Validation of methods to estimate design discharge flow rates for dam spillways with large regulating capacity

Abstract

The estimation and review of discharge flow rates in hydraulic works is a fundamental problem in water management. In the case of dams with large regulating capacity, in order to estimate return periods of discharge flow rates from the spillways, it becomes necessary to consider both peak flow and volume of the incoming floods. In this paper, the results of the validation for several methods of assessing design floods for spillways of dams with a large flood control capacity are presented; the validation is performed by comparing the maximum outflows (or the maximum levels reached in the reservoir) obtained from the routing of the design floods with those obtained from the routing of the historical annual maximum floods. The basin of Malpaso Dam, Mexico, is used as the case study.

Editor D. Koutsoyiannis

Citation Domínguez, M.R. and Arganis, J.M.L., 2012. Validation of methods to estimate design discharge flow rates for dam spillways with large regulating capacity. Hydrological Sciences Journal, 57 (3), 460–478.     

Retrowedge-related Carboniferous units and coeval magmatism in the northwestern Neuquén province, Argentina

The studied Carboniferous units comprise metasedimentary (Guaraco Norte Formation), pyroclastic (Arroyo del Torreón Formation), and sedimentary (Huaraco Formation) rocks that crop out in the northwestern Neuquén province, Argentina. They form part of the basement of the Neuquén Basin and are mostly coeval with the Late Paleozoic accretionary prism complex of the Coastal Cordillera, south-central Chile. U–Pb SHRIMP dating of detrital zircon yielded a maximum depositional age of 374?Ma (Upper Devonian) for the Guaraco Norte Formation and 389?Ma for the Arroyo del Torreón Formation. Detrital magmatic zircon from the Guaraco Norte Formation are grouped into two main populations of Devonian and Ordovician (Famatinian) ages. In the Arroyo del Torreón Formation, zircon populations are also of Devonian and Ordovician (Famatinian), as well as of Late Neoproterozoic and Mesoproterozoic ages. In both units, there is a conspicuous population of Devonian magmatic zircon grains (from 406?±?4?Ma to 369?±?5?Ma), indicative of active magmatism at that time range. The ε_Hf values of this population range between ?2.84 and ?0.7, and the TDM-(Hf) are mostly Mesoproterozoic, suggesting that the primary sources of the Devonian magmatism contained small amounts of Mesoproterozoic recycled crustal components. The chemical composition of the Guaraco Norte Formation corresponds to recycled, mature polycyclic sediment of mature continental provenance, pointing to a passive margin with minor inputs from continental margin magmatic rocks. The chemical signature of the Huaraco Formation indicates that a magmatic arc was the main provenance for sediments of this unit, which is consistent with the occurrence of tuff—mostly in the Arroyo del Torreón Formation and very scarcely in the Huaraco Formation—with a volcanic-arc signature, jointly indicating the occurrence of a Carboniferous active arc magmatism during the deposition of the two units. The Guaraco Norte Formation is interpreted to represent passive margin deposits of mostly Lower Carboniferous age (younger than 374?Ma and older than 326?Ma) that precede the onset of the accretionary prism in Chile and extend into the earliest stage of the accretion, in a retrowedge position. The Arroyo del Torreón and Huaraco formations are considered to be retrowedge basin deposits to the early frontal accretionary prism (Eastern Series) of Chile. The presence of volcanism with arc signature in the units provides evidence of a Mississippian magmatic arc that can be correlated with limited exposures of the same age in the Frontal Cordillera (Argentina). The arc would have migrated to the West (Coastal Batholith) during Pennsylvanian–Permian times (coevally with the later basal accretionary prism/Western Series). The source of a conspicuous population of Devonian detrital zircon interpreted to be of magmatic origin in the studied units is discussed in various possible geotectonic scenarios, the preferred model being a magmatic arc developed in the Chilenia block, related to a west-dipping subduction beneath Chilenia before and shortly after its collision against Cuyania/Gondwana, at around 390?Ma and not linked to the independent, Devonian–Mississippian arc, developed to the south, in Patagonia.     

Catastrophic debris flows near Machu Picchu village (Aguas Calientes), Peru

Slope movements together with intensive river erosion and the following accumulation are the leading processes in the landscape evolution in the area of Machu Picchu village (former Aguas Calientes), which is located close to the Machu Picchu Sanctuary. Debris flows affect not only the bottoms of valleys or canyons, but also debris fans at the termini of the drainage basins, which are heavily inhabited at some places. The most recent event in the Machu Picchu village occurred in April 2004, but several others were documented in a broader area in the last 50 years. The field inspections at Machu Picchu (May and September 2004; June and September 2005) together with oral testimony revealed the nature and behavior of the debris flow. Machu Picchu village can be assessed as a zone with high landslide risk in relation to its urban development. Despite that, the village recorded a rapid growth (threefold population increase) without urban control within the past two decades. Precipitation, which is the main triggering factor of the debris flows, and natural hazard management of the Machu Picchu village are discussed in this paper.     

In‐situ analysis of trace elements and Sr–Pb isotopes of K‐feldspars from Tongshankou Cu–Mo deposit,SE Hubei Province,China: Insights into early potassic alteration of the porphyry mineralization system

In the Tongshankou porphyry deposit (SE Hubei Province, South China), three types of K‐feldspars are recognized: (I) the phenocryst type in the porphyry that crystalized during the magmatic stage, (II) the megacryst type and (III) the vein type in the altered porphyry and orebody that was produced by hydrothermal fluids. A detailed in‐situ analysis of trace elements and Sr–Pb isotopes was carried out on K‐feldspars in an attempt to unravel their formation processes and to trace the element sources during potassic alteration. The Type III K‐feldspars show lower Sr contents and Sr‐isotope ratios but higher Pb contents and Pb‐isotope ratios than the Type I and II K‐feldspars, possibly reflecting a contribution from the country carbonate rocks with less radiogenic Sr but more radiogenic Pb sources, and indicate that the ore‐forming fluids and materials may have been partially derived from external sources such as the host sedimentary rocks during the early potassic alteration stage.     

Overview of integrative tools and methods in assessing ecological integrity in estuarine and coastal systems worldwide

In recent years, several sets of legislation worldwide (Oceans Act in USA, Australia or Canada; Water Framework Directive or Marine Strategy in Europe, National Water Act in South Africa, etc.) have been developed in order to address ecological quality or integrity, within estuarine and coastal systems. Most such legislation seeks to define quality in an integrative way, by using several biological elements, together with physico-chemical and pollution elements. Such an approach allows assessment of ecological status at the ecosystem level ('ecosystem approach' or 'holistic approach' methodologies), rather than at species level (e.g. mussel biomonitoring or Mussel Watch) or just at chemical level (i.e. quality objectives) alone. Increasing attention has been paid to the development of tools for different physico-chemical or biological (phytoplankton, zooplankton, benthos, algae, phanerogams, fishes) elements of the ecosystems. However, few methodologies integrate all the elements into a single evaluation of a water body. The need for such integrative tools to assess ecosystem quality is very important, both from a scientific and stakeholder point of view. Politicians and managers need information from simple and pragmatic, but scientifically sound methodologies, in order to show to society the evolution of a zone (estuary, coastal area, etc.), taking into account human pressures or recovery processes. These approaches include: (i) multidisciplinarity, inherent in the teams involved in their implementation; (ii) integration of biotic and abiotic factors; (iii) accurate and validated methods in determining ecological integrity; and (iv) adequate indicators to follow the evolution of the monitored ecosystems. While some countries increasingly use the establishment of marine parks to conserve marine biodiversity and ecological integrity, there is awareness (e.g. in Australia) that conservation and management of marine ecosystems cannot be restricted to Marine Protected Areas but must include areas outside such reserves. This contribution reviews the current situation of integrative ecological assessment worldwide, by presenting several examples from each of the continents: Africa, Asia, Australia, Europe and North America.     

Integrative taxonomic description of Plakina kanaky,a new polychromatic sponge species from New Caledonia (Porifera: Homoscleromorpha)

Four similar sponges of different colors, all unknown to science, were collected in submarine caves of New Caledonia. We aimed at determining whether the four chromotypes represented different species or phenotypic variations of a unique new species. We used an integrative taxonomic approach combining morphologic, molecular and metabolomic analyses. The main traits that define these specimens are a skeleton made of monolophose, trilophose and tetralophose calthrops only, high chemical diversity and a high abundance and diversity of prokaryotic symbionts. The symbiotic community includes two unique prokaryote morphotypes, which are described for the first time in Homoscleromorpha, and appeared to be vertically transmitted. Although several features slightly differ among chromotypes, the most parsimonious conclusion was to propose a single new species Plakina kanaky sp. nov. Our phylogenetic analysis indicated the paraphyly of the Plakina genus, with P. kanaky sp. nov. belonging to a clade that includes Plakina jani and Plakina trilopha. The present work demonstrates that integrative taxonomy should be used in order to revise the entire Plakinidae family and especially the non‐monophyletic genus Plakina.     

贝叶斯统计方法在海浪方向谱研究中的应用

较详细介绍了贝叶斯统计方法在海浪方向谱估计中的应用,指出先验分布的不同对估计结果没有影响,由于均匀分布与最大熵原则相对应,使其具有某种特殊性.数值模拟表明贝叶斯方法对双峰方向分布估计的有效性,将其应用于黑海实测资料,证明双峰方向分布的出现依赖于估计方法分辨力的大小,而用最大似然法得到的双峰方向分布值得怀疑.最后给出出现双峰方向分布的一种可能物理解释.     

基于GPS的高速公路车速全程监控方法研究

对高速公路车速进行有效监控与管理,是抑制违章超速行驶、减少高速公路交通事故的重要手段。现有的基于点速度和区间平均速度的高速公路车速监控方法,难以准确反应出车辆的实际行驶状态,实施效果有限,可靠性较差。文中提出基于GPS和地图匹配技术的高速公路车速全程监控和管理方法,建立相关算法的数学模型。经过理论分析和实例验证,车速监控与管理方法能实现高速公路车速的全程监控,极大地提高车速安全监控和管理的可靠性、准确性和有效性。     

Impact of two types of La Nia on boreal autumn rainfall around Southeast Asia and Australia

本文分析了东太平洋型和中太平洋型La Nia事件对东南亚及澳大利亚秋季降水的不同影响。合成分析结果表明东太平洋型La Nia事件对该地区降水影响较弱,而中太平洋型La Nia事件易于导致东南亚及澳大利亚东北部降水偏多。这种影响差异主要由于两类La Nia事件的冷海温位置和强度差异造成的。中太平洋型La Nia事件的冷海温偏西偏强,导致中西太平洋的西风异常以及印度洋的东风异常强度较强,并进一步引起海洋大陆区域的低层辐合增强,因此造成了显著的正降水异常。相反,东太平洋型La Nia事件的冷海温异常偏东偏弱,低层风场偏弱,相应地,低层辐合也偏弱,因此未能造成显著的降水异常发生。