Reliability analysis of soil liquefaction based on standard penetration test

A review of probabilistic and deterministic liquefaction evaluation procedures reveals that there is a need for a comprehensive approach that accounts for different sources of uncertainty in liquefaction evaluations. For the same set of input parameters, different models provide different factors of safety and/or probabilities of liquefaction. To account for the different uncertainties, including both the model and measurement uncertainties, reliability analysis is necessary. This paper presents a review and comparative study of such reliability approaches that can be used to obtain the probability of liquefaction and the corresponding factor of safety. Using a simplified deterministic Seed method, this reliability analysis has been performed. The probability of liquefaction along with the corresponding factor of safety have been determined based on a first order second moment (FOSM) method, an advanced FOSM (Hasofer–Lind) reliability method, a point estimation method (PEM) and a Monte Carlo simulation (MCS) method. A combined method that uses both FOSM and PEM is presented and found to be simple and reliable for liquefaction analysis. Based on the FOSM reliability approach, the minimum safety factor value to be adopted for soil liquefaction analysis (depending on the variability of soil resistance, shear stress parameters and acceptable risk) has been studied and a new design safety factor based on a reliability approach is proposed.     

Earth Observations based Conservation Prioritization in Western Ghats,India

Earth Observation with large suite of sensors and with capabilities to address natural resources at multiple scales has proven to be a critical resource in setting conservation priorities of a region. The role of earth observation data was recognized towards achieving international biodiversity targets by 2020. Ecosystem irreplaceability and ecosystem vulnerability are two concepts key to understanding and preparing conservation priority maps. This study presents spatial conservation prioritization analysis for forests of ‘Western Ghats biodiversity hotspot’. Earth observation data products have been used for prioritization of areas of irreplaceability and vulnerability that are significant for conservation planning. The spatial surrogates of biodiversity in terms of very dense forest, biological richness, intactness and rarity of habitat are analyzed for evaluation of ecosystem irreplaceability. Fragmentation, forest fires, plant invasion and disturbance index are surrogates included for spatial analysis of ecosystem vulnerability. Vegetation type wise analysis indicates dry deciduous forests are under high vulnerability, followed by moist deciduous forests. The high concentration of irreplaceability is observed in Shola followed by wet evergreen forests and semi-evergreen forests. Spatial prioritization approach has identified about 18% of the forest area as irreplaceable which represents overlapped area of very dense forest, shola, intact forest and high biological richness. We observed that the overlap of forest areas of irreplaceability with vulnerability in southern Western Ghats, which needs high priority of conservation. This study is the first of its kind wherein multi-source earth observation data has been analysed to examine the quantitative criteria at regional level in Western Ghats.     

Study of substrate and physico-chemical base classification of the rivers of Nepal

The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of the Koshi system, Aandhikhola, Arungkhola, East Rapti, Karrakhola, Seti and main channel Narayani of the Gandaki system, and two independent systems within Nepal, Bagmati and Tinau. Among the morphologies, river bed or the substratum was taken as the main variable for the analysis which was categ...     

Contrasting patterns in the abundance of fish communities targeted by fishers on two coral reefs in southern Mozambique

Coastal populations of maritime countries in eastern Africa rely on fish as a primary source of protein, but baseline information on the abundance of fish communities on these coastlines is often lacking. We used baited remote underwater video stations to compare the abundance and diversity of reef fishes targeted by fishing at two sites in southern Mozambique, one at Lighthouse Reef within the Bazaruto Archipelago National Park and the other to the south at San Sebastian Reef on the San Sebastian Peninsula. Fish that are known targets of fisheries (mostly small-scale and artisanal) had an abundance that was almost three-times greater at San Sebastian Reef (80.22 ind. h^–1 [SE 18.00]) than at Lighthouse Reef (29.70 ind. h^–1 [SE 8.91]). Similarly, there was greater mean species richness at San Sebastian Reef (38.74 species h^–1 [SE 2.79]) than at Lighthouse Reef (25.37 species h^–1 [SE 3.66]). The main drivers of targeted fish abundance were habitat and depth, with shallow (<15 m) and mixed reef areas having the greatest abundance and richness. More sampling was done over sand habitat at Lighthouse Reef, which likely led to the lower abundance and species richness observed at this site; however, that finding could also be attributable to the fact that protection is provided to only a section of available coral reef habitat in a small area. Nevertheless, fish community structure was comparable between the sites, with similar proportions of carnivores (78–81%), herbivores (12–14%) and omnivores (7–8%). Our findings highlight the variation in species abundance and assemblages of coral-reef fish targeted by fishing in Mozambique and emphasise the importance of localised environmental variables as a driver of these patterns. To ensure maximum protection of Lighthouse Reef fish communities, we recommend an extension of the no-take zone to include the entire reef complex.     

A high resolution global reanalysis highlighting the winter monsoon. Part I, reanalysis fields

Summary This study entails a reanalysis of the TOGA-COARE, CEPEX period covering the months December 1992 through March 1993. Four times daily data sets were reanalyzed for the period. The unique aspect of this reanalysis is that (i) it incorporates physical initialization i.e. assimilation of rainfall from raingauge and satellite (OLR and microwave radiometric data), (ii) this reanalysis is carried out at a very high resolution, T170, global spectral model (space resolution of roughly 70 km at equator) and (iii) ECMWF reanalysis is used as a first guess field for this study.This analysis is global and is carried out at 15 vertical levels using the FSU global spectral model. In this study we have analyzed a large number of meterological variables such as wind, temperature, humidity, surface pressure, vertical velocity, cloud, rainfall, surface fluxes and diabatic heating. In this part of the paper we present the monthly mean and samples of daily fields of the reanalysis. Some of the major results of the reanalysis include the relationships among the flow fields and the ITCZ convection; the shallow northeast monsoon current and its rapid turning towards westerlies with height; an overabundance of middle clouds over the region of the ITCZ; and the distribution of heat sources and sinks. A motivation for this reanalysis is the forthcoming Indian Ocean Experiment (INDOEX), which is an international field experiment to be conducted during the winter monsoon time frame in 1999.With 25 Figures     

Changes in hydrology and streamflow as predicted by a modelling experiment forced with climate models

Changes in precipitation and temperature have direct effects on crop water use, water stress, crop yield, evapotranspiration, water nutrient dynamics and other indicators. This study, built on a modelling framework with the Soil and Watershed Assessment Tool (SWAT) model for the Raccoon River Watershed in central Iowa, a typical US Midwestern agricultural watershed, examines the watershed response to changes in meteorological inputs from an ensemble of ten global climate models under the A1B scenario. Changes in climate were directly applied to observations (the delta change method) assuming that the estimates of climate change are reliable even if the simulated current climate may be biased. The ensemble average for the mid‐century (1946–1965) predicted 0.7% increase in daily precipitation (monthly variation from ?11.3% to +19.5%) and 2.78 °C increase in average temperature over the entire watershed. These predictions were translated through a well‐calibrated SWAT modelling setup into 22% decrease in snowfall, 16% decrease in surface runoff, 18% decrease in baseflow, 8% increase in evapotranspiration and 17% decrease in total water yield. The spatial impact at the subwatershed level revealed a wide variation (but no defined trend) with decrease in water yield that ranged from 10% to 23%. Flow near the watershed outlet (Van Meter, Iowa) is expected to decline by 17% on an average annual basis with the highest impact occurring during summer months with a maximum 39% reduction in August. Changes in climate were found to have a clear and significant impact signal of decreasing streamflow at the watershed outlet with far‐reaching implication for drinking water supplies for the central Iowa communities. Copyright © 2013 John Wiley & Sons, Ltd.