太湖水体3种典型水质参数的高光谱遥感反演

以富营养化污染严重的太湖为研究区,设计并实施了2次太湖航空遥感综合实验,获取了太湖7条航带、冬夏两个时相的航空高光谱遥感图像;通过6次太湖地面试验,采集了多时相的太湖水体固有光学量和表观光学量数据,分析了它们的空间分布规律,建立了单化固有光学量数据库;面向叶绿素、悬浮物和黄色物质3种典型水质参数,发展了基于生物光学模型和单位固有光学量数据库的水质参数反演分析方法;利用航空高光谱遥感器Will图像和航天高光谱遥感器CHRIS图像对这些方法进行了检验,获得了较好的水质参数图像反演结果.     

Numerical simulation of the landslide-induced tsunami of 1988 on Vulcano Island, Italy

 On 20 April 1988 a landslide of approximately 200,000 m³ occurred on the northeastern flank of the volcano La Fossa on the island of Vulcano. The landslide fell into the sea, producing a small tsunami in the bay between Punte Nere and Punta Luccia that was observed locally in the neighbouring harbour called Porto Levante. The slide occurred during a period of unrest at the volcano that was monitored very accurately. The study of this event is composed of two parts, the simulation of the landslide and the simulation of the ensuing tsunami; the former is studied by means of a Lagrangian-type numerical model in which the landslide is seen as a multibody system, an ensemble of material-deforming blocks interacting together during their motion; the latter is simulated according to the Eulerian view by solving the shallow-water approximation to Navier-Stokes equations of fluid dynamics, with the incorporation of a forcing term depending on the slide motion. Technically, the slide evolution is computed first, and this result is then used to evaluate the excitation term of the hydraulic equations and to calculate the tsunami propagation. Computed wave fronts radiate both toward the open sea, with rapid amplitude decay, and along the shore, in the form of edge waves that lose energy slowly. Comparison between model outputs and observations can be carried out only in a qualitative way owing to the absence of tide-gauge records, and results are satisfactory. Received: 14 September 1998 / Accepted: 18 December 1998     

Spatial foundation structures over no tension soil

The problem of the stress distribution induced in the soil by a single circular foundation structure is approached in a three‐dimensional analysis. Since the soil is typically made by not‐cohesive materials, its behaviour is modelled by means of the not resisting tension (NRT) hypothesis, thus assuming that its very low resistance to tensile stresses can be completely neglected and that it keeps linearly elastic under pure compression. After developing the problem from a theoretical point of view on the basis of an energetic approach, a numerical application—which is able to reproduce the stress distribution induced by a circular foundation on the soil—is performed. Copyright © 2005 John Wiley & Sons, Ltd.     

Origin and type of rainfall for recharge of a karstic aquifer in the western Mediterranean: a case study from the Sierra de Gador–Campo de Dalias (southeast Spain)

Isotope signatures in precipitation from the Global Network for Isotopes in Precipitation around the Mediterranean basin and literature data are compared with isotopic data from a large karstic aquifer in southeast Spain to explain the origin and type of the precipitation events dominating recharge. Analysis of the deuterium excess d at the scale of the Mediterranean basin and at the regional scale allows us to understand the isotopic context of the study area: Campo de Dalias and the Sierra de Gador (Almería province). The origin of precipitation can be determined from its d value. The d value changes as a function of the initial evaporation condition. It depends on the relative humidity and temperature during the evaporation producing the water vapour of the clouds. The water vapour, which dominates the study area, is generated in two areas: the Atlantic Ocean (d = 10‰) and the western Mediterranean basin (d = 15‰). With increasing precipitation volume, the western Mediterranean character dominates. These heavier storms contribute mainly to recharge, as illustrated by the d value of 13·6‰ in deep groundwater of the Campo de Dalias. Weighted d values increase with the volume of precipitation, giving a significant relationship for the southern and eastern coasts of the Iberian Peninsula. This selectivity of d to monthly precipitation was used to estimate the return period of precipitation leading to aquifer recharge at 0·9–4·9 years. Moderate rainfall, which occurs more frequently, still represents ～60–90% of the total precipitation. One of the challenges to meet ever‐growing water demands is to increase recharge from moderate events yielding intermediate quantities per event, but forming the bulk of the annual precipitation. Copyright © 2006 John Wiley & Sons, Ltd.     

A unified approach to the implicit integration of standard,non‐standard and viscous plasticity models

It is shown how modern concepts to integrate the elasto‐plastic rate equations of standard plasticity via an implicit algorithm can be generalized to plasticity without an explicitly defined yield surface and to overstress‐type models of viscoplasticity, where the stress point can be located outside the loading surface. For completeness, a tangent operator is derived that is consistent with the update algorithm. Copyright © 2002 John Wiley & Sons, Ltd.     

Stability of earth slopes. Part II: three dimensional analysis in closed‐form

A closed‐form stability analysis of earth slopes performed in 3D is proposed. The sliding surface is assumed spherical and treated as a rigid body allowing the internal state of stress to be ignored. The proposed closed‐formed solution (CFS) can be applied to both homogenous and non‐homogenous slopes of either simple or complex geometry and can also deal with any kind of additional loading. Although it is recognized that the critical failure surface is often non‐spherical, the CFS methodology for spheres described herein provides an objective tool for the evaluation of the assumptions made by other limit equilibrium methods including the role of intercolumn forces. Copyright © 2012 John Wiley & Sons, Ltd.     

Producing hybrid forests in the Congo Basin: A political ecology of the landscape approach to conservation

Environmental conservation is increasingly operated through partnerships among state, private, and civil society actors, yet little is known empirically about how such collectives function and with what livelihood and governance outcomes. The landscape approach to conservation (known also as the ecosystem approach) is one such hybrid governance platform. Implemented worldwide over the past decade by international NGOs, the landscape approach employs the ‘ecosystem principles’ of the Convention on Biological Diversity (CBD). In spite of its prominence as a conservation and development strategy, little political ecology scholarship has considered the landscape approach. This article offers a case study of a conservation landscape in the Congo Basin, the Tri-National de la Sangha (TNS), which connects tropical forests in Cameroon, Republic of Congo, and Central African Republic. Led by NGOs, the TNS has since 2001 relied on partnerships among logging companies, safari hunters, the state, and local communities. Although the landscape approach purports to facilitate re-negotiations of user rights, resource access patterns in the TNS appear to have molded to pre-existing power relations. Rather than incorporating local concerns and capabilities into management, local knowledge is discredited and livelihoods are marginalized. As a result, management occurs through spatially-demarcated zones, contrasting the fluidity of interactions among diverse groups: both human (loggers, hunter-gatherers, safari guides, NGOs) and non-human (trees, elephants). These findings are situated within a burgeoning literature on neoliberal environmental governance, and suggest that ensuring ecologically and socially positive outcomes will require careful and iterative attention to linkages between ecological processes and evolving power dynamics.     

A three‐dimensional micromechanically based model

Granular materials react with complicated mechanical responses when subjected to external loading paths. This leads to sophisticated constitutive formulations requiring large numbers of parameters. A powerful and straightforward way consists in developing micro‐mechanical models embedding both micro‐scale and meso‐scale. This paper proposes a 3D micro‐mechanical model taking into account an intermediate scale (meso‐scale) that makes it possible to describe a variety of constitutive features in a natural way. The comparison between experimental tests and numerical simulations reveals the predictive capability of this model. Particularly, several simulations are carried out with different confining pressures and initial void ratios, based on the fact that the critical state is quantitatively described without requiring any critical state formulations and parameter. The model mechanism is also analyzed from a microscopic view, wherein the evolution of some key microscopic parameters is investigated. Copyright © 2017 John Wiley & Sons, Ltd.     

The storage potential of different surface coverings for various scale storms on Wu-Tu watershed,Taiwan

An impervious surface cover is continuously spreading over the Wu-Tu upstream watershed due to the concentrated population and raised economical demands, while that area also frequently suffers from heavy storms or typhoons during the summer season. The increased flood volume due to this extended imperviousness causes a greater potential hazard than that of the past. In order to evaluate the urbanized impacts on the watershed, a set of methods were used to estimate the changes of the watershed storage. This research chose 51 observed events from three raingauges on the Wu-Tu upstream watershed, Taiwan, to study the volume characteristic of abstracted rainwater. In the study, the block Kriging method was used to estimate the area rainfall and the hourly excess was derived through the non-linear programing (NLP). A total of 40 samples were calibrated through the hydrological model and the Soil Conservation Service (SCS) model using the optimum seeking method in order to search out and establish the best parameters that illustrate the hydrological and geomorphic conditions at that time. Eleven cases were used to examine the established relationship of the parameters and the impervious coverings. A design storm approach was used to view the changes of the volume for various scale storms/typhoons because of the different degrees of urbanization. Then, a diagram was designed to show the relationships that exist among the runoff coefficient, return period, and impervious surface. The satisfactory results show that storage capability of rainwater for various scale storms on the Wu-Tu watershed would be respectively reduced about 42–156 cms in different decrements up to now.