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In this paper, we report geomorphic signatures of neotectonic activity identified from the area around Nahan Salient along Himalayan Frontal Thrust (HFT), using remote sensing and field investigations. We document two newly discovered exposures of HFT fault zone and active fault traces along the mountain front at Khetpurali, Nahan Salient, NW Himalaya, India. We demonstrate that HFT fault zone at Khetpurali is not blind, instead it is exposed at the surface along with highly deformed, folded strata in the hanging wall and its geometry is quite variable with the possibility of along strike-segmentation. The geometry of fold and various deformational features preserved in the hanging wall indicate a process of fault-propagation-fold. This is in contrast to the previous observation of fault-bent-folding within the Nahan Salient. Two-three levels of river terraces are preserved and truncated in the hanging wall, along with the active fault scarps which are linked to uplift along HFT fault zone. The Khetpurali Anticline (KA), is a fault-propagating-fold formed due to displacement and shortening along HFT which dips 30° towards north and strike WNW-ESE. The uplift (U) along the KA is calculated to be ~73 m and accommodated 7.3% shortening of the original length, before the fault tip truncated the fold. Various deformational structures have been identified within the hanging wall around-tip damage zone of ~80 m perpendicular to HFT fault zone and in the core of KA. Northwest of Khetpurali, a south-facing hogback structure ~100 m high is formed due to erosion of forelimb of the anticline. At Khetpurali, tectonic control due to folding of strata and uplift of river terraces is evident as the Dudhgarh River forms V-shaped profile near the thrust, compared to the wide floodplain before and after crossing the HFT fault zone. Along strike segmentation of HFT and associated anticlines is observed as the surface trace of HFT is offset at Khetpurali, Trilokpur, and Sabilpur due to the strike-slip faults. The study reveals that HFT has been truncated by tear faults and has different subsurface geometries in study area which may have implication on seismic hazard in the Nahan Salient where three thrusts; Himalayan Frrontal Thrust (HFT), Nahan Thrust (NT) and Main Boundary Fault (MBF) are located at relatively shorter distance of ~6 km as compared to the surrounding recesses. [ABSTRACT FROM AUTHOR]

• Landscape ecological vulnerability was assessed using bagging ANN-MLP and RF models. • B-MLP model was found best fit model for LEV assessment based on ROC curve, recall, precision, F1-score and accuracy. • Largest area under very high LEV was recorded in the southern part of the plains. • Rainfall, soil, vegetation and LULC were found influencing factors for LEV. • Plantation, embankments and geotextile technology are suggested to check erosion. Riverbank erosion is one of the most catastrophic hazards that renders floodplains vulnerable across the world vulnerable. It creates a significant negative impact on the environment and socio-economic life. This paper attempts to assess the landscape ecological vulnerability (LEV) to riverbank erosion in the Middle Brahmaputra floodplains of Assam, India by employing two machine learning models, namely artificial neural network-multilayer perceptron (ANN-MLP) and random forest (RF). Bagging ensembles were created for both ANN-MLP and RF (B-MLP and B-RF) to generate LEV zones. A total of eleven site-specific parameters were considered for the study. The receiver operating characteristic (ROC) based area under curve (AUC), accuracy, precision, recall and F1-score were used to validate the models and judge the models' performance. A sensitivity analysis was performed to deduce the most influential LEV parameters. The results revealed that B-MLP was the better-performing model compared to B-RF based on all five validation metrics. The largest area was found under very high vulnerability zone followed by very low, low, high and moderate vulnerability zones, based on both ensemble models. The western part of the floodplains was found to be more vulnerable than the eastern part. Moreover, the southern bank faced more vulnerability in comparison to the northern bank. The factors namely rainfall, soil type, vegetation and land /use land cover (LULC) influenced bank erosion vulnerability. This research provides evidence that the study area is under severe threat to riverbank erosion and urgently requires the implementation of effective mitigation measures. The study might benefit policymakers and local stakeholders to protect the floodplains from bank erosion and reduce vulnerability. [ABSTRACT FROM AUTHOR]

How far the de-linking and morphological and hydrological degradation of tie channels connecting river to the wetland are caused for the areal and hydrological transformation of a wetland was not received enough attention in previous literature. This paper tried to explain this about the confluence reach of the Dwarka and Brahmni rivers in Moribund deltaic India. In order to explain the linkages 16 tie channels' change depicting variables and seven wetland area and hydrological transformation (consistency, hydro-period, water depth, water richness etc.) related variables were taken. Ordinary least square (OLS) regression was applied for explain the linkage. Machine learning approaches were applied for water richness mapping. Tie channel evolution was digitized from the Survey of India (SOI) toposheet (1974) and historical Google Earth images. The result revealed that, the tie channel witnessed morphological and hydrological degradations like channel constriction, channel clogging, flow lowering etc. and these were further identified as some vectors of areal shrinkage and growing hydrological insecurity in the linked wetlands. The total wetland area declined from 44.89 km2 to 16.86 km2 from 1991 to 2021. The rate of areal loss, shallowing WD, growing inconsistency of water presence, narrowing HP, and weakening WR was found high in recent times due to de-linking and degradations of tie channels. This approach of explanation of hydrological insecurity of wetland in relation to tie channel degradations, de-linking and findings are quite unique. So, re-linking and morphological correction of the tie channels would be a good policy for wetland restoration. • The floodplain wetland area was reduced by 37.55% between 1991 and 2021. • Tie channels were either lost or degraded losing sufficient water-carrying capacity. • Consistency, hydro-period, wetland depth declined in relation to tie channel loss. • De-linking of tie channel deteriorated water richness zone in wetlands. • Re-linking of tie channel could improve the hydrological condition of the wetland. [ABSTRACT FROM AUTHOR]

Trace fossils are highly sensitive to the hydrodynamic conditions of depositional systems, substrate, and climate and hence yield information about spatio-temporal changes in palaeoenvironment and palaeoclimate. In this paper, we report alluvial trace fossil assemblages from the Upper Triassic Tiki Formation of the Rewa Basin, central India. Based on detailed facies analysis and architecture, two depositional environments are identified in this formation: (1) perennial braided channel belts and (2) extensive and complex floodplains containing ephemeral small fluvial channels, lakes, and crevasse splay deposits. Upper flow regime primary structures in laterally extensive sandstones encased in the floodplain deposits indicate short-lived high magnitude flood discharge, suggestive of seasonal climates. Trace fossils are sporadically distributed through these facies, generally in suites of low abundance, although in places the bioturbation index is higher. Three major ichnofacies, namely Skolithos , Scoyenia and Mermia are recognized, based on the association of different trace fossils preserved in the channel, crevasse splay of proximal floodplain and pond/lake of distal floodplain deposits, respectively. Vertical Beaconites in palaeosols and an abrupt change from Skolithos to Scoyenia ichnofacies indicate a highly variable water table, controlled by seasonal precipitation. The transitions between the Skolithos , Scoyenia and Mermia ichnofacies reveal that trace fossil preservation was variously controlled by channel abandonment, floodplain dewatering, substrate desiccation or periodic waterlogging of overbank areas. Specifically, increased water discharge over the floodplain during high precipitation, followed by post-flood recovery of hot, dry, low-water table conditions may have been a key controlling factor in shaping the ichnological characteristics of these Upper Triassic red beds. [Display omitted] • First report of fluvial trace fossils from the Upper Triassic Tiki Formation, India. • Taphonomic pathways indicate semi-arid climate with very high seasonal rainfall. • Identifying substrate characters and depositional dynamics from ichnofossils. • Ichnological model of a fluvial red bed. [ABSTRACT FROM AUTHOR]