Simulation and comparative study of two types of Topographic Index model for a homogeneous mountain catchment     

ShuFen Sun  HuiPing Deng  Qian Wang 《中国科学:地球科学(英文版)》2014,57(9):2089-2099

In order to expand the application range of the classic Topographic Index model (TOPMODEL) and develop a more appropriate submodel of hydrological processes for use in the land surface model, two types of TOPMODEL are investigated, one with saturated hydraulic conductivity change with depth obeying exponential law (classical e-TOPMODEL or e-TOPMODEL for short) and the other obeying general power law (general p-TOPMODEL or p-TOPMODEL for short). Using observation date in the Suomo River catchment located in the upper reaches of the Yangtze River, the sensitivity study of the p-TOPMODEL was conducted and the simulated results from the model were examined and evaluated first, and then the results were compared with the results from the e-TOPMODEL to find the similarities and differences between the two types of models. The main conclusions obtained from the above studies are (1) topographic index and its distribution derived from the p-TOPPMODEL for the Suomo Basin are sensitive to changes of parameter n and m; (2) changes of n and m have impacts on the simulation results of various hydrological components (such as daily runoff, monthly averaged runoff, monthly averaged surface runoff and subsurface runoff), but have the weaker impacts on forty-year averaged total runoff; and (3) for the same value of m, the simulated results of e-TOPMODEL display higher surface runoff and lower subsurface runoff than the general p-TOPMODEL does but multi-year averaged total runoffs produced from the two types of TOPMODEL show insignificant difference. The differences between the two types of models indicate that it is necessary to pay close attention to correct selection from different hydrological models for use in land surface model development. The result mentioned above is useful to provide some referential information for the model selection.  相似文献   

JCZ-1型地震仪观测的地球环型自由振荡     

吴海波  胡洪  张念 《地震》2012,32(3):15-27

本文首次采用JCZ-1型地震仪观测资料研究地球环型自由振荡, 并在2011年日本9.0级地震、 2010年智利8.8级地震和2005年印尼8.6级地震后武汉地震台JCZ-1型地震仪观测到了其激发的环型自由振荡, 从中检测了基振型₀T₂~₀T₆₇和一次振型 ₁T₂~₁T₅₀等振型的本征周期, 与PREM的理论值比较, 误差比小于0.5%, 补充了PREM中未提到的几次振型的本征周期: ₀T₁₁、 ₀T₁₅、 ₀T₁₉、 ₁T₄、 ₁T₅、 ₁T₁₄, 并观测到了日本地震 ₀T₂、 ₀T₆、 ₀T₇和 ₀T₈振型的多峰值现象。 研究结果表明, JCZ-1型地震仪具有良好的观测超低频长周期地球自由振荡的能力。  相似文献   

Gender and power contestations over water use in irrigation schemes: Lessons from the lake Chilwa basin     

《Physics and Chemistry of the Earth》2016

Over the past two decades, Malawi has been adversely hit by climatic variability and changes, and irrigation schemes which rely mostly on water from rivers have been negatively affected. In the face of dwindling quantities of water, distribution and sharing of water for irrigation has been a source of contestations and conflicts. Women who constitute a significant section of irrigation farmers in schemes have been major culprits. The study seeks to analyze gender contestations and conflicts over the use of water in the schemes developed in the Lake Chilwa basin, in southern Malawi. Using oral and written sources as well as drawing evidence from participatory and field observations conducted at Likangala and Domasi irrigation schemes, the largest schemes in the basin, the study observes that women are not passive victims of male domination over the use of dwindling waters for irrigation farming. They have often used existing political and traditional structures developed in the management of water in the schemes to competitively gain monopoly over water. They have sometimes expressed their agency by engaging in irrigation activities that fall beyond the control of formal rules and regulations of irrigation agriculture. Other than being losers, women are winning the battle for water and land resources in the basin.  相似文献   

Marine spatial planning in Scotland. Levelling the playing field?     

《Marine Policy》2017

Marine spatial planning (MSP) is the leading tool for managing human activities at sea. It is designed to assist in decision making for marine resource access and use by considering the actions of those using the resources, interactions between these groups, and their cumulative impact on the natural environment. Being informed by ecosystem based management, MSP recognises that socio-natural systems are complex and that stakeholder and public input are key components of well-informed decision making. Therefore, MSP is rooted in the principles of good governance, including those of participation and transparency. This paper considers MSP processes in Scotland's inshore waters in the context of these good governance principles. The focus is on the institutional arrangements that allow stakeholders and the public to contribute to planning Scotland's seas and coasts. Whilst acknowledging the significant challenges faced by planners, and the work conducted so far, this research suggests that improvements could be made in how – and when – engagement takes place. It appears that at an early stage of introducing MSP in Scotland powerful stakeholders shaped the images, values and principles that guide it, and that including a broader range of actors early on might positively affect the legitimacy and acceptance of MSP in its later stages. The current institutional arrangements do not appear to allow for this. Ultimately, MSP in Scotland is in danger of institutionalising – and thus legitimising – existing power relations between marine resource users, and it does little to level the playing field.  相似文献   

Flood variability east of Australia’s Great Dividing Range     

Paul Rustomji  Neil Bennett  Francis Chiew 《Journal of Hydrology》2009,374(3-4):196-208

The variability of flow in river channels influences the spatial and temporal variability of many biophysical processes including the transport of sediment and waterborne pollutants and the recruitment of aquatic animals and plants. In this study, inter- and intra-basin patterns of flood variability are examined for catchments east of Australia’s Great Dividing Range. Three measures of flood variability are explored with uncertainty quantified using bootstrap resampling. The two preferred measures of flood variability (namely a flood quantile ratio and a power law scaling coefficient) produced similar results. Catchments in the wet tropics of far north Queensland experience low flood variability. Flood variability increased southwards through Queensland, reaching a maximum in the vicinity of the Fitzroy and Burnett River basins. The small near-coast catchments of southern Queensland and northern New Wales experience low flood variability. Flood variability is also high in the southern Hunter River and Hawkesbury–Nepean basins. Using L-moment ratio diagrams with data from 424 streamflow stations, we also conclude that the Generalised Pareto distribution is preferable for modelling flood frequency curves for this region. These results provide a regional perspective that can be used to develop new hypotheses about the effects of hydrologic variability on the biophysical characteristics of these Australian rivers.  相似文献   

汶川8.0级地震前后电磁场的变化特征   总被引：3，自引：2，他引：1       下载免费PDF全文

高曙德  汤吉  杜学彬  刘小凤  苏永刚  陈彦平  狄国荣  梅东林  詹艳  王立凤 《地球物理学报》2010,53(3):512-525

2008年5月12日汶川M_s8.0地震前后,距震中320 km甘肃陇南汉王地震台的地电阻率、大地电场、ELF电磁等多种观测手段捕捉到这次地震前后的异常信息.本文采用解析方法,着重探讨汶川8.0级地震前后观测到的电磁场变化特征,从电磁现象来探讨汶川M_s8.0地震发生前后,电磁场长、中、短、临期的异常特征和变化规律.自2003年以来甘东南地区及甘川交界发生4次5.0级以上地震,从空间上看,有从南北地震带中段的西北向西南方向移动的特点,强度逐渐增强,其中,文县5.0和两次岷县5.0级以上地震可以视为汶川8.0级地震的前震;从时间上分析,震前陇南汉王地震台观测到电磁场出现了长趋势变化和短临异常变化,其特征：①2003～2008年,ZD8B地电仪观测的N54°W、N85°E和N73°W测道地电阻率均显示出长趋势变化和短期变化;②视电阻率各向异性度‘S′’年变化率在有震年（异常年）是无震年（正常年）的两倍;③ELF电磁仪观测到了（0.5～39 Hz）频率段的电场、磁场在汶川8.0级地震及余震序列中异常变化分别比正常月份大1～5个数量级,并记录到电磁同震现象;④大地电场仪（ZD9A-Ⅱ）在汶川震前17个小时也记录到高频临震变化信息.  相似文献   

Fish mortality by impingement on the cooling-water intake screens of Britain's largest direct-cooled power station     

Greenwood MF 《Marine pollution bulletin》2008,56(4):723-739

An estimated 5.66 x 10(7) fish (summed quarterly 95% confidence intervals: 3.01 x 10(7)-1.07 x 10(8)) weighing 258.4 t (143.2-467.9 t) were killed on the cooling-water intake screens of the 2400 MW Longannet Power Station (Forth estuary) in January 1999--December 2000. Abundance and number of species (40) collected were close to predictions for a power station of this size and latitude. Potential losses of equivalent adult whiting (Merlangius merlangus), cod (Gadus morhua), and plaice (Pleuronectes platessa) through deaths of juveniles were estimated at 353.1 t (208.0-603.2 t) worth approximately euro 429,266 (euro 246,592-752,765) in 1999--2000. Fish catch-per-trawl in the estuary was generally not noticeably greater during a year of low water withdrawal (coal miners' strike of 1984--1985) when compared to other years from 1982 to 2001, except for gobies (Pomatoschistus spp.). A fish-return system is being tested at Longannet to reduce mortality.  相似文献   

考虑失效相关的电力系统抗震可靠性研究   总被引：3，自引：0，他引：3  

张治勇  孙柏涛 《地震工程与工程振动》1999,19(1):81-86

本文根据电力系统的特点,对发电厂和供电系统分别提出了不同的系统可靠性模型,并对各单体之间失效的相关性也进行了较深入的探讨,同时编制了计算系统抗震可靠性的Ｍｏｎｔｅ Ｃａｒｌｏ法程序。  相似文献   

Earthquake shaking scenarios for the metropolitan area of Lisbon   总被引：2，自引：0，他引：2  

A. Carvalho  G. Zonno  G. Franceschina  J. Bil Serra  A. Campos Costa 《Soil Dynamics and Earthquake Engineering》2008,28(5):347-364

In this study, we simulate and compare ground motion shaking in the city of Lisbon and surrounding counties (metropolitan area of Lisbon (MAL)), using two possible earthquake models: the onshore source area of Lower Tagus Valley, M5.7 and M4.7 and the offshore source area, Marques de Pombal Fault, M7.6, one of the possible source of the 1755 Lisbon earthquake. The stochastic and a new hybrid stochastic-deterministic approach (DSM) are used in order to evaluate the ground shaking and to characterize its spatial variability. Results are presented in terms of response acceleration spectra (PSA) and peak ground acceleration (PGA) with respect to bedrock and surface. Site effects are evaluated by means of equivalent stochastic non-linear one-dimensional ground responses analysis, performed for a set of stratified soil profile units properly designed to cope with the soil site conditions of MAL region. A sensitive study is carried out using different input parameters and different approaches in order to give the basic information to evaluate the range of uncertainty in seismic scenarios.  相似文献   

The flood probability distribution tail: how heavy is it?     

Pietro Bernardara  Daniel Schertzer  Eric Sauquet  Ioulia Tchiguirinskaia  Michel Lang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(1):107-122

This paper empirically investigates the asymptotic behaviour of the flood probability distribution and more precisely the possible occurrence of heavy tail distributions, generally predicted by multiplicative cascades. Since heavy tails considerably increase the frequency of extremes, they have many practical and societal consequences. A French database of 173 daily discharge time series is analyzed. These series correspond to various climatic and hydrological conditions, drainage areas ranging from 10 to 10⁵ km², and are from 22 to 95 years long. The peaks-over-threshold method has been used with a set of semi-parametric estimators (Hill and Generalized Hill estimators), and parametric estimators (maximum likelihood and L-moments). We discuss the respective interest of the estimators and compare their respective estimates of the shape parameter of the probability distribution of the peaks. We emphasize the influence of the selected number of the highest observations that are used in the estimation procedure and in this respect the particular interest of the semi-parametric estimators. Nevertheless, the various estimators agree on the prevalence of heavy tails and we point out some links between their presence and hydrological and climatic conditions.  相似文献