GIS-based landslide susceptibility zonation for roadside slope repair and maintenance in the Himalayan region

Roadside slope failure is a common problem in the Himalayan region as road construction activities disturb natural slopes. Therefore, landslide susceptibility zonation is necessary for roadside slope disaster management and planning development activities. In this study, we consider a 53-kin section of a major highway in Nepal where road services are suspended for several days in the monsoon season every year. A number of methods have been used for landslide susceptibility zonation. We employed a bivariate statistical approach for this study. Relevant thematic layer maps represent- ing various factors （e.g., slope, aspect, land use, lithology, drainage density, proximity to stream and proximity to road） that are related to landslide activity, have been prepared using Geographic Information System （GIS） techniques. A total of 277 landslides （covering a total of 29.90 km2） of various dimensions have been identified in the area. A landslide susceptibility map was prepared by overlaying a landslide inventory map with various parameter maps segmented into various relevant classes. The landslide susceptibility index was seg- mented into five zones, viz. very low, low, moderate, high and very high susceptibility. Landslide susceptibility zonation maps are useful tools for the efficient planning and management of roadside slope repair and maintenance tasks in the Himalayan region.     

Use of SARAL/AltiKa Observations for Modeling River Flow

In the absence of many gauging stations in the major and mighty river systems, there is a need for satellite-based observations to estimate temporal variations in the river water storage and associated water management. In this study, SARAL/AltiKa application for setting up hydraulic model (HEC-RAS) and river flow simulations over Tapi River India has been discussed. Waveform data of 40 Hz from Ka band altimeter has been used for water levels retrieval in the Tapi river. SARAL/AltiKa retrieved water levels were converted to discharge in the upstream location (track-926) using the rating curve available for the nearby gauging site and using linear spatial interpolation technique. Steady state simulations were done for various flow conditions in the upstream. Validation of river flow model was done in the downstream location (track-367) by comparing simulated and altimeter retrieved water levels (RMSE 0.67 m). Validated model was used to develop rating curve between water levels and simulated discharge for the downstream location which enables to monitor discharge variations from satellite platform in the absence of in situ observations. It has been demonstrated that SARAL/AltiKa data has potential for river flow monitoring and modeling which will feed for flood disaster forecasting, management and planning.     

Characteristics of coronal mass ejection associated with DH type II radio bursts (All and Limb events)

We have studied the characteristics of coronal mass ejections (CMEs) associated with Deca-Hectometric (DH) type II radio bursts (1–14 MHz) in the interplanetary medium during the year 1997–2005. The DH CMEs are divided into two parts: (i) DH CMEs (All) and (ii) DH CMEs (Limb). We found that 65% (177/273) of all events have the speed >900 km?s^?1 and the remaining 35% (96/273) events have the speed below 900 km?s^?1. The average speed of all and limb DH CMEs are 1230 and 1288 km?s^?1, respectively, which is nearly three times the average speed of general population of CMEs (473 km?s^?1). The average widths of all and limb DH CMEs are 105° and 106°, respectively, which is twice the average width (52°) of the general population of CMEs. We found a better correlation between the speed and width of limb DH CMEs (R=?0.61) than all DH CMEs (R=?0.53). Only 28% (177/637) of fast >900 km?s^?1 general population of CMEs are reported with DH type II bursts counterpart. The above results gives that the relation between the CME properties is better for limb events.     

Ocean model derived global surface circulation and Vertical velocity

In this article, the authors examine Sea surface temperature (SST), Sea surface circulation (SSC) and Vertical velocity (VV) fields from simulation of 25 layers coarse resolution Modular ocean model (MOM version 3.0) with prescribed wind forcing for the region 74.25°S to 65°N, 180°W-180°E. It is found that distribution of SST simulated by the model shows its consistency with the observed climatology. However, simulated SST in the areas of Arabian Sea, Bay of Bengal, Indonesian Throughflow (ITF) region and east of North America near equator exhibit slight warming with respect to observation, which may be due to model deficiency and forcing problems. Circulation features suggest that one of the strongest current viz. Antarctic circumpolar current (ACC) along with other major current systems viz. Gulf stream current, North and South Pacific current, Agulhas current, Labrador current, Canary current, etc are captured well by the model. In the Indian Ocean and other ocean basins, current patterns are well captured by the model simulation. Intense upwelling as well as downwelling areas is marked in the horizontal distribution of VV, which is as expected. VV show quasi-stagnant and convergent regions suggesting that floating materials may be accumulated during January/July in the real ocean and wind driven circulation may act as an important contribution for such transport of floating materials in these regions. An attempt has also been made to understand the fluctuations of the SST in NINO 3.4 region during the period of model simulation using SST anomalies.     

The Nature and Distribution of Particulate Matter in the Mandovi Estuary,Central West Coast of India

Systematic seasonal variations of suspended particulate matter (SPM) along a 44-km transect of the Mandovi estuary reveal that the concentrations of SPM are low at river-end stations, increase generally seaward, and are highest at sea-end stations of the estuary. An estuarine turbidity maximum (ETM) occurs at sea-end stations during June–September when river discharge is high and also in February–May when river discharge is low. These are the two windiest times of year, the former associated with the southwest monsoon and the latter characterized by a persistent sea breeze. The salinity vs. SPM plot shows that high SPM is a seaward deposit and skewed landward. Suspended matter comprised of floccules, fecal pellets, and aggregates that consist of clay and biogenic particles occur everywhere in the estuary. Diatoms are the most common and are of marine type at the sea-end and freshwater-dominated at river-end stations of the estuary. SPM is characterized by kaolinite- and smectite-rich clay mineral suites at the river- and sea-end stations, respectively. Smectite concentrations increase seawards with the increase in SPM content and are not influenced by salinity. Wind-driven waves and currents and biogeochemical processes at the mouth of estuary likely play an important role in the formation of ETM in resuspension and transformation of SPM into floccules and aggregates and in their upkeep or removal.     

Root structure,distribution and biomass in five multipurpose tree species of Western Himalayas

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The tree root distribution pattern and biomass of seventeen year old trees of Grewia optiva, Morus alba, Celtis australis, Bauhinia variegata and Robinia pseudoacacia were studied by excavation method. B. variegata roots penetrated to a maximum depth of 4.78 m, whereas, M. alba roots were found down to 1.48 m depth. Lateral spread was minimum in B. variegata （1.10 m）and maximum inR. pseudoacacia （7.33 m）. Maximum root biomass of 6.30 kg was found in R. pseudoacacia and minimum （2.43 kg） was found in M. alba. For four species viz.,G. optiva, M. alba, C. australis andR. pseudoacacia, 68%-87% root biomass occurred within top 0-30 cm soil depth, but forB. variegata this was only45%. The soil binding factor was maximum in G. optiva and minimum in B. variegata. Soil physico-chemical properties also showed wide variation. The study suggests thatB. variegata with a deep root system is the most suitable species for plantation under agroforestry systems. R. pseudoacacia and G. optiva with deep root systems, more lateral spread and high soil binding factor are suitable for plantation on degraded lands for soil conservation.     

Enhancing the relevance of Shared Socioeconomic Pathways for climate change impacts,adaptation and vulnerability research

This paper discusses the role and relevance of the shared socioeconomic pathways (SSPs) and the new scenarios that combine SSPs with representative concentration pathways (RCPs) for climate change impacts, adaptation, and vulnerability (IAV) research. It first provides an overview of uses of social–environmental scenarios in IAV studies and identifies the main shortcomings of earlier such scenarios. Second, the paper elaborates on two aspects of the SSPs and new scenarios that would improve their usefulness for IAV studies compared to earlier scenario sets: (i) enhancing their applicability while retaining coherence across spatial scales, and (ii) adding indicators of importance for projecting vulnerability. The paper therefore presents an agenda for future research, recommending that SSPs incorporate not only the standard variables of population and gross domestic product, but also indicators such as income distribution, spatial population, human health and governance.     

Removal of lead (II) from synthetic and batteries wastewater using agricultural residues in batch/column mode

The present article explores the ability of five different combinations of two adsorbents (Arachis hypogea shell powder and Eucalyptus cameldulensis saw dust) to remove Pb(II) from synthetic and lead acid batteries wastewater through batch and column mode. The effects of solution pH, adsorbent dose, initial Pb(II) concentration and contact time were investigated with synthetic solutions in batch mode. The Fourier transform infrared spectroscopy study revealed that carboxyl and hydroxyl functional groups were mostly responsible for the removal of Pb(II) ions from test solutions. The kinetic data were found to follow pseudo-second-order model with correlation coefficient of 0.99. Among Freundlich and Langmuir adsorption models, the Langmuir model provided the best fit to the equilibrium data with maximum adsorption capacity of 270.2 mg g^?1. Column studies were carried out using lead battery wastewater at different flow rates and bed depths. Two kinetic models, viz. Thomas and Bed depth service time model, were applied to predict the breakthrough curves and breakthrough service time. The Pb(II) uptake capacity (q _e = 540.41 mg g^?1) was obtained using bed depth of 35 cm and a flow rate of 1.0 mL min^?1 at 6.0 pH. The results from this study showed that adsorption capacity of agricultural residues in different combinations is much better than reported by other authors, authenticating that the prepared biosorbents have potential in remediation of Pb-contaminated waters.     

Spectral element analysis to evaluate the stability of long and steep slopes

This paper evaluates the stability of long and steep slopes examining the effect of the critical length/depth ratio, L/H, and critical slope angle, β _cr, by comparing the results of infinite slope equation with the spectral element method. In addition, the influence of uphill and downhill boundaries on stability of long and steep slopes is also evaluated in theoretical domains. As an example, this paper presents a stability analysis of long and steep vegetated and barren slopes in saturated and seismic conditions, and also evaluates the effectiveness of the infinite slope equation for those slopes. In the vegetated slopes, the root zone may not extend to the whole depth of slope, which may lead to overestimating the factor of safety by infinite slope equation. This paper examines the applicability of the infinite slope equation for infinitely long, steep, and shallow slope model by comparing the results of the spectral element method.