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Torrential rains, landslides, and seismic activity are the common factors that are causing unprecedented damage to life, property and infrastructure in Mandakini and Bhilangana basins of Garhwal Himalaya. Owing to such conditions, we demonstrate the feedback this landscape in Garhwal Himalaya in response to episodic tectonic uplift and monsoon precipitation. We calculated conventional geomorphic parameters to access the tectonic deformation across the major thrusts and faults. We further analyzed the normalized steepness index (Ksn), Chi (χ), and knickpoints along the longitudinal course of rivers. Additionally, the study attributed to active nature of Chail/Ramgarh thrust along the Balganga valley as envisaged by five levels of unpaired fluvial terraces, entrenched stream course, river ponding, active and stabilized landslide deposits, etc. Moreover, the flooding during the heavy rainfall events induced river toe cutting makes an effect on settlement over fluvial deposits. Therefore, we suggested that the highly dissected and tilted basins with deep V shaped valleys and ongoing seismicity also fabricates the region more vulnerable for hazards which threaten the human lives.

The present investigation is focused on imprint of tectonic perturbation along a major tributary, known as the Lastar Gad (Gad = River), in southeast catchment of the Mandakini river in Garhwal Himalaya. Based on morphotectonic studies across the watershed, we recognized evidences of neotectonics along the Jutogh/Munsiari Thrust (MT/MCT-II). Various geomorphic features, e.g., ponding of streams and formation of lakes, fluvio-lacustrine deposits, waterfalls, stabilized and active landslide fans, dissected hills, paired and unpaired terraces, fault scarps and offsetting of drainage pattern etc., point to the active tectonics. The field investigations are supported by computation of morphometric indices, such as, low values of Valley Floor Width to Valley Height (Vf), Asymmetry Factor (Af), elongated and tilted river basin with narrow valley floor as well as higher Bifurcation Ratio (Rb) and sinuosity parameters, immature topography and landscape, elongation and tilting of drainage basin and accelerated erosion-all show that the basin is structurally controlled. The uplift along the valley is further manifested by two significant indexes, e.g., Stream Length (SL) and Steepness Index (Ks). Also, the mud deposits, lacustrine flats and swampy and soggy land within the valley suggest the existence of an ancient lake basin, named as Gethina palaeolake, downstream of present day Badanital lake. The 14C AMS radiocarbon chronology of the Badanital lake core as well as Gethina-Jagtoli palaeolake profiles indicate the formation of these lakes around 5–6 ka BP due to tectonic upheaval along the MT. We assume that a huge landslide activity blocked the course of a small stream (Badani Gad), forming an ancient lake at Gethina locality, followed by deposition of a landslide fan on which was created the Badanital. Subsequently, the palaeolake basin was filled with sediments due to accelerated erosion from almost vertical hills in the catchment. Owing to this, the Gethina (ancient) lake was disappeared and the modern Badanital lake shrank to its present state.

Mass wasting often results from the combined effect of tectonic and climate processes. It has not only resulted in human casualties on large scale but has also ruined agricultural land and disrupted hydro power projects and other governmental as well as private property. Despite the belief that prevention is inevitably better than cure, decrease in future hazards requires proper dissemination of knowledge to the Himalayan inhabitants. Considering this, we investigated a part of Kumaun Himalaya to understand the cause of cloud burst induced mass movements along the Saryu River that took place on 18th August 2010 and subsequently on 12–14th September, 2012. A number of Quaternary faults, e.g., Dulam fault (DF), Dulam Gadhera Fault (DGF) and Vongarh-Gason Fault (VGF) in the zone of a major thrust (Berinag Thrust) in the studied sector are invariably active as evident by various geomorphic features, e.g., saw cutting of host rocks, immature topography, deflecting river courses, ponding of ancient drainage, development of cascades, formation of unpaired fluvial terraces, and series of triangular fault facets. The fragile lithology, deep V shaped valleys, accelerating erosion and incision with higher uplift due to tectonic upheaval along the active faults are also responsible for rainfall induced catastrophes in the region. Additionally, morphometric analysis reveals that the Saryu basin is elongated and tilted. Further, the tectonic tilting and moderate to coarse drainage density may possibly be responsible for quicker runoff, amplified erosion, and subsequently increased flooding around the study area. We infer that the area is not only controlled by topography but may also have been affected by the hydraulic factors such as climate. In addition, the drainage is dominated mostly by first order streams which seem to be indicative of higher chances of flooding, as most of the water is concentrated in a single channel during monsoon season. We believe that the similar studies done in the other sectors will be helpful in reducing not only the huge loss of life but may also help in protecting ongoing and huge hydropower and other developmental projects in this newly born state.

This paper presents the first stable isotope (delta O-18 and delta C-13) data of a similar to 400 years (1590-2006 AD) long annual to decadal-resolution speleothem record collected from the Indian Lesser Himalaya. The data show a variation from -2.7 to -5.9 parts per thousand in delta O-18 and -5.3 to -8.8 parts per thousand in delta C-13. The isotopic analyses indicate that the climate during this period can be divided into two stages: a wet phase during the Little Ice Age (LIA) (1590-1850 AD) and comparatively dry phase during the post-LIA after 1850 AD. However, the record also documents the minor dry events during the LIA and a wet episode after the LIA. Within the age uncertainty, the dry spells during the LIA are linked with the historical drought events in the Indian subcontinent and similar latitudes. The isotopic record is consistent with a number of previous studies in the areas influenced by the Westerlies but appears to be conflicting to the regions, dominated by the Indian Summer Monsoon (ISM). This may be due to the possible changes in the strength of Westerlies in the study area and added by negative anomaly of North Atlantic Oscillation (NAO) during the LIA. (C) 2012 Elsevier Ltd and INQUA. All rights reserved.

An event of neotectonic activity on an NE–SW trending subsidiary fault in the zone of E–W running intracrustal boundary thrust (South Almora Thrust) in the Champawat district of eastern Kumaun Himalaya resulted in creation of a lake at ca. 21.5 BP. The lake drained in the late Holocene, leaving behind a 5.0 m thick sedimentary sequence of mostly black and carbonaceous mud, with a minor magnetic reversal between 20.5 and 19.7 ka BP at the base. The profile, studied by using multi-proxies (e.g., carbon isotopes, pollen analysis, palaeo and mineral magnetism and clay minerals) has recorded globally well established abrupt climatic events in the last 20,000 years, such as the LGM, Older Dryas (OD), Younger Dryas (YD), Holocene warming, 8.2 ka, and 4.2 ka events. Most events, estimated assuming a constant rate of sediment accumulation for similar lithologies, may be related to the rapid changes in the local climate and albedo structure. The ITCZ may have played a key role in controlling the behavior of the southwest monsoon from the LGM.