Natural Hazards Monitoring:Forest Fires, Droughts And Floods - The Example Of European Pilot Projects

This paper reviews the subject of naturalhazards and the use of existing remote sensing systemsin the different phases of disaster management forsome specific natural hazards: forest fires, droughtsand floods. It centers on the applicability of remotesensing for increasing preparedness, providing earlywarnings, monitoring the hazards in real time, andassessing the damage so that relief can be provided. Comparison of the information provided by existingsystems and that needed for operational use of remotesensing in disaster management is also addressed. Thecapability of some of the future sensors to complywith the needs in the field of natural hazards isdiscussed. In this context current pilot projectscarried on at the European Commission Joint ResearchCentre are presented.     

Genesis of the Kinabalu (Sabah) granitoid at a subduction-collision junction

The Kinabalu batholith is a late Neogene granitoid in northwestern Sabah (East Malaysia) apparently marking the locus at which subducted South China Basin lithosphere interacted with roots of the northern Sabah collision suture. The exposed batholith comprises a relatively small core of biotite quartz monzodiorite (BQM) grading out to dominant hornblende quartz monzonite (HQM). Both lithologies contain mafic igneous and metasedimentary inclusions and are cut by late-stage aplite dikes. Major element data indicate the BQM (K₂O/Na₂O ratios ranging 0.72–1.03) represents a low-K type while HQM (K₂O/Na₂O ratios ranging 1.35–5.58) is a distinct high-K type. Magmaphile element distributions support this distinction, HQM showing higher K, Rb, LREE and lower Ta and Nb contents than BQM, indicating the more extensive interaction of HQM with sial. Least-squares mass balance models suggest that HQM evolved through the combined effects of fractional crystallization and crustal assimilation while BQM was dominated by fractional crystallization. However, similar plagioclase zoning patterns in both lithologies suggest they are comagmatic rather than generated by melting of separate sources. It is concluded that low-K type melts, formed by subduction-induced remelting of underplated lower crust, underwent high pressure sialic contamination with development of high-K character. These provided access to later-formed low-K melts which were less contaminated and consolidated to form the pluton core. The unusual zonation from inner low-K to outer high-K type compositions may indicate that the cessation of subduction prevented upward migration of the melting anomaly and thermal maturation of the pluton.     

Deciphering signals of late Holocene fluvial and aeolian supply from a shelf sediment depocentre off Senegal (north‐west Africa)

High‐resolution climatic records of the late Holocene along the north‐west African continental margin are scarce. Here we combine sediment grain size, elemental distribution and mineral assemblage data to trace dust and riverine sources at a shallow‐marine sediment depocentre in the vicinity of the Senegal River mouth. The aim is to understand how these terrigenous components reflect climate variability during the late Holocene. Major element contents were measured and mineral identification was performed on three sub‐fractions of our sediment core: (i) fluvial material < 2 µm, (ii) aeolian material of 18–63 µm and (iii) a sub‐fraction of dual‐origin material of 2–18 µm. Results show that more than 80% of the total Al and Fe terrigenous bulk content is present in the fluviogenic fraction. In contrast, Ti, K and Si cannot be considered as proxies for one specific source off Senegal. The Al/Ca ratio, recording the continental river runoff, reveals two dry periods from 3010 to 2750 cal a BP and from 1900 to 1000 cal a BP, and two main humid periods from 2750 to 1900 cal a BP and from 1000 to 700 cal a BP. The match between (i) intervals of low river runoff inferred by low Al/Ca values, (ii) reduced river discharge inferred by integrated palynological data from offshore Senegal and (iii) periods of enhanced dune reactivation in Mali confirms this interpretation. Copyright © 2011 John Wiley & Sons, Ltd.     

Using 87Sr/86Sr, δ18O and δ2H isotopes along with major chemical composition to assess groundwater salinization in lower Shire valley,Malawi

Groundwater resources in some parts of the lower section of Shire River valley, Malawi, are not useable for rural domestic water supply due to high salinity. In this study, a combined assessment of isotopic (⁸⁷Sr/⁸⁶Sr, δ¹⁸O and δ²H) and major ion composition was conducted in order to identify the hydro-geochemical evolution of the groundwater and thereby the causes of salinity. Three major end-members (representing fresh- and saline groundwater, and evaporated recharge) were identified based on major ion and isotopic composition. The saline groundwater is inferred to result from dissolution of evaporitic salts (halite) and the fresh groundwater shows influence of silicate weathering. Conservative mixing models show that brackish groundwater samples result from a three component mixture comprising the identified end-members. Hence their salinity is interpreted to result from mixing of fresh groundwater with evaporated recharge and saline groundwater. On the other hand, the groundwater with low TDS, found at some distance from areas of high salinity, is influenced by mixing of evaporated recharge and fresh groundwater only. Close to the Shire marshes, where there is shallow groundwater, composition of stable isotopes of water indicates that evaporation may also be an important factor.     

NMR relaxation measurements of biofouling in model and geological porous media

Recently 2D nuclear magnetic resonance (NMR) relaxation techniques have been able to access changes in pore structures through surface and diffusion based relaxation measurements. This research investigates the applicability of these methods for measuring pore and surface changes due to biofilm growth in various model porous systems and natural geological media. Model bead packs of various construction containing 100 μm borosilicate and soda lime glass beads were used to demonstrate how changes in the measured relaxation rates can be used to non-invasively verify and quantify biofilm growth in porous media. However significant challenges are shown to arise when trying to implement the same techniques to verify biofilm growth in a natural geological media.