Prototype measurements and small-scale model tests of wave overtopping at shallow rubble-mound breakwaters: the Ostia-Rome yacht harbour case

The paper presents the comparison between the results of small-scale model tests and prototype measurements of wave overtopping at a rubble-mound breakwater. The specific structure investigated is the west breakwater of the yacht harbour of Rome at Ostia (Italy) and is characterized by a gentle seaward slope (1/4) and by a long, shallow foreshore. The laboratory tests firstly aimed at carefully reproducing two measured storms in which overtopping occurred and was measured. The tests have been carried out in two independent laboratories, in a wave flume and in a wave basin, hence using a two-dimensional (2-D) and a three-dimensional (3-D) setup. In the 2-D laboratory tests no overtopping occurred during the storm reproductions; in the 3-D case discharges five to ten times smaller than those observed in prototype have been measured. This indicates the existence of model and scale effects. These effects have been discussed on the basis of the results of several parametric tests, which have been carried out in both laboratories, in addition to the storm reproductions, varying wave and water level characteristics. Final comparison of all the performed tests with 86 prototype measurements still suggests the existence of scale and model effects that induce strong underestimation of overtopping discharge at small scale. The scale reproduction of wave breaking on the foreshore, together with the 3-D features of the prototype conditions and the absence of wind stress in the laboratory measurements, have been individuated as the main sources of scale and model effects. The paper also provides a comparison between the data and a largely used formula for wave overtopping discharges in the presence of structures similar to the one at hand. The suitable value of a roughness factor that appears in that formula is investigated and good agreement is found with other recent researches on rubble-mound breakwaters.     

威海市刘公岛地热地质特征

通过对刘公岛地热资源地质勘查,区内岩浆活动强烈,断裂切割深度大,破碎宽度大,有一定汇水区的局部地温异常区,具备形成地热的条件。刘公岛地热温泉属于温热水型低温地热资源,其水质属于锶型低温温水型矿水,适宜洗浴、理疗、保健,可与刘公岛旅游资源开发密切结合。     

山东省矿产资源的可持续利用概要

山东是矿业大省,矿产地质工作程度较高,但在国民经济中占有重要位置的４５ 种主要矿产仅有８ 种能满足２０１０ 年本省经济建设的需求。针对矿产资源勘查、开发存在的主要问题,提出了全省矿产资源可持续利用战略目标及相应的对策建议     

山东省矿产资源开发利用现状与保护对策探讨

山东是矿业大省,矿产资源的开发程度较高,但也存在着不容忽视的问题。针对产生这些问题的原因,提出了实现矿产资源可持续开发利用的六项建议,强调应从增强矿产资源的忧患意识、保护生态环境、加强矿产勘查、强化政府管理职能及依靠科技进步等方面加大工作力度。     

青岛市水环境问题及防治对策

青岛是我国缺水城市之一。但本已紧缺的水资源却存在着水质污染、开采漏斗、海（咸）水入侵及高氟水等一系列水环境问题。文中分析了其发生原因、危害程度及发展趋势,并提出了综合治理建议。     

Errors and correction of precipitation measurements in China

In order to discover the range of various errors in Chinese precipitation measurements and seek a correction method, 30 precipitation evaluation stations were set up countrywide before 1993. All the stations are reference stations in China. To seek a correction method for wind-induced error, a precipitation correction instrument called the ＂horizontal precipitation gauge＂ was devised beforehand. Field intercomparison observations regarding 29,000 precipitation events have been conducted using one pit gauge, two elevated operational gauges and one horizontal gauge at the above 30 stations. The range of precipitation measurement errors in China is obtained by analysis of intercomparison measurement results. The distribution of random errors and systematic errors in precipitation measurements are studied in this paper. A correction method, especially for wind-induced errors, is developed. The results prove that a correlation of power function exists between the precipitation amount caught by the horizontal gauge and the absolute difference of observations implemented by the operational gauge and pit gauge. The correlation coefficient is 0.99. For operational observations, precipitation correction can be carried out only by parallel observation with a horizontal precipitation gauge. The precipitation accuracy after correction approaches that of the pit gauge. The correction method developed is simple and feasible.     

Transpiration and plant water relations of evergreen woody vegetation on a recently constructed artificial ecosystem under seasonally dry conditions in Western Australia

Understanding transpiration and plant physiological responses to environmental conditions is crucial for the design and management of vegetated engineered covers. Engineered covers rely on sustained transpiration to reduce the risk of deep drainage into potentially hazardous wastes, thereby minimizing contamination of water resources. This study quantified temporal trends of plant water potential (ψ_p), stomatal conductance (g_s), and transpiration in a 4‐year‐old evergreen woody vegetation growing on an artificial sandy substrate at a mine waste disposal facility. Transpiration averaged 0.7 mm day^?1 in winter, when rainfall was frequent, but declined to 0.2 mm day^?1 in the dry summer, when the plants were quite stressed. In winter, the mean ψ_p was ?0.6 MPa at predawn and ?1.5 MPa at midday, which were much higher than the corresponding summer values of ?2.0 MPa and ?4.8 MPa, respectively. The g_s was also higher in winter (72.1–95.0 mmol m^?2 s^?1) than in summer (<30 mmol m^?2 s^?1), and negatively correlated with ψ_p (p < 0.05, r² = 0.71–0.75), indicating strong stomatal control of transpiration in response to moisture stress. Total annual transpiration (147.2 mm) accounted for only 22% of the annual rainfall (673 mm), compared with 77% to 99% for woody vegetation in Western Australia. The low annual transpiration was attributed to the collective effects of a sparse and young vegetation, low moisture retention of the sandy substrate, and a superficial root system constrained by high subsoil pH. Amending the substrate with fine‐textured materials should improve water storage of the substrate and enhance canopy growth and deep rooting, while further reducing the risk of deep drainage during the early stages of vegetation establishment and in the long term. Overall, this study highlights the need to understand substrate properties, vegetation characteristics, and rainfall patterns when designing artificial ecosystems to achieve specific hydrological functions. Copyright © 2011 John Wiley & Sons, Ltd.     

A mixing-length model for predicting vertical velocity distribution in flows through emergent vegetation

Abstract

The vertical profiles of streamwise velocities are computed on flood plains vegetated with trees. The calculations were made based on a newly developed one-dimensional model, taking into account the relevant forces acting on the volumetric element surrounding the considered vegetation elements. A modified mixing length concept was used in the model. An important by-product of the model is the method for evaluating the friction velocities, and consequently bed shear stresses, in a vegetated channel. The model results were compared with the relevant experimental results obtained in a laboratory flume in which flood plains were covered by simulated vegetation.     

西藏地热事业的喜悦与隐忧

联合国开发计划署和意大利政府最近准备再度资助西藏地热的二期项目,中国地球物理学界对此表示极大的关注。西藏高原的地热现象早就引起中外科学家的注意,最早的文字记载可以追溯到七世纪中叶,但到本世纪70年代初才提到地热发电利用。中国地球物理学界和地质学界对这一转变作出了巨大贡献。他们坚持认为西藏高原上地幔或下地壳内很可能存在局部熔融,这就为浅部的水热活动提供了深源热背景,并意味当地的地热资源具有巨大的动力开发潜力。西藏羊八井地热电站目前的装机容量已经达到16MWe,其北缘和邻近的羊易乡热田又分别钻探到202.2℃和201.8℃的高温;但是当前的西藏地热事业也存在许多隐忧。作者认为这些问题不解决,西藏地热事业便很难得到快速进展。     

Induced gravity anomalies and seismic energy as a basis for prediction of mining tremors

The results of prediction of occurrence of mining tremors and bursts in the course of the exploitation of the remaining part of the hard coal in seam 510 of the mine Pstrowski, Upper Silesia, have been presented in the paper. The exploitation has taken place under extremely difficult conditions hazardous for the mining crew.To predict the occurrence of mining tremors, bursts and direction of migration of increased elastic strain in the rock mass, the microgravity method has been applied.The microgravity observations were carried out in the measurement points located at mutual distances equal 20 m in three profiles of the lengths 700 m, 760 m and 260 m respectively. The profiles were located in mining workings in the vicinity of the exploited part of the bed. In the course of exploitation, lasting 25 months, 29 series of measurements including 3600 individual microgravity observations were carried out. Microgravity observations were made with a Worden-Master gravimeter.The observed time changes of gravity microanomalies were essential for prediction. Local negative changes of gravity microanomalies signalled the approaching mining tremor. The tremor would cover an area of the radius 60 m to 100 m. The regional time changes of the gravity microanomalies appearing as linear trends of these anomalies signalled the development of the fields of elastic strain in the whole investigated area and the approaching violent release of elastic strain energy from the rock mass.The values of the amplitudes AMP of the above-mentioned trend were the measure of this hazard. In the course of the investigations each shock was preceded by considerably increased values of AMP.