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591.
乌江东风水电站拦河大坝采用薄拱坝,泄洪洞采用斜鼻坎新型消能工,并伴有高速水流,故需通过原型观测来检验设计成果。通过对流态、时均压力及脉动压力等的原型观测成果分析,为电站安全运行提供可靠依据,并为今后同等规模的类似工程提供有价值的参考。 相似文献
592.
倒垂线是大坝位移监测的主要设施之一,常与引张线和正垂装置配合使用,具有较高的监测精度。石泉水电站于1998年开始实施大坝监测系统自动化改造工程。大坝规划设置5条坝顶倒垂线。倒垂孔施工过程中,对钻孔及纠偏,孔斜检测,保护管安装及埋设,锚块、垂线安装及埋设,浮体组安装等,均采取了严格的技术措施;对坝左倒垂孔孔斜偏差超标提出了有效的解决办法,实施效果良好,保证了倒垂孔的安装精度。 相似文献
593.
594.
《Journal of Great Lakes research》2023,49(1):112-121
Lake of the Woods spans two geological regions: the Precambrian Shield and the Glacial Lake Agassiz Lakebed. The lake watershed’s complex topography influences wind speeds and directions. We study wind variability over Lake of the Woods using reanalysis data and wind observations at seven sites. A wind variability index is proposed as a measure of lake-wide spread in wind direction. Our results show that the directional variability depends on wind speeds, with higher variability at lower speeds. The wind variability also changes throughout the year; it is more pronounced in spring (Apr-Jun) and fall (Sep-Oct) and less pronounced during winter (Dec-Jan). Observed wind directions are 60% more variable than reanalysis wind, indicating a need for higher-resolution reanalysis to resolve local wind effects due to topographic changes. Based on the statistical hierarchical clustering method, our analysis shows that geographically variable wind can be grouped into three regions to represent the predominant wind directions accurately. Clustering results also suggest spatial coverage gaps in the existing meteorological observation network. We reassess the existing network and propose a new meteorological observation site in the southeast basin near Morson, Ontario. Our study is of significance for water quality management because the wind is the key driver of water circulation, transport, and mixing in the lake, and accurate wind measurements are necessary to better constrain the underpinning physical, biological, and biochemical processes in mechanistic ecological models. 相似文献
595.
《Journal of Great Lakes research》2023,49(2):357-367
The Aerosol Robotic Network - Ocean Color (AERONET-OC) instrument located at the Pålgrunden site in Lake Vänern provides values of remote sensing spectral reflectance RRS(λ) since 2008. These in situ RRS(λ) indicated a temporal increase from 2015 at center-wavelengths in the green and red spectral regions. To investigate the environmental and climate processes responsible for this increase, water color trends in Lake Vänern were analyzed considering in situ limnological measurements, meteo-climatic quantities and additionally satellite-derived data products from the Moderate Resolution Imaging Spectroradiometer on board the Aqua platform (MODIS-A). Satellite ocean color RRS(λ) data assessed against in situ RRS(λ) from the Pålgrunden site showed satisfactory agreement at a number of spectral bands. Relying on these validation results, comprehensive statistical analysis were performed using MODIS-A RRS(λ). These indicated periodical changes between 2002 and 2021 with clear minima occurring between 2010 and 2013. The complementary analyses of temporal changes characterizing limological and meteo-climatic quantities, and also relationships between these quantities and RRS(λ), indicated the existence of complex and concurrent bio-geochemical processes influencing water color in Lake Vänern. In particular, significant correlations were observed between RRS(λ) and turbidity, and also between RRS(λ) and total biovolume. Additionally, an early warming of Lake Vänern surface waters was identified since spring 2014. This occurrence could potentially affect the vertical mixing and water exchange between turbid coastal and pelagic waters with implications for phytoplankton phenology. 相似文献