Crónicas en Japón

This is a very personal non-academic chronicle which has no theme except the one that brings together various experiences and reflections about some trips to Japan, between 2017 and 2019. Chile and the Land of the Rising Sun are devastated from time to time by earthquakes and tsunamis, triggered in the subduction zones within the Pacific Ring of Fire. Its inhabitants, however, come from cultures that face this fierce destiny in very different ways. Driven by curiosity, I shifted the everyday life at my Chilean office with the clean air from its temples, its university campuses and the labs at The Tokyo University. These lines and the videos included at the end of the text collect part of those experiences.Esta es una crónica poco académica, muy personal y sin un hilo conductor salvo aquel que aglutina varias experiencias, reflexiones y sensaciones sobre algunas visitas a Japón, entre 2017 y 2019. Chile y el país del Sol Naciente son asolados de cuando en vez por terremotos y tsunamis devastadores, nacidos en las zonas de subducción que los modelan. Sus habitantes, no obstante, devienen de culturas que se enfrentan de formas diversas a ese feroz destino. Movido por la curiosidad de un país hasta ese tiempo esquivo, moví las piezas en el camino más plano para ira respirar de sus templos, vivir de sus campus universitarios y conocer algo de la ciencia desde sus entrañas. Estas líneas y los videos que se incluyen como notas al final del texto recogen parte de esas experiencias

Coastal risk mitigation by green infrastructure in Latin America

This paper aims to highlight the prevailing experiences of Latin America and to clarify what ‘green infrastructure’ entails in addition to describing seven case studies from a range of coastal ecosystems (wetlands, coastal dunes, beaches and coral reefs) at scales varying from local to regional. The case studies are categorised according to their degree of naturalness (nature-based, engineered ecosystems, soft engineering, ecologically enhanced hard infrastructure and de-engineering). Generally, the implementation of green infrastructure projects aims to increase resilience, enhance the provision of ecosystem services, recover biodiversity, reduce the negative effects of hard infrastructure and implement corrective measures. The greatest benefits of these projects relate to the creation of multi-functional spaces, which often combine the above advantages with improved opportunities for recreation and/or economic activities. It is hoped that this paper will disseminate the experience in green infrastructure among academics and practitioners and stimulate wider adoption of green infrastructure projects and good practices

Long Waves In Channels Of Non-Uniform Cross-Section

A cross-sectionally averaged one-dimensional long wave model is developed. Three dimensional equations of motions for inviscid and incompressible fluid are first integrated over a channel cross section. To express the resulting one-dimensional equations in terms of the longitudinal component of the crosssectional averaged velocity and span-wise averaged free surface elevation, the characteristic lengths of the channel cross-section in the vertical and transverse directions are assumed to be smaller than the typical wavelength, resulting in the Boussinesq-type equations. The effects of viscous damping are also added in a heuristic manner. The new model is, therefore, adequate for describing weakly-nonlinear and weakly-dispersive waves along a channel of arbitrary non-uniform crosssection. More specifically, the new model has the following new capabilities: i) The arbitrary channel cross-section can be asymmetric with respect to the direction of wave propagation, ii) the channel cross-section can change significantly within a wavelength, iii) the effects of viscosity inside the bottom boundary layer can be considered, and iv) the three dimensional flow features in a crosssection can be recovered from the perturbation solutions. Analytical and numerical examples for uniform channels, channels where the cross-sectional geometry changes slowly and channels where the depth and width variation is appreciable within the wavelength scale are discussed to illustrate the scope of applicability of the present theory. By considering viscous boundary layer effects, the theory agrees well with experimental results for converging and diverging channels (Chang et al., 1979) and with experiments in a uniform channel with a sloping beach (Liu et al., 1979). The results for a solitary wave propagating in a channel in which the width variation is important within the wavelength are discussed. Curvature is introduced by means of orthogonal curvilinear coordinates following the channel. The resulting one-dimensional cross-sectional averaged equations contain new coefficients depending only on the geometry of the channel. To the level of approximation considered, these equations do not capture the free surface tilting due to curvature and show that the wave field is locally affected by the magnitude and sign of the curvature. The theory provides practical model equations for calculating long waves (e.g. tsunamis, tides or flood) propagation in fjord or river, which could have compelling applications in the field of hydraulics and coastal engineering. As an example, for long distance propagation of landslide tsunami in fjords, travel-times and maximum wave heights can be rapidly estimated from one-dimensional governing equations, making the present theory suitable for warning systems