The impact of internal waves on upper continental slopes: insights from the Mozambican margin (southwest Indian Ocean)     

Elda Miramontes  Gwenael Jouet  Estelle Thereau  Miguel Bruno  Pierrick Penven  Charline Guerin  Pascal Le Roy  Laurence Droz  Stephan J. Jorry  F. Javier Hernández-Molina  Antoine Thiéblemont  Ricardo Silva Jacinto  Antonio Cattaneo 《地球表面变化过程与地形》2020,45(6):1469-1482

Evidences of sedimentation affected by oceanic circulation, such as nepheloid layers and contourites are often observed along continental slopes. However, the oceanographic processes controlling sedimentation along continental margins remain poorly understood. Multibeam bathymetry and high-resolution seismic reflection data revealed a contourite depositional system in the Mozambican upper continental slope composed of a contourite terrace (a surface with a gentle seaward slope dominated by erosion) and a plastered drift (a convex-shape sedimentary deposit). A continuous alongslope channel and a field of sand dunes (mainly migrating upslope), formed during Holocene, were identified in the contourite terrace at the present seafloor. Seismic reflection data of the water column show internal waves and boluses propagating in the pycnocline near the upper slope. The channel and the dunes are probably the result of the interaction of the observed internal waves with the seafloor under two different conditions. The alongslope channel is located in a zone where intense barotropic tidal currents may arrest internal solitary waves, generating a hydraulic jump and focused erosion. However, upslope migrating dunes may be formed by bottom currents induced by internal solitary waves of elevation propagating landwards in the pycnocline. These small-scale sedimentary features generated by internal waves are superimposed on large-scale contouritic deposits, such as plastered drifts and contourite terraces, which are related to geostrophic currents. These findings provide new insights into the oceanographic processes that control sedimentation along continental margins that will help interpretation of palaeoceanographic conditions from the sedimentary record. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd  相似文献   

Eco-districts in France: What tools to ensure goals achievement?     

Boquet  Kathleen  Froitier  Charline  Li  Jinhui  Xu  Kaihua  Zeng  Xianlai 《中国科学:地球科学(英文版)》2020,63(6):865-874

Globally, to build cities and communities more inclusive, safe, resilient and sustainable is one of the most important sustainable development goals. Eco-districts in cities emerged as an answer to current global environmental concerns and have been developed in France since the 1990s. The objective of this work is to gather operational feedback from sustainable neighborhood projects owners to better understand the key barriers of such projects and how to overcome them. A case study of the eco-district Les Tanneries, Lingolsheim showed that the carbon footprint of each inhabitant annually amounted to 4 tons CO_2 equivalent, more than half of the French average. Rooms for improvements were clearly identified regarding transports and food carbon footprint. Indicators for energy consumption, social diversity and density reached the level of the eco-districts average. A governance review pointed out some superior practices such as the formalization of a specification requirements handbook, a competition between project management teams, and the use of neighborhood sustainability assessment tools to measure and track changes in performance. The validated tools and obtained results can be useful in building sustainable cities and even China's ecological civilization.  相似文献