Distribution of Botia superciliaris (Günther, 1892) ichthyoplankton in the upper mainstem of the Yangtze River preimpoundment and postimpoundment of the upstream dam cascade

Dam cascades have been a major threat to fishes of the upper Yangtze River. The remaining lotic river segment of the upper mainstem between the Xiangjiaba Dam (XJD) and the Three Gorges Reservoir (TGR) may serve as a critical refuge for endemic fishes. We investigated distribution of ichthyoplankton Botia superciliaris, an endemic species, at three sections preimpoundment and postimpoundment of the XJD, that is, Yibin (close to the XJD), Zhuyang (in the middle of the segment), and Mudong (in the tail of the TGR). Preimpoundment of the XJD, larvae occurred in all three sections, and their abundance tended to be highest at Yibin and lowest at Mudong. Postimpoundment, larval abundance dramatically decreased in all three sections. In particular, no larvae were found at Yibin, and larval abundance tended to be higher at Zhuyang than at Mudong. Eggs were collected from all three sections, and those from Zhuyang accounted for over 90% of the total. Initiation of egg occurrence at Yibin was approximately 1 month later than at Zhuyang and Mudong. Water temperature was lower, and water transparency was higher at Yibin than at Zhuyang and Mudong postimpoundment. We suggest that the decrease in abundance and delayed presence of ichthyoplankton at Yibin postimpoundment of the XJD reflected the impact of upstream dam discharge and that the lower abundance of ichthyoplankton at Mudong compared with Zhuyang both preimpoundment and postimpoundment of the XJD reflected the influence of inundation by the TGR. We recommend that the river sections around Zhuyang become high‐priority conservation areas     

熵值密切值法在陆浑水库营养状况评估中的应用

为了掌握陆浑水库的富营养化情况,采用熵值密切值法结合湖库富营养化评估标准,对其2009-2015年的营养状况进行评估。结果表明:该水库为轻度富营养化,主要表现为总氮超标;将该方法与线性插值评分法相比较,两者存在差异,线性插值法的主观性较大且没有考虑各指标对评估结果的影响,而熵值密切值法能够减少主观性,还能确定影响水质的主要因素,使富营养化状况的评估结果更符合实际。因此,熵值密切值法可以作为评估水体水质的常用方法。     

Research Progress on the Application of Google Earth Engine in Geoscience and Environmental Sciences

With the rapid development and large integration of global informatization and industrialization since the 21st century,the Internet of things and cloud\|computing have emerged.The world has entered an era of big data.There are a huge amount geographical and remote sensing data generated every day in the field of geoscience,environmental science and related disciplines.However,the traditional approaches for storing,managing and analyzing massive data on the local platform,which take up lots of resources,time and energy,have been unable to meet the needs of the current researches.Google Earth Engine(GEE) cloud platform is powered by Google’s cloud infrastructure,and it combines a large number of geospatial datasets and satellite imagery,in which the datasets could be processing,analyzing as well as visualizing on a global scale.Meanwhile,it uses Google’s powerful computational capabilities to analyze and process a variety of environmental and social issues including climate change,vegetation degradation,food security and water resource shortages.Firstly,an introduction of GEE cloud platform has been given.Secondly,recent researches that using GEE cloud platform were reviewed.Thirdly,GEE cloud platform and MODIS land cover type data were used to analyze spatio\|temporal changes patterns of major land use and land cover type in Three Gorges Reservoir in the period of 2002~2013.The results indicate the largest changes occurring in forest lands,shrub grasslands and croplands.Finally,after a rough calculation,GEE cloud platform is superior to the traditional approaches in terms of both cost and economic efficiency,improving the overall efficiency by more than 90%.GEE cloud platform could not only provide powerful support to experts in the field of geosciences and remote sensing,but also offer valuable help to researchers in related disciplines.GEE cloud platform is an excellent tool for scientific research in geosciences,environment sciences and related disciplines.     

兼顾四大家鱼产卵需求的梯级水电站生态调度北大核心CSCD

为实现流域梯级水电站水资源高效利用,以金沙江下游溪洛渡-向家坝梯级水库生态调度为例,通过已有研究成果以及实测数据推求四大家鱼产卵所需的适宜生态流量,构建梯级水库长短期耦合双层优化模型,上层模型采用非支配排序遗传算法(NSGA-Ⅱ)求解,下层模型采用遗传算法求解,进而提出兼顾四大家鱼产卵流量需求的梯级水库日调度方案。结果表明:与常规调度相比,当以促进四大家鱼产卵为主要目标时,调度期内(5—6月)梯级水库发电量减小1.91亿kW·h,减幅为1.76%;同时生态流量契合度增大0.123,有效洪水上涨作用期累计可达12 d,可较好地促进四大家鱼产卵。研究成果可为制定面向下游河道四大家鱼产卵的梯级水库生态调度方案提供参考依据。     

雨强和土地利用对豫西南山区氮磷流失的影响

为了掌握雨强和土地利用方式对丹江口水库水源区养分流失的影响,通过室内人工模拟降雨试验,对从豫西南山区采集的5种常见土地利用类型的表层土壤,开展了6种雨强下TN(总氮)、TP(总磷)的流失规律研究。结果表明:1地表产流中,雨强对TN的平均含量影响显著,雨强大于1.0 mm/min时才会对TP的含量产生影响;不同用地产生的泥沙中,雨强大于等于3.0 mm/min时才会对TN、TP的含量产生显著影响。2土地类型对TN、TP的流失量也有极大的影响,乔木林、灌草地因其具有较坡耕地、梯田与荒草地更好的土壤结构,TN、TP的流失量相对较少,但前两者之间与后三者之间的差异不大。3对径流中TN、TP的含量与雨强作回归分析,除乔木林地和灌草地略有不同外,其他各用地类均为对数拟合的效果最差,多项式拟合的决定系数较高;不同用地产沙中TN、TP含量与雨强的关系,均以多项式拟合的效果为最好。     

多河流顶托情况下水库下游水位计算方法探讨

因受下游岷江、横江涨水顶托的影响,向家坝水库出库流量与下游水位的关系较为复杂,对水文计算结果和水库调度决策产生了直接影响。以2014年7月~2015年9月向家坝水库下游水位、出库流量、横江水文站和高场水文站流量为研究数据,利用顶托法和BP神经网络模型对横江、岷江的顶托影响进行了分析。结果表明,BP神经网络法检验期最大误差0.32 m,平均误差0.11 m;顶托法最大误差0.74 m,平均误差0.40 m;顶托量大于1m时,BP神经网络法平均误差0.09 m,顶托法平均误差0.42 m。BP神经网络模型计算精度较高,尤其是在顶托量较大时计算结果较好,可用于生产实际。     

三峡库区巴东李家湾滑坡变形破坏机理研究

以三峡库区李家湾滑坡为例,对库水位变动影响下的滑坡变形机理进行了探讨。通过现场详细调查、原位声波测试和室内岩体单轴抗压和耐崩解试验分析,认为滑坡岩性组合特征、节理裂隙发育状况为其变形破坏提供了运动空间,库水位波动、水流流动为滑坡内部岩体运动提供了动力条件。由于软弱夹层的存在,在自身重力作用下,斜坡内部岩体发生剪切滑移,坡面发生拉裂。在库水位周期性波动影响下,前缘坡脚岩体受到江水侵蚀,泥灰岩软弱夹层向内发生凹陷,岩体发生弯折倾倒破坏;在江水的侧向淘蚀作用下,岩体发生滑移、错动、坍塌破坏。     

特大型水电站GIS雷电冲击试验分析

以三峡水利枢纽地下水电站开关站(GIS)设备的雷电冲击电压试验为例,对试验原理、设备和试验程序进行了详细描述。在试验过程中出现了放电现象,同时发现大电容量的试品在进行雷电冲击电压试验的波形选择和在GIS设备的安装施工中也出现了一些问题。为此,针对上述出现放电现象的原因及其他一些问题进行了分析研究,研究结果可以为大型气体绝缘开关站的雷电冲击电压试验提供借鉴与指导。     

三峡库区典型流域塘库服务功能类型及空间分布

塘库作为一种典型的人工湿地生态系统,在三峡库区分布广泛。塘库的空间分布对塘库在农业生产、居民生活以及流域生态水文过程等生态服务功能方面均有重要影响。以位于三峡库区中部的陈家沟小流域为研究区,从自然因素、社会因素、生产因素等方面建立相应指标体系,采用空间分析方法定量确定塘库分布及其服务功能类型的关联。结果表明,塘库的分布是海拔、坡度、耕地以及居民点分布等自然因素、生产因素和社会因素共同影响的结果,塘库集中分布于海拔350~550 m,坡度5°~25°以及距离农村居民点20~80 m的流域中下部区域,但其服务功能类型在空间分布上差异不显著。流域内多塘系统对流域水文调节与面源污染治理具有重要意义,塘库服务功能类型的变化则反映了农村地区经济结构与生计策略的转变。     

EH4在乐滩水库引水灌区岩溶勘察中的应用研究

介绍了EH4电导率成像系统在探测地下异常体的工作原理和测试方法。先对碳酸盐岩区的已知地质异常体进行EH4探测试验,总结其剖面布置、异常扩展效应和点距选取的规律,确定工作参数,并将试验取得的经验和参数应用到后续在该区开展的乐滩水库引水灌区工程TBM施工隧洞六浪出口段岩溶特征探测工作,并分析其应用效果。