NW Himalaya Research Articles

Assessment of soil erosion using WSA and SPR techniques for Giri watershed, Himachal Pradesh, NW Himalaya, India

A watershed is the result of several geomorphic processes such as weathering, erosion, degradation and aggradation which are influenced by several factors viz. tectonics, lithology, climate, landslides and mass wasting processes etc. In a tropical climate, watersheds contribute a significant amount of eroded material which is reflecting the impact of lithology, precipitation, tectonics, relief and anthropogenic activities. In the Himalayan region besides significant heterogeneity in lithology, stratigraphy, structure and tectonics, it is observed that variability is exhibited in climatic conditions over a small region. These factors contribute to the development of geomorphic landforms and are best studied in watersheds or river basins. In the present study, Giri Watershed (GW) is assessed to contemplate susceptibility to erosion for 66 sub-watersheds using geomorphic parameters. The prioritization of subwatersheds has been done using Weighted Sum Analysis (WSA) and Sediment Production Rate (SPR) methods. The quantitative analysis of subwatersheds is categorized into different priority classes viz. very high, high, moderate, low and very low, among which 27 subwatersheds have very high to high susceptibility to erosion.

Impact of potential flood on riverbanks in extreme hydro-climatic events, NW Himalaya

Impact of potential flood on riverbanks in extreme hydro-climatic events, NW Himalaya

Last Glacial Maximum and subsequent glacial chronology in the monsoon-dominated Sikkim Himalaya, India

The study investigates sequential evolution of glacial-landforms in relation to paleo-climate by establishing glacial chronology in Zemu and East-Rathong Glaciers valleys, Sikkim, Eastern Himalaya during the Late-Quaternary. This region is dominated by the Indian summer monsoon, followed by winter rain from the NE-monsoon and Westerlies which influence the glaciers. The study relies on field-based geomorphological mapping and geospatial datasets. The Toe-to-Headwall Altitude Ratio, Toe-to-Summit Altitude Method, and Maximum Elevation of Lateral Moraines methods have been used to calculate the equilibrium line altitudes (ELA) to assess magnitudes of glacial changes over time. OSL dating is used to assess the timing of glacial stages. Additionally, a comparison is made with ELA changes, the distance of moraines from the present glacier snouts, and established glacial chronologies in neighboring areas. The existing landscape depicts the dominant role of the region's present and past glacial processes. The region is also modified by periglacial, paraglacial, and fluvial processes. Four glacial stages have been identified in the region during the late-Quaternary period, contemporaneous to the Last Glacial Maximum, Younger Dryas, Late-Holocene, and Little Ice Age. The first stage (Sikkim-I), marked by dissected trimlines up to ∼16 km downstream, appears to belong to the global Last Glacial Maximum and dated to ∼18.276 ± 0.589 ka with a change of −519.5 m and − 3.4 °C in ELAs and temperature, respectively. The second stage, Sikkim-II is represented by lateral moraines running up to ∼5 km downstream in U-shaped valleys and seems to coincides with the Younger Dryas with ELAs depression of −261.8 m along with a − 1.7 °C drop in temperature. The third Stage (Sikkim-III), marked by small pairs of stable lateral moraines covered with shrubs within ∼3 km downstream, probably belongs to the late Holocene when ELAs and temperature dropped by −177.3 m and − 1.2 °C, respectively. The fourth stage (Sikkim-IV) is notified by a dumped heap of end moraines within ∼2 km downstream, possibly occurred during the LIA with a depression of −72.4 m in ELAs and − 0.5 °C in temperature. These glacial stages are synchronous with the glaciations in the neighboring regions of Thangu in north-Sikkim, Bhutan, and eastern Himalaya syntax. However, the findings of the study differ from the westerly dominated NW Himalayas, broadly.

Magnetic constraints and susceptible inversions of Balapur Fault at central Kashmir Basin, NW Himalaya

Research subject. Subsurface investigations of the Balapur Fault at central Kashmir Basin, NW Himalaya through groundmagnetic surveys and data interpretations. Materials and methods. The total magnetic intensity data was obtained using ground magnetic surveys carried out by proton precession magnetometers at 15 m spacing. The magnetic constraints and inversions of the Balapur fault in the central Kashmir basin of NW Himalaya were analyzed. Results. The total magnetic intensity was found averaging at 97.7 with 45.8 nT as magnetic minima and 140.9 nT as magnetic maxima. The minima’s ranging from 45.8 and 55.8 nT in the gridded profile are inferred at the Balapur fault. Further, the fault-related susceptibility index was recorded from 0.0035 SI to 0.0015 SI, and the observed and predicted response values were found ranging between 67.1 to 87.7 and 67.4 to 86.6 nT respectively. Conclusion. The study suggests that the Balapur fault in the central Kashmir has produced high subsurface hydraulic activities and, therefore, evident low magnetic anomalies. The analysis reveals a thick minima region related to the fault and also indicated the presence of associated structures with the main Balapur fault segment.

Near-surface characterization and delineation of 2-D shear wave velocity profile from geologically complex landscape of Kangra Valley, NW Himalaya, India

Near-surface characterization and delineation of 2-D shear wave velocity profile from geologically complex landscape of Kangra Valley, NW Himalaya, India

Brief communication: The northwest Himalaya towns slipping towards potential disaster

Abstract. The NW Himalaya (India) has been one of the most affected terrains of the Himalaya, subject to frequent disastrous landslides owing to active tectonics and multiple precipitation sources. This article focuses on two towns (Joshimath and Bhatwari) of Uttarakhand in the NW Himalaya, which have been witnessing subsidence for decades. Up until 9 January 2023, Joshimath had witnessed widespread cracks in more than 500 houses, which has prompted social unrest in the region. The hillslopes surrounding both towns comprise highly jointed gneisses with schistose interlayer rock mass. Both towns have subsidences and holes in the road, broken retaining walls, and displaced boulders, and the houses have cracks in the walls and holes. Recently, such slope instability phenomena have increased, which is leading to social movements in the region seeking government action such as possible evacuation and rehabilitation. The present study used a continuum-modelling-based slope stability simulation to determine the response of these hillslopes under various loading conditions: gravity, rainfall, building load, domestic discharge, and seismic load. Results revealed that the displacement in these hillslopes might reach up to 20–25 m, which will further aggravate the situation. The occurrence of frequent extreme rainfall in these towns and three major earthquakes, which occurred on 1 September 1803 (Mw 7.8), 20 October 1991 (Mw 6.8), and 29 March 1999 (Mw 6.6), having a hypocentral distance less than 30 km makes such a study more viable for decision making.

Late-Holocene hydrological variability from the NW Himalaya and southwestern Tibetan Plateau: Paleo-salinity records from Pangong Tso

Variations in lake-levels and hydrology are connected to climatic dynamics over the Trans-Himalaya and Tibetan Plateau (TP). Pangong Tso, a ~140 km long hypersaline lake, is sensitive to changes in air temperature, precipitation and snow-glacier melt over the southwestern TP. The incised tributaries entering the lake expose deltaic sequences constituting topset, foreset and bottomset. Sedimentology, chronology and diatom analysis of delta sediments; and stable isotopic and sclerochronological analysis of gastropods helped delineate the Late-Holocene variation in lake levels, surface temperature and salinity. The elevation of the topsets is considered as representing past lake high-stands from where molluscs were also recovered. Three phased lake level changes are observed during the past 3 ka. The first high-stand (+1.4–3.0 m) was at ~2.8–2.0 ka when lake surface salinity and temperature were 4.67–6.01 ppt (parts per thousand) and 5°C–7°C, respectively, against the modern average values of 7.7 ± 0.09 ppt and 16.1°C ± 2.0°C. Followed by a brief decline, another high-stand (+3.0–3.6 m) is observed at 1.1 ka when the salinity is reduced to 4.03–5.72 ppt and lake surface temperature to 5°C–8°C. A corresponding increase in freshwater diatom concentration is also observed here. The third phase over the past 1 ka witnessed a fall of ~3.6–6 m in lake level that is attributed to an abrupt rise in aridity over the TP. We demonstrate that lake level variation in the region is a function of the variability of the Indian Summer Monsoon (ISM) and the westerlies, however during the high-stand, the hydrology of the lake was dominated by ISM precipitation.

Spatiotemporal landslide susceptibility mapping using machine learning models: A case study from district Hattian Bala, NW Himalaya, Pakistan

The Himalayan region, a rugged mountain zone is among the most susceptible zones to the landslide hazard due to its terrain, geography, and active tectonics. Machine learning (ML) techniques are most advanced and precise methods to develop landslide susceptibility model (LSM). The current study was designed to analyze and assess the landslide susceptibility using ML approaches for District Hattian Bala, NW Himalayas, Pakistan. The historical satellite imageries are used to generate spatiotemporal landslide inventories of year 2005, 2007 and 2012. A spatial database was created pertaining to topographic, environmental, geologic, and anthropogenic factors including slope, aspect, elevation, curvature, plane curvature, profile curvature, topographic wetness index (TWI), lithology, distance to faults, distance to streams, distance to roads, normalized difference vegetation index (NDVI) and land use/ land cover (LULC). These LCFs were selected to analyze periodic landslide susceptibility in the region. The experimental design utilized 349, 393, and 735 landslide inventory of 2005, 2007, and 2012 respectively. Two ML models, i.e., Random Forest (RF) and Logistic Regression (LR) were applied to assess landslide susceptibility determine by thirteen landslide causative factors (LCFs). The spatiotemporal landslide inventory was partitioned into training (70%) and testing (30%) landslides for respective years to check the prediction accuracies of selected ML models. Comparative analysis of different LSMs was performed by the Receiver Operator Curves – Area Under Curves (ROC-AUC). The resultant accuracy, MAE, RMSE, Kappa, Precision, Recall, F1 indicated that RF outperformed the LR model. The study aims to minimize losses to lives and potential economic damage linked with recurrent slope instabilities in the region. It is anticipated that use of ML algorithms would support concerned authorities and organizations to effectively plan and manage landslide hazard in the region.

Geological evidence of paleo-earthquakes on a transverse right-lateral strike-slip fault along the NW Himalayan front: Implications towards fault segmentation and strain partitioning

Geological evidence of paleo-earthquakes on a transverse right-lateral strike-slip fault along the NW Himalayan front: Implications towards fault segmentation and strain partitioning

Geochemistry of Karewa deposits of NW Himalaya: implications on provenance and tectonic setting

Geochemistry of Karewa deposits of NW Himalaya: implications on provenance and tectonic setting

Late-Holocene wildfire record from the Stagmo peat section, Leh valley, NW Himalaya

Wildfire is an integral component of the terrestrial ecosystem that plays a significant role in regulating the vegetation cover. The paleofire records stored in lacustrine, peat, or marine sedimentary deposits along with environmental proxy records provide temporal information on fire activity and contemporary climatic conditions on a regional scale. A ~2.8m long peat sedimentary profile from Stagmo, Indus Valley, Ladakh Himalaya was examined for sedimentology and charcoal microfossil contents to investigate fire characteristics and reconstruct wildfires which are compared with paleoclimatic changes and past human activities to assess their significance in biomass burning. Charcoal count (CC) analysis provides a suitable method for investigating climatic and vegetation changes with human intervention when no direct evidence is available in the Late-Holocene Trans Himalaya records. The results bring new insight into the interaction between vegetation, fire, and human activity in the Ladakh Himalaya during the past ~2.8 cal kyr BP. An event characterized by high CC at ~2.8 cal kyr BP is distinct from the whole sequence and cannot easily be explained as only the result of a climatic event. This first high charcoal count phase (2.81–2.55 cal kyr BP) could be a natural response to the expansion of forest and dense vegetation with human management interruption. This paleo wildfire event likely corresponds with the time of the Tibetan Plateau’s immediate human occupation. In the second phase, a relatively low charcoal count (1.65–1.54 cal kyr BP) is supported by the high fuel availability during a transitional phase. The third phase of wildfire reconstruction in Ladakh Himalaya is identified at ~1.38 cal kyr BP. This phase can be correlated with the intensified Indian Summer Monsoon (ISM) advancing to Trans-Himalaya leading to increased human settlement in the region.

Spatial distribution and characteristics of microplastics and associated contaminants from mid-altitude lake in NW Himalaya

Despite the worldwide concern over the impact of microplastics (MPs) and associated organic contaminants, the information regarding the occurrence and characteristics of these emerging class of pollutants is limited in freshwater environment. We present data on the distribution and concentration levels of MPs and phthalate esters (PAEs) from Rewalsar Lake, a shallow eutrophic lake in Northwest Himalaya. The MPs were identified in all samples, with concentration of 13–238 particles L−1 and 750 to 3020 particles kg−1 dry weight (dw) in surface water and sediments respectively. Majority of MPs were dominated by polystyrene, polyethylene, polypropylene polymers that principally occurred in the form of pellets and fragments. The MPs distribution was different among sampling sites, being more abundant to sites in the proximity of domestic sewage effluents and high level of religious and tourist activities. The di-isobutyl phthalate, dibutyl phthalate (DBP) and its branched isomer, di(2-ethylhexyl) phthalate (DEHP) are the identified PAE congeners in sediments, and the measured total concentrations of Σ3PAE ranged from 1.69 μg/g to 4.03 μg/g dw. Notably, concentration values of DEHP were higher as compared to other detected phthalates, and exceeded recommended environmental risk limit. The findings of this study emphasize the requirement for proper waste management measures in the region to reduce entry of these pollutants into the ecosystem. Further, this work contributes to the understanding of MPs and PAEs potential contamination profiles and sources in freshwater environments, and provides valuable information for future management decisions.

Signatures of 16th and 19th centuries paleo-earthquakes along the Himalayan Frontal Thrust (HFT), NW Himalaya, India: Implications to seismic hazard assessment

The Himalayas, one of the most seismically active regions in the world, experienced several damaging earthquakes in the recent past. Historical data (limited) and paleoseismic studies indicate that some portions of the Himalayas did not rupture during the historic time and have the potential to host major earthquakes. The paleoseismic study was conducted in the mesoseismal zone of the 1905 (Mw7.8) Kangra earthquake, NW Himalaya. Two trenches (ABT1 and ABT2) excavated across the Hajipur Fault (HF2) – an imbricated fault of Himalayan Frontal Thrust (HFT) near Asparbadaliya revealed signatures of at least three paleo-earthquakes, displacing/deforming young Quaternary deposits along NE dipping thrust fault strands (F1 and F2). Exposed stratigraphy in trenches and Optically Stimulated Luminescence (OSL) calibrated/modeled ages suggest that Event I occurred at around BCE 50 - CE 400; Event II was during CE 1450–1670 and Event III at around CE 1720–1840. A larger interval of ∼900–1000 years between Event-I and Event-II suggests that Event-II was a great earthquake with 8.0 ≥ Mw ≤ 8.5 – correlated with CE 1555 earthquake reported from Kashmir with a rupture length of ∼400–450 km, extending from Kashmir to Chandigarh. Event-III that occurred with an interval of 200–300 years was a large earthquake with a magnitude 7.5 ≥ Mw ≤ 8.0, and a rupture length of ∼200–250 km. We propose that the irregular recurrence interval could be attributed to variation in the distribution of fault system between HFT and Main Central Thrust (MCT) in NW (∼100 km) and Central as well as NE Himalaya (∼40–50 km), suggesting heterogeneity exists along the arc.

Magnetization distribution and susceptibility inversions of the Balapur fault in the northern region of Kashmir basin, NW Himalaya

Ground magnetic surveys were carried out in the northern region of the Kashmir basin, NW Himalaya to calculate the total magnetic intensities and subsurface constraints at the Balapur fault. The susceptibility index of -0.020 SI to 0.001SI was found associated with the strike of the Balapur fault. Further, the susceptibility index of the associated Gulmarg fault was recorded as -0.01SI to 0.001 SI. The present study implies that the Balapur fault has produced well-developed magnetic constraints throughout its strike. The 3D inversion modeling implies that the Balapur fault in north Kashmir has developed enough subsurface strain features and can lead to high earthquake intensity. Little or no variation was found between the observed and predicted databases and the analysis recorded an accuracy factor of 0.002 with 20 iterations. The study suggests that ground magnetic surveys are very useful in understanding the subsurface fault characteristics based on the Magnetization factor.

Overgrowth competition or facilitation from cushion plants: Implication for the role of plant-plant interactions.

Overgrowth competition or facilitation from cushion plants: Implication for the role of plant-plant interactions.

Quantitative analysis of Khajjiar and Rewalsar lakes and their surroundings, Himachal Pradesh (India): Remote sensing and GIS-based approaches

In the present study, an attempt has been made to delineate anomalous morphotectonic elements in the lower valley of Ravi and Beas rivers of the NW Himalaya by utilising the digital elevation model (DEM) as well as GIS based approach. We selected the surrounding areas of both the rivers as these have developed tectonically formed lakes such as Khajjiar and Rewalsar in late Holocene and lie in the north and south of Kangra re-entrant structure. We generated topographic swath profiles, calculated normalized steepness index (ksn) and hypsometric integral (HI) and conducted lineament analysis and finally correlated the obtained data set with the contemporaneous seismicity to decode the tectonic activity in the region. Based on the calculated HI for both the areas as 0.45 and 0.47, we infer that there are anomalous changes in the steepness, pointing to the presence of active tectonics. By using lineament analysis, geological information and the quantitative analysis, we identified lineaments parallel and oblique to the regional strike of the NW Himalaya, indicating the area as tectonically active. The lower steepness values along the inferred lineaments suggest the presence of strike-slip features that absorb the oblique convergence of the Indian plate with Eurasia. The GPS based additional observations suggest significant amount of deformation, showing higher deformation rate in the vicinity of the Khajjiar as compared to the Rewalsar locality. Based on remote sensing and GIS based approaches, we conclude that the study area is tectonically very active, hence there is need of careful examination of identified structures and impact on the development of infrastructure and seismic hazard assessment of the western Himalaya.

Geoheritage Assessment of a Hermit Cave System at Lakhamandal Valley, Upper Yamuna River Basin, NW Himalaya

Geoheritage Assessment of a Hermit Cave System at Lakhamandal Valley, Upper Yamuna River Basin, NW Himalaya

Modelling the Impact of Changing Climate on Sediment Yield in a Data-Scarce High-Elevation Catchment in NW Himalayas

Modelling the Impact of Changing Climate on Sediment Yield in a Data-Scarce High-Elevation Catchment in NW Himalayas

Site effect assessment and vulnerability analysis using multi-geophysical methods for Kangra city, NW Himalaya, India

Site effect assessment and vulnerability analysis using multi-geophysical methods for Kangra city, NW Himalaya, India

Hydrological extremes and climatic controls on streamflow in Jhelum basin, NW Himalaya

Hydrological extremes and climatic controls on streamflow in Jhelum basin, NW Himalaya