Tropical cyclones and storm surges are a major threat to coastal communities of the Philippines. On 08th November 2013, category 5 Typhoon Haiyan (local name: Yolanda) made landfall on the islands of Eastern Visayas and caused more than 6000 casualties and severe damage to infrastructure and habitats. To assess the geomorphic impact of one of the strongest tropical cyclones on record, three post-typhoon surveys were conducted in 2014, 2015 and 2016 at two severely affected sites on the islands of Leyte and Samar. They aimed at documenting Haiyan-related erosional features and sand deposits. The sites have different geomorphic and geological settings, and exposure to the typhoon track. Differential global navigation satellite system (DGNSS) measurements and sediment analyses were used to document erosion and washover deposition caused by waves and coastal flooding of the beach ridge systems, as well as their recovery and changes over time. Shoreline changes were measured on high-resolution satellite images using the Digital Shoreline Analysis System (DSAS) to determine the typhoon’s impact and recovery potential at a larger spatial scale. The results show the potential to identify storm-wave erosion and washover deposits in sandy ridge sequences across larger time scales. However, fine sedimentary signatures, such as millimetre-scale lamination, may be rapidly overprinted by bioturbation and geomorphic reorganisation of the coast. The coastline tends to return to its pre-storm equilibrium, whereas the pace depends on whether eroded sands remain within reach of the long-term wave regime, on the frequency of subsequent high-category storms and very local geomorphic conditions.
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The Geological Survey of Belgium (GSB) is involved in geothermal resources assessment at European scale with GeoElec and Thermomap (very shallow) projects and at regional scale with the geothermal plate-form of Wallonia. The GSB has recently completed a first evaluation of geothermal potential of the Walloon region for medium to high enthalpy (300-6000 m). In 2008, the U.S Geological Survey (USGS) has conducted an updated assessment of geothermal resources in the United States. The volume method was the primary scheme applied to identified geothermal systems in which the recoverable heat is estimated from the thermal energy available in a reservoir. In some European countries, the temperature data available generally allow to produce a heat flow map at great depth. The subsurface temperature measurements of Belgium were first compiled by Legrand in 1975 and updated by Vandenberghe & Fock in 1989. The temperature values from the coal and hydrocarbon exploration wells are significantly spread over the reservoirs. The geothermal gradients are strongly influenced by groundwater circulation. The fold and thrust belt context of the subsoil in Wallonia makes geothermal gradient interpretation, reservoir temperatures and reservoir volume difficult to assess. The first geothermal reservoirs identified at 1 kilometer depth were mapped by Berckmans & Vandenberghe (1998). The northern Campine and Anvers regions, the Hainaut basin, and the corridor between Liège and Visé were considered as potential areas. The waloon geothermal plate-form project consisted mainly in preparing and collecting deep geological structure and geothermal resource of the underground data. Geophysical, geological, temperatures and hydrogeological data required some up to date re-interpretation to match the current model knownledge of the deep geological underground of Wallonia. More details were given by a focused study on Liege area with a 3D model realized by Liege University and a chemical geothermometer analyse conducted by GSB. Two maps of geothermal energy interests were produced: one for low to medium depth (300-3000 m), and another one for great depth (3000-6000 m). They mainly represent cartography of the Devono-Carboniferous limestones and Lower Devonian quartzites for two geothermal horizons. Simplified versions of the two maps destinated to the public and policy makers were constructed according to the USGS geothermal resource and reserve terminology, illustrated in the Mc Kelvey diagram (1980). Berckmans A., Vandenberghe N., 1998. Use and potential of geothermal energy in Belgium. Geothermics 27: 235 - 242. Legrand, R. (1975). Jalons Géothermiques. Mémoire Explicatif Cartes Géologique, Mines Belgique, 16 :46 pp. Mc Kelvey (1980). US Geologcal Survey. Principles of a Resource/Reserve classification for Minerals, Circular 831. Vandenberghe N., Fock W. Temperature data in the subsurface of Belgium, 1989. Temperature data in the susbsurface of Belgium. Tectonophysics 164, 237-250.
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