Application of a coupled discontinuous–continuous Galerkin finite element shallow water model to coastal ocean dynamics

A coupled discontinuous–continuous Galerkin (DG–CG) shallow water model is compared to a continuous Galerkin generalized wave-continuity equation (GWCE) based model for the coastal ocean, whereby local mass imbalance typical of GWCE-based solutions is eliminated using the coupled DG–CG approach. Two mass imbalance indicators for the GWCE-based model are presented and analyzed. The indicators motivate discussion on the suitability of using a GWCE-based model versus the locally conservative coupled DG–CG model. Both realistic and idealized test problems for tide, wind, and wave-driven circulation form the basis of the study. For the problems studied, coupled DG–CG solutions retain the robustness of well-documented solutions from GWCE-based models and also capture the dynamics driven by small-scale, highly advective processes which are problematic for GWCE-based models. Issues associated with the coupled DG–CG model are explored, including increased cost due to increased degrees of freedom, the necessary application of slope limiters, as well as the actual coupling process.     

A global synthesis of the economic multiplier effects of marine sectors

As competition for use of the ocean increases, coastal managers must consider the economic impacts of competing marine sectors in decision-making processes. To capture the full extent of the economic impacts of marine industries, multiplier values can be used to estimate the sum of direct, indirect, and induced effects on associated industries. This study provides a global synthesis of multiplier effects on four economic indicators of eight marine sectors in regions of varying size and development status. The average multiplier was 1.82, indicating that every dollar generated by a direct marine industry leads to an additional 82 cents generated by associated industries. The industry of offshore energy and the economic indicator of revenue had the largest multiplier effects. No significant difference was found between multiplier values in developed and developing regions, and weak correlations were found between multiplier value and region size. This synthesis offers the first global view of the economic multiplier effects of marine industries and can serve as a tool to support city- to country-level marine industry development decisions throughout the world, especially where similar data are not available.     

Magnetite/Ilmenite–series Classification and Magnetic Susceptibility of the Mesozoic-Cenozoic Batholiths in Peru

Abstract: Plutonic rocks of the Coastal Batholith of Peru were evaluated in terms of the granitoid-series classification using the bulk ferric/ferrous ratio from the literature and new measurements of magnetic susceptibility. The batholith is largely composed of magnetite-series plutonic rocks; the magnetite series make up 85% by number of chemical analyses (n=130) and 80% by measurement of magnetic susceptibility (n=210). The ilmenite-series rocks are mostly found in the felsic facies of the batholith. Asymmetrical distribution of magnetic susceptibility is not clear as in the Japanese Islands and Peninsular Range Batholith, but the magnetic susceptibility may decreases continentward (i. e., Peninsular Range type).
The Cordillera Blanca Batholith and stocks are also composed of mainly magnetite series plutonic rocks, but ilmenite-series rocks may be more predominant than in the Coastal Batholith, which is also indicated by the presence of Sn and W mineralizations.     

Satellite monitoring of spatio-temporal dynamics of China’s coastal zone eco-environments: preliminary analysis on the relationship between the environment,climate change and human behavior

In this paper, temporal dynamics of eco-environmental changes in coastal areas of China during 1981–2000 are investigated based on four key surface parameters including normalized difference vegetation index (NDVI), thermal index, moisture index and surface broadband albedo derived from quantitative remote sensing techniques and meteorological data. Firstly, land surface temperature (LST) and land surface broadband albedo are retrieved by the split-window algorithms and high-order polynomial regression method, respectively, using NOAA/AVHRR series images. Then, moisture index and thermal index, indicators of climate and moisture conditions in the study area, are computed from meteorological data and LST using principal component analysis (PCA). Finally, long-term dynamics of these eco-environmental factors and the reasons responsible for these changes are analyzed further. The results show that during the years from 1981 to 2000, the study area experienced a gradual increase in annual NDVI and climate factors and a decrease in surface annual broadband albedo, which indicates that the coastal thermal and moisture conditions and the subsistence conditions of natural vegetation have changed to a considerable extent. According to the results, a warming and wetting tendency over the last two decades is obvious in the China’s coastal zone that are mainly due to land use changes as of growing urbanization, exhaust emissions from industries and transportations and, partly global climate change. Uncontrolled rapid development of the study area may be blamed for these negative changes as a major driving force. The positive feedback mechanisms between albedo, NDVI and climate factors also partly explain these changes. This study suggests that the method integrating biophysical parameters retrieved from remote sensed images and meteorologic data provides a novel and feasible way to monitor large scale eco-environmental changes.

Development of a sharp interface model that simulates coastal aquifer flow with the coupled use of GIS

A simulation program, which works seamlessly with GIS and simulates flows in coastal aquifers, is presented in the present paper. The model is based on the Galerkin finite element discretization scheme and it simulates both steady and transient freshwater and saltwater flow, assuming that the two fluids are separated by a sharp interface. The model has been verified in simple cases where analytical solutions exist. The simulation program works as a tool of the GIS program, which is the main database that stores and manages all the necessary data. The combined use of the simulation and the GIS program forms an integrated management tool offering a simpler way of simulating and studying saline intrusion in coastal aquifers. Application of the model to the Yermasogia aquifer illustrates the coupled use of modeling and GIS techniques for the examination of regional coastal aquifer systems.

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Resumen Se ha desarrollado un modelo casi tridimensional de elementos finitos para simular el flujo de agua dulce y salada, tanto en régimen estacionario como en transitorio, en sistemas acuíferos costeros, bajo la hipótesis de separación por medio de una interfaz abrupta. Las ecuaciones del modelo han sido discretizadas mediante un esquema de Galerkin de discretización en elementos finitos. El modelo ha sido verificado en casos sencillos para los que existe solución analítica. Todos los datos necesarios se introducen y gestionan con un Sistema de Información Geográfica [SIG] por ordenador. El programa de simulación forma parte del programa de SIG, constituyendo una herramienta integrada de gestión para estudiar la intrusión salina en acuíferos costeros. La aplicación del modelo al acuífero de Yermasogia ilustra el uso acoplado de las técnicas de modelación y de SIG con el fin de examinar sistemas acuíferos costeros a escala regional.

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Résumé Pour étudier un système aquifère côtier, nous avons développé un modèle aux éléments finis en quasi 3-D qui simule les écoulements deau douce et deau salée en régime aussi bien permanent que transitoire. Les équations qui les régissent sont discrétisées par un schéma de discrétisation de Garlekin aux éléments finis. Le modèle a été vérifié dans des cas simples où il existe des solutions analytiques. Toutes les données nécessaires sont introduites et gérées grâce à un logiciel de gestion de SIG. Le programme de simulation est utilisé comme un outil du logiciel de SIG, constituant ainsi un outil de gestion intégrée dont le but est de simuler et détudier lintrusion saline dans les aquifères côtiers. Lapplication du modèle à laquifère de Yermasogia illustre lutilisation couplée de la modélisation et des techniques de SIG pour létude des systèmes aquifères côtiers régionaux.

     

The use of geoprocessing to assess vulnerability on the east coast aquifers of Rio de Janeiro State,Brazil

The east coast of Rio de Janeiro State, Brazil, shows a worrying overlap between areas with intrinsic groundwater vulnerability and the most significant urban expansion zones. It experienced a rapid population growth in recent years, mainly due to the tourism industry, resulting in a significant pressure on drinking groundwater resources. In this regard, development and use of techniques to control and protect areas susceptible to contamination is crucial. The elaboration of aquifer vulnerability maps is thus extremely helpful to support water resources management. The aim of the work is to present the methodological approach in the use of Geoprocessing techniques to obtain a suitable groundwater vulnerability model in Rio de Janeiro east coast. Considering the existing problems and the current land use and characteristics of the study region, it is clear that the most vulnerable areas (that is, “extreme” and “very high” vulnerability areas), coincide with the most significant zones of urban occupation, corresponding to 11% of the total study area, demanding adoption of urgent measures in the near future. Geoprocessing tools and remote sensing for characterization of Rio de Janeiro’s east coast aquifer vulnerability gave good results, representing a satisfactory method for management actions at low cost.     

Karst groundwater resources in the countries of eastern Mediterranean: the example of Lebanon

The hydrogeological study of some karst systems in Lebanon shows important storage capacity, up to 27 billions m³ for Zarka system, the spring of Orontes River. Their geological and morphological settings, as well as their hydrodynamic function, show structures developed below the level of present springs, probably up to several hundreds meters at depth. Since Miocene, those carbonate formations were subject to a remarkable instability of their base levels. Variations of sea level, of which the Messinian salinity crisis is the major phase, and effects of the alpine orogenesis, combined with climate variations to develop complex, multiphased karst systems. Karstification occurs frequently in the whole formation, often deeply below sea level or underneath sediment filling of continental basins. The surface karst landscape is often intensely eroded. Those multiple, superimposed karst phases give the carbonate aquifers their large extension and storage capacity. These karst aquifers show the typical easy restoration of storage. They have the ability to bear large interannual recharge variations and support exploitation under high pumping rates. However, these aquifers have some disadvantages for sustainable management. In some regions, successful boreholes, which allow high pumping rates also induce uncontrolled exploitation. Another consequence is natural seawater intrusion, as well as the submarine discharge of fresh groundwater, in coastal aquifers. Those carbonate aquifers are subject to important economical stress which jeopardizes their durability. The systematic study and understanding of carbonate aquifers in Eastern Mediterranean is a preliminary condition to any integrated and sustainable management of water resources. Studies in progress in Lebanon may serve as examples to the whole region.     

Modelling the formation of residual dune ridges behind barchan dunes in North-east Brazil

Residual dune ridges are often formed by vegetation growing along a line some distance upwind of the lower stoss slope of migrating dunes. This process is common in areas where vegetation germinates along the edge of the water during the rainy period when the water level is higher and interdune areas are flooded. The phenomenon occurs on a large scale in North‐east Brazil, because of the rise and fall in groundwater level at the end of the rainy season. Each residual dune ridge corresponds to the position of the dune during the wet period in each year. Therefore, variations in the distance between these residual dune ridges could be used potentially to monitor climatic fluctuations in rainfall and wind. To examine the potential use of these residual dune ridges for the reconstruction of past climatic fluctuations, a model that simulates them under varying conditions of wind, rainfall and evaporation rates was formulated. The model was tested for sensitivity to climatic variability in North‐east Brazil and validated against residual dune ridge displacements as measured in the field and from high spatial resolution satellite images. Based on the results, it is concluded that residual dune ridges may not form in North‐east Brazil in years which are exceptionally dry, as may happen during El‐Niño events. When this type of event happens, the distance between adjacent residual dune ridges corresponds to more than one year and, therefore, the correlation between dune displacements and wind power becomes weak or even disappears. Additionally, because of biotic, aeolian and hydrological processes, these arcuate residual dune ridges may not preserve their initial shape for long periods. The presence of residual dune ridges testifies to the temporary flooding which may or may not be seasonal. However, the potential for using residual dune ridges to reconstruct the palaeo‐climate of wind regime on a yearly basis or to identify past El‐Niño events seems to be limited.     

Holocene geoarchaeology of the Sixteen Mile Beach barrier dunes in the Western Cape, South Africa

Holocene evolution and human occupation of the Sixteen Mile Beach barrier dunes on the southwest coast of South Africa between Yzerfontein and Saldanha Bay are inferred from the radiocarbon ages of calcareous dune sand, limpet shell (Patella spp.) manuports and gull-dropped white mussel shells (Donax serra). A series of coast-parallel dunes have prograded seaward in response to an overall marine regression since the mid-Holocene with dated shell from relict foredunes indicating periods of shoreline progradation that correspond to drops in sea level at around 5900, 4500 and 2400 calibrated years before the present (cal yr B.P.). However, the active foredune, extensively covered by a layer of gull-dropped shell, has migrated 500 m inland by the recycling of eroded dune sand in response to an approximate 1 m sea level rise over the last 700 yr. Manuported limpet shells from relict blowouts on landward vegetated dunes indicate human occupation of coastal dune sites at 6200 and 6000 cal yr B.P. and help to fill the mid-Holocene gap in the regional archaeological record. Coastal midden shells associated with small hearth sites exposed in blowouts on the active foredune are contemporaneous (1600-500 cal yr B.P.) with large midden sites on the western margin of Langebaan Lagoon and suggest an increase in marine resource utilisation associated with the arrival of pastoralism in the Western Cape.     

广州南部滨海地区工程地质问题及对策

松软土地基、活动断裂、砂土液化和海水入侵是滨海城市普遍存在的主要工程地质问题。对广州南部地区这四种问题进行深入地研究,绘制广州南部工程地质专题分区图。对滨海城市建设可能引发的工程地质问题进行评价和分析,并提出相应对策。