Multivariate statistical analysis and geospatial approach for evaluating hydro-geochemical characteristics of meltwater from Shaune Garang glacier, Himachal Pradesh, India

The study focuses on the hydro-geochemistry of Shaune Garang glacier’s meltwater concerning glacial geomorphology. Seventy-nine water samples (53 in 2016 and 26 in 2017) of ablation season were analysed. The cations were dominant in the order Ca2+ > Mg2+ > Na+ > K+, and the anions in the order HCO3− > SO42− > Cl− > NO3−. The result demonstrated that HCO3− were the abundant ions, accounting for 41.03 and 34.84% of the total ionic budget (TZ). The high ionic proportions of (Ca2+ + Mg2+) versus TZ+ and (Ca2+ + Mg2+) versus (Na+ + K+) were identified as the primary factors influencing dissolved ion chemistry in meltwater. Piper diagram shows that Ca2+–HCO3– type water is the most common, followed by Mg2+–HCO3–. In addition, a remote sensing approach has been used to find the possible source of the chemical constituents in the meltwater. The catchment geology has been mapped on various scales, including diverse rocks and unconsolidated surface materials containing “quartz and carbonate minerals”. Layered silicates (LS) and “hydroxyl-bearing minerals” are not as common as they used to be, but their availability varies greatly in the area where they are found. The distribution of LS minerals within the catchment are majorly found at lower altitudes, which implies the weathering mechanism due to the interaction of meltwater and parental rock. Multivariate analysis revealed that CO3 and SiO2 weathering, sulphate dissolution, and pyrite oxidation dominate dissolved ion concentrations. Chemometric analysis of meltwater hydro-geochemistry through principal component analysis explains 72.1% of the total variance of four PCs. PCs 1, 2, 3, and 4 explain 39.21%, 12.91%, 10.24%, and 9.74% of variance, respectively, in 2016. Similarly, in 2017, four PCs explain 69.91% of the total variance. PC 1, 2, 3, and 4 can explain 26.62%, 20.12%, 12.64%, and 10.52% of variance.


Introduction
The Hindu Kush Himalayan Mountain ranges and the Tibetan Plateau extend across several Asian countries (Bolch et al. 2012) and are recognized as the cryospheric region beyond the polar latitudes (Bolch et al. 2019;Wood et al. 2020). The Hindu Kush Himalayas, the source of many essential river systems in Asia, are the highest mountain range (Kaser et al. 2010;Singh et al. 2020;Immerzeel et al. 2020), which provide a source of livelihood for millions of people living in this region. The Hindu Kush Himalaya, also known as the "Third Pole" and the "water tower of Asia", provides ecosystem services, particularly water, the lifeblood of all organisms. The ecosystem services produced in the region provide support for 240 million people who 1 3 live in the hills and mountains and approximately 1.7 billion people who live downstream in the major river basins. The increasing metropolitan infrastructure in the Himalayan region in the last three decades has put additional strain on the region's limited water resources (Tiwari et al. 2018). Other than natural forces, the primary causal variables in the Himalayas include extraordinary urbanization, increasing tourism, shifting land-use patterns, garbage disposal, and agricultural runoff which are all factors to consider (Thakur et al. 2019;Kumar et al. 2019c). Snow/glaciers meltwater is a vital water source for domestic use in the higher Himalayas. At the same time, it is essential for irrigation, industrial use, and hydroelectric power generation for the downstream population (Singh et al. 2008). When the other water sources are low in supply, the glacier discharge plays a more prominent role in sustaining the demand Singh et al. 2022). The meltwater drains from the glaciers meet the various soil particles and are subsequently influenced by the various mineral components. According to recent research, climate and land-use/cover changes caused by human endeavours significantly impact the chemical composition of Himalayan freshwater (Pant et al. 2021a, b;Thapa et al. 2020). Hydro-geochemical characterization of the glacier meltwater varies between glaciers due to differential lithology (Collins 1979). When it comes to glacier meltwater chemistry and, consequently, the quality of meltwater, the geology of the catchment is one of the most important factors to consider. Such studies also improve our understanding of the interactions of meltwater with the underlying geological strata and provide insights into the hydro-climatic regime of a region. There is a need to conduct more research in these areas to create a robust database to determine hydrochemistry confidently. The widely varying geology makes the hydro-chemical study of Himalayan glaciers even more exciting. Earlier studies on the chemistry of the major ions in the Himalayas engrossed in recognizing chemical input in glacial meltwater. Various studies of Himalayan glaciers have suggested that water transients over sub-glacial waterways encounter rock substrate experiencing a significant chemical change in meltwater . Some studies specify that the high degree of differential erosion in Himalayan glaciated areas is the consequence of the long interaction time of meltwater through bedrock (Haritashya et al. 2010;Singh et al. 2015). Investigating hydrochemistry in the Himalayas is highly important, and several researchers (Haritashya et al. 2010;Singh et al. 2015;Kumar et al. 2019a, b, c) have contributed to this regard.
All the previous studies in the Himalayan region on water chemistry have focused only on the chemical characterization of meltwater from glaciers. Documentation of such investigations substantially allows precise lithological mapping and erosion rate estimation in these high-mountain areas. This helps in understanding large-scale links between glacio-hydrology and geochemistry. Considering possible sources and their differential erosion rates can give us a better idea about the possible future trajectory of meltwater chemistry in these high-mountain catchments. Photogrammetry, high-resolution terrain modelling and hyperspectral imaging are used in lithological mapping and estimation of erosion rates in high mountains. Further, it helps establish large-scale links between glacio-hydrology and geochemistry on a global scale.
In the present study, the remote sensing approach has been used to identify chemical species' sources of origin in meltwater through the catchment scale lithological mapping, mineral detection, and many other perspectives. Also, ASTER-SWIR data were used to delineate types of rocks in the Shaune Garang catchment to interpret and measure minerals and the geochemical composition of debris on the glacial surfaces. This study validates several features of ASTER (SWIR and TIR) data and their processing techniques; analysis has been used to map several minerals containing indices. These exploration approaches are suitable for low-cost identification and mapping of minerals containing indices such as layered silicates (LS), calcite (CA), hydroxyl-bearing (OH), alunite (AL) on the SWIR band and carbonate, quartz, and mafic index on TIR band in ASTER data. In this research, we focus on identifying: (1) major ion concentrations, chemical characteristics, and their variability; (2) hydro-geochemical processes and solute sources during the study period; and (3) lithological mapping of the Shaune Garang catchment. Hence, the results of this study enrich the catchment findings in terms of glacio-hydrology and geochemistry. Furthermore, this would be a significant step towards a more precise interpretation of weathering and hydrological processes in the catchment. This research includes applying various chemometric analyses such as principal component analysis (PCA) and factor analysis to understand better the dominant weathering process in the Shaune Garang catchment.

Study area
The hydro-geochemical analysis has been performed in the Shaune Garang glacier catchment, located in Himachal Pradesh. The glacial meltwater of this catchment merges to the Baspa River, a stream of the Sutlej River and finally joins the Indus River system. The study area is shown in Fig. 1, where locations of the instruments like the Automatic Weather Station (AWS) discharge gauge have also been shown. The watershed and glaciated area in the catchment have also been presented along with the contour map. This catchment receives precipitation from the winter westerlies and the monsoon in summer (Singh et al. 2018), but summer precipitation 1 3 dominates winter precipitation. The winter precipitation in this region is received through the Western Disturbance (WD) (Dimri 2004). This region experiences ablation from May to September . It covers an area of 38.13 km 2 above the discharge site. The hypsometric distribution of the catchment is shown in Fig. 2.  Hypsometry distribution clearly shows that 75% of the catchment has a non-glaciated area, while 25% is glaciated. In the glaciated area, the debris-covered glacier has its share of 5%, while the debris-free glacier has 20%. The rocks of this region resemble the Higher Himalayan Crystalline. It contains pelitic and psammopelitic meta-sediments having acid and basic intrusive. Granite and gneiss rocks in the Himalayan region have a familiar presence of late-stage pegmatitic veins feldspar (Kumar et al. 1987). Rohtang gneiss is the principal constituent of the Himalayan glaciers. Chalcopyrites' presence is also noticed in lateral morainic deposits of the Himalayas. The morphology of the Shaune Garang catchment describing the area vs aspect and area vs slope is shown in Fig. 3. The aspect ratio suggests that most of the part of the catchment falls in the east and south, southwest and west direction and receives higher solar insolation, making it prone to weathering. Further, the primary area falls in the middle slope zone of 24° to 40° and the higher slope zone 40° to 56°, which transfers the weathered materials very quickly to the glacier.

Sampling and analysis protocol
In the higher Himalayas, the physical accessibility is limited to the summer season. Water samplings were performed during the summer seasons of 2016 and 2017 at the selected locations of the channel (Fig. 1). Selected cations and anions of glacial meltwater were examined in 2016 and 2017. Fiftythree water samples in 2016 and 26 water samples in 2017 were collected during ablation season. The sampling sites were chosen as per the geology, altitude, terrain, and convergence of tributaries. Polyethylene sample bottles (250 ml) were rinsed with distilled water after being cleaned with nitric acid for accuracy in data. Water samples were taken from 20 cm deep to have a well-mixed concentration. Sampled glacial meltwater was filtered on 0.45 µm Whatman filter paper. The conductivity and pH measurements have been performed in the field by a handheld multi-parameter instrument (HANNA, model No. HI9829). The essential cations (Ca 2+ , Mg 2+ , K + , and Na + ) analyses were performed using atomic absorption spectroscopy. The instrument has a precession of 0.05 parts per million (ppm) for Ca 2+ , Mg 2+ , K + , Na + , and 0.01 parts per million (ppm) for the remaining parameters. Ion chromatography was used to analyse the anions (Cl − , SO 4 2− , and NO 3 − ). The bicarbonate concentration was based on the results of the titration method (APHA 2005) and the charge balance method. The precautions were made as per the specified norms, and we used non-powder vinyl cleanroom gloves and masks for sampling and analysis. A new standard of identified concentration and procedural blank was analysed for every analytical run. During the investigation, no detectable contamination was obtained. The data from physio-chemical analysis of the meltwater samples were subjected to multivariate statistical analysis. The study used multivariate statistical tests to examine relationships among multiple variables in the data set. Excel add-on XLSTAT was used for the analysis of normalized data under PCA. Bartlett's sphericity test was applied to both years' melting season data, and a correlation matrix was prepared. The principal component analysis has been analysed to understand problems under different measurement scales of the original variable, which is avoided by diagonalizing the correlation matrix. The dissolved ions composition of the meltwater from Shaune Garang glacier were subjected for the error analysis in the charge balance, which has been computed through the given formula: where (TZ + ) = total cations and (TZ − ) = total anions.
The errors of TZ + and TZ − were < 10% for two consecutive melting periods (2016 and 2017), which is indicative of the good quality of data.

Remote sensing data and characteristics
Air temperature of glacier surface was measured in ablation season (June to October) during the study period. Satellite data have been validated by the ground-based temperature records of snow, ice, and debris-covered glacier at twenty sites during the satellite passes at 10:30 AM over the study area. ASTER data were used in this investigation to obtain lithological and mineralogical evidence from the Shaune Garang catchment. A subset of the high-resolution and cloud-free images (ASTER) were used throughout the study to determine the precise lithological mapping of the exposed rock present in the catchment. The imagery of nine bands was used in this study, with band-1 being blue (0.43-0.45 µm), band-2 being blue (0.45-0.51 µm), band-3 being green (0.53-0.59 µm), band-4 being red (0.64-0.67 µm), band-5 being near-infrared (0.85-0.88 µm), band-6 being shortwave infrared (1.57-1.65 m), band-7 being shortwave infrared (2.11-2.29 µm), band-8 being panchromatic (0.50-0.68 µm), and band-9 being cirus (1.36-1.38 µm). Respective bandwidths and subsystems characteristics are presented in Table 1.

Hydro-geochemistry of glacial meltwater
The physical analysis of meltwater indicates a little alkaline with pH ranging from 6.86 to 8.56 with an average value of 7.45 ± 0.48 and 7.45 ± 0.45 for 2016 and 2017, respectively (Table 2). Higher pH indicates that the process of dissolution is higher due to the more considerable contact period with rock, soil, and rainwater. These would have imparted alkalinity to the meltwater (Kumar et al. 2014). Electrical conductivity indirectly measures the mineralization that explains the ionic strength of water (Kumar et al. 2019a, b). The standard value of electrical conductivity was 86.14 ± 16.96 μS/cm in 2016 and 91.25 ± 16.62 μS/cm in 2017. The higher EC must result from the weathering, evaporation, and crystallization  processes. Furthermore, the lesser conductivity in glacier discharge is influenced by increased precipitation making higher discharge and decreased influence of the evaporite dissolution process. The measured value of EC suggests that hydrochemistry of location is regulated through the interface of water and rock and depends on the weathering of rocks. Different rocks and their solubility influence the proportional concentration of ions in glacial meltwater (Pant et al. 2021a, b). Table 2 displays the distribution of dissolved ionic concentrations with standard deviation in the meltwater discharge of the Shaune Garang glacier. The results presented in Table 2 indicate that Ca 2+ contributes 39.57% and 42.53% in the total cationic budget in both the consecutive study periods 2016 and 2017. However, Ca 2+ + Mg 2+ contributes 82.10% and 71.02% of the total cationic budget in the catchment. The other two cations, Na + and K + , contribute only 16.78% and 17.57%, respectively, during the study period 2016 and 2017. Bicarbonate (HCO 3 − ) is the most dominant anion contributing 62.18% and 54.44%, respectively, in the total anionic budget of the ablation period of 2016 and 2017. Its average concentration was observed as 369.65 ± 79.41 µeq/l, and 316.73 ± 83.23 µeq/l in the consecutive study period. Sulphate (31.10% and 38.11%) was the second most dominant anion, followed by chloride (5.58% and 6.64%) and nitrate (1.18% and 0.79%) during consecutive years' observation. The dominance of bicarbonate in Shaune Garang catchment is due to the silicate dominating geomorphology of the catchment. According to the findings, weathering of silicate minerals is less visible than carbonate minerals. Figure 4 displays the concentration of different anions and cations and electrical conductivity for the glacier's meltwater at different parts of the Indian Himalaya. The concentration of cations and anions varies as per the morphology of rocks in the catchments and weather system. Meltwater draining from the Himalayan region shows the dominance of Ca 2+ and HCO 3 − , whereas Bagni, Chaturangi, Gangotri, and Dudu glaciers demonstrate the dominance of SO 4 2− in their catchment. The dominating presence of silicate-bearing rocks is the important factor for the higher concentration of bicarbonate (HCO 3 − ) in the meltwater of the Himalayan glacier. In addition, the dominancy of SO 4 2− in the Bagni, Chaturangi, Gangotri and Dudu glaciers could be due to pyrite oxidation that enhances sulphate concentration. Cl − and SO 4 2− ' domination is influenced by halite and sulphide oxidation and weathering of soft sulphate minerals such as gypsum (Thomas et al. 2015). The chemical composition analysis reflects the dominance of bicarbonate (HCO 3 − ) as an anion in most of the glacial meltwater in the Himalayan region due to the dissolution of atmospheric carbon dioxide and carbonate (Sharma et al. 2013a, b;Kumar et al. 2014;Singh et al. 2015). Concentration of cations in the meltwater of Dokriani, Bara Shigri, and Gangotri glaciers follows a trend like Ca 2+ > Mg 2+ > K + > Na + , while it follows Fig. 4 Average hydro-geochemical characteristics of glacial meltwater from Shaune Garang glacier and its comparison with the other Himalayan glaciers a trend of Ca 2+ > Mg 2+ > Na + > K + for meltwater of Kafni and Chhota Shigri, the only alteration in the concentration of Na + and K + for different basins. However, the Bagni glacier meltwater showed the potassium ion as the second most abundant. In the Bara Shigri glacier, meltwater concentration of cations varied as Ca 2+ > Mg 2+ > Na + > K + like the Chhota Shigri of its vicinity and the Kafni of Kumaun Himalaya, whereas anions concentration followed the pattern of HCO 3 − > SO 4 2− > NO 3 − . It has been observed from the comparative analysis in Fig. 4 that the central Indian Himalayan glacier's meltwater has the highest concentration of Ca 2+ cation, and a similar observation is from the present study. Interestingly, the graph shows a higher concentration of anions and cations in discharge from glaciers located in the central part of the Indian Himalayan region than the glaciers in the western part.

Hydro-geochemical process in the glacial catchment
Dissolved ions in the glacial meltwater are generally contributed through rock weathering, precipitation, anthropogenic influence, and atmospheric conditions (Jeelani 2011;Kumar et al. 2019a, b, c). Generally, the chemical composition of glacial meltwater is governed by the chemical weathering between the interaction of water and bedrock beneath the glacier (Kumar et al. 2009(Kumar et al. , 2014. The cation and anion in the glacier discharge are elucidated concerning the nature of rock and its weathering processes. Dissolved solute particles present in the glacial melt are determined by the processes involved in the glacial environment. The interrelationship between the physical and chemical parameters is presented through a scatter plot (Fig. 5) of (Ca 2+ + Mg 2+ ) and (Na + + K + ) against total cation (TZ + ). A positive correlation is observed between (Ca 2+ + Mg 2+ ) and TZ + . It further shows a ratio ranging from 0.75 to 0.85 with an average equivalent value of 0.75 ± 0.05 during the study period.
The result demonstrates that the impact of Ca 2+ + Mg 2+ in the glacial meltwater is comparatively high compared to the total cation TZ + . The ratio of Ca 2+ and Mg 2+ determines the input source of calcium and magnesium ions in water. Ca 2+ /Mg 2+ ≤ 1 (Table 3) indicates a process of dolomite dissolution, and a value > 1 recommends the dominance of silicate weathering in water (Kumar and Singh 2015). As a result, silicate weathering could be a factor in the dominant concentration of Ca 2+ and Mg 2+ among cations in the Shaune Garang glacial discharge. The scatter plot (Fig. 5) among Na + + K + and TZ + displays a small contribution of Na + + K + in total dissolved ion with 0.24 ± 0.04 and 0.25 ± 0.08 during both ablation years. The results reveal carbonate weathering as a leading factor in the glacial meltwater ionic characteristics of the Shaune Garang catchment. The large equivalent ratios 3.23 ± 0.75 and 3.28 ± 1.14 for (Ca 2+ + Mg 2+ )/(Na + + K + ) in the consecutive melting period of 2016 and 2017 further strengthen the understanding of carbonate weathering dominance in the catchment. High ratio of (Ca 2+ + Mg 2+ )/(Na + + K + ) and (Ca 2+ + Mg 2+ )/TZ + in the glacial meltwater demonstrate that hydro-geochemistry of the meltwater of Shaune Garang catchment is mainly administrated by CO 3 weathering with a minor contribution of SiO 2 . However, the evaporation process enhances the TDS concentration in water (Prasanna et al. 2010;Xing et al. 2013). The average ratio of Na + /Cl − was measured to be 4.77 ± 2.27 and 3.83 ± 1.90 in 2016 and 2017 (Table 3). The Na + /Cl − ratio indicates a minor contribution of atmospheric constituents in the chemical characterization of meltwater of the catchment.
The ion exchange process in the water is mainly defined because of (Ca 2+ + Mg 2+ ) versus (HCO 3 − + SO 4 2− ) (Srinivasamoorthy et al. 2008). Dominant dissolution process Fig. 5 Scatter plot of (Ca 2+ + Mg 2+ ) against TZ + and (Na + + K + ) against total cation (TZ + ) during the study period of 2016 and 2017 from Shaune Garang glacier catchment 1 3 of calcite, dolomite, and gypsum ion exchange may shift the points rightward owing to excess of (HCO 3 − + SO 4 2− ). Further, the reverse ion exchange process turns leftward due to a surplus (Ca 2+ + Mg 2+ ). (Ca 2+ + Mg 2+ ) versus (HCO 3 − + SO 4 2− ) indicates carbonate and silicate weathering with ion exchange as leading geochemical processes in the catchment (Fig. 6). The diagram displays that contribution of (HCO 3 − + SO 4 2− ) to the total ionic concentration in the glacial meltwater is greater than the (Ca 2+ + Mg 2+ ), indicating an excess of (HCO 3 − + SO 4 2− ) which is contributed by silicate weathering. The dominance of calcium and magnesium ions is calculated through Ca 2+ /Na + and Mg 2+ /Na + ratios, a product of weathering of CO 3 and SiO 2 . The Ca 2+ / Na + ratio was observed as 2.57 ± 0.80 and 2.64 ± 1.06, while Mg 2+ /Na + was, respectively, 2.16 ± 0.67 and 2.07 ± 0.81 in the meltwater of Shaune Garang glacier (Table 3). This ratio shows the dominance of Ca 2+ and Mg 2+ over Na + . The result further confirms that hydro-geochemistry is governed by weathering of CO 3 minerals in the catchment. Hydrogen ion availability is responsible for rapid CO 3 weathering (Das and Kaur 2001). Na + normalizes Ca 2+ and HCO 3 − concentration and determines the effect of SiO 2 weathering, evaporative dissolution or CO 3 weathering in meltwater (Kumar et al. 2015). To understand the chemical weathering, sulphate mass fraction (SMF) and the ratio of sulphate (SO 4 2− ) to (SO 4 2− + HCO 3 − ) have been calculated in the study catchment. The chemical characteristics of meltwater show the importance of carbonation if the SMF value is (< 0.5). The SMF value indicates the chemical attributes of meltwater affected by sulphide oxidation and the termination of CO 3 (Tranter et al. 1993). In the Shaune Garang catchment, an average SMF value of 0.33 ± 0.07 and 0.41 ± 0.09, respectively, during the study period 2016 and 2017 indicates the dissolution of carbonate and sulphide oxidation. In addition, ) has also been calculated to find the significance of proton-producing effects necessary for the chemical weathering of carbonate rocks. During 2016 and 2017, the C-ratios were 0.67 ± 0.07 and 0.59 ± 0.09, demonstrating the domination of the carbonate and sulphate weathering processes.

Mineral mapping
The short-wavelength infrared (SWIR) and thermal infrared (TIR) spectral resolution agree for mapping surface mineralogy. These spectral bands are available in (ASTER) and have been used to map the distribution of minerals on supraglacial debris. Minerals are mapped through the band indices like "SWIR indices", "TIR indices", and "TIR emissivity silica weight per cent" in the Shaune Garang catchment. The mineral measurement reflects the primary presence of quartz, feldspar, carbonate, and mica. High-altitude glacier debris reflected the fact of "quartz, feldspar as calcium albite, and mica as biotite". The debris on the Shaune Garang glacier is dominated by muscovite (mica), calcium albite (feldspar), and quartz. Though in lesser quantity, the presence of calcite has also been noticed. To create thematic mineral abundance maps and quantitative estimation of minerals, "SWIR and TIR indices" have also been used (Ninomiya 2004).

SWIR indices
Short-wavelength infrared (SWIR) mineral indices were used to wavelength-dependent absorption patterns in estimating minerals in the catchment. The SWIR mineral indices were used to evaluate the mineral's dominance in the catchment. Equations (2), (3), (4), and (5) have been used, respectively, for understanding the dominance of layered silicate (LS), calcite (CA), hydroxyl-bearing (OH), and alunite (AL): where ASTn is band number (n) related to ASTER.
The varying indices are related to the variable absorption properties, which helps measure the types of minerals. A sensor, "radiance band ratios", can reduce the influence of the atmosphere and the topography of a region and the variation in illuminance (Abrams et al. 1983;Mather 1987). The evidence also indicates the nonsignificant evidence in "single band or three-band true or false colour composite imageries". It is also helpful in having the quantitative estimation of mineral abundances. In this study, images of the 4-shortwave infrared (SWIR) mineral indices are shown in Fig. 7, reflecting the relative dominance of minerals and their presence on the surface. Alunite has been most dominant and abundant in higher altitudes up to the accumulation zone. "Layered silicates" and "hydroxyl-bearing minerals" are less productive, while "calcite and hydroxyl-bearing minerals" vary location-wise. Alunite index displays little white patches in the higher region with high abundance. Figure 7 shows kinematics and pulse flow movements of layered silicate debris, which can be understood through their variability and abundance. The evidence of alunite at a higher altitude might be due to its formation mechanism. The formation of Alunite through the reaction of sulfuric acids with potassium-rich feldspars is called "alunitization". Layered silicates and "hydroxyl-bearing minerals" are in short supply, but "calcite and hydroxyl-bearing" minerals vary significantly within the catchment. Layered silicate consists of octahedral layers bound to the tetrahedral and primary component of soil. Its distribution within the catchment at lower altitudes implies the weathering mechanism due to meltwater and parental rock interaction. They have been the excellent water trapping mechanism held between layers. The essential minerals in layered silicates are kaolinite, nacrite, and dickite.

TIR indices
To evaluate various minerals in the Shaune Garang catchment area, thermal infrared (TIR) mineral indices of carbonate, quartz, and mafic were used. The thermal spectrum is instrumental in distinguishing the geology of earthy minerals, where TIR satellite spatial resolution is noticeably lesser than VNIR or SWIR (VNIR 15 m, SWIR 30 m, TIR 90 m). However, TIR is exclusive in targeting the profusion of carbonate, quartz, and silicate minerals. Band ratios derived from TIR estimate carbonate, quartz, and silica bearing lithology (Fig. 8). Equations (6), (7), and (8) were used for carbonate index (CI), quartz index (QI), and mafic index (MI), respectively: where "ASTn" is band number (n) based on the properties of ASTER spectral. The CI is better used to detect primary carbonate minerals such as "calcite and dolomite". These two carbonates mineral have higher absorption features, which indicates the availability of calcite and dolomite. The absorption features of calcite are about 11.4 to 11.2 μm in the case of dolomite minerals. Minerals of carbonates with "hydrothermal origin" are very challenging to identify through a CI map due to an inadequate percentage of carbonate presence. However, calcite-bearing propylitic alteration is accredited as the "ASTER TIR" feature. The chlorite and epidote had lower emissivity between TIR bands 11 and 13 but slightly higher between 13 and 14 (Salisbury et al. 1992). Aspects of the spectrum with these characteristics resemble the mafic index minerals. Mafic and quartz index minerals found uneven distribution within the catchment, but carbonate minerals were found at lower altitudes along the riverside. The reason behind the occurrence of carbonate minerals along river channels might be due to the higher weathering across the river.

Principal component and factor analysis
Excel add-on XLSTAT was used for the analysis of normalized data under PCA. The sphericity test of Bartlett was performed on the data of both years. The Bartlett sphericity test shows that observed χ 2 (342.85) is considerably more significant than the critical χ 2 (85.96) in 2016 and χ 2 (observed) = 125.25 larger than the critical value χ 2 (critical) = 48.3 in 2017. The principal component analysis helped to understand problems under different measurement scales of the original variable avoided by diagonalizing the correlation matrix. Table 4 demonstrates the PC value of more than 1, which explains 72.1% of the total variance of four PCs. PCs 1, 2, 3, and 4 are capable of explaining 39.21%, 12.91%, 10.24%, and 9.74% of variance in 2016. Similarly, in 2017, scree plot ( Fig. 9) shows four PCs, which explains 69.91% of the total variance. PC 1, 2, 3, and 4 can explain 26.62%, 20.12%, 12.64%, and 10.52% of variance. Table 4 further depicts the eigenvalues, the percentage of variance calculated through varimax rotation matrix with Kaiser normalization and rotated factor, and the percentage of variance in each PC. High SO 4 2− and K + loadings are observed in both the years, indicating silicate weathering dominance in the catchment. Moderately high loading values of Ca 2+ , Mg 2+ , and Na + in both years indicate the dominance of the process, which is prevailing in factor 1. Table 5 indicates that factor 4 shows the negative pH in both the years and the acceptable value of Cl − in the consecutive study period. The first two principal component loading are presented to understand the grouping and relationship of all chemical parameters. The PC loading has been calculated to understand correlations among variables and know the most influential variables. It could result from the minerals present in the soil (Yakubo et al. 2009). Throughout the study, higher loadings in Na + and Mg 2+ may be accredited to the ionic conversation between water through dissolution minerals containing sodium.
Statistically, the coefficient of determination (R 2 ) indicates one variable's level of statistical agreement with another. Here, it is applied among the hydro-geochemical parameters and represented in Table 6 during the study period. Water chemistry parameters such as EC and Na + are highly interrelated with Ca 2+ , Mg 2+ , and HCO 3 − . Similarly, a decent relationship among (Ca 2+ -Mg 2+ ), (Ca 2+ -HCO 3 − ), and (Mg 2+ -HCO 3 − ) has been observed. The above parameters have a good positive correlation (R 2 > 0.50) and are an indicator of control by these parameters in the solute chemistry of the study region. The correlation values greater than 0.50 has been marked bold in the Table 6 to demarcate easily. The strong correlation between parameters such as Ca 2+ , Mg 2+ , (Ca 2+ -HCO 3 − ), (Mg 2+ -HCO 3 − ) indicates strong carbonate weathering ). In the case of sulphate (SO 4 2− ) ion concentration, it shows a good relationship with Ca 2+ and Mg 2+ , indicating the sulphate mineral's high dissolution in the glacier's catchment.

Hydro-geochemical facies of the glacial meltwater
Hydro-geochemical facies of the meltwater helps interpret the dominant anions and cations, which have been determined through a Piper plot (Fig. 10). It is used to find similarities and dissimilarities among all water types, where the analogous water qualities fall together (Todd 2001). In the cation plot, it can be seen that most of the water is concentrated in a trilinear pattern in the middle, indicating that it is a mixed water type. The calcium ions predominate in the glacial discharge. The hydro-geochemical cations in the bottom left triangle of Shaune Garang glacial discharge prove calcium ions' dominance. It substantiates the conclusions reached in the sections on hydro-geochemistry and hydro-geochemical processes, both included in the previous section. Slightly elevated sodium and potassium ion concentrations in several samples confirm the presence of sources at the various sampling locations of the Shaune Garang catchment. This must be contributing to the overall cation concentration (Karim and Veizer 2000;Ravikumar 2017). The Piper plot aids in the understanding of the fact, Ca 2+ , Mg 2+ , and HCO 3 − are the most prevalent ions in the Shaune Garang catchment. The average percentage value  of (Ca 2+ + Mg 2+ ) is about 77% and 81%, respectively, in the years 2016 and 2017; however, for the (Na + + K + ), it showed about 33% and 29%, respectively, demonstrating that alkaline earth metals are prevailing over alkali metals . It further supports the dominance of dolomitic limestone containing gypsum and pyrite in the region (Figs. 7 and 8). The piper diagram demonstrates that carbonate-type weathering has been more instrumental in governing hydro-geochemistry in this catchment. The figure indicates the presence of the (Ca 2+ -HCO 3 − ) type of water with little influence from (Ca 2+ -SO 4 2− ) type. Significant ions and TDS were found in higher concentrations in this catchment, indicating more significant interactive processes between rock materials and water having influential weathering due to moisture.
Apart from the Piper plot, Gibb's diagram (Gibbs 1970) was applied to understand how hydro-geochemical techniques such as precipitation, rock-water interface, and vaporization impact the environment's hydrogeology. According to the Gibbs diagram (Fig. 11), the chemical weathering of rock minerals and a minimal extent of evaporation crystallization are the essential variables to consider the meltwater quality in the Shaune Garang catchment. Gibb's diagram advocates the higher rock-water interaction resulting in higher ionic concentration in meltwater. Chemical weathering, carbonate dissolution, and ionic exchange between water and clay indicate the rock-water interaction processes (Kumar et al. 2014). Increased evaporation, chemical weathering and anthropogenetic actions raise the total dissolved solids. Furthermore, the findings show that water contamination from poor sanitation has increased Na + and Cl − ions and increased total dissolved solids (TDS) (Kumar et al. 2014).

Conclusion
The current study focused on the hydro-chemical analysis of meltwater from the Shaune Garang catchment, located within the Baspa Basin. According to the findings, meltwater is slightly alkaline with Ca 2+ and HCO 3 − the most prevalent ions during the study. Ca 2+ and Mg 2+ were the dominant cations constituting (41.03%, 42.53%) and (34.84%, 32.89%) of the total cationic budget in the consecutive study period. The predominance of carbonate weathering is indicated by the ratio of (Ca 2+ + Mg 2+ )/(Na + + K + ) and (Ca 2+ + Mg 2+ )/(TZ + ) and a strong positive association between Ca 2+ -Mg 2+ , Ca 2+ -HCO 3 − , and Mg 2+ -HCO 3 − . Piper plot demonstrated that alkaline earth metal dominates alkali metal, and weak acid exceeds strong acid. This plot also indicated that the Ca 2+ -HCO 3 − is most influential, assessed by Mg 2+ -HCO 3 − type of water in this area. The Gibbs plot also revealed that rock corrosion is the primary process regulating meltwater concentration. The values in the chloro-alkaline indices in this study were negative, indicating the conversation of Ca 2+ and Mg 2+ ions by Na + and K + ions of rock material. The geological mapping of the catchment has been done on varying scales, including diversified rocks and unconsolidated surface materials that possess "quartz and carbonate minerals". The results were verified through the geological, stratigraphic, and structural maps in the multifaceted lithological terrain of the region. Based on the lithological map of the Shaune Garang catchment, layered silicates and "hydroxyl-bearing minerals" are less abundant. However, "calcite and hydroxyl-bearing minerals" have significantly varying availability in the catchment. The distribution of layered silicate minerals within the catchment is majorly found at lower altitudes, which implies the weathering mechanism due to the interaction of meltwater and parental rock. The chemometric analysis includes a principal component (PC), eigenvalues, the percentage of variance calculated through varimax rotation matrix with Kaiser normalization and rotated factor, and the percentage of variance in each PC. High SO 4 2− and K + loadings are observed in both years, indicating silicate weathering dominance in the catchment. Moderately high loading values of Ca 2+ , Mg 2+ , and Na + in both years indicate the dominance of the process, which is prevailing in factor 1. The strong correlation between parameters such as Ca 2+ , Mg 2+ , (Ca 2+ -HCO 3 − ), (Mg 2+ -HCO 3 − ) indicates intense carbonate weathering ). In the case of sulphate (SO 4 2− ) ion concentration, it shows a good relationship with Ca 2+ and Mg 2+ , indicating the sulphate mineral's high dissolution in the glacier's catchment.