Chorabari Glacier Research Articles

Inter–Intraseasonality of Meteorological Drivers of Chorabari Glacier, Central Himalaya: Implications for Mass Fluctuations and Associated Hazards

Abstract High-altitude meteorological data are scarce in the Himalayan region, particularly for glacierized catchments. In-depth knowledge of meteorological variables is crucial to describe numerous cryospheric processes and associated hazards. The present study comprehensively assesses time series data (2013–16) of meteorological parameters in the Chorabari Glacier catchment (CGC) using an automatic weather station (∼4270 m MSL). Results revealed that average near-surface air temperature varied seasonally, ranging from 6.4°C in the summer monsoon (June–September) to −6.3°C in the winter season (December–February). The minimum temperature (Tmin) remained positive throughout the monsoon seasons in the higher elevations (∼5050 m MSL), indicating the melting of glaciers and their reduced mass. The daily relative humidity in different seasons fluctuated from 39% to 90%, whereas the highest seasonal average (∼63%) was observed in the monsoon season. The average wind speed was high (∼1.7 m s−1) during winter and dropped to 1.1 m s−1 in the monsoon season. The average daily influx of solar radiation ranged from 19 to 374 W m−2, with the highest value recorded during the premonsoon (March–May ∼ 212 W m−2) and the lowest during the winter (∼149 W m−2) season. The daily outflux solar radiation varied from 18 to 186 W m−2, with the maximum value in premonsoon (∼145 W m−2) and the minimum value in the monsoon season (∼30 W m−2). The mean zero-degree isotherm was found above the equilibrium line altitude (ELA ∼ 5120 m MSL) during the monsoon season, indicating a considerable mass depletion of the Chorabari Glacier. The abnormal variations in climatic variables on 16–17 June 2013 were signs of the Kedarnath disaster. Significance Statement The main objective of this study is to understand the variability of meteorological drivers at daily, monthly, and seasonal scales and how these changes may impact glacier mass and downstream hydrology. Our research revealed considerable variations in maximum temperature throughout the year and positive minimum temperature at higher elevations during monsoon months, which significantly control the glacier mass changes. Meteorological variables showing cyclic behavior and indicators of the “monsoon lowering phenomenon” are important in determining the timing and intensity of the seasonal shift. Investigation of abnormal changes in the climatic drivers in the 2013 Kedarnath disaster provides valuable insight into the glacier-related hazards and draws attention to decision-makers to create robust strategies to monitor the dynamic response of Himalayan glaciers.

Isotope Hydrograph Separation Reveals Rainfall on the Glaciers Will Enhance Ice Meltwater Discharge to the Himalayan Rivers

AbstractThe Indian Summer Monsoon (ISM) and meltwater from the Himalayan are the two most important sources of water in the Indian subcontinent. However, the impact of ISM on Himalayan glaciers and subsequent stream hydrology remains largely unknown. To provide new insight into the impact of rainfall on glacial hydrology, here we present hydro‐meteorological and time‐series observations of meltwater stable water isotope compositions from the snout of the Chorabari glacier in the Upper Ganga Basin, Central Himalayas across the ablation season corresponding to 2019. We observe that rainfall events (>2 mm d−1) on the glacier enhance discharge driven by ice meltwater in River Mandakini. Energy balance calculations reveal that one of the drivers behind enhanced ice meltwater contribution could be rain‐induced melting of the glacier where rainfall on the ice surface melts the glacier producing up to 13% of the total discharge at the glacier snout. Further, rainfall on glacier surface have other control on glacial processes—for example, snow metamorphism, ice flow dynamics such as short‐term acceleration in ice speed flow, and reorganization of the englacial and subglacial drainage network—that are poorly studied and needs further investigation. We conclude rainfall events on the glacier have a complex control on mountain hydrology. This study, therefore, provides an interpretative framework that calls for additional assessments of the direct and indirect impact of rainfall in glacial hydrology.

Avalanche Hazards Around Kedarnath Temple, Mandakini River Valley, Uttarakhand – A Case Study

Abstract The Shri Kedarnath town is located in the western extremity of the Central Himalaya (30°44'6.7" N; 79°04'1"E) in the Mandakini River valley. This has a total catchment area of ~67 km2 (up to Rambara), out of which 23% area is covered by glaciers. In September 2022, avalanches were observed repeatedly in the mountains to the north of Kedarnath town. Based on aerial survey and ground observations of the area around Kedarnath, we found that the avalanches initiated ~6 km (Aerial distance) uphill of the Kedarnath Temple from the peaks of the Mahalaya Parvat (5970 m asl) of the Companion Glacier adjacent to the Chorabari Glacier. The Companion Glacier does not have a well-defined accumulation zone but receives accumulation mostly from the avalanches. The run-out and deposition zones of the avalanches are located ~5 km uphill of the Kedarnath Temple. The avalanche activity thus poses no threat to the Kedarnath Temple and township. In addition, fifteen avalanche sites (A1-A15) have been identified based on slope morphology, grass clearing, the presence of snow drifts, and debris cones in the area. We observed that the Temple of Shri Kedarnath Complex is located at a reasonably safe place as far as avalanche hazards are concerned.

A high-altitude calibration set of modern biotic proxies from the Western Himalaya, India: Pollen–vegetation relation, anthropogenic and palaeoclimatic implications

We analysed the pollen composition, non-pollen palynomorphs (NPPs) and stable carbon isotope data (δ13C values) of surface sediments (soil), from the proglacial deposits (outwash plain and the two levels of kame-terraces) of the Chorabari Glacier, Kedarnath, India. The main objective was to develop the modern-proxy analogues, for the calibration of fossil records, for use in palaeoclimatic reconstructions. The pollen–vegetation relation is incompatible (non-linear) with the present vegetation, as the pollen assemblages are marked by the prolific over-representation of extra-local pollen, especially Pinus, over the local herbaceous taxa. Multivariate principal component analysis (PCA) was applied on the palynological data to ascertain the major groups of pollen in relation to the vegetation types and reveal variations in the pollen records between the kame-terraces and the outwash plain. δ13C values of the soil organic matter (SOM) show an average of − 27.0‰, indicating a C3 dominant vegetation. The pollen records have also revealed the anthropogenic activities in the form of degradation of tree-line and over-grazing by the domesticated animals. The NPPs reflect the prevalence of grazers in the present times, and would be useful in tracing the advent and intensification of grazing in the region. The modern pollen analogues show a good correlation with the fossil pollen data. The present study provides the much needed modern biotic analogues for vegetation-based past climatic reconstructions from the alpine regions of the Western Himalaya.

Source characterization of suspended sediments transported from debris-covered Chorabari Glacier in Central Himalaya, India

Source characterization of suspended sediments transported from debris-covered Chorabari Glacier in Central Himalaya, India

Size-dependent chemical depletion of sediments in glacial environments: a case study of Mandakini Valley, central Himalaya, India

ABSTRACT The size-dependent chemical maturity of sediment cycling in a high-altitude glacial/periglacial environment was studied by examining the sediments of the Chorabari Glacier, Mandakini Valley, central Himalaya, India. Sediments evacuated from glacial debris and a periglacial area were studied via particle-size analysis, X-ray fluorescence, and X-ray diffraction of different grain-size fractions. The results suggest a clear control of grain-size fraction over chemical weathering and release of its attendant nutrients from the glacial substrate. Elemental indices suggest the release of nutrients is principally controlled through comminution and sub-glacial chemical weathering of leachable minerals such as feldspar, mica, and apatite. Owing to biogeochemical cycles, the release of nutrients like phosphorous and calcium is predominantly controlled through mineral dissolution process of aluminosilicate rocks containing apatite, carbonate minerals and organic complexes. Overall, the size-dependent chemical maturity of glacial sediments suggests a much more chemically active system than previously thought. This study is of particular importance for downstream weathering tracer studies of detrital sediments.

Misinterpreting proxy data for paleoclimate signals: A reply to Srivastava and Jovane, 2020

Srivastava and Jovane (2020) have made several comments on our assessment of proxy data and challenged the outcome of Shukla et al. (2020) based mainly on interpretation of environmental magnetic parameters. We respond to their criticisms and re-evaluate our paper, remove ambiguities and validate our conclusions through additional proxies (grain-size and geochemistry). We welcome their comments and do not entirely rule out their interpretation for magnetic mineralogy. We highlight the importance of proxy validation for high-energy environments like Chorabari lake. However, single proxy data correlation is likely to produce biased results with no relevant meaning. The objective of our study was to understand complexities in the glacial-climate system by reconstructing late-Holocene climate variations using the glacial lake sediment records from the Mandakini River Basin, Central Himalaya, India. We presented the complexities in Shukla et al. (2020), and this was also highlighted by Srivastava and Jovane (2020). In response, we provide additional justification of proxy response and substantiate our results with present-day estimates from the Chorabari glacier valley. We disagree with the thesis put forward by Srivastava and Jovane (2020) in their conclusion as they overemphasize the interpretation of a single proxy. We maintain that the investigation of present-day glacial settings is an important precursor of paleoclimatic data interpretation and that this supports our conclusions. We will try to incorporate the important suggestions of Srivastava and Jovne (2020) relating to the interpretation of magnetic data in future work.

Spatio-temporal fluctuations over Chorabari glacier, Garhwal Himalaya, India between 1976 and 2017

The current research work deals with the health of Chorabari glacier between 1976 and 2017, using multi spectral and multi dated satellite data series of LANDSAT (MSS, TM, and ETM+) and RESOURCESAT II (LISS IV). Result closely reveals that the studied glacier receding continuously with inconsistent rate for the last 41 years and rate of receding dominates significantly after 2012. It lost ~306.43 ± 61 m total length (7.46 ± 1.48 m a−1); 0.074 km2 frontal area (0.0018 km2 a−1); 0.31 km2 (24%) glaciated area (0.007 km2 a−1); 0.015 km3 (32.60%) glaciated volume. The upward migration of SLA (Snow Line Altitude) from 5265 m to 5290 m also suggests that the melting process were prevailing during the study tenure. An existence of supra glacial lakes and its successive growth over the surface of Chorabari glacier further justifies that the temperature of the surroundings has increased significantly and influences the melting process as well. The melting process between 1976 and 1990 of the studied glacier directly influenced by the frequent episodes of precipitation and temperature anomalies of central Himalayan region during 1960–1990. While the melting process after 1990 is directly influenced by the increase in average mean temperature and decrease in average mean precipitation of Garhwal Himalayan region. The tree ring data of Garhwal Himalaya region also well matches the precipitation data of IMD (Indian Meteorological Department). The overall analysis explains that the Chorabari glacier is retreating continuously since 1976.

Late-Holocene climate response and glacial fluctuations revealed by the sediment record of the monsoon-dominated Chorabari Lake, Central Himalaya

We studied a periglacial lake situated in the monsoon-dominated Central Himalaya where an interplay of monsoonal precipitation and glacial fluctuations during the late Holocene is well preserved. A major catastrophe occurred on 16–17 June 2013, with heavy rains causing rupturing of the moraine-dammed Chorabari Lake located in the Mandakini basin, Central Himalaya, and exposed 8-m-thick section of the lacustrine strata. We reconstructed the late-Holocene climatic variability in the region using multi-parametric approach including magnetic, mineralogical and chemical (XRF) properties of sediments, paired with grain size and optically simulated luminescence (OSL) dating. The OSL chronology suggests that the lake was formed by a lateral moraine during the deglaciation phase of Chorabari Glacier between 4.2 and 3.9 ka and thereafter the lake deposited about 8-m-thick sediment sequence in the past 2.3 ka. The climatic reconstruction of the lake broadly represents the late-Holocene glacial chronology of the Central Himalaya coupled with many short-term climatic perturbations recorded at a peri-glacial lake setting. The major climatic phases inferred from the study suggests (1) a cold period between 260 BCE and 270 CE, (2) warmer conditions between 900 and 1260 CE for glacial recession and (3) glacial conditions between ~1370 and 1720 CE when the glacier gained volume probably during the ‘Little Ice Age’ (LIA). We suggest a high glacial sensitivity to climatic variability in the monsoon-dominated region of the Himalaya.

Topographic and climatic influence on seasonal snow cover: Implications for the hydrology of ungauged Himalayan basins, India

Himalayan glaciers exert considerable influence on basin hydrology and its response to climate change. Melt-runoff generated from ungauged Himalayan basins (UHB) requires an understanding of snow and ice cover extent along with prevailing meteorological conditions. Therefore, an estimation of seasonal snow cover distribution, topographic (elevation, aspect, and slope) and climatic variability was carried out using satellite data and meteorological observations from three automatic weather stations (AWSs) located at different elevations in an UHB (Chorabari Glacier). Results suggest that the topography and the meteorological conditions of the basin influence the dynamics of snow cover and the corresponding processes responsible for the melt-runoff generation. The snow cover area (SCA) has high variability in the elevation range of 3799–5000 m, indicating that as glacier ablation begins, SCA below this elevation primarily contributes to the melt-runoff. Likewise, the eastern aspect and the slopes (0–10° and 70–80°) show higher variability. Further, the annual distribution of air temperature gradients (dT/dZ) or temperature lapse rates (TLRs) exhibits a bimodal pattern. The mean annual TLR for the basin is 6.0 °C km−1, which is lower than the traditionally used adiabatic or environmental lapse rate (6.5 °C km−1). We also established the role of TLRs in the dynamics of SCA, which is an important parameter used for the computation of melt-runoff. The 0 °C isotherm established indicates that the elevation zone above 5000–5500 m has persistent snow cover throughout the year and snow cover below this zone contributes to the melt-runoff during the ablation season. Therefore, validating the equilibrium line altitude (ELA) of Chorabari Glacier lies within this zone. Since the TLR and SCA vary with space and time, our study in an ungauged glacierized basin of river Ganga could be useful for policymakers as well as other researchers working on the regional hydrology.

Hydrometeorological assessments and suspended sediment delivery from a central Himalayan glacier in the upper Ganga basin

Integrated hydrometeorological investigations are not frequently available at a regional scale over a longer time period, especially near the terminus of Indian Himalayan glaciers. An integrated approach to the collection of hydrological data has major advantages for understanding the runoff generation mechanisms at basin scale, particularly when coupled with meteorological observations. The current study involves time series analysis of hydrometeorological records collected near the terminus of the Chorabari Glacier, for four consecutive ablation seasons (June–Sept.) 2009–2012. The analysis shows that variation in rainfall was higher (cv = 0.9) at the same elevation over proximal sites, while the intensity of extreme rainfall events was 121–160 mm/d. The diurnal temperature range (DTR) has a tendency to reduce over the ablation season because of the onset of the Indian Summer Monsoon (ISM) and then further increases during the ISM withdrawal indicating humid-temperate conditions. The peak discharge (Qpeak) was found to be higher during July and August. Snow and glacier melt contributed 76% of the total suspended sediment transport during peak ISM months (July and August) reflecting seasonal evolution of the hydrologic conduits. The results indicate that Karakoram and western Himalayan glaciers produce comparatively low sediment yield compared to central Himalayan glaciers. The hydrological variations are depicted through flow duration curves (FDC) for meltwater discharge and sediment load. The flow corresponding to Q50, Q75, and Q90 (where Qx is the discharge that is exceeded x percent of the time referred to as % dependability) are 4.2, 3.7, and 2.8 m3/s; and the corresponding dependability for suspended sediment loads (SSLs) are 409.0, 266.0, and 157.2 t/d, respectively. The daily SSL and discharge (Q) from 2009 to 2012 were used to develop a sediment rating curve (SSL = 39.55 × Q1.588, R2 = 0.8). Multiple regressions are used to determine the impacts of meteorological parameters on glacier melt. The meteorological conditions, hydrological characteristics, and suspended sediment delivery for the Chorabari Glacier provide insight on meltwater generation processes and sediment transport patterns during the ISM season.

Modern pollen deposition in glacial settings in the Himalaya (India): abundance of Pinus pollen and its significance

ABSTRACTThirty-five surface sediment samples from three glacial sites – [Chorabari Glacier (Kedarnath), Hamtah and Chhatru glaciers (Lahaul-Spiti)] – situated in the western Himalaya, India, were palynologically analysed to explore the relationship between the modern pollen assemblages and the extant vegetation. The Chorabari Glacier is located in the Greater Himalaya and influenced by the Southwest Summer Monsoon; whereas the Hamtah and Chhatru glaciers are located in the Trans-Himalaya and affected more by the Western Disturbances (winter precipitation). The area around Chorabari Glacier receives abundant rainfall, while the Hamtah and Chhatru glaciers are in a high-altitude cold desert. Palynological studies have revealed an overwhelming dominance of Pinus pollen in all the samples. Though the sampling sites are 2 to 8 km away from the treeline and characterised by herbaceous ground vegetation, the marked predominance of arboreal pollen (especially Pinus) in the sediments stresses the importance of a proper interpretation of modern pollen data, so as to have an appropriate standard for deciphering the pollen–vegetation relationship in the respective study areas.

Tracing isotopic signatures (δD and δ18O) in precipitation and glacier melt over Chorabari Glacier–Hydroclimatic inferences for the Upper Ganga Basin (UGB), Garhwal Himalaya

Study regionChorabari Glacier in Upper Ganga Basin, Garhwal Himalaya. Study focusAuthors attempt to characterize the isotopic signatures in different components of the hydrological cycle and decipher the role of summer and winter precipitation on glacier melt using stable isotopes (δD, δ18O) coupled with existing hydrometeorological observations during the glacier ablation season (June–September) for the years 2011–2012. New hydrological insightsThe isotopic composition of various components of hydrological cycle i.e., precipitation (rainfall and snowfall), glacier surface ice and glacier melt have partly overlapping isotopic ranges. δ18O, δD and d–excess compositon indicates that precipitation during pre-monsoon (May/June) and post-monsoon (September/October) season have mixing of local moisture with that from westerlies. While during monsoon (June–September) rainfall-runoff contributes to the streamflow with snow and glacier melt. The depletion pattern of snow covered area (SCA) reflected by snow depletion curves (SDC) imply that most of the solid precipitation in the region results from westerlies, while during summers the precipitation from the Indian Summer Monsoon (ISM) is in the form of rainfall over higher altitudes. The isotopic depletion curve (IDC) of meltwater follows the trend of SDC’s. The backward wind trajectories for the precipitation events also indicate that the source of winter precipitation is from westerlies while summer precipitation is from ISM. Present day δ18O, δD and d–excess composition and their climatic interpretation are site and time specific.

Modelling of Meteorological Parameters for the Chorabari Glacier Valley, Central Himalaya, India

In the present study, we have developed empirical relationships to estimate meteorological parameters at the glacier altitude from the data on non-glacier altitude. Meteorological data collected from automatic weather station at Chorabari Glacier from November 2011 to May 2013 are analysed and empirical equations for air temperature, relative humidity and incoming global radiation are proposed. The dataset of one year (November 2011-October 2012) is used in the calibration of models, while data for the next seven months (November 2012-May 2013) are employed to validate the models. Moreover, an analytical study is also conducted on incoming diffuse radiation (estimated through the established model for India). Further, a relationship is established to correlate the diffuse component of two sites. Variation trend of meteorological parameters with altitude is found to be different for each of the parameters, viz. quadratic for air temperature, logarithmic for relative humidity, and linear for global and diffuse radiation. Performance of the generated equations is tested through various statistical methods. The study reveals that developed correlations are able to give a good match with in situ measurements.

Hazard assessment in rockfall-prone Himalayan slopes along National Highway-58, India: rating and simulation

A massive disaster occurred in June 2013 in Kedarnath, India, due to cloudburst and extremely heavy rain along the Chorabari glacier. The resulting flash floods further aggravated the instability of natural and hill cut slopes at different places on the downstream side. The village Rambara that existed in close proximity of Kedarnath was swept away under flow of debris and water. The immediate surrounding area, which housed over a hundred and fifty shops and hotels, was completely washed away leaving no trace of civilization. This calamity in Uttarakhand is considered as India’s worst natural disasters after the tsunami in December 2004. On the downstream of the affected areas lie other pilgrim destinations that witness innumerable footfalls every year. Investigation of the health of the slopes on the routes to these destinations is therefore very important to ensure minimal damage to humans and machinery. The Himalayan terrain is a tectonically active mountain belt, having a large number of unstable natural and road cut slopes. Such slopes with rugged topography lie in the high seismic vulnerability zone. Further, the instability is aggravated by natural and anthropogenic activities increasing at a rapid and uncontrollable rate. In the light of the Kedarnath tragedy, more advanced research is being conducted along the National Highways to monitor and prevent slope/structure failures. This study was conducted to evaluate the hazard potential along National Highway-58, near Saknidhar village of Devprayag district by analysing rockfall using hazard rating systems and numerical simulation. Rockfall hazard rating systems were applied to evaluate the conditions of the slopes and to identify the associated risks. Based on the field and laboratory analyses, the parameters required for numerical models were determined. The bounce height, roll-out distance, kinetic energy and speed of the detached blocks were determined by using a competent rockfall simulator. The results obtained were used to identify rockfall risk in the region. Optimization strategies were applied during investigation by modifying the slope angle, ditch width and ditch angle to assess the possibility of a hazard to occur in different scenarios. The simulation studies revealed that an increasing slope angle could significantly increase the kinetic energy of the rock blocks. However, an increase in the ditch angle and the ditch width reduces the energy of moving blocks. The maximum bounce height above the slope varied from 0.003 m to 0.8 m for 10-kg blocks, whereas the maximum velocity and the maximum kinetic energy under such circumstances were 7.882 m/s and 379.89 J, respectively. The barrier capacity was found to be 233.18 J for 10-kg falling blocks at a height of 10.02 m. From the optimization studies, it was found that the risk can be reduced by up to 13 % if the slope of 70° has a ditch angle of 15° while on a flat ditch, the maximum risk will be at an angle of 65°. If the ditch angle is increased, the vertical component of the falling blocks is more effective than that in case of a flat ditch. These optimization studies lay foundation for advanced research for mitigation of rockfall hazards in similar potential areas.

Hydroclimatic influence on particle size distribution of suspended sediments evacuated from debris-covered Chorabari Glacier, upper Mandakini catchment, central Himalaya

Sediments released from high altitude glaciers exhibit varying evacuation patterns and transport characteristics owing to the presence of thick debris cover over the glacier. Despite the recent needs for integrated hydrometeorological studies in the Himalaya, little is known about the impacts of suspended sediment on hydropower generation, reservoir sedimentation, and abrasion of turbine components. Present study involves analysis of particle size distribution of suspended sediments to understand sediment evacuation patterns and transport characteristics in variable energy conditions during the ablation season. Peak suspended sediments were evacuated during extreme rainfall events. The estimated seasonal modern sediment erosion rate varies from 0.6 to 2.3mmy−1 for the study period (2009–2012). The analysis shows dominance of medium silt-sized to fine sand-sized particles having sediment size of 0.0156–0.25mm corresponding to 70–80% without any significant seasonal variation. These transported sediments show that they are poorly sorted, coarser in nature with a nearly symmetrical to coarse skewed texture and kurtosis analysis suggesting mesokurtic distribution of sediments. The particle size fraction ranges between 4.65 and 5.23 ϕ, which is dominantly medium to coarse silty in texture. Results indicate that suspended sediments are evacuated in highly variable energy conditions through subglacial transport pathways because of increase in availability of meltwater with the progressive ablation season. Bulk geochemical characterization has been carried out to differentiate the source of suspended sediments and intensity of weathering. Chemical Index of Alterations (CIA) values of sediment flux range from 54.68 to 55.18 compared to the Upper Continental Crust (UCC) ~50, indicating moderate intensity of weathering. Mean seasonal (2009–2012) elemental fluxes and their contribution to the suspended sediment flux reflect that Si and Al are responsible for about 85% of the total detrital elemental flux. Trace elements show high concentrations of radioactive elements like U, Th, Pb, and Rb that suggest their high anomalous presence in the catchment lithology. An overall study indicates that the hydroclimatic conditions over the debris-covered glacier play a dominant controlling factor in erosion, transportation, and evacuation of suspended sediments during the ablation season.

Erratum to: Extended T-index models for glacier surface melting: a case study from Chorabari Glacier, Central Himalaya, India

Two enhanced temperature-index (T-index) models are proposed by incorporating meteorological parameters viz. relative humidity, wind speed and net radiation. The models are an attempt to explore different climatic variables other than temperature affecting glacier surface melting. Weather data were recorded at Chorabari Glacier using an automatic weather station during the summers of 2010 (July 10 to September 10) and 2012 (June 10 to October 25). The modelled surface melt is validated against the measured point surface melting at the snout. Performance of the developed models is evaluated by comparing with basic temperature-index model and is quantified through different efficiency criteria. The results suggest that proposed models yield considerable improvement in surface melt simulation. Consequently, the study reveals that glacier surface melt depends not only on temperature but also on weather parameters viz. relative humidity, wind speed and net radiation play a significant role in glacier surface melting. This approach provides a major improvement on basic temperature-index method and offers an alternative to energy balance model.

Extended T-index models for glacier surface melting: a case study from Chorabari Glacier, Central Himalaya, India

Extended T-index models for glacier surface melting: a case study from Chorabari Glacier, Central Himalaya, India

Monitoring of Glacier Changes and Response Time in Chorabari Glacier, Central Himalaya, Garhwal, India

Chorabari Glacier (6.6 sq. km) in the Mandakini River basin, a tributary of the River Alaknanda, Central Himalaya, Garhwal (India) has been monitored in terms of its length and frontal area (snout) changes for the period between 1962 and 2012. Global Positioning System, Survey of India toposheet (1 : 50,000) and ground-based measurements were used to obtain the changes in morphology and size of the glacier. The result shows that the frontal area of the glacier has shrunk by 1% and 344 ± 24 m length loss, with an average rate of 6.8 ± 0.5 m a -1 from 1962 to 2012. The observed terminus records of Chorabari Glacier indicate that the positive mass balance can cause terminus advance in about a 17-year timescale. The lag time of glacier signal transferred from accumulation area to the snout by glacier flow is about 562 years. These observations as well as other studies carried out in the region show a significant reduction in glacier area. The increased retreat rate of the glacier snout is probably a direct consequence of global warming.

Influence of debris cover on terminus retreat and mass changes of Chorabari Glacier, Garhwal region, central Himalaya, India

AbstractRecent studies of Himalayan glacier recession indicate that there is wide variability in terminus retreat rate and mass balance in the different sectors of the mountain range, primarily linked to the topography and climate of the region. Variable retreat rates of glacier termini and inadequate supporting field data (e.g. mass balance, ice thickness, velocity, etc.) in the Himalayan glaciers make it difficult to develop a coherent picture of climate change impacts. In this study, the results of a detailed mapping campaign and ground-based measurements of ablation rate, terminus retreat and ice loss are reported for the period 2003–10. In addition, background information from an old glacier map (Survey of India, 1962) was compiled and terminus recession measurements were carried out from 1990 field photographs of Chorabari Glacier, central Himalaya. Our ablation stake network results suggest that the influence of debris cover is significant for Chorabari Glacier mass balance and terminus retreat. The terminus survey finds that the glacier is retreating, but at a lower rate than many other non-debriscovered glaciers in the region. The recession and ablation data (particularly in the upper ablation area at higher altitudes) suggest that the ice volume loss of the glaciers is of greater magnitude than the slow terminus retreat and, if the process continues, the lowermost part of the glacier may reduce to a quasi-stationary position while significant ice loss continues.