the melt runoff (2011-2020) by coupling two models: Glacier Bed Topolology (GlabTop2) and Spatial Process in Hydrology (SPHY). This study performs the two-step calibration approach utilizing the observed discharge and Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover data. The R² values for SPHY-modelled runoff (Q) and observed Q at Bhojwasa are found comparable (~0.73 on a daily scale) and the proportions of glacier Q and snow Q in total Q are computed as 22.11% and 66.91%, respectively. In comparison to Chaturangi and Raktavaran, Gangotri glaciers experienced a higher rate of change in thickness, and a reduction of ~9.40% in the mean glacier thickness is calculated during 2011-2020. [ABSTRACT FROM AUTHOR]

This study examines the proportional contribution of snow/ice melt, rainfall, and groundwater to Sutlej River discharge at various locations. Sutlej River is a major tributary of the Indus River system and an important water supply source for irrigation through the canal network in northwest India. Here, we used hydrograph separation and associated uncertainty and applied the snowmelt runoff model (SNOWMOD) to estimate the contribution from different water sources to the Sutlej River. We used δ18O and electrical conductivity values of different waters for the hydrograph-separation approach. The first-order Gaussian error propagation and Monte-Carlo simulation are used to assess the accuracy. The estimated contribution at Rampur is ~ 62.7% (snow/ice melt), 18.7% (rainfall), and ~ 18.4% (groundwater); for Ropar is 59 ± 2% (snow/ice melt), 23 ± 2% (rainfall), and 18 ± 2% (groundwater); and for Yusufpur, 25 ± 3% (snow/ice melt), 39 ± 3% (rainfall), and 36 ± 2% (groundwater) during July–December 2013. The findings from the hydrograph-separation and SNOWMOD analysis established a fundamental understanding of the hydrological processes in the Sutlej River system, providing valuable baseline data essential for developing sustainable water resource management strategies. [ABSTRACT FROM AUTHOR]

High Mountain Asia (HMA) is among the most vulnerable water towers globally and yet future projections of water availability in and from its high‐mountain catchments remain uncertain, as their hydrologic response to ongoing environmental changes is complex. Mechanistic modeling approaches incorporating cryospheric, hydrological, and vegetation processes in high spatial, temporal, and physical detail have never been applied for high‐elevation catchments of HMA. We use a land surface model at high spatial and temporal resolution (100 m and hourly) to simulate the coupled dynamics of energy, water, and vegetation for the 350 km2 Langtang catchment (Nepal). We compare our model outputs for one hydrological year against a large set of observations to gain insight into the partitioning of the water balance at the subseasonal scale and across elevation bands. During the simulated hydrological year, we find that evapotranspiration is a key component of the total water balance, as it causes about the equivalent of 20% of all the available precipitation or 154% of the water production from glacier melt in the basin to return directly to the atmosphere. The depletion of the cryospheric water budget is dominated by snow melt, but at high elevations is primarily dictated by snow and ice sublimation. Snow sublimation is the dominant vapor flux (49%) at the catchment scale, accounting for the equivalent of 11% of snowfall, 17% of snowmelt, and 75% of ice melt, respectively. We conclude that simulations should consider sublimation and other evaporative fluxes explicitly, as otherwise water balance estimates can be ill‐quantified. Plain Language Summary: The Himalayan mountains are a crucial source of water for local communities and the densely populated lowlands. Snow and glaciers are important for the water cycle in mountains, and many studies have focused on them. However, vegetation can play a central role, too. To better understand the water cycle in a high‐elevation Himalayan basin, we use a computer model that considers physical processes of snow and glaciers, soil, and vegetation in high detail. We simulate the catchment water balance and investigate the importance of single components at different elevations and in different seasons. We find that the transfer of water, in vapor form from the ground, snow and ice and the transpiration of plants are important for the water budget in the study basin, causing more water to return to the atmosphere than ice melt contributing to river runoff. Above 6,500 m above sea level, it is the transformation of snow into water vapor and below 4,000 m the transpiration from vegetation that dominate the water budget. We conclude that models simulating the water cycle in high mountain regions should consider vapor fluxes, as otherwise estimates of the water balance can be misleading. Key Points: Land surface modeling reveals high altitudinal/subseasonal variability in water balance partitioning in a glacierized Himalayan catchmentWater loss through evapotranspiration, dominated by snow sublimation, exceeds water production from glacier melt by 59% at catchment scaleDepletion of cryospheric water budget is dominated by snow melt, but at high elevations is primarily dictated by snow and ice sublimation [ABSTRACT FROM AUTHOR]

The high-altitude Hindu Kush-Himalayan region (HKH, average ~5 km from msl) and the adjacent Indo-Gangetic plains (IG plains, ~0–250 m msl), due to their geographical location and complex topography, are reported to be highly sensitive to climatic changes. Recent studies show that the impacts of climate change and associated changes in water resources (glacial/snow melt water and rainfall) in this region are multifaceted, thereby affecting ecosystems, agriculture, industries, and inhabitants. In this study, 45 years of Microwave Sounding Unit/Advanced Microwave Sounding Unit (MSU/AMSU)-derived mid-tropospheric temperature (TMT, 3–7 km altitude) and lower tropospheric temperature (TLT, 0–3 km altitude) data from the Remote Sensing Systems (RSS Version 4.0) were utilized to analyze the overall changes in tropospheric temperature in terms of annual/monthly trends and anomalies. The current study shows that the mid-tropospheric temperature (0–3 km altitude over the HKH region) has already alarmingly increased (statistically significant) in Tibet, the western Himalayas, and the eastern Himalayas by 1.49 °K, 1.30 °K, and 1.35 °K, respectively, over the last 45 years (1978–2022). As compared to a previous report (TMT trend for 30 years, 1979–2008), the present study of TMT trends for 45 years (1978–2022) exhibits a rise in percent change in the trend component in the high-altitude regions of Tibet, the western Himalayas, and the eastern Himalayas by approximately 310%, 80%, and 170%, respectively. In contrast, the same for adjacent plains (the western and eastern IG plains) shows a negligible or much lower percent change (0% and 40%, respectively) over the last 14 years. Similarly, dust source regions in Africa, Arabia, the Middle East, Iran, and Pakistan show only a 130% change in warming trends over the past 14 years. In the monthly breakup, the 'November to March' period usually shows a higher TMT trend (with peaks in December, February, and March) compared to the rest of the months, except in the western Himalayas, where the peak is observed in May, which can be attributed to the peak dust storm activity (March to May). Snow cover over the HKH region, where the growing season is known to be from September to February, is also reported to show the highest snow cover in February (with the peak in January, February, or March), which coincides with the warmest period in terms of anomaly and trend observed in the long-term mid-tropospheric temperature data (1978–2022). Thus, the current study highlights that the statistically significant and positive TMT warming trend (95% CI) and its observed acceleration over the high-altitude region (since 2008) can be attributed to being one of the major factors causing an acceleration in the rate of melting of snow cover and glaciers, particularly in Tibet and the Eastern Himalayas. [ABSTRACT FROM AUTHOR]

Studying the dynamics of snowline altitude at the end of the melting season (SLA-EMS) is beneficial in predicting future trends of glaciers and non-seasonal snow cover and in comprehending regional and global climate change. This study investigates the spatiotemporal variation characteristics of SLA-EMS in nine glacier areas of the Himalayas, utilizing Landsat images from 1991 to 2022. The potential correlations between SLA-EMS, alterations in temperature, and variations in precipitation across the Himalayas region glacier are also being analyzed. The results obtained are summarized below: (1) the Landsat-extracted SLA-EMS exhibits a strong agreement with the minimum snow coverage at the end of the melting season derived from Sentinel-2, achieving an overall accuracy (OA) of 92.6% and a kappa coefficient of 0.85. The SLA-EMS can be accurately obtained by using this model. (2) In the last 30 years, the SLA-EMS in the study areas showed an upward trend, with the rising rate ranging from 0.4 m·a−1 to 9.4 m·a−1. Among them, the SLA-EMS of Longbasaba rose fastest, and that of Namunani rose slowest. (3) The SLA-EMS in different regions of the Himalayas in a W-E direction have different sensitivity to precipitation and temperature. However, almost all of them show a positive correlation with temperature and a negative correlation with precipitation. [ABSTRACT FROM AUTHOR]

Temperature lapse rate (TLR) is an important parameter for simulations of snow/glacier melts in alpine watersheds. However, the traditional scheme estimates TLR mainly based on a limited number of stations and may not be suitable for alpine watersheds with scarce observations. To overcome this problem, this study developed a new basin-oriented TLR scheme based on Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature data which was applied in a typical glacierized watershed on the northern slope of the Himalayas. The new TLR scheme was evaluated by comparison with the station-based traditional TLR scheme in terms of performance in simulations of both snow cover area and runoff using the same hydrological model. The results showed that the monthly TLRs estimated by the new scheme presented a more reasonable seasonal pattern than those estimated by the traditional scheme. The model using the new TLR scheme showed better performance in discharge simulations of low-runoff months than that using the traditional TLR scheme. The R-squared value of multiyear mean monthly snow cover area of the former (0.82) was also higher than that of the latter (0.56). This study provides an efficient framework for estimating TLR based on remote sensing for alpine watersheds with scarce observations. [ABSTRACT FROM AUTHOR]

On 7th February 2021, a catastrophic flash flood occurred in Raunthi Gad, Rishi Ganga catchment of Dhualiganga Basin. It caused the death of around 200 people and devastated the hydropower projects and other associated infrastructure in the downstream areas of the basin. While the extent of damage and devastation in the downstream region around Rini and Tapovan has been extensively reported, the reconstruction of the event has still not been definitively established. Based on an analysis of the data reported in previous papers and our field and remote-sensing data, we present a detailed reconstruction of the events that occurred in Raunthi Gad that morning. Our analysis supports previous reports that the basic cause was that a portion of the hanging glacier located at Raunthi peak (5600 m asl) along with a large amount of rock fell and hit the Raunthi valley at about 1.5 km downstream of the current snout of Raunthi glacier at an elevation of around 3800 m asl. We present evidence, supported by previous data of transient ponding in the region between the impact zone and the confluence of Raunthi Gad and Rishi Ganga. We estimate the flood volume at Rini to be around 10 MCM and the volume of water available in the valley in the form of ice and snow to be around 6 MCM. We argue that this deficit can be accounted for by the debris volume. The material gained around 8 × 1014 J of energy during the initial slide whereas around 1.5 × 1014 J is required to melt the ice and snow. [ABSTRACT FROM AUTHOR]

Knowledge about the distribution and dynamics of seasonal snow cover (SSC) is of high importance for climate studies, hydrology or hazards assessment. SSC varies considerably across the Hindu Kush Himalaya both in space and time. Previous studies focused on regional investigations or the influence of snow melt on the local hydrological system. Here, we present a systematic assessment of metrics to evaluate SSC dynamics for the entire HKH at regional and basin scale based on AVHRR GAC data at a 0.05° spatial and daily temporal resolution. Our findings are based on a unique four-decade satellite-based time series of snow cover information. We reveal strong variability of SSC at all time scales. We find significantly decreasing SSC trends in individual summer and winter months and a declining tendency from mid-spring to mid-fall, indicating a shift in seasonality. Thanks to this uniquely spatio-temporally resolved long-term data basis, we can particularly highlight the unique temporally variable character of seasonal snow cover and its cross-disciplinary importance for mountain ecosystems and downstream regions. [ABSTRACT FROM AUTHOR]

The current work investigated the seasonal evolution of the Tibetan Plateau (TP) snow cover (TPSC) induced atmospheric moisture anomalies from May to August, by analyzing TP snow‐diabatic and TP snow‐hydrological processes during the 1979–2020 period using both observational data and a baroclinic atmospheric model. The results show that the TPSC and its related atmospheric moisture are featured by a westward retreat from the eastern TP in May to the western TP in August. The TPSC variation related atmospheric apparent heat source shows that excessive TPSC can cause local diabatic cooling to the above atmosphere and can be attributed to a local cyclonic pattern in the upper troposphere. This cyclonic pattern also moves westward along with the seasonal evolution of the TP snow during this period. Anomalous TP snow can impact atmospheric moisture through snow melt and snow evaporating process. Associated with the changes in TP snow, its related anomalous atmospheric moisture and circulations, significant moisture divergence appears over the mid‐eastern Himalaya during May and June (MJ) and the water vapor is mainly transported from the Himalaya to southeastern TP regions including Bhutan, Myanmar, Bengal and eastern India. Differently, during July and August (JA), significant atmospheric moisture divergence is located over the mid‐western Himalaya, and the water vapor is mostly transported from the Himalaya to southwestern TP areas including Nepal and western India. Further analysis shows that the TPSC anomaly induced anomalous atmospheric moisture accounts for 22%–45% of the climatological moisture for the mid‐eastern Himalaya during MJ, whereas it accounts for 65%–78% of the climatological moisture for the mid‐western Himalaya during JA. Key Points: The Tibetan Plateau (TP) snow cover (TPSC) and its related atmospheric moisture are featured by a westward retreat from May to AugustAnomalous TPSC can impact the atmospheric moisture through snow melt and snow evaporating processThe TPSC related water vapor is mainly transported from Himalaya to southeastern TP in May‐June and to southwest TP in July and August [ABSTRACT FROM AUTHOR]

This paper investigates the annual and seasonal variations in the minimum and maximum air temperature (Tmin and Tmax) and precipitation over Kashmir valley, Northwestern Himalayas from 1980–2019 by using the innovative trend analysis (ITA), Mann-Kendall (MK), and Sen's slope estimator methods. The results indicated that the annual and seasonal Tmin and Tmax are increasing for all the six climatic stations, whereas four of them exhibit significant increasing trends at (α = 0.05). Moreover, this increase in Tmin and Tmax was found more pronounced at higher altitude stations, i.e., Pahalgam (2650 m asl) and Gulmarg (2740 m asl). The annual and seasonal precipitation patterns for all climatic stations showed downward trends. For instance, Gulmarg station exhibited a significant downward trend for the annual, spring, and winter seasons (α = 0.05). Whereas, Qazigund showed a significant downward trend for the annual and spring seasons (α = 0.05). The overall analysis revealed that the increased Tmin and Tmax trends during the winter season are one of the reasons behind the early onset of melting of snow and the corresponding spring season. Furthermore, the observed decreased precipitation trends could result in making the region vulnerable towards drier climatic extremes. Such changes in the region's hydro-meteorological processes shall have severe implications on the delicate ecological balance of the fragile environment of the Kashmir valley. [ABSTRACT FROM AUTHOR]

Recent progress has been made in quantifying snowmelt in the Himalaya. Although the conditions are favorable for refreezing, little is known about the spatial variability of meltwater refreezing, hindering a complete understanding of seasonal snowmelt dynamics. This study aims to improve our understanding about how refreezing varies in space and time. We simulated refreezing with the seNorge (v2.0) snow model for the Langtang catchment, Nepalese Himalaya, covering a 5-year period. Meteorological forcing data were derived from a unique elaborate network of meteorological stations and high-resolution meteorological simulations. The results show that the annual catchment average refreezing amounts to 122 mm w.e. (21% of the melt), and varies strongly in space depending on elevation and aspect. In addition, there is a seasonal altitudinal variability related to air temperature and snow depth, with most refreezing during the early melt season. Substantial intra-annual variability resulted from fluctuations in snowfall. Daily refreezing simulations decreased by 84% (annual catchment average of 19 mm w.e.) compared to hourly simulations, emphasizing the importance of using sub-daily time steps to capture melt–refreeze cycles. Climate sensitivity experiments revealed that refreezing is highly sensitive to changes in air temperature as a 2°C increase leads to a refreezing decrease of 35%. [ABSTRACT FROM AUTHOR]

The Himalayan cryosphere system is a major source of freshwater supply for the Indian subcontinent. The rivers originating from the Himalaya are strongly influenced by the behaviour of glaciers depending upon the regional climatic variables. Therefore, understanding the mass budget of glaciers is important. In the present study, we discuss the hydrological mass balance of the largest Siachen glacier in the Karakoram range. The computations of runoff and other parameters on such a large glacier are challenging due to data scarcity, difficult accessibility and complex topography of the region. The snowmelt runoff model (SRM) coupled with in-situ and remotely sensed information was used to simulate the glacier runoff for the past three decades (1986–2018). The accumulation in the form of snowfall and ablation in the form of snowmelt and evaporation were used as inputs for the estimation of hydrological mass balance. The SRM has well estimated the discharge of Siachen glacier with the coefficient of determination (R2) 0.92 and average volume difference (Dv) 4.4% for the validation period. The study revealed that the Siachen glacier experienced few marginally mass gain episodes before 2000 but after that, a rapid and continuous mass loss has been observed. The average mass balance during the past three decades was found to be −0.11 ± 0.24 m w.e./year. This suggests that glaciers of East Karakoram have started losing mass; still, it is not as significant as generally observed in other parts of the Hindu Kush Himalaya. [ABSTRACT FROM AUTHOR]

Hydrological processes play an important role in stable isotopic compositional variations of the river water. The present study includes spatial distributions of stable hydrogen and oxygen isotopes (δD and δ18O) of a Himalayan River (the Teesta) to trace various hydrological processes and their associated roles on isotopic fractionation of river water. The δ18O compositions of the water samples varies between −12.2‰ and −5.4‰ (mean: −8.01‰ ± 1.81‰) and that of δD between −95.1‰ and −38.5‰ (mean: −57.6‰ ± 15.6‰). The observed compositional variation in δ18O, δD and d values of river water is mainly governed through snowmelt input, evaporation, and recycled moisture contribution. The variation of δ18O and δD values point towards an early melting of snow in the basin and a significant contribution of snowmelt to the river water. The orographic induced precipitation front appears to control the hydrological regimes in a distinct manner as reflected in the trend between d values and elevation. The rain shadow affected northern reaches of the basin are characterized with dry & arid climate triggering evaporation whereas, the windward southern side witness temperature influenced evaporation. The study suggests that the differential degree of recycled moisture contribution to the local precipitation is also a key component in bringing the stable isotopic variation in the river water. This varied magnitude of moisture recycling could result from uneven distribution of evapotranspiration and surface water evaporation. Results found that a rapid change in the altitude of a river basin can give rise to different hydrometeorological conditions, thereby resulting in simultaneous operation of almost all the major hydrological processes and a complex isotopic compositional variation in the river water. Also, the rainout percentage in the Teesta basin is found to be higher owing to this rapid rate of elevation increase. [ABSTRACT FROM AUTHOR]

The role of aerosol on the snow darkening effect is considered one of the main factors contributing to snow melting and glacier retreat over the Himalayas and Tibetan Plateau (HTP). Using the International Centre for Theoretical Physics (ICTP)'s regional climate model, RegCM4, we examine the changes induced by aerosol deposition over the HTP snow and its dynamical impacts over northern India during the pre-monsoon season (March to June), which is critical for the inception and development of the monsoon. Sensitivity experiments with and without aerosol-induced snow darkening effects for the period 2006–2010 reveal that this effect causes a significant reduction of snow cover fraction by 10 to 15% and an increase in surface temperatures (> 4 °C), which improves the model performance when comparing against observations over the HTP. This response is dominated by dust deposition, which covers a larger area of the HTP compared to the black carbon. While incorporating aerosol-induced snow darkening effect, the precipitation decreases (~ 0.4–2 mm/day) over northern India due to intrusion of dry winds, which also enhance dust emissions over the Thar Desert. As a result of the decrease in precipitation, surface temperature increases and generates a low-pressure system over northern India, which further strengthens the dust transport and its burden. We also find decreases in precipitation extremes and increases in the number of consecutive dry days and extreme temperature conditions over northern India, implying strong links with changes in pre-monsoon dynamics. The aerosol-induced snow darkening effect thus facilitates an earlier monsoon onset over southern India, but the northward propagation of the precipitation band is limited by the enhanced northwesterly winds over the Indo-Gangetic Plain. [ABSTRACT FROM AUTHOR]

Aerosol‐induced snow darkening and its feedback on seasonal snow cover, snowmelt, and runoff were investigated using the Regional Climate Model (RegCM4.6) coupled with SNow, Ice, and Aerosol Radiation (SNICAR) and aerosol modules over the Himalayas during the melting season (March‐September). The snow albedo reduction due to the deposition of absorbing aerosols increases the 2 m air temperature (1.47°C) and thus decreases the snow cover (10.6%) over the Himalayas during spring. This aerosol‐induced excess warming accelerates the seasonal snowmelt (1.2 mm day−1), which reduces the number of snow‐covered periods by more than 20 days throughout the Himalayas. The accumulated total snowmelt also increased by 41.3% over the Himalayas during the melting season. The early snowmelt and increase in runoff due to aerosol forcing have significant implications on rivers originating from the western Himalayas (Indus Basin). The change in snowmelt distribution and doubling of snowmelt extremes due to aerosol‐induced snow darkening could also translate to an increase in flood risks across the Himalayan river basins. Therefore, the present study highlights the importance of aerosol‐induced snow albedo forcing and its feedback on snowmelt and runoff over the Himalayan region, which has further implications on water availability over the South Asian region. Key Points: Snow darkening due to aerosol deposition accelerates the seasonal snowmelt over the HimalayasAerosol forcing shift the snowmelt timing over the Himalayas by more than 20 daysAerosol‐induced surface warming increase the occurrence of the snowmelt extremes by almost twice during the melting season [ABSTRACT FROM AUTHOR]

Seasonal and annual water supplies of the rivers originating in the Hindukush-Karakoram-Himalaya (HKH) region of Pakistan are important to manage the Indus basin irrigation system for better agricultural production and its dependent agrarian economy. In this study, we simulated the current and future snowmelt runoff in a poorly gauged river basin of the Hindukush region under Representative Concentration Pathways (RCP) climate change scenarios. Snowmelt Runoff Model (SRM) furnished with satellite snow cover maps and hydro-meteorological data were used to simulate the daily river discharge for the period 2000‒2005. The results indicated that SRM has effectually simulated the runoff in Chitral River with Nash-Sutcliffe model efficiency coefficient of 0.85 (0.84) and 0.88 (0.83) in the basin-wide (zone-wise) application during the calibration and validation periods, respectively. The results obtained under future climate change scenario showed ∼14‒19% increase in mean summer discharge under three mid-21st century RCP (2.6, 4.5 and 8.5) scenarios. While an increase of ∼13‒37% is expected under late-21st century RCP scenarios. This study can help water resource managers to plan and manage peak discharges from the Chitral River Basin in the future and can thus prevent major losses due to floods in the area. [ABSTRACT FROM AUTHOR]

In the present study, we used stable water isotopes (δ18O and δD) of source waters (rain, snow, and glacier melt) and groundwater to identify and estimate the sources of recharge in alluvial aquifer(s). The stable water isotopic composition of source waters showed a significant correlation with altitude (R2 = 0.75). Unlike source waters, the groundwater did not show significant spatio-temporal variation. The attenuation in the isotopic signal of groundwater may be due to lag and mixing of different waters recharging from different altitudes. The results revealed that snowmelt (44 ± 0.9% to 68 ± 2.7%) predominantly recharges the groundwater. The glacier melt contribution to groundwater recharge (2 ± 0.1% to 14 ± 0.9%) in Upper Jhelum Basin (UJB), although limited to some summer and autumn months, has tremendous significance in sustaining the groundwater recharge. The early and rapid melting of winter-accumulated snow due to climatic variability may disturb the seasonal water balance and decrease the annual groundwater recharge. [ABSTRACT FROM AUTHOR]

The upper Indus River basin has large masses of glaciers that supply meltwater in the summer. Water resources from the upper Indus River basin are crucial for human activities and ecosystems in Pakistan, but they are vulnerable to climate change. This study focuses on the impacts of climate change, particularly the effects of receding glaciers on the water resources in a catchment of the upper Indus river basin. This study predicts river flow using a hydrologic model coupled with temperature-index snow and glacier melt models forced by observed climate data. The basin is divided into seven elevation zones so that the melt components and rainfall-runoff were calculated at each elevation zone. Hydrologic modeling revealed that glaciers contributed one-third of the total flow while snowmelt melt contributed about 40%; rainfall contributed to the remaining flow. Some climate scenarios based on CMIP5 and CORDEX were employed to quantify the impacts of climate change on annual river flows. The glacier retreat in the mid and late centuries is also considered based on climate change scenarios. Future river flows, simulated by the hydrologic model, project significant changes in their quantity and timing. In the mid-century, river flows will increase because of higher precipitation and glacier melt. Simulations projected that until 2050, the overall river flows will increase by 11%, and no change in the shape of the hydrograph is expected. However, this increasing trend in river flows will reverse in the late century because glaciers will not have enough mass to sustain the glacier melt flow. The change will result in a 4.5% decrease in flow, and the timing of the monthly peak flow will shift from June to May. This earlier shift in the streamflow will make water management more difficult in the future, requiring inclusive approaches in water resource management. [ABSTRACT FROM AUTHOR]

The Third Pole experiences accelerated glacier retreating particularly in the eastern‐Himalaya, coinciding with a decrease of monsoon‐precipitation in the early 21st century. The extent to which the vanishing abundant maritime glaciers buffer the declining precipitation‐runoff remains unclear. Here, with a state‐of‐the‐art enthalpy‐based distributed cryosphere‐hydrology model and first‐hand hydrometeorology observations at Motuo (latest accessible Chinese county), we carefully examine the Yarlung Zangbo basin along Himalayas. We find that during 1998–2019, the rising downstream runoff (lower Nuxia; +6.40 × 108 m3/yr) offsets the dropping upstream runoff (upper Nuxia; −6.89 × 108 m3/yr); however, only the marginal contribution from the vanishing eastern‐Himalaya and Nyainqêntanglha glaciers. During 1998–2019, dry upstream illustrates limited glacier melt (15.7 mm/yr) with dominated snow melt (78.8 mm/yr); while much larger at humid downstream (144.8 mm/yr for glacier melt and 219.1 mm/yr for snow melt). From 1981 to 2019, we observe glacier‐to‐snow melt transition in both upstream and downstream due to glacier degradation and growing nonmonsoon‐season precipitation. Plain Language Summary: The extent to which the vanishing abundant maritime glaciers buffer the declining precipitation‐runoff in the upstream of upper Brahmaputra basin (UBB) remains unclear. Here we use a distributed cryosphere‐hydrology model to study the hydrological regimes of the UBB, in conjunction with our own in situ water level observations (first‐hand hydrometeorology observations at the latest accessible Chinese county Motuo). We find contrasting discharge trends between the upstream (decreasing) and downstream (increasing) after 1998, and explain the underlying causes. In contrast with continental glaciers, Himalaya and Nyainqêntanglha glaciers feeding the Brahmaputra headwaters do not provide a significant contribution to total annual discharge. This is primarily because the abundant monsoon‐precipitation coincides with the warmest temperatures at higher altitudes, and the contribution from glacier melt is then insignificant compared to the water volume generated by rainfall. Key Points: There is the largest fraction and retreat speed of glaciers in upper Brahmaputra (Yarlung Zangbo) among large rivers from Tibetan PlateauRising downstream runoff offsets the dropping upstream runoff with marginal contribution from vanishing southeast Tibetan Plateau glaciersGlacier‐to‐snow melt transition in both upstream and downstream due to glacier degradation and growing nonmonsoon‐season precipitation [ABSTRACT FROM AUTHOR]

Increased human influence has warmed the atmosphere, ocean and land thereby resulting in widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere (IPCC, 2021). High altitude lakes are generally small and quite sensitive to natural and anthropogenic perturbations. The present work is a preliminary work to investigate different hydro chemical processes and factors that controls the geochemistry of a high altitude lake, Lam Lake (dal) and its consecutive six lakes flowing through the Chamba district, Himachal Pradesh. Two hundred and eighty (n=280) water samples were collected in the year 2017 during the pre-monsoon and post-monsoon season. The anion concentration for all the seven lakes followed the trend HCO3- > NO3- > Cl- > SO42- > PO43- whereas the order of cation concentrations was Ca2+> Mg2+> Na+> K+ for both the seasons. Less EC of the water samples shows its serene nature. Components of bicarbonate (HCO3-) were found to be the major anion whereas calcium (Ca2+) was found to be the major cation present in the lakes. Piper Plot and Durov plot indicated Ca2+ – HCO3- as the major hydrogeochemical facies with comparatively less contribution from Mg2+–HCO3- type. The dominance of Ca2+ – HCO3- over Mg2+– HCO3- reflects the possibility of the natural order of dominance in the geology of the catchment area. The low Na+ + K+/TZ+ (total cations) ratios and the high Ca2+ + Mg2+/TZ+ (total cations) and (Ca2+ + Mg2+)/(Na+ + K+) ratios showed dominance of carbonate weathering. The average carbon ratios during pre-monsoon and post-monsoon were found to be 0.97 and 0.98, respectively, suggesting that proton is primarily derived from the oxidation of sulphide involving carbonate dissolution. The baseline data generated for a high-altitude lake shows that weathering and erosion during monsoonal precipitation and snow melt runoff during ablation season are the main sources of the chemical composition of lake water. Further to trace the imprints of climate change and seasonal variations in the high-altitude lakes, long term monitoring is recommended along with isotopic tracer techniques. [ABSTRACT FROM AUTHOR]

Precipitation over the southern rim of the Indian Himalayan Region (IHR) mainly occurs due to two dominant synoptic weather systems: Indian winter (IWM: December, January, February) and summer monsoon (ISM: June, July, August, September). The genesis and evolution of these systems are extensively researched. Additionally, geographical location, season, orography controls the strengths of these systems along and across the southern rim of the IHR. However, plausible positioning of the frontal threshold limit of precipitation during IWM and ISM over the IHR remains an elusive scientific question. Thus, with the help of water samples collected in the upper Bhilangana River Basin (BRB in the central Himalayas), an attempt has been made to assess this frontal threshold limit of precipitation and is defined as "quasi monsoon front (QMF)" in the IHR. Results show depleted (enriched) stable water isotopic values at higher (lower) altitudes suggesting an elevation control. The intercepts of local meteoric water lines (LMWLs) of glacier ice/glacier melt (2.5), snow packs/snow melt (7.7), and stream water (10.3) reflect mixing of precipitation due to IWM and ISM. The d-excess values in water samples lie between the d-excess value of a typical IWM (~20‰) and ISM (~10‰), suggesting mixing of moisture from both Atlantic ocean – Mediterranean sea and Indian ocean-Bay of Bengal-Arabian sea. The tracer based hydrographic analysis indicates dominance of snow melt contributions to the regional hydrology. Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) model in the back trajectory mode estimates moisture sources of the IWM and ISM. Based on precipitation isotopic composition and associated moisture source regions, QMF oscillates in the northwest and southeast direction of the IHR depending on the strength and/or weakness of IWM and ISM. This work hypothesizes for upscale determination and description of the pulsatory extension of QMF in the central Himalayas (along BRB). [ABSTRACT FROM AUTHOR]

The Indus River is the most prominent freshwater source of the northwestern part of the Indian subcontinent. Glacier/snow melting during the summer season is the main source of water. Here, we are presenting the major ion chemistry of the Indus river water, its tributary rivers, including small streams (nallahs), mainly in the territory of India, to know the overall quality of water, and geochemical processes controlling the solute acquisition and sources of elements in the catchment region. The analytical results indicate that the water samples are mildly acidic to alkaline in nature and have Ca2+ and Mg2+ dominance in cationic and HCO3- and Cl- in anionic composition. Overall, alkaline-earth elements (Ca2+ + Mg2+) dominate over alkalis (Na+ + K+), and weak acids (HCO3-) exceed strong acids (SO42- + Cl-) in the river/stream water samples. The hydrogeochemical diagrams, molar ratios, and statistical analysis suggest that carbonate and silicates minerals' weathering mainly control the solute acquisition process with negligible contribution from marine or anthropogenic sources. Most of the surface water samples are fit for drinking and domestic uses except the hot spring and saline lake waters. [ABSTRACT FROM AUTHOR]

Long term (2002–2017) satellite-retrieved and reanalysis datasets are utilized to assess the daily and interannual timescale impact of aerosol loadings on the cloud properties, precipitation amounts, and freezing level height over the southern slopes and adjacent foothills (SSFH) of the Himalayas during the Indian summer monsoon season. Daily timescale composites during polluted days suggest the development of widespread deeper clouds and higher precipitation amounts. Significant efforts were carried out to isolate the role of weather forcing in the daily timescale from the outlined aerosol-cloud-precipitation relationship by using the environmental relative humidity (RH) and vertical velocity (ω). Results provide strong evidence suggesting that regardless of weather pattern forcing, the direct association of aerosol optical depth (AOD) with precipitation, and cloud properties remained consistent for day-to-day timescales. The spatial correlation analyses of daily AOD with cloud properties and precipitation during both wet and dry monsoonal years indicate a positive association of higher aerosol concentration with cloud vertical development and precipitation. The 0 °C isotherm altitude is found to be higher by 136.82 ± 18.82 m (mean ± standard deviation) during the polluted days in comparison to relatively cleaner environments, which can be crucial for the change in snow line and melting of glaciers impacting the hydroclimate of the Himalayas. Our results suggest that the influence of aerosol on modulating the regional precipitation and freezing level height can be significant for the hydroclimate of the Himalayan region in a daily to interannual timescale. [ABSTRACT FROM AUTHOR]

• End member contribution on supraglacial runoff in the Himalaya. • Snowmelt contribution accounts for ∼ 70 % of supraglacial runoff. • Comparison of isotope-based results with a glacio-hydrological model (GHM). • Discrepancies in GHM and EMMA are attributed to subglacial complexities. Conservative tracers are often used in mixing models to estimate the contribution from different end-members to proglacial streams. The supraglacial runoff generated below the equilibrium line represents a combination of snow and ice melt, and rainfall, since additional mixing from englacial and subglacial drainage is not possible. Thus, supraglacial runoff offers a reliable proxy for the seasonal variations in end-member contribution to glacier-fed streams. In this study, we used stable water isotopes (δ18O, δD and d-excess) to estimate the seasonal variations in end-member contributions to the supraglacial runoff with a novel mixing model. During the early, mid, and late summer 2016, we collected and analysed the supraglacial runoff and its potential water sources: rain, ice, and snow. Accounting for fractionation processes occurring from solid to liquid phases, we calculated the isotopic signatures of the snowmelt and the ice melt. Based on our models, the supraglacial runoff was mainly composed of snowmelt (68.1 ± 7.9 %), followed by rainwater (16.6 ± 6.4 %) and ice melt (15.3 ± 6.1 %). Our results partially agree with those from a numerical glacio-hydrological based model estimates on the outflow of the same glacier. We discuss the slight discrepancies of the two modelling frameworks, and attribute them to the hydrological relevance of the subglacial aquifer system. [ABSTRACT FROM AUTHOR]

• The first combined assessment of surface and subsurface flow from the cold-arid region of Ladakh. • Snowmelt is the largest contributor to annual discharge. • Most of the available meltwater flows through the subsurface. • Surface flow ceases during the winter, but subsurface flow remains active throughout the year with high seasonal variability. Hydrological assessments of high-altitude catchments in Trans-Himalayan Ladakh are necessary for a better understanding of water availability in the context of irrigated cultivation under conditions of insufficient quantitative information on cryospheric meltwater discharge. In this study, an integrated spatially distributed temperature index model and a coupled surface/subsurface flow model were used to simulate daily, seasonal, and annual surface and subsurface flows to assess the proportion of corresponding source contributors from the Stok catchment. Snow and glacier meltwater discharge secures irrigated agriculture of more than 300 households in this catchment. The models were forced by temperature, precipitation, ice- and snow-covered areas at daily time steps with calibration (2019; 108 days) and validation (2018; 93 days) against the observed discharge. The simulated discharge shows a good agreement with the observed discharge with R2 and RMSE of 0.8 (p < 0.01) and 0.6 m3/s, respectively. The results between 2003 and 2019 show that the snowmelt contribution to the total annual discharge is largest with 65 %, followed by glacier melt and rainfall contributions of approximately 19 % and 16 %, respectively. A reduction in glacierised areas by 4.2 % was observed while snow-covered areas showed high inter-annual variation. Simulated subsurface flow makes up 62 % (mean = 37.2 × 106 m3) of the total discharge with less inter-annual variation. The simulation suggests that while surface flow ceases during the winter period and peaks in August, the annualized mean flow amounts to ∼23.7 × 106 m3. More than 50 % of the melt occurs in the summer months of June, July and August, when the intensity of snowmelt, ice melt, and rainfall reach its maximum. The findings of this study on meltwater availability and surface/subsurface flow is important for irrigated agriculture of Stok village on a local scale, and it might also help to better understand socio-hydrological dynamics and situations of water scarcity in the wider cold-arid region of Ladakh. [ABSTRACT FROM AUTHOR]

The Indus Basin is referred to as a "water tower" which ensures water storage and supply to sustain environmental and human needs downstream by a balanced combination of precipitation, snow, glaciers, and surface water. The Upper Indus Basin (UIB) combines the high mountain ranges of the Hindukush, Karakoram, and Himalaya (HKH); this unique region is largely controlled by seasonal meltwater associated with snow and glacier melt during the summer months. The present study seeks to evaluate changes in hydrological and meteorological variable data collected through a network of 35 hydrometric and 15 climatic stations, respectively, across the UIB, Jehlum, and Kabul river basins in Pakistan. The Innovative Trend Significance Test (ITST) in combination with the Modified-Mann-Kendall (MMK) test was used for seeking trends, while Sen's method was applied for the slope determination of detected trends over four periods of differing lengths (T1: 1961–2013; T2: 1971–2013; T3: 1981–2013; and T4: 1991–2013). Significant decreases were observed in the mean summer and distinct months of (June–August) temperature (Tmean) at most of the stations during T1, while significant increases were dominant over the shorter T4. The mean precipitation (Pmean) was observed as significantly negative at ten stations during July; however, positive trends were observed in August and September. For streamflow, significantly upward trends were observed for mean summer, June and July flows (snowmelt dominant) during T1 and T2, within the glacier-fed basins of Hunza, Shigar, and Shyok; in contrast, streamflow (glacier melt dominant) decreased significantly in August and September over the most recent period T4. For snow-fed basins, significant increases were observed in summer mean flows at Indus at Kachura, Gilgit at Gilgit, and Alam Bridge, Astore at Doyian during (T1–T3). In particular, a stronger and more prominent signal of decreasing flows was evident in T4 within the predominantly snow-fed basins. This signal was most apparent in summer mean flows, with a large number of stations featuring significant downward trends in Jehlum and Kabul river basins. The present study concludes that the vulnerability of this region related to water stress is becoming more intense due to significantly increased temperature, reduced precipitation, and decreasing summer flows during T4. [ABSTRACT FROM AUTHOR]

Snow Depletion Curve derived from satellite images is a key parameter in Snowmelt Runoff Model. The fixed temporal resolution of a satellite and presence of cloud cover in Himalayas restricts accuracy of generated SDC. This study presents an effective approach of reducing temporal interval between two consecutive dates by integrating normalized Snow Cover Area estimated from multiple sources of satellite data. SCA is extracted by using Normalized Difference Snow Index for six snowmelt seasons from 2013 to 2018 for Gangotri basin situated in Indian Himalayas. This work also explores potential of recently launched Sentinel-3A for estimating SCA. Normalized SCA is utilized to eliminate the effect of difference in spatial resolution of various satellites. The result develops an important linear relation between SDC and time with a decrease in snow cover of 0.005/day that may be further refined by increasing the number of snowmelt seasons. This relationship may help scientific community in understanding hydrological response of glaciers to climate change. [ABSTRACT FROM AUTHOR]

Assessment of the response of the Himalayan river flows to climate change is complex due to multiple contributors: rainfall, snowmelt, and glacier‐melt. The number of studies is limited in this direction due to lack of data availability as well as non‐availability of models considering all the above‐mentioned components. As for example, the state‐of‐the‐art variable infiltration capacity (VIC) model does not account for the glacier melt. Here we integrate a glacier‐melt model with VIC and validate the model output with observed streamflow in five river basins in the Himalayas, at daily scale. Our model simulates the streamflow with Nash‐Sutcliffe estimates greater than 0.65 in all basins. The sensitivity analysis shows that the contribution from snowmelt decreases substantially in all the five basins with highest decrease of 36% in Dudh Kosi (DK), in a warm and dry scenario. The glacier‐melt increases (15%–70%) in a warmer environment with its present volume, but decreases (3%–38%) substantially, when the volumes are reduced to half. However, such a decrease is found to be compensated by increased precipitation in a wetter scenario with a net increase of 3%–13%. Climate model simulations show a decrease in the spring onset times for Sutlej basin while increase for DK basin for both RCP4.5 and RCP8.5 scenarios. Sutlej and Arun basins show decreases of more than 6 days in the center of volume of streamflow, which suggests that there will be increased flows in the early part of year and reduced flows later in the year. Plain Language Summary: Water is one of the resources essential for our survival. Climate change impacts water resources globally, and the impacts are adverse in regions which rely on water from snowpacks and glaciers. The Himalayas is the most magnificent mountain range and has vast reserves of ice and snow. The climate change has affected the Himalayas and reduced storages of ice and snow; lesser snowfall and more melt are evident across the mountain range. These changes affect about a billion people that reside in the basins of the Indus, Ganges, and Brahmaputra rivers. The water in these rivers is contributed by rainfall, snowmelt and glacier‐melt. Here, we studied changes in streamflow and its components in the Central Himalayas with changing precipitation and temperature scenarios. We found that in warming climate, snowmelt will reduce substantially, and glacier melt will increase initially, but with significantly reduced volumes in the latter end of the century, it will start to decrease. However, in a wetter scenario, increased precipitation may compensate for such a decrease. The changes in streamflow in early spring and autumn vary from basin to basin in the Himalayas. Key Points: Integration of temperature index glacier model with state of art variable infiltration capacity model to consider melts from clean and debris covered glaciersThe rainfall dominates the Central Himalayan water resources, and the streamflow is highly sensitive to precipitation changesSutlej basin shows decrease in the sprint onset times while Dudh Kosi shows increases for RCP 4.5 and 8.5 scenarios [ABSTRACT FROM AUTHOR]

The Soil and Water Assessment Tool (SWAT) model was configured to simulate streamflow under data scarcity scenario for a snow-dominated, forested, mountainous Mago River basin located in the Eastern Himalayan region of India. To account for the role played by snowmelt dynamics on streamflow and its influence on water balance components of the basin, two separate projects were set up: a Reference project in which only hydrological parameters related to streamflow were considered without regard to snow-related parameters, elevation bands, and associated lapse rates and another project referred to as Elevation Band project in which 10 elevation bands were set up for six snow-dominated headwater sub-basins. Sensitivity analysis and calibration was performed using SWAT Calibration Uncertainty Programs/Sequential Uncertainty Fitting 2 for both the projects. The result of the sensitivity analysis showed that curve number (CN 2) was found to be most sensitive. The comparison between the two calibrated projects revealed that inclusion of snow-related parameters, elevation bands, and the associated lapse rates in the snow-dominated headwater catchments improved the hydrological simulation performance and this improvement propagated downstream towards the outlet of the basin. This enhancement highlighted the ability of SWAT to capture the snowmelt dynamics prevailing in the Eastern Himalayan region. Analysis of the water balance components showed that water yield and percolation increased, while evapotranspiration decreased under the effect of snow cover. The contribution of snowmelt runoff to the annual streamflow of the basin was about 8%, and the maximum contribution was made during the pre-monsoon period. This study also highlighted the importance of the presence of snow cover to sustain the ecosystem of the region. [ABSTRACT FROM AUTHOR]

Glaciers are storehouses for freshwater. Glaciers Monitoring is one of the most important research areas especially when climate change has been accelerated snowmelt process. The major goal of research was to find snow cover trend for glaciated regions of Pakistan followed by estimation of snow mass balance. The area chosen for it was Upper Indus basin, which includes ranges of Hindukush, Karakoram and Himalayas extended in Pakistan, India and China. This region exhibits high topographic relief and climate change variability. Snow cover trend analysis was performed for eleven years ranging from 2004 to 2014 using Moderate Resolution Imaging Spectroradiometer (MODIS) data imagery product with daily temporal resolution. These results were combined with respective year's average monthly temperature. Further quantitative analysis was performed to relate presence of greater vegetation as an indication of greater snowmelt using Landsat Imagery for these years. Snow mass balance curves reveal that glaciers are regaining their mass balance after losing mass balance in middle of last decade. In addition to that, only freely available data is used for this study. This purpose behind this approach is to prove RS and GIS has an effective and low-cost tool for snow cover monitoring, also mass balance calculations. Continuous monitoring of snow cover dynamics is effective for prediction and mitigation of hazards associated with areas in proximity of glaciated regions. One common hazard is glacial lake outburst phenomenon, which cause severe flash flooding in downstream areas. Year 2004 has the lowest mass snow balance and 2014 has the highest snow mass balance. These different parameters were analysed and results show that snow start melting in months of May and June and faster melting rate observed in months of July and August. With the advancement in computing technologies, it has been easier for computers to handle and manipulate massive datasets. Remote sensing has proved to be an excellent tool for extraction of data from glaciers, snow and oceans for remote areas. In particular, snow cover/snowmelt can tell us continuously changing melting patterns, which helps concerned authorities to take necessary measures for preserving these storehouses of water and to mitigate effect of global warming. [ABSTRACT FROM AUTHOR]

Himalayan rivers originating generally from >4000 masl, sustain large number of population downstream. However, these river basins are highly data scarce, and in situ data for hydro-meteorological parameters is available mainly from the regions below 2000 masl. Considering the high level of human dependence on these rivers, it is important to develop policies and plans based on the hydrology of these rivers. Thus it is important to quantify the contribution of various runoff components like snow and ice melt, baseflow, etc. This paper has used conceptual hydrological model, HBV model to estimate the composition and contribution of various runoff components, for the Chenab river basin, Western Himalayas. Similar to hydrological modelling results for other basins of western Himalayas, this study shows that snow and ice melt contribution is significant in the basin and ranges between 40–66% of the total runoff in different seasons. During the post monsoon period, baseflow sustains the perennial nature of river. This research attempts to quantify the seasonal contributions to river runoff and provides valuable insights into hydrological processes operating in this high altitude hydrological catchment to facilitate improved management of water resources in the basin. The study further outlines the uncertainty in simulating low flows in ungauged catchments being fed by snow/ice melt. [ABSTRACT FROM AUTHOR]

The present study attempts to investigate the phenological changes of herbaceous plant species in early snowmelt microsite and late snowmelt microsite in treeline ecotone (3200-3300 m asl) at Tungnath, western Himalaya. Four sites, each with two microsites (early snowmelt: ES and late snowmelt: LS) were selected and within each microsite, 3 quadrats (1x1m each) were permanently laid and studied for phenology. Eighty-six species were recorded, of which the proportion of perennial forbs, hemicryptophytes and natives was 90, 84 and 70%, respectively. The early phenophase was noticed in the majority of species in ES microsite than that of LS microsite and the timing of different phenophases varied among microsites. The vegetative phase peaked July (75.6%), while flowering, fruiting and seed maturation phases peaked in August (72.1% and 23.3%, respectively) and 71% species attained the senescence during September. This indicates that species might adapt to the different adaptation to a warming climate. Immediately after the snowmelt 10 species were observed in flowering, while 11 species were in the bud development phase. Comparing 13 common species of the present study with those of past in same or similar study areas indicates that timing and duration of vegetative and flowering phenophase (77% and 69%, respectively) have advanced and lengthened, while fruiting and seed maturation have shortened. Furthermore, phenophase initiation has advanced for flowering (69% species), fruiting (46% species) and senescence (38% species) phases. It seems that the early snowmelt influences spring phenology of herb species on the microsite level and may continue to influence the overall phenology of species for the whole growing season in timberline. [ABSTRACT FROM AUTHOR]

Glaciers and snow cover are important constituents of the surface of the Tibetan Plateau. The responses of these phenomena to global environmental changes are sensitive, rapid and intensive due to the high altitudes and arid cold climate of the Tibetan Plateau. Based on multisource remote sensing data, including Landsat images, MOD10A2 snow product, ICESat, Cryosat‐2 altimetry data and long‐term ground climate observations, we analysed the dynamic changes of glaciers, snow melting and lake in the Paiku Co basin using extraction methods for glaciers and lake, the degree‐day model and the ice and lake volume method. The interaction among the climate, ice‐snow and the hydrological elements in Paiku Co is revealed. From 2000 to 2018, the basin tended to be drier, and rainfall decreased at a rate of −3.07 mm/a. The seasonal temperature difference in the basin increased, the maximum temperature increased at a rate of 0.02°C/a and the minimum temperature decreased at a rate of −0.06°C/a, which accelerated the melting from glaciers and snow at rates of 0.55 × 107 m3/a and 0.29 × 107 m3/a, respectively. The rate of contribution to the lake from rainfall, snow and glacier melted water was 55.6, 27.7 and 16.7%, respectively. In the past 18 years, the warmer and drier climate has caused the lake to shrink. The water level of the lake continued to decline at a rate of −0.02 m/a, and the lake water volume decreased by 4.85 × 108 m3 at a rate of −0.27 × 108 m3/a from 2000 to 2018. This evaluation is important for understanding how the snow and ice melting in the central Himalayas affect the regional water cycle. [ABSTRACT FROM AUTHOR]

Combining multiple data sources with multi-physics simulation frameworks offers new potential to extend snow model inter-comparison efforts to the Himalaya. As such, this study evaluates the sensitivity of simulated regional snow cover and runoff dynamics to different snowpack process representations. The evaluation is based on a spatially distributed version of the Factorial Snowpack Model (FSM) set up for the Astore catchment in the upper Indus basin. The FSM multi-physics model was driven by climate fields from the High Asia Refined Analysis (HAR) dynamical downscaling product. Ensemble performance was evaluated primarily using MODIS remote sensing of snow-covered area, albedo and land surface temperature. In line with previous snow model inter-comparisons, no single FSM configuration performs best in all of the years simulated. However, the results demonstrate that performance variation in this case is at least partly related to inaccuracies in the sequencing of inter-annual variation in HAR climate inputs, not just FSM model limitations. Ensemble spread is dominated by interactions between parameterisations of albedo, snowpack hydrology and atmospheric stability effects on turbulent heat fluxes. The resulting ensemble structure is similar in different years, which leads to systematic divergence in ablation and mass balance at high elevations. While ensemble spread and errors are notably lower when viewed as anomalies, FSM configurations show important differences in their absolute sensitivity to climate variation. Comparison with observations suggests that a subset of the ensemble should be retained for climate change projections, namely those members including prognostic albedo and liquid water retention, refreezing and drainage processes. [ABSTRACT FROM AUTHOR]

Melting snow and glacier ice in the Himalaya forms an important source of water for people downstream. Incoming longwave radiation (LWin) is an important energy source for melt, but there are only few measurements of LWin at high elevation. For the modelling of snow and glacier melt, the LWin is therefore often represented by parameterizations that were originally developed for lower elevation environments. With LWin measurements at eight stations in three catchments in the Himalaya, with elevations between 3,980 and 6,352 m.a.s.l., we test existing LWin parameterizations. We find that these parameterizations generally underestimate the LWin, especially in wet (monsoon) conditions, where clouds are abundant and locally formed. We present a new parameterization based only on near‐surface temperature and relative humidity, both of which are easy and inexpensive to measure accurately. The new parameterization performs better than the parameterizations available in literature, in some cases halving the root‐mean‐squared error. The new parameterization is especially improving existing parameterizations in cloudy conditions. We also show that the choice of longwave parameterization strongly affects melt calculations of snow and ice. [ABSTRACT FROM AUTHOR]

The paper aims to look at the relation of livelihood and mobility, and the health hazards faced by the pastoral Bakarwal tribe based in the union territory of Jammu and Kashmir. Livelihood pattern of Bakarwals constitutes mostly of herding animals, and seasonal migration plays an all-important role in attaining the same. With the exhaustion of winter pastures in plains, they move to the highland pastures in Greater Himalayas in early spring along with their herds and household items by crossing various passes in the Pir Panjal and Siwalik ranges. Melting snow, gusty winds, dangerous ravines and valleys along with threats of the wild pose high risks to the health and lives of this people and their livestock. Moreover, various factors have led to the loss of this age-old tradition and the Bakarwals are quickly adopting a settled way of life. Data about the study has been collected through various ethnographic techniques among the community in the intervening pastures of the Kashmir valley. [ABSTRACT FROM AUTHOR]

In this work, we investigate a slow-moving, large landslide (∼20 km2) in the Chitral district in Northern Pakistan, near several villages. The slow-moving landslide was reported more than four decades ago but has never been examined afterward. Interferometric Synthetic Aperture Radar (InSAR) analyses, using Sentinel-1 data that span a period of six years, allowed us to retrieve the spatio-temporal pattern of hillslope deformation. We combined both ascending and descending orbits to identify vertical and horizontal deformations. Our results showed that the crown is moving relatively fast in comparison to the nearby regions; 30 mm/year and 40 mm/year in downward and eastward directions, respectively. Also, step-like deformations observed over the crown reflect a deep-seated landslide. At the footslope, on the other hand, we captured relatively high deformations but in an upward direction; specifically 30 mm/year and 30 mm/year in upward and eastward directions, respectively. We have discussed the possible roles of meteorologic and anthropogenic factors causing hillslope deformation occurred during the six-year period under consideration. We observed a seasonal deformation patterns that might be mainly interpreted to be governed by the influence of snowmelt due to increasing temperatures during the start of spring. Overall, the same mechanism might be present in many other hillslopes across the whole Hindukush-Himalayan-Karakoram range, where seasonal snowmelt is an active agent. In this context, this research provides a case study shedding a light on the hillslope deformation mechanism at the western edge of the Himalayan range. [ABSTRACT FROM AUTHOR]

The torrential rains in June 2013 combined with melting of snow caused voluminous floods in the rivers of Uttarakhand and subsequently triggered widespread mud, landslides and debris deposition. The event caused instability of the channel by shifting the banks. Erosion rendered many locations along the banks vulnerable to economic and human loss. The shifts in reaches are calculated by digitizing the bank line using satellite imageries of year 2005, 2010 and 2015. The extent and magnitude of risks have been assessed based on information of past events, rapid field assessments, current mitigation measures and interactions with the locals. The findings from these interactions, and secondary data based on geospatial analysis of bank line changes have been used in the identification of vulnerable reaches along the major rivers. Criteria to identify the vulnerable reaches are based on risk, exposure and hazards in that area. The magnitude of risks due to flood hazards on various exposures along the riverbank is calculated based on qualitatively derived scores. River basins focusing on rainfall, topography, drainage pattern, soil, landslide and exiting infrastructure in relation to vulnerability of the region using GIS data are discussed in details. A fuller understanding will enable decision makers towards more efficient resources management for prevention and protection of river banks due to flood events. In addition to this, an official online decision support system (www.urmis.dhi-india.com) with collaborating partners and organizations for relevant data, information and document has been created. [ABSTRACT FROM AUTHOR]

In a context of climate change and water demand growth, understanding the origin of water flows in the Himalayas is a key issue for assessing the current and future water resource availability and planning the future uses of water in downstream regions. Two of the main issues in the hydrology of high-altitude glacierized catchments are (i) the limited representation of cryospheric processes controlling the evolution of ice and snow in distributed hydrological models and (ii) the difficulty in defining and quantifying the hydrological contributions to the river outflow. This study estimates the relative contribution of rainfall, glaciers, and snowmelt to the Khumbu River streamflow (Upper Dudh Koshi, Nepal, 146 km 2 , 43 % glacierized, elevation range from 4260 to 8848 m a.s.l.) as well as the seasonal, daily, and sub-daily variability during the period 2012–2015 by using the DHSVM-GDM (Distributed Hydrological Soil Vegetation Model – Glaciers Dynamics Model) physically based glacio-hydrological model. The impact of different snow and glacier parameterizations was tested by modifying the snow albedo parameterization, adding an avalanche module, adding a reduction factor for the melt of debris-covered glaciers, and adding a conceptual englacial storage. The representation of snow, glacier, and hydrological processes was evaluated using three types of data (MODIS satellite images, glacier mass balances, and in situ discharge measurements). The relative flow components were estimated using two different definitions based on the water inputs and contributing areas. The simulated hydrological contributions differ not only depending on the used models and implemented processes, but also on different definitions of the estimated flow components. In the presented case study, ice melt and snowmelt contribute each more than 40 % to the annual water inputs and 69 % of the annual stream flow originates from glacierized areas. The analysis of the seasonal contributions highlights that ice melt and snowmelt as well as rain contribute to monsoon flows in similar proportions and that winter outflow is mainly controlled by the release from the englacial water storage. The choice of a given parametrization for snow and glacier processes, as well as their relative parameter values, has a significant impact on the simulated water balance: for instance, the different tested parameterizations led to ice melt contributions ranging from 42 % to 54 %. The sensitivity of the model to the glacier inventory was also tested, demonstrating that the uncertainty related to the glacierized surface leads to an uncertainty of 20 % for the simulated ice melt component. [ABSTRACT FROM AUTHOR]

Light-absorbing particles (LAPs), mainly dust and black carbon, can significantly impact snowmelt and regional water availability over high-mountain Asia (HMA). In this study, for the first time, online aerosol–snow interactions are enabled and a fully coupled chemistry Weather Research and Forecasting (WRF-Chem) regional model is used to simulate LAP-induced radiative forcing on snow surfaces in HMA at relatively high spatial resolution (12 km , WRF-HR) compared with previous studies. Simulated macro- and microphysical properties of the snowpack and LAP-induced snow darkening are evaluated against new spatially and temporally complete datasets of snow-covered area, grain size, and impurity-induced albedo reduction over HMA. A WRF-Chem quasi-global simulation with the same configuration as WRF-HR but a coarser spatial resolution (1 ∘ , WRF-CR) is also used to illustrate the impact of spatial resolution on simulations of snow properties and aerosol distribution over HMA. Due to a more realistic representation of terrain slopes over HMA, the higher-resolution model (WRF-HR) shows significantly better performance in simulating snow area cover, duration of snow cover, snow albedo and snow grain size over HMA, as well as an evidently better atmospheric aerosol loading and mean LAP concentration in snow. However, the differences in albedo reduction from model and satellite retrievals is large during winter due to associated overestimation in simulated snow fraction. It is noteworthy that Himalayan snow cover has high magnitudes of LAP-induced snow albedo reduction (4 %–8 %) in pre-monsoon seasons (both from WRF-HR and satellite estimates), which induces a snow-mediated radiative forcing of ∼30 –50 Wm-2. As a result, the Himalayas (specifically the western Himalayas) hold the most vulnerable glaciers and mountain snowpack to the LAP-induced snow darkening effect within HMA. In summary, coarse spatial resolution and absence of snow–aerosol interactions over the Himalayan cryosphere will result in significant underestimation of aerosol effects on snow melting and regional hydroclimate. [ABSTRACT FROM AUTHOR]

This study assesses the impact of glacier changes and their effects on glacier melt runoff over three different Himalayan river basins located in western Himalaya (i.e. Baspa and Ganga) and eastern Himalaya (Teesta). For computation of glacier melt runoff, a fully distributed snow-glacier melt runoff model viz. SPHY has been used. The glacier area changes have been computed by preparing the glacier maps for different years for all selected river basins viz. Baspa (for year 2000 & 2018), Ganga (for year 1990, 2000, 2010 and 2020) and Teesta (for year 2000 and 2020). Results showed that the glacier areas have noticeably reduced for all Himalayan river basins viz. Baspa (∼19.8%), Ganga (∼5.01%) and Teesta (∼5%). It has been observed that smaller glaciers have more significantly reduced than large glaciers. The strength of the glacier melt induced runoff computation has been evaluated with reference to observed discharge at different gauges in all selected river basins, which showed a reliable agreement between modeled and observed runoff (R2 > 0.7). To see the behavior of runoff for different glacier sized watersheds, the three basins have been divided into a number of watersheds. In Baspa four watersheds while for Ganga and Teesta basins, six watersheds have finally selected depending on quantum of glacier. As per the decadal computation of glacier melt scenarios for all river basins viz. Baspa (i.e. 2003–2010 and 2011–2018), Ganga (1986–1995, 1996–2005, 2006–2015, and 2011–2020) and Teesta (1996–2010 and 2006–2020), observations showed that watersheds having large glaciers, the melt runoff has increased, while in cases of the watersheds having small glaciers, the melt runoff has decreased due to reduced glacier cover. In case of Baspa basin, glacier melt runoff has decreased by 5% while for Ganga and Teesta basins it has increased by 1%. Similarly, for Baspa basin, snowmelt runoff has increased by 6% and for Ganga and Teesta it has decreased by 3%. • This study demonstrates the comparative assessment of glacier changes and their impacts on melt runoff. • Separation of snowmelt runoff and glacier melt runoff from the total runoff. • Analysis of the behavior of runoff for different glacier sized watersheds under varying glacier characteristics. • Glacier melt runoff and snowmelt runoff change assessment at different stations using varying degree-day factors. [ABSTRACT FROM AUTHOR]

Recharge assessment is a challenge in snow and glacier dominated Himalayan basins. Quantification of recharge to karst springs in these complex geological environments is important both for hydrologic understanding and for effective water resource management. We used spring hydrographs and environmental tracers (isotopes and solutes) to distinguish and estimate the sources of spring water and to identify the flow paths of the recharging waters in three mountainous basins of the western Himalaya. The karst springs are perennial with high discharge amplitudes. The results indicate that ambient temperature has a strong influence on the hydrological behavior of the springs. Although the spring flow is dominantly controlled by the melting of snow and/or glaciers, rain events produce sharp spikes in spring hydrographs. The facies patterns in springs within the Bringi basin (Ca-HCO 3 ) and the Liddar basin (Ca-HCO 3 and Ca-Mg-HCO 3 ) suggest flow dominantly through limestone and dolomite. Higher concentrations of SO 4 2− and Na + in warm springs of the Kuthar basin indicate flow through carbonate, silicate and other rocks. The isotopic composition (δ 18 O, δ 2 H) of precipitation, snowpacks, glacier melt and karst springs show wide variation both in space and time, and are strongly influenced by the basin relief and meteorology. The tracer-based two- and three-component mixing models suggest that the snowmelt dominantly contributes to the spring flow (55–96%), followed by glacier melt (5–36%) and rain (4–34%). Based on tracer tests with good recovery rates, springs are dominantly recharged through point sources rather than by diffuse infiltration. Changes in the timing, form, and amount of winter precipitation substantially affect the timing and magnitude of spring discharge during the rest of the year. [ABSTRACT FROM AUTHOR]