2D Wave setup behind submerged breakwaters

In addition to reducing the incoming wave energy, submerged breakwaters also cause a setup of the sea level in the protected area, which is relevant to the whole shadow zone circulation, including alongshore currents and seaward flows through the gaps. This study examines such a leading hydraulic parameter under the simplified hypothesis of 2D motion and presents a prediction model that has been validated by a wide ensemble of experimental data. Starting from an approach originally proposed by Dalrymple and Dean [(1971). Piling-up behind low and submerged permeable breakwaters. Discussion note on Diskin et al. (1970). Journal of Waterways and Harbors Division WW2, 423–427], the model splits the rise of the mean water level into two contributions: one is due to the momentum flux release forced by wave breaking on the structure, and the other is associated with the mass transport process. For the first time, the case of random wave trains has been explicitly considered.     

Atmospheric-induced variability of hydrological and biogeochemical signatures in the NW Alboran Sea. Consequences for the spawning and nursery habitats of European anchovy

The north-western Alboran Sea is a highly dynamic region in which the hydrological processes are mainly controlled by the entrance of the Atlantic Jet (AJ) through the Strait of Gibraltar. The biological patterns of the area are also related to this variability in which atmospheric pressure distributions and wind intensity and direction play major roles. In this work, we studied how changes in atmospheric forcing (from high atmospheric pressure over the Mediterranean to low atmospheric pressure) induced alterations in the physical and biogeochemical environment by re-activating coastal upwelling on the Spanish shore. The nursery area of European anchovy (Engraulis encrasicolus) in the NW Alboran Sea, confirmed to be the very coastal band around Malaga Bay, did not show any drastic change in its biogeochemical characteristics, indicating that this coastal region is somewhat isolated from the rest of the basin. Our data also suggests that anchovy distribution is tightly coupled to the presence of microzooplankton rather than mesozooplankton. Finally, we use detailed physical and biological information to evaluate a hydrological-biogeochemical coupled model with a specific hydrological configuration to represent the Alboran basin. This model is able to reproduce the general circulation patterns in the region forced by the AJ movements only including two variable external forcings; atmospheric pressure over the western Mediterranean and realistic wind fields.     

Justifying non-compliance: The morality of illegalities in small scale fisheries of Lake Victoria,East Africa

The literature on compliance in small scale fisheries provides evidence of the normative foundations of fishers’ behaviour. However, the mechanisms through which normative reasoning translates into non-compliance remains unclear due to the tendency to conceive non-compliant behaviour simply as an outcome of ‘moral deficit’. This paper identifies such mechanisms by focusing on moral reasons which undermine the legitimacy of fisheries regulations. Taking the case of Lake Victoria, East Africa, the paper explores how non-compliance can be founded on diverse and competing concepts of fairness by creating a typology of the modes of justification used by respondents who engage in illegal fishing. The paper establishes four areas of justification: the principle of superfluousness, the principle of autonomy, the principle of futility, and the principle of necessity. Investigating the evidence for each, the analysis finds that the majority of fisherfolk believe that regulations are necessary and support government action in fisheries management. However, fishers expressed futility in fishing legally, given the extent of illegal fishing, and justified their non-compliant behaviour through reference to the cost of legal fishing compared to illegal and the need for better catches and income associated with illegal fishing.     

Towards the economic viability of local seafood programs: Key features for the financial performance of community supported fisheries

Community supported fishery (CSF) programs are emerging as appealing alternatives to large-scale industrial fisheries for some seafood consumers and commercial fishers. While CSFs provide many social, economic, and environmental benefits to their local communities, the associated financial costs can make it difficult for such programs to remain solvent. The goal of this research was to identify specific features that influence the financial performance of CSF programs. Using data collected online and from surveys of past and current North American CSFs, this research identified a combination of three key features associated with positive profit margins: engaging in social media, offering a retail option, and having a fisher as a founding member. The potential reasons behind the influence of these features on financial performance is explored, and recommendations for how they can be incorporated into CSF programs are presented. It is hoped that through integrating these features, prospective and currently operating CSFs could potentially improve their long-term financial performance, enabling them to focus on their non-financial goals and increase their overall economic viability.     

Social and ecological constraints on decision making by transhumant pastoralists: a case study from the Moroccan Atlas Mountains

Transhumant pastoralism is an important activity in southern Morocco. Migration pattern of transhumant pastoralists can be affected by physical factors (e.g. droughts and diseases) or socioeconomic factors (e.g. schooling options for children and migration costs). We studied the spatio-temporal rangeland usage of the three tribes Ait Mgoun, Ait Zekri, and Ait Toumert in the south-central Atlas region with a two-fold approach. First, we tracked the migration movements of one representative transhumant herd using the Advanced Research and Global Observation Satellite (ARGOS) collars, which record coordinates from satellite signals. Second, we interviewed herders to obtain information about general grazing practices of the respective tribe and to gain more direct information on motivations underlying decisions. For each tribe we observed small-, medium- and large-scale movements. We found that the most important drivers of migration decisions were seasonal fodder availability and weather conditions in combination with herd-specific risk and cost assessment, as well as personal factors. In conclusion, general migration patterns vary in time, both between and within the tribes, but according to a regulatory framework. Moreover, it appears that both the customary rules and its flexible adaptation to physical constraints are generally beneficial in terms of conservation of the arid and semiarid rangeland resources.     

Natural hazard impacts in small island developing states: A review of current knowledge and future research needs

Small island developing states (or SIDS) are exposed to a large number of natural hazards and many characteristics of small island developing states make them particularly vulnerable to the impacts of natural hazards. In spite of this acknowledged vulnerability, there are relatively few studies which focus on the impacts of natural hazards in these countries. This paper presents a review of our current state of knowledge of impacts in small island developing states and highlights a number of research needs. Central to these is the need to integrate natural hazards research within a sustainable development context and the need to exploit existing procedures such as government coordinated disaster impact assessments to generate a detailed understanding of natural hazards impacts.     

Study on the Anomaly of Small Earthquake Activity Before Moderate-strong Earthquake in the Northeast Margin of the Qinghai- Xizang （Tibet） Block

26 earthquakes with MS ≥5. 0 have been recorded in the northeast margin of the Qinghai- Xizang (Tibet) block since 1980,22 of which were relatively independent of other moderate- strong earthquakes. Research on the increase of small earthquake activity before the 22 moderate-strong earthquakes has indicated that small earthquake activity was enhanced before 17 of the moderate-strong earthquakes. Though the increased seismicity is a common phenomenon in the northeast margin of the Qinghai-Xizang ( Tibet ) block,we have difficulty in predicting the moderate-strong earthquakes by this phenomenon. In order to predict the moderate-strong earthquakes through the increased seismicity of small earthquakes,this paper attempts to propose a new method, which calculates small earthquake frequency through the change of distribution pattern of small earthquakes, based on the characteristics of small earthquake activity in the northeastern Qinghai-Xizang (Tibet) block,and then make primary applications. The result shows that we are able to obtain obvious anomalies in the frequency of small earthquakes before moderate strong earthquakes through the new method,with little spatial range effect on the amplitude of this small earthquake frequency anomaly. We can obtain mid to short-term anomaly indices for moderate-strong earthquakes in the northeast margin of the Qinghai-Xizang (Tibet) block.     

小型水库集约化养鱼技术研究

江苏省瓦沟水库和石山头水库,面积为8.9和17.3hm~2,1984年起分别进行集约化养鱼试验。内容是改革我国传统的水库养鱼方式,设计多种混放密养的养殖模式,增加外源性饵料,改善水库饵料基础,加大鱼种放养规格,缩短饲养周期,实行库湾、池塘等多种培育鱼种形式,实现鱼种自给,开展网箱养鱼,设置网箱簖进行轮捕,饲养家禽家畜,种植青绿饲料,注重综合养鱼。试验结果每公顷鱼产量,瓦沟水库由试验前(1983年)每公顷195kg至1986年达4176kg;石山头水库由1984年的86kg至1989年增加至7822kg,公顷渔业利润为10140元。现这项技术已在江苏省51座小型水库中推广应用。     

天山南坡小尤尔都斯盆地表土孢粉初步研究

通过天山中部小尤尔都斯盆地南北方向采集的27个表土样品的孢粉分析, 探讨了孢粉和植被带的关系及盆地中美天鹅湖的孢粉来源问题. 结果表明: 孢粉组合主要成分是云杉属、 菊科、 禾本科、 蒿属、 藜科、 唐松草属、 莎草科、 水龙骨和其他蕨类孢子, 表土孢粉组合与各植被带之间有良好的对应关系.主成分分析表明, 研究区植被分布主要受温度因素控制. 上升气流和水流是影响针叶林带云杉属花粉传播的主要因素, 由山谷风从巩乃斯云杉林带来的云杉花粉受到美天鹅湖北侧小山阻挡, 沉降在湖泊以南的山坡上, 之后随降雨和雪山融水进入美天鹅湖. 大部分表土孢粉属种的空间分布与相应的植物分布一致, 而蒿属和藜科花粉百分含量在一定程度上代表了区域花粉雨的信号, 利用A/C比值重建古环境时须要谨慎.蒿、 藜花粉计数较少时, A/C比值波动较大, 计数值大于约280粒时, A/C比值趋于稳定.     

Hydrodynamics and sediment-transport in the nearshore of Poverty Bay, New Zealand: Observations of nearshore sediment segregation and oceanic storms

Nearshore regions act as an interface between the terrestrial environment and deeper waters. As such, they play important roles in the dispersal of fluvial sediment and the transport of sand to and from the shoreline. This study focused on the nearshore of Poverty Bay, New Zealand, and the processes controlling the dispersal of sediment from the main source, the Waipaoa River. Hydrodynamics and sediment-transport in water shallower than 15 m were observed from April through mid-September 2006. This deployment afforded observations during 3-4 periods of elevated river discharge and 5 dry storms.Similar wind, river discharge, wave, current, and turbidity patterns were characterized during three of the wet storms. At the beginning of each event, winds blew shoreward, increasing wave heights to 2-3 m within Poverty Bay. As the cyclonic storms moved through the system the winds reversed direction and became seaward, reducing the local wave height and orbital velocity while river discharge remained elevated. At these times, high river discharge and relatively small waves enabled fluvially derived suspended sediment to deposit in shallow water. Altimetry measurements indicated that at least 7 cm was deposited at a 15 m deep site during a single discharge event. Turbidity and seabed observations showed this deposition to be removed, however, as large swell waves from the Southern Ocean triggered resuspension of the material within three weeks of deposition. Consequently, two periods of dispersal were associated with each discharge pulse, one coinciding with fluvial delivery, and a second driven by wave resuspension a few weeks later. These observations of nearfield sediment deposition contradict current hypotheses of very limited sediment deposition in shallow water offshore of small mountainous rivers when floods and high-energy, large wave and fast current, oceanic conditions coincide.Consistently shoreward near-bed currents, observed along the 10 m isobath of Poverty Bay, were attributed to a combination of estuarine circulation, Stokes drift, and wind driven upwelling. Velocities measured at the 15 m isobath, however, were directed more alongshore and diverged from those at the 10 m isobath. The divergence in the currents observed at the 10 and 15 m locations seemed to facilitate segregation of coarse and fine sediment, with sand transported near-bed toward the beach, while suspended silts and clays were exported to deeper water.