Remote sensing and GIS‐based flood vulnerability assessment of human settlements: a case study of Gangetic West Bengal,India

Flooding due to excessive rainfall in a short period of time is a frequent hazard in the flood plains of monsoon Asia. In late September 2000, a devastating flood stuck Gangetic West Bengal, India. This particular event has been selected for this study. Instead of following the conventional approach of flooded area delineation and overall damage estimation, this paper seeks to identify the rural settlements that are vulnerable to floods of a given magnitude. Vulnerability of a rural settlement is perceived as a function of two factors: the presence of deep flood water in and around the settlement and its proximity to an elevated area for temporary shelter during an extreme hydrological event. Landsat ETM⁺ images acquired on 30 September 2000 have been used to identify the non‐flooded areas within the flooded zone. Particular effort has been made to differentiate land from water under cloud shadow. ASTER digital elevation data have been used to assess accuracy and rectify the classified image. The presence of large numbers of trees around rural settlements made it particularly difficult to extract the flooded areas from their spectral signatures in the visible and infrared bands. ERS‐1 synthetic aperture radar data are found particularly useful for extracting the settlement areas surrounded by trees. Finally, all information extracted from satellite imageries are imported into ArcGIS, and spatial analysis is carried out to identify the settlements vulnerable to river inundation. Copyright © 2005 John Wiley & Sons, Ltd.     

Hydraulic routing of extreme floods in a large ungauged river and the estimation of associated uncertainties: a case study of the Damodar River, India

Many developing countries are very vulnerable to flood risk since they are located in climatic zones characterised by extreme precipitation events, such as cyclones and heavy monsoon rainfall. Adequate flood mitigation requires a routing mechanism that can predict the dynamics of flood waves as they travel from source to flood-prone areas, and thus allow for early warning and adequate flood defences. A number of cutting edge hydrodynamic models have been developed in industrialised countries that can predict the advance of flood waves efficiently. These models are not readily applicable to flood prediction in developing countries in Asia, Africa and Latin America, however, due to lack of data, particularly terrain and hydrological data. This paper explores the adaptations and adjustments that are essential to employ hydrodynamic models like LISFLOOD-FP to route very high-magnitude floods by utilising freely available Shuttle Radar Topographic Mission digital elevation model, available topographical maps and sparse network of river gauging stations. A 110 km reach of the lower Damodar River in eastern India was taken as the study area since it suffers from chronic floods caused by water release from upstream dams during intense monsoon storm events. The uncertainty in model outputs, which is likely to increase with coarse data inputs, was quantified in a generalised likelihood uncertainty estimation framework to demonstrate the level of confidence that one can have on such flood routing approaches. Validation results with an extreme flood event of 2009 reveal an encouraging index of agreement of 0.77 with observed records, while most of the observed time series records of a 2007 major flood were found to be within 95 % upper and lower uncertainty bounds of the modelled outcomes.     

The scientific rationale for the C1XS X-ray spectrometer on India's Chandrayaan-1 mission to the moon

The UK-built Chandrayaan-1 X-ray Spectrometer (C1XS) will fly as an ESA instrument on India's Chandrayaan-1 mission to the Moon, launched in October 2008. C1XS builds on experience gained with the earlier D-CIXS instrument on SMART-1, but will be a scientifically much more capable instrument. Here we describe the scientific objectives of this instrument, which include mapping the abundances of the major rock-forming elements (principally Mg, Al, Si, Ti, Ca and Fe) in the lunar crust. These data will aid in determining whether regional compositional differences (e.g., the Mg/Fe ratio) are consistent with models of lunar crustal evolution. C1XS data will also permit geochemical studies of smaller scale features, such as the ejecta blankets and central peaks of large impact craters, and individual lava flows and pyroclastic deposits. These objectives all bear on important, and currently unresolved, questions in lunar science, including the structure and evolution of any primordial magma ocean, as revealed by vertical and lateral geochemical variations in the crust, and the composition of the lunar mantle, which will further constrain theories of the Moon's origin, thermal history and internal structure.     

LunarEX—a proposal to cosmic vision

While the surface missions to the Moon of the 1970s achieved a great deal, scientifically much was also left unresolved. The recent plethora of lunar missions (flown or proposed) reflects a resurgence in interest in the Moon, not only in its own right, but also as a record of the early solar system including the formation of the Earth. Results from recent orbiter missions have shown evidence of ice or at least hydrogen within shadowed craters at the lunar poles.     

What’s New in Adaptive Management and Restoration of Coasts and Estuaries?

Adaptive learning about nature, based on observations and continual rethinking, dates back to Native Americans in what we call Traditional Ecological Knowledge. Fast forward to 1950+, when Eugene, Howard, and William Odum promoted sound science and its use in managing ecosystems—called adaptive management (AM). What began as an instinctive way of thinking and deciding how to obtain resources using accumulated information became a structured, science-based process that improves over time, given continual critiques of projects, clarification of definitions, and analyses of outcomes. The basic need is still to sustain ecosystem services despite uncertainties, such as climate change. I report recent innovations in the AM of estuaries and coasts that can add knowledge and improve future efforts. Innovations include new guidelines and approaches to confront uncertainty, engage stakeholders, improve governance, prioritize actions, centralize the role of science, and manage holistically. AM has been effective along the coast of Denmark and in several estuaries, and it is evolving elsewhere. In The Netherlands, Spain, California, and Oregon, large field experiments are generating “learning while restoring” (adaptive restoration, AR). AM and AR can help managers of coastal ecosystems and watersheds mitigate the impacts of rising sea levels, sea storms, and human disturbances. Science-based decision-making will become more nimble and protection/restoration more effective as innovations and model approaches are tailored to individual estuaries and coasts.     

Discarded containers on a kent beach

Winter beach surveys of discarded containers at Sandwich Bay showed a wide range of fabrication materials and contents. These were manufactured world-wide and probably distributed by seaborne disposal from local shipping. Although blow moulded polyethylene bottles containing toilet cleansers were commonly observed, there was no evidence to indicate an accumulation of these items in the marine environment.     

Natural radionuclides in the water of Narragansett Bay

The concentrations of radionuclides of the U-Th series (²³⁸U,²³⁴Th,²³⁴U,²³⁰Th,²²⁶Ra,²¹⁰Pb,²¹⁰Po, and²³²Th,²²⁸Ra,²²⁸Th) in the water of Narragansett Bay are reported. Analysis of the total, particulate, dissolved and colloidal forms of Th isotopes reveal a consistent removal behavior which is controlled mainly by the particulate matter concentration and the sediment resuspension rate. Half-removal times of Th from solution onto particles range from 1.5 to 15 days, and settling velocities of Th containing particles range generally between 1 and 11 m/day.²¹⁰Pb and²¹⁰Po concentrations are seasonally dependent, with higher concentrations and slower removal during the early summer (half-removal times from solution onto particles of 1–5 days in winter and up to 2 months in early summer).     

Rates of magma emplacement and volcanic output

This study includes a compilation of about one hundred estimates of volumetric rates of magma emplacement and volcanic output that are average rates for durations of igneous activity greater than 300 yrs. These data indicate that the rate of volcanic output is about 10⁻¹ km³ yr⁻¹ in regions that are the most active magmatically. Factors that correlate with rates of magma emplacement and volcanic output are: magma composition, crustal thickness, tectonic setting, and regional stress. Of the ninety rates of magma emplacement and volcanic output that were studied, the highest for basaltic magmas are greater than the highest for silicic magmas, regardless of the volumes erupted or areal extent of magmatism. Rates of volcanic output for oceanic areas tend to be greater than rates in continental areas, perhaps because of thinner crust, a predominance of basaltic magma, and higher rates of magma generation. Ratios of intrusive to extrusive volumes are typically about 5 to 1 for oceanic localities and 10 to 1 for continental localities. This difference apparently reflects dissimilar rates of magma ascent related to different crustal thicknesses and magma compositions. The total rate of magma emplacement and volcanic output for the Earth, averaged over the last 180 m.y., is between about 26 and 34 km³ yr⁻¹. About 75% of this total is contributed by ocean-ridge magmatism. Oceanic intraplate magmatism contributes about 5%. Igneous activity in subduction zones, about half of which is continental, adds about 20%. Intracontinental magmatism, more than 95% of which is flood and plains basalts, provides less than 5% of the total global rate of magma emplacement and volcanic output.     

Sustained Ability of a Natural Microbial Community to Remove Nitrate from Groundwater

Microbial-mediated nitrate removal from groundwater is widely recognized as the predominant mechanism for nitrate attenuation in contaminated aquifers and is largely dependent on the presence of a carbon-bearing electron donor. The repeated exposure of a natural microbial community to an electron donor can result in the sustained ability of the community to remove nitrate; this phenomenon has been clearly demonstrated at the laboratory scale. However, in situ demonstrations of this ability are lacking. For this study, ethanol (electron donor) was repeatedly injected into a groundwater well (treatment) for six consecutive weeks to establish the sustained ability of a microbial community to remove nitrate. A second well (control) located upgradient was not injected with ethanol during this time. The treatment well demonstrated strong evidence of sustained ability as evident by ethanol, nitrate, and subsequent sulfate removal up to 21, 64, and 68%, respectively, as compared to the conservative tracer (bromide) upon consecutive exposures. Both wells were then monitored for six additional weeks under natural (no injection) conditions. During the final week, ethanol was injected into both treatment and control wells. The treatment well demonstrated sustained ability as evident by ethanol and nitrate removal up to 20 and 21%, respectively, as compared to bromide, whereas the control did not show strong evidence of nitrate removal (5% removal). Surprisingly, the treatment well did not indicate a sustained and selective enrichment of a microbial community. These results suggested that the predominant mechanism(s) of sustained ability likely exist at the enzymatic- and/or genetic-levels. The results of this study demonstrated the in situ ability of a microbial community to remove nitrate can be sustained in the prolonged absence of an electron donor.