人工沟渠对流域水文格局的影响研究

人工沟渠是指以排水和灌溉为主要目的的人工挖掘的水道。目前,国内外对人工沟渠的研究主要集中在控制沟渠对农田或斜坡影响的水文过程上,而有关人工沟渠对流域水文格局影响的研究比较少,并且缺乏人工沟渠景观及其所携带污染物管理的研究。在流域的尺度上,从人工沟渠对流域径流、污染物传输和水文连通性的影响三方面,详细阐述了人工沟渠对流域水文格局的影响;并对目前人工沟渠对流域水文格局影响研究中存在的问题进行了讨论,同时指出了需要进一步开展的相关研究工作。     

Application of the geographical information systems approach to watershed mass balance studies

This study was undertaken to test the utility of a geographical information systems (GIS) approach to problems of watershed mass balance. This approach proved most useful in exploring the effects that watershed scale, lithology and land use have on chemical weathering rates, and in assessing whether mass balance calculations could be applied to large multilithological watersheds. Water quality data from 52 stations were retrieved from STORET and a complete GIS database consisting of the watershed divide, lithology and land use was compiled for each station. Water quality data were also obtained from 7 experimental watersheds to develop a methodology to estimate annual fluxes from incomplete data sets. The methodology consists of preparing a composite of daily flux data, calculating a best fit sinusoid and integrating the equation to obtain an annual flux. Comparison with annual fluxes calculated from high resolution data sets suggests that this method predicts fluxes within about 10% of the true annual flux. Annual magnesium fluxes (moles km⁻² yr⁻¹) were calculated for all stations and adjusted for fluxes from atmospheric deposition. Magnesium flux was found to be a strong function of the amount of carbonate in the watershed, and silica fluxes were found to increase with the fraction of sandstone present in the watershed. All fluxes were strongly influenced by mining practices, with magnesium fluxes from affected watersheds being 6–10 times higher than fluxes from comparable pristine watersheds. Mining practices enhance chemical weathering by increasing the surface area of unweathered rock to which water has access and by increasing acidity and rate of mineral weathering. Fluxes were also found to increase with watershed size. This scale dependence is most likely caused by the sensitivity of weathering fluxes to even minor quantities of carbonates, which are likely to be found in all lithologies at larger scales. Mass balances were carried out in watersheds where gauged sub-watersheds made up more than 95% of the area. The calculations show large magnesium flux and water balance discrepancies. These errors may be a result of significant groundwater inputs to streams between gauges. The results suggest that improvements in how we measure discharge and estimate fluxes may be required before we can apply mass balance techniques to larger scales. © 1997 John Wiley & Sons, Ltd.     

Capabilities and limitations of detailed hillslope hydrological modelling

Hillslope hydrological modelling is considered to be of great importance for the understanding and quantification of hydrological processes in hilly or mountainous landscapes. In recent years a few comprehensive hydrological models have been developed at the hillslope scale which have resulted in an advanced representation of hillslope hydrological processes (including their interactions), and in some operational applications, such as in runoff and erosion studies at the field scale or lateral flow simulation in environmental and geotechnical engineering. An overview of the objectives of hillslope hydrological modelling is given, followed by a brief introduction of an exemplary comprehensive hillslope model, which stimulates a series of hydrological processes such as interception, evapotranspiration, infiltration into the soil matrix and into macropores, lateral and vertical subsurface soil water flow both in the matrix and preferential flow paths, surface runoff and channel discharge. Several examples of this model are presented and discussed in order to determine the model's capabilities and limitations. Finally, conclusions about the limitations of detailed hillslope modelling are drawn and an outlook on the future prospects of hydrological models on the hillslope scale is given.The model presented performed reasonable calculations of Hortonian surface runoff and subsequent erosion processes, given detailed information of initial soil water content and soil hydraulic conditions. The vertical and lateral soil moisture dynamics were also represented quite well. However, the given examples of model applications show that quite detailed climatic and soil data are required to obtain satisfactory results. The limitations of detailed hillslope hydrological modelling arise from different points: difficulties in the representations of certain processes (e.g. surface crusting, unsaturated–saturated soil moisture flow, macropore flow), problems of small‐scale variability, a general scarcity of detailed soil data, incomplete process parametrization and problems with the interdependent linkage of several hillslopes and channel–hillslope interactions. Copyright © 1999 John Wiley & Sons, Ltd.     

Calibration of local magnitude scale for Hindukush continental subduction zone

Hindukush is an active subduction zone where at least one earthquake occurs on daily basis. For seismic hazard studies, it is important to develop a local magnitude scale using the data of local seismic network. We have computed local magnitude scale for Hindukush earthquakes using data from local network belonging to Center for Earthquake Studies (CES) for a period of three years, i.e. 2015–2017. A total of 26,365 seismic records pertaining to 2,683 earthquakes with magnitude 2.0 and greater, was used with hypocentral distance less than 600 km. Magnitude scale developed by using this data comes to be M_L = logA + 0.929logr + 0.00298r – 1.84. The magnitude determined through formulated relation was compared with that of standard relation for Southern California and relation developed by the same authors for local network for Northern Punjab. It was observed that Hindukush region has high attenuation as compared to that of Southern California and Northern Punjab which implies that Hindukush is tectonically more disturbed as compared to the said regions, hence, seismically more active as well. We have calculated station correction factors for our network. Station correction factors do not show any pattern which probably owes to the geological and tectonic complexity of this structure. Standard deviation and variance of magnitude residuals for CES network determined using Hutton and Boore scale and scale developed in this study were compared, it showed that a variance reduction of 44.1% was achieved. Average of magnitude residuals for different distance ranges was almost zero which showed that our magnitude scale was stable for all distances up to 600 km. Newly developed magnitude scale will help in homogenization of earthquake catalog. It has been observed that b-value of CES catalog decreases when magnitude is calculated by using newly developed magnitude scale.     

军曹鱼生物学特性及苗种规模化繁育技术

简要介绍了军曹鱼(Rachycentron canadum)的形态、分布、食性、生殖、胚胎和仔稚鱼发育过程等生物学特性以及军曹鱼苗种繁育的技术工艺。选择2~3龄鱼作为亲鱼,在海区网箱中采用营养强化结合激素诱导的方法,使其在整个繁殖季节多次成熟产卵。在大亚湾地区其繁殖季节为4~10月,亲鱼繁殖的适宜水温为25~31℃、适宜盐度为30~34,大批量人工催产的受精率为30%~60%、孵化率为55%~82%。采用室外池塘进行种苗大规模培育,初孵仔鱼在水温26~32℃、盐度28~33条件下培育35~40 d,全长8~11 cm,达到商品苗规格。     

Revealing ecosystem services relationships and their driving factors for five basins of Beijing

A clear understanding of the relationships among multiple ecosystem services(ESs) is the foundation for sustainable urban ecosystem management. Quantitatively identifying the factors that influence ES trade-offs and synergies can contribute to deepening ES research, from knowledge building to decision making. This study simulated soil conservation, water yield and carbon sequestration in Beijing, China, from 2015–2018. The spatial trade-offs and synergies of these three ESs within the five major river basins in Beijing were explored using geographically weighted regression. Furthermore, geographical detector was applied to quantitatively identify the driving mechanism of the environmental factors for the ES trade-offs and synergies. The results show the following:(1) the spatial relationships between soil conservation and water yield, as well as between water yield and carbon sequestration, were mainly trade-offs. There was a spatial synergy between soil conservation and carbon sequestration.(2) Regarding the spatial trade-off/synergy between soil conservation and water yield in Beijing, the dominant influencing factor was temperature/elevation, and the dominant interactions of the spatial trade-off and synergy between these two ESs in Beijing and the Chaobai River Basin are all manifested in the superposition of precipitation and potential evapotranspiration, temperature, and elevation.(3) Topographic factors were the dominant factors influencing the spatial relationship between soil conservation and carbon sequestration in Beijing and its five major river basins. As a result of the distribution of water systems and hydrological characteristics of the basins, differences were observed in the effects of different combinations of interaction factors on the spatial relationship between these two ESs in different basins.(4) Temperature had the strongest explanatory power in terms of the spatial trade-offs and synergies between water yield and carbon sequestration. The interactions between precipitation and temperature and between precipitation and elevation were the dominant interactions affecting the spatial relationship between water yield and carbon sequestration in Beijing. Overall, the explanatory power of influencing factors on the trade-offs and synergies and the degree of interaction between factors coexist in different basins with consistency and differences. Therefore, understanding the quantitative characteristics of basin-scale spatial trade-offs and synergies between ESs is important for ecosystem management and the promotion of synergy in different basins.     

数字水准仪测量系统尺度改正数检定方法的研究

论述了数字水准仪的基本特点,基于这些特点将数字水准仪主机、条码尺和数据处理软件作为一个整体进行系统检定是一种恰当的方法。文中给出了系统检定的原理、测点数及位移量的确定方法。最后用模拟数据进行了计算,模拟计算结果表明:正确的位移量是求解尺度改正数的前提。     

大比例尺高精度磁测在卡休他他铁(金、钴)矿生产中的应用

卡休他他铁矿床是20世纪70年代由甘肃省地质六队在内蒙古阿拉善右旗发现的一处中型磁铁矿床,并伴生有钴和金.该矿床由南北2个矿带组成,已由内蒙古庆华集团开采多年.目前正面临资源短缺的局面,为扩大矿山潜在资源,在矿区开展了大比例尺高精度磁测,突出异常细节,可弥补矿床勘探阶段工作比例尺偏小之不足,对提高矿山生产效益,扩大潜在资源量意义重大.文章着重介绍了野外观测技术和室内数据处理方法(磁异常化极、化极向下延拓和交互式二维剖面反演),探讨了地质解释成果在矿山生产中的应用效果.     

国际地球化学填图新进展

欧洲和中国在国际地球化学填图中起着积极而重要的作用,而且进展也是最显著的。欧洲地球化学基准值填图计划于1996年被欧洲26个国家地质调查局长论坛(FOREGS)正式批准。经过近10年的工作,于2005年出版了电子版欧洲地球化学图集。中国不仅自己开展了多层次地球化学填图计划,而且还与发展中国家合作开展了全球尺度和成矿带尺度地球化学填图合作。欧洲和中国无论是在全球尺度,还是在区域尺度地球化学填图做法上都存在较大的差异。在采样介质上中国使用统一的采样介质,在分析技术上中国使用几种大型设备作为骨干配合使用多方法分析系统;欧洲恰恰相反,欧洲在采样介质上趋向于多介质,而分析技术上只使用少数几种大型设备。欧洲的做法尽管使用多介质采样获得了元素在更多天然介质中的分布信息,但使用单一分析技术,使得很多关键元素没有分析出来,如贵金属元素Ag,Au,Ir,Os,Pd,Pt,Rh,Ru;卤族元素F,Cl,Br,I;分散元素Ge,In,Se,Te;与生命密切相关的元素N,S,B等。尽管欧洲强调以环境为目的,但很多与环境密切相关的元素都没有分析,所以欧洲的全球尺度地球化学填图的信息量大打折扣。这些不统一的做法,特别是在全球尺度地球化学填图不统一的做法,会影响到以后全球地球化学图的编制。     

一个新的生态旅游者分类指标的有效性分析——以北京市百花山自然保护区为例

借鉴NEP尺度的指标构造思路以及国外相关研究进展,结合在北京市百花山自然保护区生态旅游者研究的相关数据,提出从生态旅游者与一般游客两方面的典型动机特征入手,构建一个新的生态旅游者分类指标生态旅游兴趣尺度EI,以综合评定游客对生态旅游的感兴趣程度。使用指标替代和增补的方法对EI尺度的有效性进行检验,结果表明EI尺度确实可提高生态旅游者判别的准确率,EI与NEP和VIS一起构成了识别生态旅游者的最重要的三个指标。同时,Logistic回归分析也表明,EI尺度目前在三个特征向量中对于分类的作用还较弱,这与中国处于生态旅游发展的早期阶段,生态旅游者与一般游客在动机特征方面的分异不大有关。